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March 17

Trachelospermum jasminoides

what would happen if u consumed the leaves,flower...ect. of this plant? would the effects of ibogain be felt? or is the plant poisones? —Preceding unsigned comment added by 76.14.124.175 (talk) 00:48, 17 March 2009 (UTC)

According to this reference, "the whole plant is poisonous." - Eron^Talk 00:59, 17 March 2009 (UTC)

piperazine

beacause Piperidine and piperazine are very similar, do they have the same effects on the brain? —Preceding unsigned comment added by 76.14.124.175 (talk) 01:00, 17 March 2009 (UTC)

I'm not aware of human therapeutic uses of piperidine or piperazine. Both of those articles do list derivatives, among them antipsychotics. --Scray (talk) 02:10, 17 March 2009 (UTC)

(post e.c.) Neither article mentions psychotropic functions for either Piperidine or Piperazine, although some of their derivatives are psychoactive as Scray mentioned above. I'm not sure about the metabolites. Although they have similar functional groups and are fairly close in shape and size, that does not always translate to similar behavior biologically. Docking (molecular) describes the basic idea: small differences in shape can have major effects on the ability of a compound to bind to an enzyme's active site (or other relevant portion). Sifaka ^talk 02:33, 17 March 2009 (UTC)

Both piperidine and piperazine block nicotinic cholinergic receptors. Piperidine is more potent than piperazine. [By the way, piperazine is used to treat parasitic infections in people.] Axl ¤ [Talk] 10:47, 17 March 2009 (UTC)

Yeah, because it's substantially more toxic. To humans too. The reason why these are on drug schedules isn't because they're psychoactive or remotely close to it. It's because they're very common precursors in organic chemistry. Which would include drug synthesis. --Pykk (talk) 19:46, 17 March 2009 (UTC)

Theory of Chemical Emotions: Pointless to Pursue Happiness?

Since most of our emotions are chemical reactions in the brain, and while the events of our lives do trigger the release of those chemicals, they do not increase or decrease production (apparent from exercise, stress, eating habits, and drugs). So two genetically identical twins with similar exercise, stress, and eating habits should experience the same total amount of happiness, right? Regardless of what is happening to them? (assuming they can keep themselves from getting stressed out about the events). One of the twins might have events that trigger lots of happiness in short bursts while the other has a more constant rate of happiness, but they should both experience the same total amount.

If this is true, doesn't this completely undermine the point of perusing things that make us happy if we will inevitably experience the same amount of happiness regardless? Thus we should foremost pursue good eating habits, exercise habits and controlling our stress levels and not worry about anything else (especially since worrying lowers our Serotonin production)? Also if this were true it would redefine what services we need to provide to 3rd world countries as charity as they will find their own happiness in their poverty as long as they can be well fed and control their stress levels, correct?

Something seems really wrong about this theory but I'm not sure where the hole is. It does readily explain why people who have everything find sadness in small details (like being spoiled) and people who have nothing still find happiness in the small details, though to say that we each have an amount of happiness specifically determined by genetics, stress, eating, and drugs seems a little much. What am I missing? Thanks. Anythingapplied (talk) 01:53, 17 March 2009 (UTC)

I don't see how any of this changes the way we should treat the less fortunate (including what we call the third world). Actually the whole thing about people having "nothing" being just as happy as others is bunk. In case you've never tried it being poor is really stressful. Wealth makes people happier until they reach some place around middle to upper middle class, additional wealth after that point doesn't do anything for happiness. Since what it means to be middle class changes over time I imagine this response ties to our evolved sense of justice which is tied into the chemical system you mentioned. Anyways I'm not going to offer a well wrapped answer but I will say that Walt Disney said something to the effect that "for every smile there must be a tear" and XKCD make a good point about arboreal rodents.--OMCV (talk) 02:17, 17 March 2009 (UTC)

I'm not at all familiar with this particular topic but I have a feeling that part of the problem may lie in your premise: happiness is not the same as the level of neurotransmitters. The interactions in the brain that translate out to one's state of mind are not necessarily correlated with the simple total amount of particular neurotransmitters. I'm not a neuroscientist but my guess is that there is a good spread of natural variation in global neurotransmitter levels and that two people with rather different neurotransmitter level profiles can report similar moods while people with similar profiles can report very different moods. If it was clearcut, scientists would be reporting conclusive findings to that effect long ago (and wikipedia would have the info in the relevant articles). I think it's fair to say that scientists pretty much don't know how biochemical interactions in the brain scale up to things like mood although there are some decent theories as to what factors are relevant. Sifaka ^talk 03:19, 17 March 2009 (UTC)

While I'm far from an expert on this, I'm pretty sure your premise "do trigger the release of those chemicals, they do not increase or decrease production (apparent from exercise, stress, eating habits, and drugs)" is incorrect. When neurotransmitters are released they are eventually replaced. It's not like you can use up all of your neurotransmitters in the long term and never have them again (in the short term obviously the level may get low). In any case there is also the fact there is bound to be some natural turnover (it's all very well having the neurotransmitters but there's clearly a big difference between when they affect you and when they don't) and I'm pretty sure some studies have shown you can get an increase in the baseline level with things like exercise etc. Also I don't think it makes much sense to say "One of the twins might have events that trigger lots of happiness in short bursts while the other has a more constant rate of happiness, but they should both experience the same total amount" for starters how the heck do you quantitise hapiness like that and secondly why can't one of the twins have events that trigger lot of happiness while also having a high constant rate? Nil Einne (talk) 11:18, 17 March 2009 (UTC)

There is some research that indicates a persons "happiness" measured by a variety psychological tests is rather resistant to most environmental influences. People who are happy are happy despite what happens to them and people who are sad are sad despite what happens to them. This is also true for self-confidence and a number of other moods/personality traits. This means regardless of what people do they won't be substantially happier. So the levels of neurotransmitters might fluctuate but they keep a steady average, a baseline. Grounding this phenomenon to biological/chemical basis is only reasonable. I wouldn't know how to cite any of this.--OMCV (talk) 11:44, 17 March 2009 (UTC)

Anyway what's the point of pursuing happiness? You might as well drug yourself up as do something so pointless with your life is my feeling. Though I guess I'm fairly happy anyway so it's no great deal to me. Dmcq (talk) 12:24, 17 March 2009 (UTC)

The idea is mentioned in happiness where it says "The happiness set point is a notion proposed by Lykken and Tellegen that we all have a baseline level of happiness that we return to. Although good and bad events may shift us from this baseline temporarily, we cannot permanently increase or decrease our happiness levels in the long term. Others have since challenged this pessimistic view, some drawing on neuroplasticity as evidence that our happiness level is not set in stone." although the reference looks crap. But better [1] and [2]. From a brief skim thorough, neither appear to accept the notion that happiness is a permanent unchangable baseline so there's no point trying to increase happiness. Instead they suggest people go about it the wrong way. (The second also notes there are some events which lead to a permanent reduction in the baselione.) Indeed the fact that we know our happiness can change even if only temporary is in direct contrary to the original OPs contention and IMHO suggests it's unlikely we should think happiness is an unchangable baseline so don't bother trying to change it. The notion of a baseline means that eventually people normally adapt back to their baseline. It does not mean that the happiness they had was irrelevant. It's not like their go thorough a period of sadness to pay back for the short term happiness. Clearly someone who has no blips would have been 'less happy' (if you really want to quantitise it like that) then someone with the same baseline with several happiness blips. Even if you can never change your baseline, the fact that you have had quite a lot of blips in your life seems significant to me. Note neither of the references mention neurotransmitters at all, not surprising IMHO since our understanding of human psychology and how that relates to the way the brain works is still way too much in it's infancy to go making such bold assertations. So I still stick by most of my original post, if you really want to talk about neurotransmitters our a happiness blip may result in a temporary increase in the production of neutrotransmitters. It may not result in a permanent increase (I didn't suggest it would) but there is likely to be an increase. Over time, the level usually comes back to normal (or alternatively we adapt to a permanently higher level, do we know which?) but it's still incorrect to suggest it doesn't result in an increase in the short term. Now as for the second part while I may have been slighly inaccurate in my suggestion you can have a higher constant level (or baseline) the fact remains the twin who has many blips of happiness is likely to have had more 'happiness' then the twin who had a constant level. The twin with the blips doesn't reduce their level to compensate rather the normal level remains static with blips except the other twin doesn't have blips. Now obviously there is a risk when you have blips of happiness you're going to have blips of sadness (dating someone, ooops you broke up; going on a trip to *name location here*, ooops kidnapped and held for ransom) but that's surely a different issue. (In any case, it seems to me that any consideration of achieving happiness should not start of from the notion that you have similar "exercise, stress, and eating habits" since surely these should be a consideration in persuing happiness. Nil Einne (talk) 21:01, 17 March 2009 (UTC)

Flashbangs

How do flashbangs work? How can they make a person temporarily blind and make the ears go numb? —Preceding unsigned comment added by 116.71.46.119 (talk) 17:18, 17 March 2009 (UTC)

Did reading the flashbangs article help? DMacks (talk) 17:28, 17 March 2009 (UTC)

(After ec) The entry for Stun grenades in our hand grenade article explains how they work. In brief, they use a bright flash of light that activates all photosensitive cells in the retina combined with loud blast that disturbs fluid in the semicircular canals of the ear.- Eron^Talk 17:30, 17 March 2009 (UTC)

car farts

When I turn the steering wheel of my 2005 Ford 500 all the way in one direction, moving at a slow speed, like backing up or easing into the garage, I sometimes hear a noise that sounds like a fart. I'm thinking it might have to do with the power steering. What do you suppose might be happening? --Halcatalyst (talk) 20:14, 17 March 2009 (UTC)

I've had this before, my tire was rubbing against the wheel well. 192.45.72.26 (talk) 20:42, 17 March 2009 (UTC)

There are actually MANY possibilities:

• An tire that's about to fail due to tread-separation.
• A tire that's rubbing against the wheel liner (but WHY? is the important question - has a plastic wheel liner come loose? Is your steering badly screwed up? Did you recently change wheels or something?)
• The plastic shroud around the steering column may be catching against the steering wheel.
• At the extremes of travel, you are stressing the power steering to the max - and if you try to steer 'past the end-stop' then "very bad things" can happen to it.
• If the noise is coming from behind you then it could be a problem with the differential.

It would help to eliminate some of these if you could try to have someone push the car while you turn the steering that hard with the engine turned off and the drive in neutral. If it doesn't make the noise then that eliminates the power steering. You can usually remove the plastic shroud around the steering column with just a couple of screws and eliminate that. Knowing where the sound is coming from would be fantastically helpful...if you can get someone to stand outside the car while you slowly drive in tight circles in a parking lot or something - they can listen at each corner and perhaps identify the sound's location. SteveBaker (talk) 21:07, 17 March 2009 (UTC)

If the RefDesk doesn't give medical advice, should we also refrain from providing automotive advice and suggest that the OP seek an evaluation by a professional mechanic?  :)

Actually, it would seem to make sense given the possibility of a car accident resulting from a serious mechanical malfunction. —Preceding unsigned comment added by 64.91.177.4 (talk) 23:23, 17 March 2009 (UTC)

I suspect that the issue of medical and legal advice is likely because of legal reasons, as while an individual might be correctly certified to give such advice, there is no convenient way to determine that. Are there laws against uncertified individuals giving auto repair advice in the same manner as giving medical advice without a license? I rather doubt it. 65.167.146.130 (talk) 13:32, 18 March 2009 (UTC)

There's also the risk of real harm. That applies here. Doesn't matter if its legal or not. If there's a risk soemone could be harmed from dud advice - then we shouldn't be offering it. Mattopaedia ^{Have a yarn} 05:11, 19 March 2009 (UTC)

Then we shouldn't give advice on dieting, exercise, carpentry, or anything involving someone moving, or coming into contact with anything, as there is risk in nearly everything anyone ever does. If all else fails, I say use common sense. 65.167.146.130 (talk) 14:05, 20 March 2009 (UTC)

I promise I won't sue you guys! IMO the restriction on legal and medical advice is a matter of not having a license. Someone could check over on the Humanities desk, but I'm pretty sure. I'm completely certain I appreciate the advice you've given here. Thanks! --Halcatalyst (talk) 14:36, 20 March 2009 (UTC)

Argh! How can we discuss this so many times, and still people think we don't give medical or legal advice simply because we're afraid of legal consequences? I strongly suggest that anyone taking part in this thread who thinks we don't give this advice because of legal concerns/not having a license goes to the talk page and reads through a few posts. Ask there if you are unsure about anything. 79.66.127.79 (talk) 22:08, 20 March 2009 (UTC)

I was trying to be a tiny bit satirical in my post, not to stir up a hornet's nest... the point is exactly that this is a "reference desk" not an "advice desk". Some advice-giving is probably inevitable, but when it comes to things that are inherently dangerous (medical and legal things being paramount, but not excluding other things) we should probably refrain.

@65.167.146.130 - there are no laws against giving medical advice on a message board without a license. Anyone can give any advice or make any diagnoses or recommendations that they'd like, so long as they don't purport to be practicing medicine (i.e. engaging in a physician-patient therapeutic relationship). There are regulations against practicing medicine without a license. Most state medical boards also have regulations (or at least ethical guidelines) against licensed practitioners giving medical advice or recommending treatment to people who are not personally their patients -- which would apply to this type of answer board. But that isn't the point. The point is that we should be offering solid references that answer questions, not simply personal anecdotes, no matter how well thought out. IMHO. —Preceding unsigned comment added by 64.91.177.4 (talk) 14:12, 21 March 2009 (UTC)

Astronomy/night sky question

Hi, I have one of those awful, "I saw something, what was it?" questions. I hope someone can give me some clues though.

Tonight (while waiting for a bus) I saw 2 lights in the sky. 1 was about the brightness of bright stars (eg. the 3 of orion's belt), and another to the lower right of this one was fainter. I feel as though there may have been a faint line connecting the two, but can't be sure. Orientation shown here:

*1 bright

    *2 faint

They moved up and left together, relative to stars. As they did, first "2" faded and disapeared, then the brighter light also faded, became redder, and disapeared. The distance between the 2 lights was 1-2 thumb widths at arms length. The speed they moved was about the speed of other planes (that were also visible in the sky), but they seemed to be too far apart for this obvious explanation. Also their fading and changing colour makes me think it probably wasn't a plane.

Oh, this was in Germany (Berlin-ish), facing South to SW ish. Not very high in the sky, I only just had to tilt my head back to see it clearly. About 8-8.30pm 17/3/09.

Any suggestions, or requests for clarification? Thanks!

77.12.14.73 (talk) 21:41, 17 March 2009 (UTC)

It appears you were lucky enough to catch a glimpse of the Space Shuttle as it approached the ISS. This site indicates that the IIS was briefly visible in your area, and I would expect the Space shuttle to be nearby. -- Tcncv (talk) 22:12, 17 March 2009 (UTC)

I don't know precisely what you saw (Tcncv's suggestion is possible), but they certainly sound like satallites. When they faded and disappeared that was because they were moving into the Earth's shadow - they turned red for the same reason the moon appears red during a lunar eclipse, the light reflecting off them has travelled through the Earth's atmosphere to get there. The fact that there were two of them could mean with was the ISS and Space Shuttle (although I would expect the ISS to be quite a bit brighter than the stars that make up Orion's belt), or it would just have been coincidence that two satalites appeared nearby in the night sky (they could have been at very different distances, so not very close together). --Tango (talk) 22:21, 17 March 2009 (UTC)

According to this report, the shuttle was scheduled to dock with the ISS at about 16:12 CDT (UTC-5), which would have been about 22:12 your time (UTC+1). The sightings web site indicated that both would have been visible simultaneously between 20:09 and 20:11 local time, so it's pretty clear that's that you saw saw the the space shuttle Discovery as it approached the IIS for rendezvous as part of mission STS-119. I've seen the ISS pass overhead before, and it appears like a bright star, maybe not quite as bright as Venus. The apparent motion is comparable to a high flying passenger airliner. The same site I referenced above can be used to predict sightings just about anywhere else on earth, as long as it is withing the latitudinal extent of the orbit. -- Tcncv (talk) 23:03, 17 March 2009 (UTC)

The separation mentioned sounds about right for 2 hours before docking, so I agree, that's almost certainly it. A lucky sighting! I've seen the ISS too, it's very bright (brighter than any star, I think) - I expect the OP misjudged the brightness (easily done if you aren't don't have much experience with astronomy). --Tango (talk) 23:12, 17 March 2009 (UTC)

For comparison, the Apparent magnitude article puts the ISS close to Venus in brightness, depending on the angle of the station and the phase of Venus. -- Tcncv (talk) 23:27, 17 March 2009 (UTC)

The ISS is already a pretty good naked eye object - it crosses the sky in a matter of a minute or two - so it's easy to mistake it for an aircraft or something. Just before dawn or just after dusk when the sun is at the right angle to have it be sunlit in an otherwise dark sky - even with the naked eye, you can see it's not just a bright dot - it has quite visible 'wings'. Before today, it has not been as bright as Venus - but while the shuttle is docked - and after it leaves in a few days and they deploy the new solar panels that it's delivering - the ISS will get appreciably brighter than Venus and stay that way. SteveBaker (talk) 01:57, 18 March 2009 (UTC)

This 2006 image at the Astronomy Picture of the Day will give you a good ideas of the apparent size. The station is several times larger now, but its roughly 100m size viewed at 350km altitude (farther if you consider the viewing angle towards the horizon) is still a fly at the end of a football field. (OK, maybe it's a big fly.) -- Tcncv (talk) 03:19, 18 March 2009 (UTC)

More like a golf ball at the other end of a football field...in proportion to a 100m football field, I make it about 3cm. But it's glowing pretty bright - it's more like looking at a lit-up light bulb at the other end of a football field - but I watched it during the last shuttle mission (it's always more visible with the shuttle docked next to it because the shuttle faces its white upper-side towards the sun so the solar collectors inside the doors can do their thing - so it's particularly reflective. For sure, I had no trouble seeing that it was more than just a dot...you could tell it has "wings". SteveBaker (talk) 05:13, 18 March 2009 (UTC)

No solar arrays on the shuttle, the inside of the doors have radiators. When docked to the station the shuttle/station stack attitude isn't determined by the sun either, instead the attitude is one where no propellant is required to maintain the attitude. anonymous6494 08:24, 18 March 2009 (UTC)

March 18

Launching a satellite via balloon

I recently read a story of 4 teenage spaniards who were able to take a bunch of meteorological equipment and a camera 20 miles high. The pictures that were returned are stunning. A camera and meteorological equipment sounds very much like a satellite to me. If you add a couple of fireworks to the mix for a second stage, or whatever you guys can dream up...how difficult would it be for a bunch of teenagers to make a satellite orbit the Earth a few times? I mean really, is it that hard? Sappysap (talk) 01:36, 18 March 2009 (UTC)

Sadly, yes, it really is that hard. Balloons are relatively easy. You don't need any fuel - just a big enough envelope and a lot of suitable lightweight gas and you'll get up to "the edge of space" (whatever THAT means)...however, as soon as you run out of air - there is no more bouyancy and you can't go any higher no matter how clever you are. To get into low earth orbit means getting your rocket up to around 8 kilometers PER SECOND. 28,000 kilometers per hour. 17,000 miles per hour....that's pretty serious stuff. SteveBaker (talk) 01:49, 18 March 2009 (UTC)

That's not to say it's impossible to do, of course. Da Vinci Project was an X-Prize attempt. (They were not able to complete their space-craft.) However, I'm sure that their balloon would have been considerably larger than a weather balloon.

Here's another really cool balloon project that I read about recently. It's pretty awesome if you ask me. High Altitude Glider Project APL (talk) 12:50, 18 March 2009 (UTC)

For average teenagers, putting something into orbit is not feasible. If however, you took an exceptional group of teenagers, and adequately funded their project, it is possible, but how many teenagers do you know that would be able to maintain focus for long enough to build a suitable launch vehicle from scratch? 65.167.146.130 (talk) 13:26, 18 March 2009 (UTC)

And would they still be teenagers when they finished? APL (talk) 13:32, 18 March 2009 (UTC)

The term for this technique seems to be "Balloon Assisted Launch". And it would not be easy, and probably not within the grasp of hobbiests, but the airforce and other space agencies seem to be considering it seriously. APL (talk) 13:38, 18 March 2009 (UTC)

Yes, the current system of launching rockets from a stationary position, close to sea level, seems designed to waste as much fuel as possible. I suspect that as the era of cheap fuel ends, this practice may end, too. Launching from a balloon or piggyback on a large jet would reduce fuel and vehicle size requirements considerably. They could also launch from a mountaintop, with a great deal of momentum, if a launch tube was hollowed out of the mountain (or placed on the side of the mountain) and the rocket was accelerated using steam pressure, similar to the catapults on aircraft carriers. StuRat (talk) 16:38, 18 March 2009 (UTC)

The problem that most people don't understand is that getting into orbit isn't just about getting high enough - that is something a balloon with a simple rocket could probably manage. The problem is that to be in ORBIT - you need a horizontal speed of 8km/sec. The balloon doesn't really help you in that regard. In fact, if you got a rocket going at 8km/sec horizontally at sea level - barring air resistance, it would go into orbit. Really all that the balloon buys you is getting above enough atmosphere that your rocket motor's power can be devoted to getting up to that orbital speed. That's not an inconsiderable amount mind you...but you've still got to get that 8km/sec from somewhere - and that's hardly a science fair project! Launching from aircraft at high altitude HAS been done - Scaled Composites SpaceShipOne, for example. It didn't get into orbit either - same reason - it did get up high enough - but without that 8km/sec - it just came right back down again - as expected...but launching from a plane definitely helped. But recall that a pretty large plane (a 747 for example) can only just lift an empty space shuttle - and that's without a full fuel load, SRB's, payload and so forth. We'd need entirely bigger aircraft to launch the kinds of substantial loads we need for things like assembling space stations and trips to the moon. Rockoons (rockets launched from balloons) have also been tried. Problems in that case are to do with injecting the rocket into the DESIRED orbit rather than from just any old orbit from a spinning, drifting who-knows-what balloon. The idea of launching from a tube (whether in a mountain or whatever) has also been attempted...just before the first war against Iraq, Saddaam had started to build 'Project Babylon' - a gigantic gun that would have been able to propel a satellite into orbit (or shoot a nuclear weapon to any point on the globe). The US 'Project HARP' was a similar idea. So I guess that all of these things have been tried - one way or another. SteveBaker (talk) 01:39, 19 March 2009 (UTC)

I wonder which portion of a rocket's fuel is used to fight air resistance. Note that there's no fixed amount of air resistance to overcome to reach orbit, as a slower ascent would require less fuel to overcome air resistance. Hence the advantage of a balloon, which could rise at a much slower rate and cause less air resistance. StuRat (talk) 15:21, 19 March 2009 (UTC)

Well, we do launch rockets vertically - and not horizontally - and in fact we gradually transition from vertical flight to horizontal (well, perhaps "radial" to "tangential" is better here) - and I suspect that the reason for that is that taking off vertically gets you through the densest air resistance in the shortest distance. Ascending through the atmosphere relatively slowly - and then kicking it up a notch once you're out of the worst of the atmosphere is EXACTLY what modern multi-stage rockets do. The most intense g-forces in a shuttle flight are long after take-off. But in the absence of atmosphere - you'd climb vertically only enough to clear any nearby mountain ranges - then head off more or less tangentially. As your speed builds, you'd get higher. SteveBaker (talk) 19:52, 19 March 2009 (UTC)

Your "relatively slowly" is indeed relative, as a rocket takes minutes to clear the densest atmosphere, while a balloon could take hours, and encounter much less air resistance as a result. StuRat (talk) 04:42, 22 March 2009 (UTC)

Light can't be seen unless it's reflecting off of matter

Is this a fair statement to make? That light is invisible unless it's reflecting off of matter? ScienceApe (talk) 02:09, 18 March 2009 (UTC)

Only photons that strike a detector are detectable by it, so unless they enter the eye, the eye can't see them. Now I don't know about reflecting be required (you can see a lit light-bulb directly:), but somehow the light has to become directed towards the eye. DMacks (talk) 02:18, 18 March 2009 (UTC)

Sort of depends on what you mean by the verb see, or more precisely, what you intend by using a term as the direct object of that verb. It could be argued, if one wanted to be argumentative for the sake of it, that you can never see light at all, not in the sense that you can see, say, a desk. What you see would be the source of the light, or the thing illuminated by the light.

Unless of course the light beam you're looking at is so intense that you can shine another light source on it and get a significant amount of scattering of light by light, which is a redlink that someone should really direct to the correct article. But in that case I'm not sure how long you'd live. --Trovatore (talk) 02:32, 18 March 2009 (UTC)

Until that happens, there's visibility of light through scattering at Light and the Tyndall effect. Julia Rossi (talk) 02:37, 18 March 2009 (UTC)

Well, no, that's different — you're still not "seeing" the light in the sense of detecting how it scatters other light. You're seeing the air or the dust or something. --Trovatore (talk) 02:39, 18 March 2009 (UTC)

Does Rayleigh scattering work that way? erm, still looks like matter particles in there though. :/ C'mon Trovatore, get that article blue-ing! Julia Rossi (talk) 02:40, 18 March 2009 (UTC)

Yeah - in both Rayleigh and Mie scattering (related but different things), the light is scattered off of something. SteveBaker (talk) 02:44, 18 March 2009 (UTC)

OK, so what about SOLBL? I would have assumed that the article must exist and I was just using the wrong search term. But searches like photon-photon scattering also come up blank. On the other hand a Google search for "scattering of light by light" gets lots of hits under that exact name and doesn't immediately suggest any synonyms. --Trovatore (talk) 02:54, 18 March 2009 (UTC)

Well, contrary to popular opinion - there are still a few things we don't have articles about. SteveBaker (talk) 04:49, 18 March 2009 (UTC)

There is no important difference between the light reflected from a surface and the light emitted from a surface...as far as the eye is concerned, it's all just light...so yeah - you can see light without it being reflected off of something...if your eye happens to be in the way. What I suspect our OP is wondering is if (for example) you were out in deep space - in a vacuum - with a big chunky laser beam shining a beam off into space just a foot in front of your face...would you be able to see the beam? And the answer there is no - because none of the light is reaching your eye - it's just shooting off into the distance. So in that sense, you can't see the light unless it's "reflected" (or perhaps "scattered" or "refracted") into your eyes. In all the action TV series when the good guy is breaking into the bank vault and all of the red security lasers are entirely visible...that's pretty much bogus. The light is somewhat scattered off of dust and such in the air - but even so, only the very brightest lasers actually light up the air as they travel through it. SteveBaker (talk) 02:44, 18 March 2009 (UTC)

I was making a linguistic point, not a physics one. As I said, a deliberately picky point, at that, not intended seriously. The point is that you say that you see the desk, not the light reflected from the desk. So "seeing" light, in that sense, is mostly impossible. Modulo SOLBL, which I'd still like to hear more about. --Trovatore (talk) 02:56, 18 March 2009 (UTC)

Yes - I suppose so. The problem here is that the linguistics pre-date the science by a considerable amount of time. As recently as when Newton was alive and trying to get a grip on what light is, there was still a common belief that somehow light came OUT of our eyes in order to see things. So it's not surprising that we talk about "seeing a desk" as a shorthand for "seeing light reflected from a desk". But it does go a little deeper than that. We can "see a desk" by virtue of it blocking light rather than reflecting it. If the sun is behind the object and all you can see is a sillhouette, you STILL talk about "seeing the object" rather than seeing by the lack of light behind it. We're also in a slightly odd position when we talk about seeing an object that's reflected in a mirror - when what we're really "seeing" is the mirror itself (by those standards). But when we talk about "seeing a desk" - we don't say "seeing the sun"...even though what we're really seeing is the sun reflected in the desk. So language is (as always) a mess - and we're better off defining our terms when it comes to proper scientific matters. SteveBaker (talk) 04:49, 18 March 2009 (UTC)

But light does come out of my — er, I mean, Superman's eyes. Yeah, that's the ticket. Because I'm not Superman, of course. Ha ha. Nope, not me. --Trovatore (talk) 07:54, 18 March 2009 (UTC)

It's true in POV-Ray, unless the light_source has a looks_like modifier. —Tamfang (talk) 21:16, 23 March 2009 (UTC)

Despite all the linguistic niceties the OP ask a prety simple question: "Is this a fair statement to make? That light is invisible unless it's reflecting off of matter?" to which there is no other reasonable answer then: No, that's not a fair statement, all light within the visible spectrum is visible as long as it reaches your eyes. That last requirement applys wheather the light has been reflected by a surface or not. Dauto (talk) 05:03, 18 March 2009 (UTC)

Probably you're trying to describe the fact that a "beam" of light can't be seen directly. But you're neglecting the case where light strikes your eye directly from the source. (ie: Look at the sun. (PS: Not for long.))

It'd be reasonably correct to say "Light is invisible unless it's reflecting off of matter or striking your eye directly.". APL (talk) 12:46, 18 March 2009 (UTC)

You could simplify further with "Light is invisible unless it enters your eye". Everything else is window dressing; your retina doesn't care what path the photon took to get there. TenOfAllTrades(talk) 13:37, 18 March 2009 (UTC)

technology

what are the roles of technology in growth of the economy.citing examples& applications —Preceding unsigned comment added by Solit (talk • contribs) 05:56, 18 March 2009 (UTC)

You might start with our articles on Technology and Economic growth. --Allen (talk) 06:56, 18 March 2009 (UTC)

We will not do your homework. Sorry. —Cyclonenim (talk · contribs · email) 11:42, 18 March 2009 (UTC)

How does it affect our lives to know why particles have mass

well i recently read that the Large Hadron Collider will also reveal through its experiments about WHY particles have mass? But what real use is this of to us? I mean there must be some big way in which this can be used but i fail to understand how?!?!?! Like technologically - how is it useful to figure out WHY a particle has mass? Wouldn't it be better to use all that time and money in using the LHC for some better useful experiment?Vineeth h (talk) 06:57, 18 March 2009 (UTC)

Thank you for signing this time but in future, please modify your original question if you make a mistake rather then posting again. I have removed the duplicate question Nil Einne (talk) 07:34, 18 March 2009 (UTC)

I don't know if this is what you're looking for, but here's one possible answer:

"The first question which you will ask and which I must try to answer is this, 'What is the use of climbing Mount Everest?' and my answer must at once be, 'It is no use.' There is not the slightest prospect of any gain whatsoever. Oh, we may learn a little about the behavior of the human body at high altitudes, and possibly medical men may turn our observation to some account for the purposes of aviation. But otherwise nothing will come of it. We shall not bring back a single bit of gold or silver, not a gem, nor any coal or iron. We shall not find a single foot of earth that can be planted with crops to raise food. It's no use.

So, if you cannot understand that there is something in man which responds to the challenge of this mountain and goes out to meet it, that the struggle is the struggle of life itself upward and forever upward, then you won't see why we go. What we get from this adventure is just sheer joy. And joy is, after all, the end of life. We do not live to eat and make money. We eat and make money to be able to enjoy life. That is what life means and what life is for."

— George Leigh Mallory, 1922

For a rather different answer see this article. -- BenRG (talk) 13:00, 18 March 2009 (UTC)

It is the nature of basic research that we don't know beforehand what usefulness any discoveries that come up will have. Faraday was asked about what practical use could there possibily be for his researches on electricity. Turns out our modern society would not work at all without the knowlege of electricity. I would not expect any immediate practical aplications to come out of LHC's discoveries, but that's not why we do it. The purpose of the LHC is knowlege, nothing more. Dauto (talk) 15:13, 18 March 2009 (UTC)

You forgot Faraday's response: "What use is a new-born child?" Confusing Manifestation(Say hi!) 22:23, 18 March 2009 (UTC)

We don't know why. But then we didn't know why we needed to know about quantum theory either...yet the computer you are reading this email on right now wouldn't exist if we hadn't figured that out. Perhaps discovering the properties of the Higgs Boson will allow us to teleport objects - or maybe time travel will become possible - or perhaps we'll discover that an old coke can plus a discarded copy of the New York Post dated 13th January 1956 is all we need to fix up global warming. I very much doubt it'll be any of those thinge - but we don't know BECAUSE we don't know. What we DO know is that in almost every 'pointless' experiment of this kind, we've found something that eventually became useful - perhaps directly - perhaps indirectly. Hence doing this kind of thing - even though the cost is outrageous - is what keeps technology purring along. SteveBaker (talk) 22:32, 18 March 2009 (UTC)

Plus, it will strengthen the resolution between the ongoing conflicts in the unifying theories of the universe. It will give us a direction in the knowledge of how this universe came about. Higgs is a theoretical particle not having been detected so far, only predicted by theories. It will confirm whether or not those theories are right, whether or not we need another physical theory. I can't wait to see the resumption of the LHC experiment. - DSachan (talk) 22:40, 18 March 2009 (UTC)

Evolution

I posted this on the evolution talk page, and apparently Wikipedia isn't a forum so I'm posting it here:

"I know this has been posted a million and three times and is covered in the FAQ but I want to be absolutely sure, could I in good concious go on national television tomorrow and declare "Evolution is a fact"? The article "Evolutions as theory and fact" is too complicated and doesn't have a simple "if you look at in a general way then A, if you look at it this way then B". I get other pages on the web written by biologists and doctors saying that "Evolution is not a fact, but is likely to be true". Wikipedia keeps mentioning something like mathematical meaning and logical meaning and I just want some disambiguation- I know Wikipedia is not a forum, so just delete this is no-one is willing to answer, I just wanted to make sure. If someone could give me a good "phrase" I could say if I would be going on television to explain this (I'm not really going to be on a TV, just for the sake of an argument), i.e. in a concise and simple manner: "Simply put, if you look at it from a scientific viewpoint... but if you look at it from a logical viewpoint..."." --BiT (talk) 08:08, 18 March 2009 (UTC)

The reference desk isn't a forum either and sorry but I don't understand what you are asking. But evolution is a fact and a theory. You can confidentally go on to television tomorrow and declare it if you want. This is explained about as simply as possible in our article "First, the "fact of evolution" refers to the observed changes in populations of organisms over time, which are known to have occurred. Second, the "theory of evolution" refers to the modern evolutionary synthesis, which is the current scientific explanation of how these changes occur." There is also Evolution as theory and fact#Evolution compared with gravity which may or may not help. But if you want to be able to confidentally go on to national television and explain evolution then you really need to understand it. You can't confidentally go on to television and defend something without understanding it IMHO, there is no shortcut. If not you're liable to make similar mistakes in defending evolution to those creationists make when attacking evolution which helps nothing (and creationists are notorious for being very well prepared and picking at any little mistake). Our wikipedia articles are decent enough so start reading and come back if you have any specific questions Nil Einne (talk) 09:00, 18 March 2009 (UTC)

The OP mentioned going on television to ask how true the statement "Evolution is a fact" is, not because he actually plans to go on television. --Bowlhover (talk) 15:00, 18 March 2009 (UTC)

The OP said "I want to be absolutely sure, could I in good concious go on national television tomorrow and declare "Evolution is a fact"?" and "If someone could give me a good "phrase" I could say if I would be going on television to explain this (I'm not really going to be on a TV, just for the sake of an argument)". I'm not sure if I understand this but I think the OP is saying he/she wants sufficient understanding such that they can be confident enough that they could say it on television without fear of looking stupid (not because they actually plan on going on television but as an example of the depth they want although IMHO a better example would be being able to explain it to a conference of evolutionary biologist :-P). Perhaps my understanding is wrong but I don't believe your claim the OP wishes to go on television to ask how true the statement is is correct either. Nil Einne (talk) 19:36, 18 March 2009 (UTC)

Yes, you are absolutely correct. A conference of evolutionary biologists might have been a better way of putting it but I doubt I can teach them anything about biology :p --BiT (talk) 10:53, 19 March 2009 (UTC)

Sir David Attenborough recently went on the BBC and did exactly what you want to do. I suggest you go onto the BBC website and see if you can find the part relating to this: I suspect it's part of their Darwin season. --TammyMoet (talk) 09:53, 18 March 2009 (UTC)

Carl Sagan also said it on Cosmos. A Quest For Knowledge (talk) 17:00, 18 March 2009 (UTC)

That evolution has occurred is a fact, like gravity is a fact. How evolution occurs, like how gravity works, is a theory. --Scray (talk) 11:02, 18 March 2009 (UTC)

You might find Evidence of common descent useful. Zain Ebrahim (talk) 11:07, 18 March 2009 (UTC)

To put it another way, the word "evolution" has two different meanings which people routinely conflate. I don't think it's a good idea to say "evolution is a fact and a theory". It's a syllepsis or antanaclasis or some such thing. Better to say something like "there's a fact of evolution and a theory of evolution and they're different things". Better still would be not to use the phrase "theory of evolution", or for that matter "theory of gravity", since the theories explain a lot more than just evolution or gravity. There's a scene in Dirk Gently's Holistic Detective Agency in which Dirk mocks Newton's contribution to physics by releasing an object, watching it fall to the ground, and saying "someone was bound to notice sooner or later". Well of course that kind of gravity was known to the ancients; what Newton figured out was that a single force could explain both gravitation (i.e. things falling to earth) and the motions of the heavenly spheres. I don't know if that mistake was Dirk Gently's or Douglas Adams's, but either way it wouldn't have happened if we didn't use the term "theory of gravity". Darwin's theory didn't only explain evolution (i.e. the changes in organisms over time as seen in the fossil record), it also explained, for example, the existence of species (which, unlike evolution, was known to the ancients). You could call it "Darwin's theory of species". At least that would force the creationists to be more specific about what they're railing against. -- BenRG (talk) 12:38, 18 March 2009 (UTC)

First of all I don't know the difference between syllepsis and antanaclasis. I understand that evolution can be both a fact and a theory but what does the theory of evolution refer to, and what does the fact of evolution refer to? What parts of evolution aren't proven? --BiT (talk) 11:06, 19 March 2009 (UTC)

Personally, I avoid using the word "fact" in science, it causes no end of problems. Science is made up of theories. Some of those theories have so much evidence supporting them that the chance of them being wrong is minute - some people like to call those theories "facts", but really it's an arbitrary cutoff. There is no qualitative difference between a "theory" and a "fact". --Tango (talk) 14:19, 18 March 2009 (UTC)

I'd say avoid worrying about terminology altogether. Evolution is a model of the natural world, and just because of that, it's a theory. It also has a certain amount of evidence. Whether that amount of evidence is enough to make evolution a fact is up to the individual to decide. --Bowlhover (talk) 15:00, 18 March 2009 (UTC)

Just because evolution is a fact, does not mean that everything connected with it is a fact. There are modern legends such as our ancestors developing in a warm pool of slime, or that they crawled out of the sea. These ideas are not proven sufficiently to be called facts. Graeme Bartlett (talk) 20:57, 18 March 2009 (UTC)

Actually the origin of life has nothing to do with evolution. That would be abiogenesis. ScienceApe (talk) 02:04, 19 March 2009 (UTC)

• could I in good concious go on national television tomorrow and declare "Evolution is a fact"? - on National Television - yes, absolutely. In front of the Nobel Prize committee...maybe not. We have to be careful about the word "fact" in rigorous scientific debate. It is possible that everything we know and see comes out of a large computer called "The Matrix" and evolution is totally false. That's a certainly a possibility. Hence we can't say (with 100% scientific rigor) that ANYTHING AT ALL is a "fact". However, if you were to ask "Is it as likely that Evolution is true as Gravity is true" - then yes, evolution is true - and that's plenty good enough for ALL practical matters.
• The article "Evolutions as theory and fact" is too complicated and doesn't have a simple "if you look at in a general way then A, if you look at it this way then B". - Sorry about that. That IS a subject for the article's talk page.
• I get other pages on the web written by biologists and doctors saying that "Evolution is not a fact, but is likely to be true". - See my response to your first question. Evolution is as true as Gravity - neither are 100% certain. Evolution is at least as true as ANYTHING you know to be true - Gravitation, Quantum theory, Relativity, Thermodynamics, your home phone number. That's "good enough" for all but the most ridiculously hardened sceptics - and philosophers (who, as I have pointed out in the past - are a waste of quarks).
• Wikipedia keeps mentioning something like mathematical meaning and logical meaning and I just want some disambiguation...If someone could give me a good "phrase" I could say if I would be going on television to explain this... - Oh - you want a sound-bite! Why didn't you just say so?!

"Evolution is a scientific fact that is at least as solidly proven to be true as are (for example): Gravitation, Quantum theory, Relativity, Thermodynamics, Electromagnetism, The Big Bang, Atomic theory, The Germ Theory of Disease, Genetics and the scientific theory that "The Earth Is Not Flat" - HOWEVER, neither Evolution - nor ANY of those other things are quite as certain to be true as that 2+2=4 or that there are infinitely many prime numbers. For these mathematical truths are things that may be proven by the power of thought alone - where the other things require us to believe that the results of our experiments are meaningful when applied to the real world. It is just possible that none of our senses are to be trusted. If it should somehow turn out that we are living in a world of make-believe or that we live in a simulation of a real universe that's running (like "The Matrix") in a big computer someplace - then 2+2 still equals 4 - but we can't know that anything we've experienced is true. Since we have no way to prove that we aren't inside "The Matrix" - we can't regard Evolution - or any other scientific theory as "fact" to the same degree as we regard 2+2=4 as a "fact". In practical terms, we accept these other big scientific principles as "true" - and Evolution is right up there with the rest."

The trouble is that the 'nut jobs' who want the universe to be run by supernatural deities need to find any chink in the armor that is scientific proof that they possibly can. Hence, they are more than happy to corner some poor unsuspecting scientist and ask things that are (in essence) like asking: "Is Evolution as certain to be true as that there are an infinite number of prime numbers?" - and an honest, serious scientist has to say "No - it's not". The nut jobs then happily frolic off into TV-land and say "Scientists everywhere will tell you that Evolution isn't necessarily true" - without considering what exactly the scientist actually meant. So, should you happen to get onto national television - you should ON NO ACCOUNT say that evolution might not be true. You have to use a circumlocution such as "Evolution is as true as that I'm standing in front of you right now!" or "How sure are you that if I drop this brick that it'll fall to the floor? Well, that's how sure we are that evolution is true.".

SteveBaker (talk) 23:09, 18 March 2009 (UTC)

Ok I've got to give a standing ovation to SteveBaker, props to you. Bear with me while I respond:

• I wasn't really meaning in the sense of being so philosophical (I forgot which branch of philosophy says that it's possible that the world is a lie) that you don't believe anything at all, but other than that you explained it pretty well. I want to point out that I don't plan on holding lectures for the Nobel Prize committee, I'll just say thanks for the awards and leave. Of course we can't be 100% sure that evolution is correct, who knows, maybe some god made the world just as it is to fuck with evolutionary scientists and maybe all paleontologic evidence is just god fucking with us as some claim, maybe god made gravity seem like 'fact' just to make it stop working one time to see the reaction. Also I want to point out that evolution wouldn't have been any more false in the Matrix than it was in the 'real world' (if we assume that the real world was 'real' and not a part of another Matri system) as it was a replica of the world as it was around 2000 if I remember correctly, so if we assume that evolution is correct here it would have also been correct in the Matrix.
• True.
• I went through a phase where I tried to be as sceptical as I could, never assuming anything and staring every sentence with "it could be assumed in correlation with the environment that I detect that, in the terms of this world that I perceive to be true, that what you seem to say can be wrong" (a slight hyperbole). That didn't last long.
• No way! You aren't going to give me an actual soundbite?? Awesome. Ok, I get your point. Only things that are based on something that is predetermined to be true can be 100% true. We give that if we add two apples then we get four apples, then 2+2=4 is an absolute truth in the same way that "every man is a rapist, I am a man, therefore a rapist" if we assume that what I'm saying is true about every man being a rapist.

Thanks you so much for this, I agree with you an the 'nut jobs' and I decided to look this up after seeing a clip of Bill O'Reilley that just pissed me off. Now I know that I can declare that evolution is pretty much as proven as the common man cares. The problem is as Bertrand Russell pointed out that "...fools and fanatics are always so certain of themselves, but wiser people so full of doubts." Those are good points about what I should say instead saying "evolution isn't true" but rather giving people a quick point of reference like you've given me here (i.e. if you believe that we aren't really in the Matrix and that I'm here talking to you then yes, evolution is real). Of course wondering whether the world really exists when asking such questions is really nitpicking because that's not the point of topic. I also see that you use Linux and develop games? I like you --BiT (talk) 10:53, 19 March 2009 (UTC)

The philosophical viewpoint that you're thinking of is "solipsism". Axl ¤ [Talk] 11:11, 19 March 2009 (UTC)

OK - so now that we've established that our OP is indeed sane and NOT going to discuss anything like this in front of the Nobel Prize committee - we can stretch the point a little. I actually believe that Evolution is as true as 2+2=4 or that there are infinitely many primes. It is a mathematical truth that:

• in a system in which entities can replicate themselves to make subsequent 'generations'...and...
• the information about the construction of entity is contained within the entity itself and is copied into the 'next generation'...and...
• when that replication process has a small - but non-zero error rate...and...
• where small details of the construction of these entities can change the probability of them replicating...

THEN evolution must be true for that system.

As true as that 2+2=4 in fact because you can prove all of that from those basic requirements. So in ANY system in which those conditions prevail, evolution must actually happen.

So EVOLUTION (as a process) is as true as that 2+2=4. What is only as true as (say) the theory that the earth is not flat - is that evolution actually happens here on earth and explains everything we see around us. That's a teeny-tiny bit less true. But I could write a computer program that demonstrates evolution working using only arithmetic and logic. (This has in fact been done, many times). If I was sufficiently careful, bored and determined - I could run that program in my head instead of in some computer and the results would be the same (Church-Turing thesis and whatnot). So I could - in theory demonstrate an actual evolutionary system working in practice using only what's inside my head.

Hence we need a new sound-bite. Meh - write your own.

SteveBaker (talk) 19:32, 19 March 2009 (UTC)

With some credit to John Lynch (based on his ideas, but with my errors added on top of it), evolution can be viewed as an observation, but also a process and a mechanism.

• The "fact" of evolution is the observation that species change. Either direct observation (like the evolution of citrate metabolism in Richard Lenski's amazing experiment) or the observation of the fossil record. These changes are, in essence, observations, which is what we call facts.
• The process of evolution is the observation of how these changes occurred. This overlaps with the former, but adds sequences of events. Horse evolution is a classic example, but gene tree reconstruction is pretty powerful too. It's an inference based on observations. Not quite a "fact", but it's a very strong inference. There are multiple independent lines of evidence. It's about as close to a "fact" are you get in science.
• The mechanism of evolution is a theory. Actually a body of theories - some very solidly supported, some untested hypotheses. A good, solid body of science, but not something you'd be inclined to call a fact. Guettarda (talk) 15:36, 20 March 2009 (UTC)

Methanol again

Thanks for your suggestions in my previous question about methanol. I have a more basic question now. In a mixture of MeOH/water, do the 2 substances evaporate at different rates/temperatures, or does the mixture behave as a new "pure" liquid? I'm not talking about distillation, more like just the first step of distillation where the liquids are evaporated.

Hope that makes sense.

141.14.245.244 (talk) 09:21, 18 March 2009 (UTC)

You may find Vapor_pressure and Raoult's_law interesting --91.6.16.55 (talk) 11:17, 18 March 2009 (UTC)

And Vapor-Liquid_Equilibrium#Boiling_point_diagrams. --NorwegianBlue ^talk 20:01, 18 March 2009 (UTC)

Raoult's law (already mentioned) is the important bit here. Basically, the vapor pressure (which in an open container is essentially the rate of evaporation) of each component will depend both on the concentration of each component AND on the temperature of the mixture. Take the case of a 50/50 methanol/water mixture. At any given temperature, the methanol will evaporate faster, so initially, the mixture will become a lower proportion of methanol. However, as the methanol concentration decreases, it's rate of evaporation will ALSO decrease compared to that of the water; water's rate of evaporation is increasing at the same time since its proportion in the mixture is rising as well. Since we have two competing processes (the higher initial evaporative rate, which is decelerating due to lower concentrations later on), the mixture will arrive at an equilibrium at some point along the way. Basically, at any given temperature, there will be a characteristic equilibrium ratio of methanol-to-water that the entire system will settle into. As you increase temperature, that ratio will tend towards the "azotropic ratio" at the boiling point of the lower-boiling liquid, which for methanol/water would be 0/100 (per our earlier discussion)... --Jayron32.talk.contribs 03:41, 19 March 2009 (UTC)

learning languages

Hello Wikipedia,

I read last night that, should a human not have learnt a language by the age of 6, he loses the ability too. This, i cannot believe. Whats the theory behind it and how can there possibly be any evidence for it (its hopefully unethical to deprive a child of his development?!).. thanks81.140.37.58 (talk) 11:06, 18 March 2009 (UTC)

I don't know, but you don't have to deprive a child of language development to know that some people don't develop language skills. I suspect it's probably because by the age of 6, the language centers of your brain are fully developed and capable of learning language. If, by the age of 6, you have not achieved some form of language retention, there's probably a problem elsewhere that means you can't. All speculation. —Cyclonenim (talk · contribs · email) 11:36, 18 March 2009 (UTC)

There is some evidence (from feral children, for example) that a human who has not had the opportunity to learn any human language by around 6 will never be able to do so later - see Critical Period Hypothesis. 87.112.22.179 (talk) 11:38, 18 March 2009 (UTC)

Sure, it's unethical to deprieve a child of his critical period, and it's a general rule that everything unethical has already been done. --Bowlhover (talk) 14:45, 18 March 2009 (UTC)

You may also wish to consider posting on the languages desk, once this thread has been archived in a few days. (Posting in two places at once is considered rude.) The linguists who hang out there know a thing or two about language acquisition. BrainyBabe (talk) 15:56, 18 March 2009 (UTC)

Now for some thoughts on why this might be. Our brains are initially "like a blank slate", in that nothing beyond some basic instincts is actually hardwired. The rest all must be learned. As we get older, our brains are no longer as open to learning. This is because things we've already learned become permanently burned into our brains. Why ? So we don't forget critical things we've learned, like how to walk. Small children have the ability to learn rapidly, but at the cost of forgetting quickly and being unable to distinguish fantasy from reality.

Communication is similar, in that we learn a method of communication and then tend to use that all our life. We can learn new words, as that's just a small change, but learning a whole new language is a bit trickier. Many can only learn an additional language by relating it back to their original language. Thus, if they had no original language, they couldn't learn the new one. There are exceptions though, as some people can learn, and actually think in, a new language. StuRat (talk) 15:58, 18 March 2009 (UTC)

What do you mean by "the age of 6"? I believe the critical age for learning a language is the age of 6 months.--Mr.K. (talk) 16:12, 18 March 2009 (UTC)

What? Many children don't start speaking until they are one or two years old, so that's patently not true. Unless you're thinking of something different. —Cyclonenim (talk · contribs · email) 18:57, 18 March 2009 (UTC)

Just because they can't speak doesn't mean they can't learn the language. Learning which sounds have which meaning is the first step, and learning how to make those sounds with their mouths is the next step. StuRat (talk) 14:54, 19 March 2009 (UTC)

I meant, children must get exposure to language before the age of 6 months or they won't be able to learn any full-fledged language. Of course, empirically testing this assertions may be immoral, however, it has happened.--Mr.K. (talk) 16:59, 19 March 2009 (UTC)

Surgery complications and PT age

What "percentage" is there for possible complications with inguinal hernia repair for an otherwise healthy 40 year old, compared to an 83 year old with Atrial Fib on Wafarin (but otherwise healthy/normal weight etc).

IE: <10% chance of complications for the 40 year old? >25% for the 83 year old due to having to stop Warfarin 4 days prior to surgery?

Is there a data bank that can provide this information?

Thanks Dave —Preceding unsigned comment added by 70.67.93.36 (talk) 13:56, 18 March 2009 (UTC)

The complication rate for any procedure varies depending on multiple factors, such as: age, sex, other health problems (which you already identified), as well as the location (the country, the hospital), there are also slight seasonal variations, and individual surgeons may have slightly differing complication rates for a given procedure. The other big variable is what type or types of complication you want to know about - since the rate of these also vary widely, and are also affected by everything else I mentioned. As far as I know, there's no one data bank for this, and if there was, I wouldnt rely too heavily on whatever it said because it'd necessarily have to average out all of those factors. If its a procedure you're contemplating having, discuss this with your surgeon. S/He will be aware of the local factors that affect risk and will be able to discuss them with you. Mattopaedia ^{Have a yarn} 05:29, 19 March 2009 (UTC)

Question about the knee

Im not seeking medical advise, i just want to know if a torn ACL can cause artrithis and in how much time? Thank you DST —Preceding unsigned comment added by DSTiamat (talk • contribs) 14:09, 18 March 2009 (UTC)

I don't think a torn anterior cruciate ligament can lead to arthritis, which is a disease affecting the joints, not ligaments or tendons. If you are concerned, however, please see a physician. —Cyclonenim (talk · contribs · email) 15:24, 18 March 2009 (UTC)

Our article Osteoarthritis#Two types? says "Some investigators believe that mechanical stress on joints underlies all osteoarthritis.." These researchers found a complete tear to be worse than a partial tear [3]. Maybe related or unrelated researchers have found that interrupted blood supply to the extracellular matrix of joints following surgery inhibited formation of cartilage when compared to methods where care was taken to preserve blood supply. Scarring (we don't seem to have a page on internal scarring) could be a factor here. 76.97.245.5 (talk) 16:33, 18 March 2009 (UTC)

From the Oxford Textbook of Orthopaedics and Trauma, pages 1207–1208: "Episodes of giving way may cause further injury to menisci and the articular surface. Reconstruction of the ACL has not been shown to prevent the development of osteoarthrosis. Reconstruction of the ACL may accelerate the development of osteoarthrosis." No timescale is indicated.

In paediatrics, page 2757: "Angus and Hall retrospectively studied ... the outcome of 27 children with arthroscopically documented ACL tears, 18 of which were partial tears. No activity restrictions were placed on the patients following diagnosis. At follow-up, 11 of 12 patients under the age of 14 were not satisfied because of functional knee instability. Most authors agree that functional instability, with associated damage to the menisci and articluar cartilage, will ensue in a patient with an ACL tear who returns to a high demand sport.... McCarroll et al. followed 38 patients with arthroscopically documented complete ACL tears for an average of 4.3 years following injury and found that 27 of the 38 patients treated nonoperatively developed subsequent symptomatic meniscal tears."

Axl ¤ [Talk] 18:43, 18 March 2009 (UTC)

Yes, a torn ACL can lead to OA. As for how long it takes- that depends on what you do with the knee. Lots of high impact, high demand activity generally equates with a faster rate of progression to OA (& a higher rate of re-injury), than low impact, low demand activity. Age also figures, as does sex, insofar as these factors are related to the types of activities one may be likely to undertake (for example a 20-something male football player may have a higher rate of progression than than a 50-something female who walks & swims a few times a week & has a sedentary job). Genetic susceptibility may also play a part. in other words: How long is a piece of string? Mattopaedia ^{Have a yarn} 05:38, 19 March 2009 (UTC)

Materials

Moved from Miscellaneous desk

I'm back! Based on facts ( and opinion, if you wish. Just make sure I know it's opinion.) which material do you think would work best for a windmill? Also based on how sturdy it is, how the weather effects it, cost, stuff like that. It can have drawbacks.

1. Titanium
2. Carbon Fiber
3. Magnesium

If you have any other suggestion, feel free to add. I'm just having trouble deciding on which to choose. <(^_^)> Pokegeek42 (talk) 22:27, 17 March 2009 (UTC)

Ah yes! Tensile strength! I think that might be important. <(^_^)> Pokegeek42 (talk) 22:32, 17 March 2009 (UTC)

For what parts of the windmill? The demand in the case of blades (for example) might be lightness or rigidity or tensile strength - but for the framework, extra weight might actually be beneficial and you'd perhaps be more interested in compressive loads. A lot depends on the design of your windmill too. SteveBaker (talk) 03:04, 18 March 2009 (UTC)

An interesting and somewhat relevant article: [4]. Bus stop (talk) 04:02, 18 March 2009 (UTC)

Maybe this should be on the science desk? That's where all the smart engineering types hang out. --JGGardiner (talk) 04:43, 18 March 2009 (UTC)

Carbon fiber would be pretty good as it's light and strong, except it's very expensive in the quantity that you'd want. Titanium is very strong, but heavy and therefore probably wouldn't be greatly affected by the wind. Magnesium, if pure, could be compared to Aluminum in terms of strength and weight, so it's probably the best option there. That's just in regards to the blades, though, because as Steve mentioned weight may well be beneficial to the framework of the windmill, in which case Titanium could be a good option (but also fairly expensive for large quantities). I'd have thought a steel structure would work better for that aspect. —Cyclonenim (talk ·contribs · email) 15:21, 18 March 2009 (UTC

I'd go with plastic for the blades (painted to protect against UV degradation) and steel for the frame (painted to prevent rust). The materials you named are rather expensive and probably only needed for the most extreme windmills. If looking at it in terms of amount of time until the windmill pays for itself, you'd want to keep the costs down as much as possible. The magnesium might also have the problem of burning when struck by lightning. The titanium is highly reflective, so you'd need to paint it to keep from blinding people from the Sun's reflection on the blades. Carbon fiber might be decent, but, again, is much more expensive than plastic. StuRat (talk) 15:39, 18 March 2009 (UTC)

You might be interested in Ceramic engineering. Glass-reinforced plastic and Biopolymer#Biopolymer as materials. 76.97.245.5 (talk) 15:41, 18 March 2009 (UTC)

Don't forget about galvanic corrosion if you use Mg. —Preceding unsigned comment added by 65.167.146.130 (talk) 20:14, 18 March 2009 (UTC)

Alrighty then. I've got enough to get started here. Thanks, guys! <(^_^)> Pokegeek42 (talk) 22:17, 18 March 2009 (UTC)

INDENTED CONCRETIONS

The Tununk Shale Member of the Mancos Shale Formation in Emery County, Utah, contains many spherical “cannonball” concretions. In one unique area, about 1.5km x 200m, the familiar cannonballs are outnumbered by others, 10 to 30cm in diameter, in which the spherical shape is modified by one or more indentations, 1.5 to 5cm in diameter and 1.5 to 4cm deep. (Pix @ http://picasaweb.google.com/fossilcrete/ForWeb#slideshow/5314320039662488930) Opening the concretions reveals a septarian-like interior with one of the dark septaria connected to the indentation. One concretion, bisected along the axis of the indentation, contains an inclusion connected to the indentation which appears to have cell structure and possibly be biological in origin. Do similar indented concretions exist in other areas? What caused the indentations? What is the the cellular inclusion? BobPeyton (talk) 15:54, 18 March 2009 (UTC)

My first thought on looking at the inclusion was that it was a fossilised bone of some kind such as seen here [5]. Bones of marine vertebrates have been reported from the Tununk Shale [6] so I would go with that as at least a possibility. Many concretions have a fossil at the centre, presumed to have acted as a nucleus for the growth. Can't come up with a good reason for the indentation though. Mikenorton (talk) 16:40, 18 March 2009 (UTC)

Super conducting armor vs. Lightning

Lets say you have a tank with armor that's super conducting and has zero electrical resistance. You zap it with an electron particle beam or lighting over and over again. Is it true, that it will never take any damage? ScienceApe (talk) 15:55, 18 March 2009 (UTC)

This may be a very naive approach, but I'm imagining whether lightning rods would take any damage struck again and again. I imagine there is probably some small amount of damage not from the charge directly but indirectly—say, if it created pressure effects in the air or ignited or burned something very close to the rod? --140.247.254.34 (talk) 17:04, 18 March 2009 (UTC)

The resistance would cause the conductor to heat up, which a super-conductor would not. That heating would probably result in damage eventually. --Tango (talk) 19:41, 18 March 2009 (UTC)

Thinking out loud -- the superconductor is still going to accumulate charge even if it doesn't accumulate heat, right? And that charge will eventually have to do something. Pump in charge at a high enough rate and you're likely to overwhelm whatever mechanism deals with it -- discharge to ground melts the rock underneath you, spark jumps across to the interior of the tank, something. So, while your armor may be invulnerable, your tank likely isn't. — Lomn 20:12, 18 March 2009 (UTC)

At the point where the lightning hits the superconductor, there is a hot plasma, possibly several thousand degrees. This is quite likely to damage your superconductor. Graeme Bartlett (talk) 20:37, 18 March 2009 (UTC)

Superconductors lose their superconductivity when the current density gets too big. They are not magic or invulnerable. Edison (talk) 23:25, 18 March 2009 (UTC)

To expand on the point about hot plasma most superconductors need to kept at sub liquid helium temperatures. If they rise above these temperatures their conductivity is lost and the electronic energy they contain is released as heat. Its a very delicate process charging and handling super conducting magnets. It possible for NMR and MRI magnets loss their superconductivity if they are jarred or damaged. The loss of superconductivity is called a quenching, in an uncontrolled the coil rapidly heats spreading resistance through the coil which boils the coolants, liquid helium and liquid nitrogen. This can be very dangerous for researchers, patients, doctors since they can be frost bitten or suffocated by the boiling coolant. For these and the other reasons mentioned superconductors don't make good armor.--OMCV (talk) 03:47, 19 March 2009 (UTC)

Laser application

Re-glazing of bathroom ceramics is mostly done with acrylic based products. I find the results only marginally satisfactory. Would it be possible to use a laser to melt Ceramic glaze / Vitreous on to the existing tile/cast iron tub? (following appropriate prepping.) Would the thermal stress induced in the tile crack it? Could a suitable laser be constructed cheaply and portable enough to be a DIY or rental unit? 76.97.245.5 (talk) 16:48, 18 March 2009 (UTC)

A portable laser with enough power to melt ceramic is unlikely to be safe enough to use without specialist safety equipment. It is also likley that such a laser would need more power than a standard house could provide. Most industrial lasers, which would have the power you require run from a 3-phase supply with a high current rating. Most also have water coolers attached to extract the excess heat - lasers are not efficient at converting electricity into light beams. -- SGBailey (talk) 16:56, 18 March 2009 (UTC)

It would also take a long time, I would imagine - a laser is, by design, very concentrated and ceramic has very low thermal conductivity, so I would expect you would have to point the laser at every single point on the tile you want to reglaze. That would mean running the laser up and down the tile in very thin strips. --Tango (talk) 17:10, 18 March 2009 (UTC)

Good question. I used to use a iron bathroom sink as a forge, the glaze would get sticky when it got hot but the whole thing was fine when it cooled down. Whether or not you could heat only part of the iron and glaze is a question I would like to know the answer to also. 121.214.10.38 (talk) 03:06, 19 March 2009 (UTC)

@Tango one could construct a mirror/prism thingy to guide the beam (sort of like at a disco) that should be doable. This paper I found indicates it would still be too slow overall [7]. A focus area of 0.3 mm seems feasible. Staying with metric that would take 50 passes per 15 cm² tile. So one would have to be able to generate sufficient heat to take only of a fraction of a second per pass or you'd need an hour per tile. Bailey's answer indicates it wouldn't be feasible anyway. I had hoped, since one wouldn't need a specific wavelength nor narrow specs, a high power output laser would be possible. Too bad. Maybe something like a blow torch with an automated guidance system could work. That would be a lot more likely to set the house on fire, though. :-( Thanks for all the input. 76.97.245.5 (talk) 05:02, 19 March 2009 (UTC)

earliest/latest snow

I am looking for info on the earliest and latest recorded snowfalls for several cities including St Paul MN, Omaha NE, Des Moines IA, Chicago IL, and St Louis MO. Does anyone have a website or something to point me to?

Thanks 65.167.146.130 (talk) 20:54, 18 March 2009 (UTC)

Here's one for Chicago: [8] However, I think it's worth noting that as you move northward, you'll need to rigorously define "earliest" and "latest". What happens if it snows in June? — Lomn 21:23, 18 March 2009 (UTC)

Or July (1816, Year Without a Summer), or August (Alberta, Canada), for that matter? Also, do a few flakes on the outskirts of a city witnessed by a few people count as a snowfall event? ~AH1^(TCU) 22:21, 18 March 2009 (UTC)

And you can get hail even in the middle of summer in warm climates, frequently associated with tornadoes. StuRat (talk) 14:32, 19 March 2009 (UTC)

A city will usually have an official weather station (generally at the airport), run by an official weather service with rules on how to measure the weather, and it's what happens there that counts as the city's weather. --Carnildo (talk) 23:26, 18 March 2009 (UTC)

http://www.wunderground.com may be helpful for researching historical weather conditions in U.S. cities. --Jayron32.talk.contribs 05:10, 19 March 2009 (UTC)

Hail doesn't count as snow, not even close. I remember one occasion where soft hail (graupel) fell in the summer in Northern Ontario, and it was reported as 27C (80F) and snow, but actual snow doesn't fall at those temperatures. However, snow can sometimes fall at temperatures as high as 10C (50F) with low humidity and at high elevations, but the highest temperature I've seen snow at where I live (S. Ontario) was about 6C (43F), and the latest and earliest days I've seen snow here were in late May and mid-October. ~AH1^(TCU) 17:44, 19 March 2009 (UTC)

How to write on a photgraph

The instructions for a photo contest are 'label the back of the photograph with your name, phone number, etc. etc.'

Are there particular types of labels that are good for this purpose? E.g., they won't damage the photo; they can be removed later if desired?

Thank you, Wanderer57 (talk) 21:24, 18 March 2009 (UTC)

Write on a piece of paper, sellotape that piece of paper to the back of the photo - should work fine. Alternatively use a soft-tip marker pen that doesn't smudge.

While I have no specific information, I suspect that the rules for a marker pen may be the same as for writing on CDs, i.e. use a "non-toxic" pen which doesn't deposit strong solvents in the ink which could soak through and damage the image surface on the other side. I use a Staedtler Lumicolor CD-R pen. Franamax (talk) 02:17, 19 March 2009 (UTC)

I think what you want is a grease pencil, a.k.a. wax or chinagraph pencil. The wax does not penetrate, so you can wipe it off later. --Scray (talk) 03:07, 19 March 2009 (UTC)

This must be a rather old-fashioned contest. I'd have expected it to say "label the CD containing your (digital) pics with your name, phone number, etc.". StuRat (talk) 14:29, 19 March 2009 (UTC)

If you do write on a paper photo, use a very hard surface under the photo to avoid putting an indentation into it which will be visible on the front. This could be a smooth shhet of class or metal. Graeme Bartlett (talk) 20:15, 19 March 2009 (UTC)

Thank you all for your inputs.

StuRat: You are correct, it is a very old-fashioned contest. Imagine looking at photographs on paper!

Wanderer57 (talk) 08:24, 20 March 2009 (UTC)

Speaking from professional publishing experience garnered in ye olde pre-digital age, it can be difficult to know if a felt tip will or will not bleed through and mar the picture (as per Franamax), or how little pressure might cause reproductible indentations/bumps (as per Graeme Bartlett), until you've already tried it (perhaps on a similar non-important picture). To be on the safe side, I'd suggest you write what you need to on a sticky-backed white address (or similar) label while it's still on its backing paper, and then stick the label on to the back of the photo(s). This method is always used by professional picture libraries on old prints, where the original negative may not be available. 87.81.230.195 (talk) 00:30, 21 March 2009 (UTC)

I agree. The stick-on label will also have the advantage of allowing me to swap the label on your pic with the label on my Xeroxed pic of my butt, allowing me to walk away with the grand prize. Then again, it would be just my luck that this is the year the judges finally understand my artistic vision.  :-) StuRat (talk) 17:25, 22 March 2009 (UTC)

Black hole thermodynamics and gravity

The zeroth law of black hole thermodynamics states that the surface gravity of a black hole is constant at a given temperature, right? Isn't this essentially proof of existence of a force carrier particle for gravity? I'm thinking that in standard thermodynamics, this applies because a change in temperature equates to a change in entropy, and we observe this by looking at the vibrational aspect of particles. Can this not be transfered over to black hole thermodynamics? I'm probably missing something big, so feel free to rip this idea to shreds. —Cyclonenim (talk · contribs · email) 21:50, 18 March 2009 (UTC)

I read somewhere that the only three laws of physics that probably aren't broken by black holes are gravitation, electromagnetism, and rotation. So, I'm not sure if the usual rules involving temperature apply properly in a black hole. However, it's probably still possible to predict the laws of physics as they apply to a black hole, and maybe some experiments such as those at the LHC will help improve our understanding, but I'll wait for someone with a more detailed answer as well. ~AH1^(TCU) 22:17, 18 March 2009 (UTC)

Perhaps you should better explain the point you are making and the reasoning behind it. It is not clear (at least to me) how you want to go from the zeroth law to the existence of a force carrier particle. Your idea about entropy seems to be going in the right direction but you did not develop it enough. Dauto (talk) 01:08, 19 March 2009 (UTC)

Surface "temperature" of a black hole is likely determined by events like Hawking radiation, and the rate of of "evaporation" due to Hawking radiation is mathematically proportional to the "size" and therefore surface gravity of the black hole. So if you measure the "temperature" of the black hole, what you are measuring is the kinetic energy of the particles lost via "evaporation". Our article on Hawking radiation covers this in exhaustive mathematical detail, but the basic principle is stated in the article more or less... --Jayron32.talk.contribs 03:26, 19 March 2009 (UTC)

My point was, in a completely speculative manner, that because the surface gravity of a black hole is proportional to the temperature, this seems remarkably similar to standard thermodynamics where the energy of a particle is given by its temperature (because of more vibration). —Cyclonenim (talk · contribs · email) 07:41, 19 March 2009 (UTC)

meteorite

Could this rock that was found in Ohio be a meteorite? It weighs 8.6 lbs.

• File:100 0537.jpg
• File:100 0541.jpg
• File:100 0542.jpg
• File:100 0545.jpg

I can't see the pictures.. is it just me? I'm not good enough at wiki to see where code may or may not be wrong. Can I get a second opinion? -Pete5x5 (talk) 01:37, 19 March 2009 (UTC)

Those images don't seem to exist either here or on Commons. I think you might need to put the "File:" prefix in front, but doesn't matter, 'cause I can't find them anyway... Franamax (talk) 01:54, 19 March 2009 (UTC)

I can't see it either. Dauto (talk) 01:47, 19 March 2009 (UTC)

Well, the <gallery> is incorrect - you need to put "Image:" or "File:" in front of each image - but I tried doing that and none of the images showed up. Then, the image uploader removes underscores from filenames - but doing that doesn't make them show up either. I suspect that the OP has not uploaded them successfully. SteveBaker (talk) 01:54, 19 March 2009 (UTC)

The trouble is not in your set. It's me. My next question is will a laptop still work after I throw it out the window? I will try to add the pictures when one the kids stops by. Please stay tuned.Curiouspatty45 (talk) 00:14, 20 March 2009 (UTC)

How does one teach a parrot to ride a tricycle?

Not a joke question. You can seriously buy small tricycles designed to be ridden by parrots online. How does that work then? If I bought one and showed it to my macaw, she'd probably just look at me as though to say "what do you expect me to do with THAT thing?". On the other hand, it might be a lot of fun for her, if I had the first idea about how I was supposed to teach her to pedal. Anyone know what I'm talking about here? --84.70.216.219 (talk) 23:15, 18 March 2009 (UTC)

See Operant conditioning and Shaping (psychology). Positive reinforcement is the key. Also be extremely patient, and do not continue a session when the bird does not want to play any more. You might start with basic bird training [9]. Edison (talk) 23:23, 18 March 2009 (UTC)

March 19

Natasha Richardson's fall

She didn't hit anything. Could the fall have been the result of a brain condition? How may a simple fall cause such a death. 69.203.78.244 (talk) 03:48, 19 March 2009 (UTC)

It can take surprisingly little to cause a serious head injury and what seems like a minor injury can become life-threatening very quickly. See traumatic brain injury. (And wear a helmet. They save lives.) - Eron^Talk 03:59, 19 March 2009 (UTC)

Complete and utter speculation based on TV medical dramas and 'stuff I read somewhere' here - but AFAIK, a bang to the head can cause a bleed in the brain which, whilst not immediately fatal (or even apparent) can continue to leak blood into the surrounding spaces in the following hours. Eventually, if there's no more space for the blood to go, the intercranial pressure starts to build up to a dangerous level and the brain starts to gets squeezed. Without immediate medical attention, the base of the brain gets squeezed out, toothpaste-like through the hole in the base of the skull - at which point, the only effective treatment for the condition is a pine box. --Kurt Shaped Box (talk) 04:03, 19 March 2009 (UTC)

Since there's no publicly released information about the mechanism of injury or her medical condition, any response to this question is purely speculative as it applies to Ms. Richardson, and what follows is not intended to imply any one mechanism or cause of death, only what is possible.

That said, the are numerous ways a person could die from a closed head injury, including the slow bleeding scenario KSB described, which is usually a subdural haematoma. Other causes attributable to bleeding include extradural haemorrhage, subarachnoid haemorrhage, although this usually has a more precipitous onset, and intracerebral haemorrhage, to name a few. There are many conditions that increase the risk of some of these catastrophic bleeding problems, some of which are berry aneurysms and arteriovenous malformations. Contre coup type head injuries, and other blunt force, closed-head, traumatic injuries can lead to death through increasing cerebral oedema, ultimately causing the herniation of the lowest parts of the cerebellum throught the foramen magnum, which causes compression of the brain stem, where important things like consciousness, breathing and heart rhythm are controlled. This causes death. This is the process KSB described above, and is described by many doctors as "coning." It is caused by anything that increases intracranial (inside the skull) pressure sufficiently. More obscure causes in the setting of trauma exist, the first that comes to mind is acute high-pessure hydrocephalus that can be caused by a colloid cyst of the third ventricle blocking drainage of cerebrospinal fluid from the lateral ventricles. I could go on, but I won't! Mattopaedia ^{Have a yarn} 06:07, 19 March 2009 (UTC)

It is reported that it was an epidural haematoma which sadly affected Natasha. This occurs when a bleed occurs in your head, between a layer called the dura and the skull. This causes an increase in intracranial pressure, resulting in a sort of compressive mechanism on the brain. Roughly 15-20% of people die from this condition, often because it's not as easy to diagnose as the other haemorrhages and haematomas listed above by Mattopaedia. —Cyclonenim (talk · contribs · email) 07:45, 19 March 2009 (UTC)

But she didn't hit anything, if the reports are correct! Thanks for the impressive list, too--though the skull is strong it's crazy how many ways the brain can go wrong. 69.203.78.244 (talk) 13:18, 19 March 2009 (UTC)

Brain injuries don't require an external impact. Sudden deceleration can do it, too, due to the brain's inertia causing it damage when it slams against the inside of the skull. StuRat (talk) 14:21, 19 March 2009 (UTC)

And, she did hit something - she hit the ground. That acounts for both impact and sudden deceleration. This story quotes a couple of ski patrollers who note that falls on flat sections of ski runs can be more dangerous than falls on slopes, as the skier just drops and stops rather than tumbling or sliding down the hill, which can absorb some of the impact. - Eron^Talk 15:04, 19 March 2009 (UTC)

Indeed - I can tell you from experience that compacted snow is very hard. I've hit my head on the ground after a skiing fall, and it isn't pleasant (I've never required hospitalisation, fortunately). The worst such time was, indeed, on a flat section - right at the bottom of a dip, so I was going flat out, hit a bump, hit the ground and stopped immeadiately. I was completely dazed for several seconds. I don't find it at all hard to believe that someone less fortunate than me could get a fatal head injury from a similar fall. --Tango (talk) 19:16, 19 March 2009 (UTC)

Yellow cheese

What causes some cheeses to be yellow/orange? 99.245.16.164 (talk) 03:53, 19 March 2009 (UTC)

Annatto. Cheers! --Jayron32.talk.contribs 04:00, 19 March 2009 (UTC)

Also Vitamin A or beta-Carotene. On European labels E160 or E160a. 76.97.245.5 (talk) 05:21, 19 March 2009 (UTC)

A possible problem with spinning for Artificial Gravity

I have heard several way involving spinning a ring, or surface, or something to create centrifugal force for artificial gravity. I have always wondered: What would happen if I jumped up off the surface? Once I lost contact with the spinning surface, would I be weightless, or would my velocity bring me down again? Tiailds (talk) 04:18, 19 March 2009 (UTC)

If you start out spinning with the ring, you will have a lateral velocity. When you jump, that lateral velocity component does not change, so you will continue moving in that direction until you encountered the ring again. You will also have some amount of angular momentum, that will keep you rotating with the ring, so you will likely land in a roughly upright position. In extreme cases this would not be true and you could land at an awkward angle.

In contrast, if you started running in the direction opposite the ring rotation and managed to match that rotation, the centrifugal force would disappear and a jump would launch you into a weightless condition with the ring rotating around you. You could almost think of this as the equivalent of achieving orbital velocity in this inside-out environment. -- Tcncv (talk) 04:55, 19 March 2009 (UTC)

(EC with above)The idea is that you are on the inside of the spinning surface. Under those conditions, regardless of where you jump from, your straight-line motion (which your inertia will have once you are no longer in contact with a rotating frame of reference) will always bring you back into contact with the surface again. It's the centripetal force which is spinning the ring or whatever that provides you with that motion, not centrifugal force (a fictional force), which is really just the effect of losing contact with a rotating frame of reference and not a real force at all. Since your tendancy will be to move away from the center in both cases, being OUTSIDE the spinning ring will cause you to drift away, but being INSIDE the spinning ring will cause you to always drift into the ring. So you fall back to your "ground". --Jayron32.talk.contribs 05:08, 19 March 2009 (UTC)

Obligatory xkcd reference. There would also be a slight effect from the Coriolis effect, moving you a little in the direction you're spinning when you jump. — DanielLC 16:06, 19 March 2009 (UTC)

This "FreeFall" strip is more applicable than the xkcd one. It matches what Tcncv was saying. APL (talk) 19:16, 20 March 2009 (UTC)

I spent a year and a half on Mars and all I got was this stupid t-shirt...

I have a few questions about a manned missions to Mars which Manned mission to Mars sadly does not answer:

1. First of all, what would be the length of such a mission? I hear people say that the trip there would take 3 months or so, but the entire trip would take much longer, wouldn't it? I mean, once you've taken three months getting there, haven't you pretty much missed your window of opportunity to get back? The article on exploration of Mars states that the launch window comes around every 780 days, so would that mean that the poor astronauts would have to spend something like a year and a half living on the surface of Mars? I'm having trouble even imagining how much food and fresh water you'd need to bring to stay alive that long (not to mention the psychological effects, I've read The Three Stigmata of Palmer Eldritch).
2. Second, what about communications with Earth? I mean, when Earth and Mars are sort-of near to each other, it wouldn't be much of a problem (you could live with a twenty minute latency, even if it's a pain in the ass), but assuming I'm right on part number one (a bold assumption), for most of the mission, Mars and Earth would be on opposite sides of the sun! Can you reliably communicate with someone when the sun is up? I'd imagine that the interference would be huge.
3. Third, what tangible benefits would a manned mission to Mars yield? Yes, I get the whole "triumph of the human spirit" thing and it would make a great television event, but if we just went up there to make measurements and bring back rocks for analysis, can't we just get robots to do that? I mean, yeah, the rovers didn't bring anything back, but I imagine it would be WAY easier to make a return trip with a robot compared to making one with a human being. No need to worry about some dude going ape-shit crazy and slaughtering the rest of the crew for one thing (presumably the robot would have a "become_self_aware = false" line in its code somewhere).

Can any of you fine scholars enlighten me on the subject? Belisarius (talk) 05:25, 19 March 2009 (UTC)

I'll comment on the second point only. The Sun would certainly block communications when directly in line between Earth and Mars, although that configuration might never occur during the mission (the two planets orbit in different planes, remember). I don't know about the more likely situation where it is almost directly in line, but experiments could be done to find out if it is a problem. And if it is, the thing to do is launch a communications relay satellite into a solar orbit that will keep it far enough away from the Earth-Sun line.

For single-mission use there would be a wide choice of orbits, but for long-term stability, the obvious thing is to use one of the Trojan positions, 60° ahead of behind of the Earth in its orbit. Incidentally, this solution was anticipated in science fiction as early as 1942, with George O. Smith's lighthearted Venus Equilateral stories. Smith was writing in the days of vacuum tube electronics and assumed the relay station would be manned -- as did Arthur C. Clarke when he invented the geosynchronous communications satellite in a nonfiction article about the same time. Smith's first story, "QRM—Interplanetary", is particularly worth looking for. --Anonymous, on Earth, 08:59 UTC, March 19, 2009.

(A) We're not talking about a solo flight. so the 790 days in point one wouldn't be spent in isolation. I would imagine an expedition consisting of a number of ships - minimum three - and dozens in the crew. (B) Magellan's Victoria took three years to circumnavigate the globe; FitzRoy's second Beagle expedition - the one with Darwin - took five. (C) Supplies need not all be carried along. Unmanned ships stuffed with MREs could be launched separately - starting before the manned component - and either inserted into orbit or dropped to the surface. (D) BTW, a second on the Venus Equalateral recommendation. B00P (talk) 09:40, 19 March 2009 (UTC)

While you're right we're not talking about a solo flight, the psychological effects of such a long trip in which a few people will be in constant close contact and very far from earth with limited contact are definitely something that has received a great deal of consideration (as with the physical effects) and is one thing that has been studied in numerous ways (e.g. [10] & [11]). Take a look at [12] and is also mentioned in Manned mission to Mars. I saw one suggestion a while back that choosing too many astronauts which are too perfect, as is the norm may actually be a mistake because they may not get along very well with each other over such a long time so there are definitely lots of different ideas. Basically of course, we will never know until it happens since there's no way you can simulate the conditions exactly. P.S. I've never heard a suggestion of multiple simultaenous crewed ships before. While I'm sure it has been proposed somewhere, I don't think it's high on the current list of ideas. Nil Einne (talk) 13:19, 19 March 2009 (UTC)

As having groups of people who can get along well together for years in confined spaces would be critical for the mission, they should make each group go through a test run for several years of isolation first. StuRat (talk) 19:00, 19 March 2009 (UTC)

That would be an extremely inefficient use of time. A 6 month spell on the ISS together might be good, although not all the people that would go on such a mission would be useful on the ISS (there aren't many rocks for geologists to study in LEO!). --Tango (talk) 19:04, 19 March 2009 (UTC)

The isolation test could be done on Earth, in an old bomb shelter. No need for any major expenses. StuRat (talk) 14:53, 22 March 2009 (UTC)

As for supplies, such a mission would likely benefit from far more recycling than is currently done. Oxygen could be recycled from the air, and carbon dioxide removed (and maybe used to grow plants). Water could be recycled from the air (respiration and evaporation from skin and eyes) and from urine. Recycling food could also be done, say by using feces to grow food. Mushrooms, anyone ?

Another option is to produce some of the things we need directly on Mars. There is water ice at the poles, which could be used to supply water, and, after some electrolysis provided by solar power, oxygen. StuRat (talk) 11:55, 19 March 2009 (UTC)

An interesting thing that happens with my local NPR radio station periodically is that they'll say "at about X o'clock today, we'll lose transmission of this program due to the Sun passing behind the satellite that gives us our feed". And that's with your transmitter in front of the Sun. --Sean 13:34, 19 March 2009 (UTC)

Manned mission to Mars still has that elephant of "Health threat from cosmic rays" in the closet. I haven't seen us make all that much progress in figuring out sufficient shielding. (Nanotube polymers are a very nice theory, but the spaceship would need more than a thimble full.) As to why, sooner or later our own planet is going to face a huge calamity. It would be nice for the survival of the species - if you are interested in that - to have a population stashed elsewhere by that time. If we intend to head in that direction we'd have to start some when somewhere. 76.97.245.5 (talk) 15:26, 19 March 2009 (UTC)

I may be misreading this, but in the original post, Belisarius says, "...Mars and Earth would be on opposite sides of the sun! Can you reliably communicate with someone when the sun is up?" The phrase "sun is up" usually refers to it being daytime and the earth does not orbit the sun during the course of a day, but over the course of a year. The sun being "up" would not necessarily be a problem; the sun being "between" would certainly be. Matt Deres (talk) 17:02, 19 March 2009 (UTC)

Yes, but you can only communicate when the Earth is above the horizon, which would be at the same time as the Sun was above the horizon. The OP's question does make sense. The Sun being up isn't actually a big problem, though, it's only a problem if it is very close to the Earth in the sky. --Tango (talk) 18:08, 19 March 2009 (UTC)

I'll take a shot at these:

1. First of all, what would be the length of such a mission? I hear people say that the trip there would take 3 months or so, but the entire trip would take much longer, wouldn't it? - yeah - it's partly the launch-window thing, partly that having spent 3 months getting there - and needing another 3 months to get back, it would be kinda silly to stay just a couple of days as we did on the moon. Plus, prolonged periods in zero G aren't good for you - and the guys will need time to recover some of their lost muscle and bone mass for the trip back home. This is also going to be a ruinously expensive trip - we won't be sending half a dozen manned missions there as we did to the moon.

• I'm having trouble even imagining how much food and fresh water you'd need to bring to stay alive that long (not to mention the psychological effects - those are all very serious concerns. The plan currently is two-fold. One is to send an unmanned vehicle to mars to manufacture water and (by electrolysis) oxygen and some hydrogen fuel for the return trip - using sunlight for energy, subterranean ice as a water source...whatever. When it has enough supplies built up - we send out our manned mission with enough fuel for a one-way trip - and only enough water and oxygen for the ride out there. We'd need to recycle (we already do that on the ISS for example) - and we'd need to grow our own food en-route using hydroponics and such like. It's not easy - and that's why we didn't do this LONG ago! When we get there - we land a short distance from the robotic mission's landing site - fill up on fuel, water oxygen for the stay - refill again for the trip home. Psychological concerns have been somewhat addressed. Plenty of people have been cooped up in the ISS and in MIR for a year and managed to keep it together that long. Being able to leave the spacecraft and wander out across Mars should make that easier - not harder.

2. Second, what about communications with Earth? - No problem. We've been communicating with the 'Spirit' and 'Opportunity' rovers non-stop for something like five years now! We can still send messages to (and get data back from) the clunky old Voyager probes that have completely left the solar system. This is really not a problem.

3. Third, what tangible benefits would a manned mission to Mars yield? - I have a problem with this too. There is value for sure in having LOTS of humans living their lives on Mars - we need a 'backup planet' in case something terrible happens to ours. For that reason only - we need to make a start on being there - and the first step is to get a small crew out there.

• No need to worry about some dude going ape-shit crazy and slaughtering the rest of the crew for one thing - again, it didn't happen with people cooped up in the TINY space of MIR over an entire year (although they certainly had their problems). I think once they get to Mars - they'll be too busy to worry.
• (presumably the robot would have a "become_self_aware = false" line in its code somewhere). -  :-) Indeed - Asimov's first law of robotics is a "must have" kind of thing...and no putting red LED's in it's fake eyesockets either...that's just not funny! Particularly avoid: "if ( become_self_aware == true ) eye_socket_LED_illumination_level = 1.0f ;"

SteveBaker (talk) 19:12, 19 March 2009 (UTC)

And extra-extra-specially avoid:

if ( become_self_aware = true ) eye_socket_LED_illumination_level = 1.0f ;

-- Speaker to Lampposts (talk) 03:01, 20 March 2009 (UTC)

It took me a while to work out what you were saying that (I didn't cheat and click the link!), but I laughed out loud when I got there - very good! --Tango (talk) 14:54, 20 March 2009 (UTC)

Strictly speaking, we haven't communicated with Spirit and Opportunity non-stop - there are short periods when they are out of contact due to the position of the Sun. It's only a couple of days a year, or so, though. The lack of real-time communication with anyone other than your crewmates might make life on Mars a little harder than life on MIR/ISS - the psychological issues certainly need to be dealt with, but I don't think any of them are deal-breakers. --Tango (talk) 14:54, 20 March 2009 (UTC)

To answer the OP's third question: Mars can be explored much faster with humans than with robots because robots are nowhere near as intelligent as a human. Consider this recent possible discovery of liquid water on Mars, for example. It's been months since the pictures were sent back, yet scientists still aren't sure whether what they're seeing is liquid water. If any human saw that substance, he could poke at it and figure out whether it's water within a few seconds.

Another example: Spirit and Opportunity, the two rovers exploring Mars, are constantly meeting obstacles, stopping, and asking Earth for directions. Just read this update archive. It took days for Spirit to get around a potato-sized rock. It's hard to imagine anything a human failing to navigate around anything smaller than a mountain.

So, why should robots not be made self-aware? I'd think conscious robots would be extremely helpful in exploring Mars, as they'd presumably allow the planet to be explored with on-the-spot decisions (as opposed to decisions made by Earth, which take a long time). --Bowlhover (talk) 00:57, 21 March 2009 (UTC)

"Mars can be explored much faster with humans than with robots because robots are nowhere near as intelligent as a human. " An opposing argument is that it is cheaper to send a robot, because we don't care if it never comes back. A "Hero Astronaut" must have a return capability, with multiple redundant everything. A robot just goes there and is abandoned when it quits working. If it crashes or falls in a hole, too bad, and we send another a bit later. It is far cheaper to send an analytical lab there than to send a Hero Astronaut to walk around for a bit and then bring rocks back. Plus, we avoid the Andromeda Strain scenario wherein pathogens wreak havoc back on Earth. Edison (talk) 02:15, 21 March 2009 (UTC)

Another way to look at is that we could probably send dozens of rovers, more quickly, and for less cost, than a human crew. Those rovers could stay functional on Mars for longer than a human, who would likely need to head home after a brief visit. StuRat (talk) 05:39, 24 March 2009 (UTC)

Research with Blood

What is the easiest way to overlay blood on to a FiCol or similiar medium before centrifugation? Currently you have to poor blood from one test tube to another prefilled with medium (ficol) 15-50 mL test tube. —Preceding unsigned comment added by 98.154.31.61 (talk) 07:36, 19 March 2009 (UTC)

I suggest that you start with a tube containing blood diluted 1:1 (to reduce loss of mononuclear cells at the interface) and underlaying with Ficoll. You need a very clean interface to get good separation. To achieve this, use a long pipette attached to a pipette-aide, load it with the desired amount of Ficoll for the blood volume and tube size you're using, insert through the blood to the bottom of the tube, then very slowly dispense the Ficoll, being careful to avoid ejecting a bubble of air! Spin with the brake off, of course. --Scray (talk) 11:07, 19 March 2009 (UTC)

Waterflow of the Amazon River

I am interested in knowing more about the force and speed of the waterflow/steady stream of the Amazon, i.e. close to the outlet but before the flow is divided by the "branches" of the delta. Perhaps this can be calculated from the daily amount of water going from the river into the sea, with the tide taken into account?

Does anyone have information about the speed of the flow out to sea? It would be an interesting addition to the page.

—Preceding unsigned comment added by 195.67.112.146 (talk) 10:17, 19 March 2009 (UTC)

On the Amazon river page, the information box notes that the "Discharge - average" at the mouth is 219,000 m³/s; I'll let you do the conversion, but you should get a little over 10¹³ L/day (a truly mind-boggling amount). My impression is that this takes into account tides, etc. The Drainage area section notes that this can increase almost 40% to 300,000 m³/s during the wet season. What is it you wanted to add? The Talk page might be a good place to discuss additions. --Scray (talk) 11:24, 19 March 2009 (UTC)

Using Scray's numbers, roughly 10¹³ L/day, divide by 24, then by 60 and then 60 again to get per second which gives us approx. 1.16 x 10^9 L/sec. Seeing that one liter of water is approximately one kilogram, we can assume 1.16 x 10^9 kg if the mass of the water.

Speed of the Amazon is approximately 3 miles per hour, which is 1.34 m/s^-1. Seeing as one liter of water weights approximately one kilogram, we can convert Scray's value of 10¹³ per day into 1.16 x 10⁹ kg of water flowing per second. Using F=ma, 1.16 x 10⁹ x 1.34 gives us 1.55 x 10⁹ N of force. I feel that's unusally high, but I'm not a good physicist so I'll let others rip that working out to shreds. —Cyclonenim (talk · contribs · email) 16:58, 19 March 2009 (UTC)

A liter of water has a mass of exactly one kilogram, by definition, not approximately, though there are obviously additives that will change the actual measured mass/weight. Matt Deres (talk) 17:06, 19 March 2009 (UTC)

I was just wondering how much suspended sediment load there would be in a litre of Amazon river water, so I did a back of the envelope calculation taken from some annual figures of discharge and sediment load (6300 km³ per year & 1200 x 10⁶ tonnes per year [13]), and came up with a mere 0.2 g of suspended sediment in each litre; enough to make it look a bit murky but not enough to seriously affect the approximation. Mikenorton (talk) 19:14, 19 March 2009 (UTC)

Wow, so there's 2.32 x 10⁵ kg of suspended sediment in the Amazon? That's a lot of sediment! —Cyclonenim (talk · contribs · email) 19:34, 19 March 2009 (UTC)

Just as an aside, the Amazon is recognised as the largest river in the world by volume, but is it true what I read that there is an underground "river" underneath the Nile that is six times bigger than the river on land? ~AH1^(TCU) 01:46, 20 March 2009 (UTC)

That would be the undercurrent of denial, right?  ;-) --Scray (talk) 10:44, 20 March 2009 (UTC)

Beneath the Nile there is an enormous canyon created by the drop in base level associated with the Messinian salinity crisis. That is now filled with silt, I don't know if there is likely to be any significant groundwater flow through this great pile of sediment (2400 m thick beneath Cairo) that could be compared to the surface flow. There is interaction between the Nile and aquifers in its banks in the Cairo area, both discharge and recharge,[14] but I'm not sure you would call any of that an underground river. Mikenorton (talk) 11:44, 20 March 2009 (UTC)

query

Practical methods of production of callus cultureVidya mandava (talk) 11:07, 19 March 2009 (UTC)

Web search for "callus culture" provides plenty of information. If you have a specific question, please state it clearly and I'm sure people here will respond with similar care. --Scray (talk) 12:48, 19 March 2009 (UTC)

Biochemical processes within crocodile...

how can crocodile stay under water so long time? what biochemical processes are within it when it's under water? —Preceding unsigned comment added by Beqa22era (talk • contribs) 11:11, 19 March 2009 (UTC)

1) They don't. Their nostrils stay above the waterline in their normal floating position, so they can breathe normally.

2) When they do go underwater, just being a reptile allows them to hold their breath much longer, since reptiles are cold-blooded. Warming the body requires a great deal of energy, and "burning" that energy requires oxygen. Therefore, the oxygen requirements for cold-blooded animals are far lower. StuRat (talk) 11:39, 19 March 2009 (UTC)

Cold-hearted orb that rules the night....

I'm under the impression that the center of the Moon is far cooler than the center of the Earth. This brings up some Q's:

1) What are those two temps ?

2) Why the diff ? Does it have anything to do with the Moon being tidally locked to Earth, but the Earth not being tidally locked to the Moon ?

3) Is there a formula which can predict the temp at the center of a planet or moon, based on it's mass and distance from the Sun ? (I'd include density, but that may also be somewhat dependent on the temperature). StuRat (talk) 11:35, 19 March 2009 (UTC)

Partial answer to part 1: Various sources for the earth's core temperature are listed here with 7000 c. being most prevalent, 10,000 c. here, and 9,000 here, so as you can see there's little agreement, which is unsurprising given that we have no direct measurements and all answers are currently based on extrapolation. By the way, are you a Moody Blues fan? (or were they quoting someone else when they used that line?)—70.19.64.161 (talk) 12:17, 19 March 2009 (UTC)

Yes, very good, it's from the Moody Blues Late Lament, immediately following Knights in White Satin (is that about the Ku Klux Klan ?). That quote seemed to match my Q rather well. StuRat (talk) 13:56, 19 March 2009 (UTC)

Actually it's "Nights in White Satin": a song which is from an LP "Days of Future Passed" which is about the events of days and nights. Wherever do you get KKK from??? I'm not sure 5 lads from Birmingham (England) would even have heard of the KKK in 1967! --TammyMoet (talk) 14:24, 19 March 2009 (UTC)

The redirect made me think my spelling was correct. I wish they had a different color for links which point to redirects, to avoid this problem. The KKK members fancy themselves to be feudal knights, and often wear white satin robes (and many would consider them to be "white satans", too). The Birth of a Nation poster demonstrates both aspects. StuRat (talk) 14:50, 19 March 2009 (UTC)

For (2), that's likely some part of it, but our structure of the Earth article suggests that the prime source of heat is left over from planetary contraction. Given that the Earth is on the order of 80 times more massive than the Moon, I expect that explains the discrepancy nicely. For a partial answer to (1), inner core puts it at approximately the temp of the sun's surface, 5800K. — Lomn 12:21, 19 March 2009 (UTC)

That value is actually for the outer core-inner core boundary, according to the source quoted, so probably significantly hotter at the centre. Mikenorton (talk) 12:45, 19 March 2009 (UTC)

This source [15] gives a temperature for the centre of the moon as 830°C (1003°K). It also suggests that this temperature means that the concentration of radiogenic isotopes is greater than within the earth. If it wasn't for this heat source both bodies would be a whole lot colder (or need to be much younger). Mikenorton (talk) 12:58, 19 March 2009 (UTC)

I had no idea it was that hot. That means there's some point under the surface which is always a good temp for people, doesn't it ? It would also mean that "lunarthermal" power might be possible. StuRat (talk) 14:14, 19 March 2009 (UTC)

I prefer the word 'selenethermal' power. :) Dauto (talk) 23:32, 19 March 2009 (UTC)

How about princessserenitythermal power ? StuRat (talk) 04:53, 22 March 2009 (UTC)

Might have to hold back on the lunarthermal energy, the quoted values for heatflow from the Apollo program are somewhat less than the average for the earth and the average is not enough to make geothermal energy a viable option (aside from heat pumps). As far as reaching a liveable temperature, I would guess just being below the direct influence of the diurnal temperature variation would be sufficient. Mikenorton (talk) 14:56, 19 March 2009 (UTC)

That and isnt the traditional method for geothermal energy involve large quantities of water to convert into steam? Something the moon lacks. 65.167.146.130 (talk) 15:24, 19 March 2009 (UTC)

I'd say that density has an effect on it too: Neptune's density and core temperature are both higher than Uranus', for example. ~AH1^(TCU) 17:29, 19 March 2009 (UTC)

Stents

Hi does anyone know why stents, e.g. those used to counteract constriction of the common bile duct; are mesh like in appearance? Why are solid lumps of metal not used instead? Is there any point in them having a mesh structure? Thanks. —Preceding unsigned comment added by 139.222.240.225 (talk) 11:41, 19 March 2009 (UTC)

I would guess the mesh stints are flexible and move with the tissue better. I think its also good to minimize the amount of foreign matter in any body. The mesh stints can also be compressed while they are being put in place and then allowed to expand to their working dimensions.--OMCV (talk) 12:12, 19 March 2009 (UTC)

One reason may be that the mesh tubes are somewhat flexible (as noted above), a second one would be that the gaps allow for the continuing function of the walls of the duct and prevent some atrophy of a small section of the relevant passage (coronary, urinary, etc). --Cookatoo.ergo.ZooM (talk) 12:16, 19 March 2009 (UTC)

Stents have to be cylindrical to allow normal flow through the vessel (or duct) where they are located. They are inserted using a catheter that has a balloon around which the stent is wrapped. The balloon is passed into the narrow section, inflated, and then deflated leaving the stent to maintain the enlarged diameter. If solid-walled, the balloon would have to actually stretch the metal. Instead, the balloon just bends the metal mesh stent to conform to the wall of the vessel/duct (the length of the stent decreases as the diameter increases). --Scray (talk) 12:41, 19 March 2009 (UTC)

Similar to tights/stockings, really - a mesh is a very stretchy structure. --Tango (talk) 13:45, 19 March 2009 (UTC)

Well thats cleared that up - thanks to all who helped. —Preceding unsigned comment added by 139.222.241.162 (talk) 20:50, 20 March 2009 (UTC)

Help Me! I am stuck on some issues about Evolution

Evolution does away with God. No God. I then worship myself, doing whatever I want owing to no one. Evolution does not happen around me. I have never seen a chicken turn into a dog. I frequently see gaps in evolution. “Dino dung contains grass”. About the dino bird: Why on earth does a dino turn into a bird. Why do anything when the universe is just going to go kaboom in a billion years. The Creation “myths” seem alright with me because I know Volcanoes and Floods can create what Evolution scientists claim to have taken millions of years. The Bible is bullied. People use evolution for racist ideas. Evolution seems to allow racism. Compassion only came into existence because of chance. The Bible is also used to allow racism, but I read that we are to love every one as ourself. None of the: “I just evolved, no point in life, don't need to love coz love just evolved”. DNA does not grow on trees. My science teacher recons that the only way to gain more DNA so I can grow wings is to ask God for it. [Year 11 student in Perth, Australia] —Preceding unsigned comment added by 60.230.212.29 (talk) 11:45, 19 March 2009 (UTC)

You have a lot of questions there, and it might help to organize them better, say as a numbered list, if you expect answers to all of them. Also, evolution says nothing about the existence of God, just that God isn't necessary for the step of one species evolving from another (although you could still argue that God controls mutations). God may still be used as the cause of the Big Bang, etc. God (or "the gods") used to be thought of as doing everything, from making day and night to the seasons, but we now know that is all just a consequence of the Earth's rotation and revolution. In another example, we now know that the variation in children in a family is due to random combinations of DNA in chromosomes. StuRat (talk) 12:04, 19 March 2009 (UTC)

Let me say that it's really poor logic to conclude that anything you haven't witnessed personally doesn't exist. Also note that this would apply to everything in the Bible, unless you're a lot older than you seem. :-) StuRat (talk) 12:27, 19 March 2009 (UTC)

As for gaps in evolution, they are relatively small, and closing all the time as we find more fossils. Gaps in the Bible are absolutely huge, on the other hand, and not getting any smaller. For example, how did we get from Adam and Eve to all mankind ? Was there a lot of incest (as opposed to a Lot of incest) ? StuRat (talk) 12:31, 19 March 2009 (UTC)

As for your "Why do anything when the universe is just going to go kaboom in a billion years" (it's actually many billions), the same is true in the Bible, only on the order of thousands of years, isn't it ? That nasty Armageddon bit in Revelations ? And in billions of years, who knows, perhaps we will be able to travel to parallel universes which aren't about to die. StuRat (talk) 12:21, 19 March 2009 (UTC)

You said "Volcanoes and Floods can create what Evolution scientists claim to have taken millions of years". You seem to be confusing evolution with geology. There are some geological formations which are formed quickly, yes. There are others which take millions or even billions of years to form. Plate tectonics is a good example of the later, where the continents all used to fit together. In some cases, it's obvious just by looking at them that they once did. The rate at which they are moving tells us it took many millions of years for them to get where they are now. Rates of radioactive decay also tell us that the oldest rocks on the Earth are around 4.3 billion years old. StuRat (talk) 12:51, 19 March 2009 (UTC)

To take on another of your Q's, let's talk about why a dinosaur might evolve into a bird. First, feathers are useful for flight, but also provide for good insulation. There are many flightless birds, like penguins, which use them for insulation. Next, flaps of skin can develop on arms to allow for longer jumps from tree to tree or on the ground. This has happened in flying squirrels, too. Then, once these basic items are in place, even a small improvement can allow for longer jumps or glides, both of which are helpful for survival. This eventually leads to all the birds. StuRat (talk) 12:14, 19 March 2009 (UTC)

If you pray to God for wings, and they sprout out and you fly away, then, by all means, believe in God. If that actually happens, I may even join you in your beliefs. StuRat (talk) 12:46, 19 March 2009 (UTC)

Neither evolution nor the Bible can be used to define a moral code. Evolution says nothing about morality. The Bible says a great deal; so much, in fact, that it has parts that can support any moral code you want, from slavery, genocide, and hate crimes against homosexuals, to the oppression of women. So, in either case, you come up with your moral code on your own, and only use evolution or the Bible to justify what you already believe. StuRat (talk) 12:42, 19 March 2009 (UTC)

Evolution does away with the literal interpretation of the bible god; it does away with the YEC's god, but evolution has little to say to millions who have compartmentalized enough to conform their mythos to the real world. Inductive logic is what does away with god. But based on your post, I'm wasting my breath. You need to take evolution in baby steps. Start with biology 101 and move progressively. I doubt that will happen but the problem is that you're so lost in the fundamentals, your knowledge of the subject so narrow, that you can actually say something like "I have never seen a chicken turn into a dog." By saying this you show that you have no understanding of evolution at all. Not even the tiniest scintilla, but have some one or two sentence idea of "things turning into other things for mysterious reasons" that is called evolution. The poster above is trying to be helpful but he's skipping the part where we sit down with you for months and months teaching you the basics so you have the slightest understanding to put his post in context.—70.19.64.161 (talk) 12:30, 19 March 2009 (UTC)

Have a look at Introduction to evolution and let us know if you have more questions. Btw, if you asked your teacher how you could "gain more DNA to grow wings", he/she probably thought you were joking. Zain Ebrahim (talk) 12:51, 19 March 2009 (UTC)

If you "know" that volcanos and floods can cause things that scientists say take millions of years than you're mistaken. Perhaps you're thinking of a common claim that the Grand Canyon could have been created during the Great Flood. This doesn't even stand up to casual examination by a layman. A massive amount of water unleashed at once would cut a wide, shallow swath, not a sharp deep one like a canyon. (And of course, once it's completely covered, even this effect would slow greatly.) You can verify this in your backyard with a large tub of water and a garden hose.

"My science teacher recons that the only way to gain more DNA so I can grow wings is to ask God for it." He is right. The only way you -personally- will will gain additional DNA is divine intervention. Evolution is caused by children having slightly different DNA than their parents. Once you're born you're stuck with whatever DNA you've already got.

"Why do anything when the universe is just going to go kaboom in a billion years." Frankly, I've always thought the answer to this is : "To see how much cool stuff we can do before then." APL (talk) 13:24, 19 March 2009 (UTC)

And finally, just for the record, DNA does grow on trees! --Sean 13:45, 19 March 2009 (UTC)

In the form of fruit, no doubt. As for sprouting wings, eventually scientists may be able to use a virus to insert genes (to grow wings) into our DNA. However, the wings we would grow would only be decorative. To make a human capable of flight would require a total redesign of our entire body, including tiny legs. StuRat (talk) 13:54, 19 March 2009 (UTC)

You say on the first line without God you would do what you want owing to no-one. Have you asked yourself if there really is anything much different you would actually do without God looking over your shoulder? Or are you thinking that other people would behave any differently? Dmcq (talk) 14:19, 19 March 2009 (UTC)

On the subject of sprouting wings. There is a slight problem with the fact that the Angel type of construction basically adds another set of limbs when compared to ordinary things with wings like birds or bats. You'd not only need divine intervention to get wings, you'd also need a constant miracle to move them or would have to add a rather unsightly hump to your ordinary back.

Artist pictures don't show any muscles needed to move the wings. (Not to mention the joint that connects them to the body). I assume they are just a decorative appendage and your divine entity would actually provide for Levitation. 76.97.245.5 (talk) 14:57, 19 March 2009 (UTC)

Oh my - what a lot of questions. Well, now that you've asked so many - you are honor bound to slowly read through ALL of my carefully thought-out answers! No cheating and skipping the ones you don't agree with!

• Evolution does away with God. No God. - Not precisely. Evolution does away with the need to use god or gods to explain how we came to be. You are still at liberty to assume that god(s) made the world in one night on September 12th 1962 - and just made it all "look" like there was evolution. It's a pretty crazy thing to believe - but if you've gotta have a god to sleep at nights - there you go.
• I then worship myself, doing whatever I want owing to no one. - Well, you COULD - but you live as a part of society that imposes rules in order to make life bearable - and if you do literally "what you want" - then the odds are good that other people will get pissed about it and you'll find that you are physically unable to continue doing what you want. Societal pressures to behave according to the norms are considerably more effective than religious pressures simply because the punishment or restraint is immediate and vastly more certain. I'm fond of pointing out that the Bible is the most shop-lifted book in the USA. Clearly people who are going into bookstores and stealing them aren't afraid of divine retribution.
• Evolution does not happen around me. I have never seen a chicken turn into a dog. - No, but if you lived in New York, you'd have seen rats turn into Warfarin-resistant rats that thrive on eating rat poison. If you worked in a hospital, you'd have seen tuberculosis-causing-bacteria turn into tuberculosis-causing-bacteria-that-you-can't-kill-with-antibiotics. The process is relatively slow. However - (for example) humans appear to have evolved to become lactose-tolerant over a space of a few thousand years - and the process isn't complete yet...that's truly evolution in action. There are MANY cases where evolution can be observed happening for real right in front of your eyes in a test-tube. But to change a chicken into a dog might require millions of years of evolution - and that's something you obviously can't see happening before your very eyes. Just because a process takes a long time isn't a reason to assume that it's not true. It took a long time for a relatively small river to carve out the Grand Canyon...but we don't go around denying that this is how it happened.
• I frequently see gaps in evolution. - no you don't. You frequently hear like-minded "intelligent design" idiots CLAIMING that there are gaps in evolution. You've never personally spotted one. In fact, science is still plugging holes - finding fossils isn't something you can do "on demand". If you don't happen to have a fossil that shows something halfway between a smooth-skinned fish and one with scales doesn't mean that there is a horrible "gap" that completely blows away the theory - it simply means that nobody has yet found a fossil of that particular animal. Because we HAVE found long chains of very similar animal fossils that DO show continuous, gradual, gapless change from one species to another - we KNOW for 100% certain that those particular species evolved. And with every 'chain' of fossils we find, the gaps get smaller and less frequent - but to expect to have complete evidence for the pathway from every single creature to every single other creature is stupid. There comes a point (and we're WELL past it) where the evidence is simply overwhelming and the gaps are perfectly explicable. "Absence of evidence is not evidence of absence."
• About the dino bird: Why on earth does a dino turn into a bird. - Because of some sort of evolutionary pressure. If running along the ground is too dangerous because of predators (say) then maybe a small genetic change allows the creature to have the musculature to climb trees. That creature does better than the earth-bound dinosaurs - so it survives when the ground-based ones are all eaten by predators. However, the ones in the trees still have to climb down out of one tree and up into the next - so they are vulnerable still. If one baby tree-dino happens by luck to have genetically stronger legs and can jump from a tree to another nearby - it'll spend less time on the ground and it (and it's offspring) will thrive while the ones that have to climb down don't. Now, they only have to go to the ground to get from one clump of trees to the next. But if they evolve a flap of skin or feathers and lighter weight bones - they'll be able to glide between trees that are still further apart. Then they may evolve powerful muscles to allow them to flap a bit. Before you know it (and over half a million years) you have birds. Then something happens to all of the predators (like maybe a meteorite kills them all) and the birds have no more predators on the ground - so evolving to be more capable on the ground so you can eat stuff you only find down there - makes sense. Now you have flightless birds like chickens. When the predatory mammals come back - they evolve into ostritches that can kick the hell out of a predator...and so on and so on.
• Why do anything when the universe is just going to go kaboom in a billion years. - Indeed, why? Guess what? It's evolution again. If a bunch of humans got it into their silly heads that they should just lie in bed until they die because life is pointless - then they'll fail to pass their crappy genetic makeup onto any children - so only the kids of the people who suck it up and try to make something of themselves will survive into succeeding generations. Before you know it - we've evolved a powerful drive to survive - to have children and to look after them. Hence we are genetically PROGRAMMED not to shrug our shoulders and give up on the world.
• The Creation “myths” seem alright with me because I know Volcanoes and Floods can create what Evolution scientists claim to have taken millions of years. - Bullshit. Please explain how a volcano or a flood turns a dinosaur into a chicken? I explained how evolution can do it. What you are REALLY saying is that this is all too hard for your tiny little brain and you're too stupid to think for yourself so you'd rather be spoon-fed a bunch of nonsense than to actually examine how the universe works - look at the evidence - take your sorry ass down to the nearest decent natural history museum and ASK one of the curators if they can show you some fossil sequences to help you to understand. Nope - it's better for you to have some idiot in a silly costume get up there on a sunday morning and tell you that it all happened by magic. Well, good luck with that!
• The Bible is bullied. - The Bible is WRONG. I've actually read the Bible - not just a verse here and there as instructed by some Sunday school teacher. I started at page one and read it all the way through - like a real book. It's CRAP! It's self-contradictory, inconsistent, flat out unbelievable. It starts off with this rabid lunatic of a god who does the nastiest things imaginable for the smallest reason - to someone who is supposed to be kind and caring and it's all rainbows and unicorns. You actually have to read the book with open eyes to see what a pile of steaming crap it really is.
• People use evolution for racist ideas. Evolution seems to allow racism. - I don't understand why you'd say that. People have certainly used the Bible to promote racist ideas. Just take a look at the KluKluxKlan nut-jobs! They are passionately religious - and equally passionately racist - and they justify every word of their racist nonsense from the Bible.
• Compassion only came into existence because of chance. - Actually, there is evidence that compassion and being nice to people and stuff like that is evolved too.
• The Bible is also used to allow racism, but I read that we are to love every one as ourself. - And I read (in the Roman Catholic/Lutheran bible - the first of the 10 commandments - that if you worship an idol - your children, grandchildren, greatgrandchildren and great-great-grandchildren will be punished. Sheesh! So if my great-great-grandfather was worshipping idols - I get punished for it!?! Nice god! The bible also says that if your son swears at you - you should kill him. (Although you aren't actually ALLOWED to kill him...hmmm tricky). Really - it doesn't stand up to close examination.
• None of the: “I just evolved, no point in life, don't need to love coz love just evolved”. - Nobody who believes evolution to be true says that. We have EVOLVED to have point to our lives. Heck - I'm an out and out atheist - I love life. I had fun as a kid learning stuff - I loved - I married (although a civil contract would have been OK by me). I have a son - we enjoyed bringing him up right - teaching him moral values - things that make society run well "Don't kill people - don't steal things - but go ahead and covet your neighbours ass - I don't give a damn about that". We've EVOLVED those concerns because we're a tribal society. Getting on with a village of people is how we're programmed to be. Passing our DNA onto the next generation is something we're powerfully driven to do. Anyone who didn't have those drives - passed on in their DNA from their parents - would not have children of their own - their DNA would not get passed on. So only the people with genes that give them the drive to have children get to pass their DNA on...so after not too many generations, pretty much everyone wants kids - most people like raising them. It's evolution that does that.
• DNA does not grow on trees. - yes it does! :-)
• My science teacher recons that the only way to gain more DNA so I can grow wings is to ask God for it. - your science teacher is 100% correct in that! Certainly you can't "gain more DNA" by any known scientific means - you're absolutely stuck with what you were born with. If/when you pass your (and your partner's) DNA onto your children, their DNA will be a little bit different - and the DNA of THEIR children will be different still. If there is an evolutionary pressure for humans to sprout wings and fly - then perhaps over tens of thousands of generations, that MIGHT happen. Evolution is a slow process. So - if there is a god - you could certainly pray for DNA to grow wings with...and by all means try that. Pray your darnest...plead with God for those wings. Do you REALLY think he'll give them to you? I don't.

SteveBaker (talk) 18:53, 19 March 2009 (UTC)

Steve, the refdesk is not a soapbox. —Preceding unsigned comment added by 65.167.146.130 (talk) 19:10, 19 March 2009 (UTC)

Soapboxing refers to a situation where someone pretends to ask or answer a question, but is actually just propagating his agenda (or, in some cases, doesn't even bother with the question part at all). Clearly, Steve is answering the original poster's specific questions, and doing a pretty good job of it, too. Yes, absolutely, you can also tell that Steve has opinions about the matter at hand, but he's not expressing them instead of answering the questions. -- Captain Disdain (talk) 19:30, 19 March 2009 (UTC)

I actually don't see a question from the OP, merely a long list of statements.65.167.146.130 (talk) 19:57, 19 March 2009 (UTC)

He may not be soapboxing, but Steve, please dont bite. Livewireo (talk) 20:07, 19 March 2009 (UTC)

As an aside, I will worship any god, demon, or other deity that gives me the capacity for free flight without any technological support. (I would prefer a pair of wings, but Superman-style flight would also have its advantages.) It goes without saying that I expect this ability up front before I start with the worshiping. I'm an atheist, But I can be bought. :-) APL (talk) 21:19, 19 March 2009 (UTC)

I'll join you in that religion, but if it's going to be superman-style flying someone had better give me a cape - I'd look stupid without one! --Tango (talk) 23:08, 19 March 2009 (UTC)

Could I take the free flying stuff - then weasel out of the whole worshipping thing afterwards? SteveBaker (talk) 23:34, 19 March 2009 (UTC)

Might be unwise. The Lord giveth, and the Lord taketh away - and if He taketh away thy flying at 25,000 feet, thou art screwed. - Eron^Talk 23:36, 19 March 2009 (UTC)

That's why sensible gods don't give all their rules in written form - it makes it too easy to find loopholes. If you keep the rules nice and vague you can make them fit the situation however you need. --Tango (talk) 23:39, 19 March 2009 (UTC)

The Bible is WRONG Hm Steve, what about the very first chapters of the Bible (and some other chapters) being just symbolic? One should read the Bible for it's moral teaching, it's not intended to be used as a science book. Too bad some zealots try to regard it (and try to enforce it) still as a science book, destroying the main concept behind it... and by doing so they are making religion to look ridiculous too. —Preceding unsigned comment added by 79.116.91.3 (talk) 01:19, 20 March 2009 (UTC)

You haven't read it have you? I tell you - start from page 1 and read to the last page...it's an education. The old testament is NUTS - yeah, yeah - it's all symbolic. So why the heck does it matter if it's just a work of fiction? I don't think the stories surrounding the ten commandments are intended to be symbolic. That bit is really pure slapstick - the guy spends an age up there chatting with god - chiseling the words into literal stone tablets - and when he gets back he drops them (oopsie!) and the break so and has to go back up to god and get another set...but this time, God has obviously lost his train of thought because the second set have completely different rules...this combined with a God who really needs to switch to decaf. SteveBaker (talk) 04:03, 20 March 2009 (UTC)

Symbolic or not, you can't just cherry-pick the parts that sound nice -- bring up the cuddly "let's all just get along" bits as proof of how wonderful moral guidance the Bible provides and ignore the crazy-ass "the hero of the story murders 200 people for their foreskins to prove his righteousness and get some poontang" bits.

Oops, that was me. I forgot to sign. -- Captain Disdain (talk) 12:08, 20 March 2009 (UTC)

Let's just play the Devil's advocate again :) What if the moral is contained in the New Testament, and the old one is just for showing... well, how crazy it was before it/would be without it. --79.116.89.247 (talk) 23:46, 22 March 2009 (UTC)

But that is simply not what it says. The Old Testament is clearly full of commandments from God. It was also written hundreds of years before the New Testament, so clearly wasn't intended to be compared to it. --Tango (talk) 00:00, 23 March 2009 (UTC)

If the moral is contained in the New Testament, then you're cherry-picking. You're making a judgment call on what parts to glorify and what parts to ignore as insignificant. The problem with that is that if it's up to you to figure out what's right, then you're by definition following your own morality, not some great ancient divine wisdom. You can't have it both ways. (Anyway, the New Testament isn't that much better. It still advocates slavery and doesn't exactly say a lot of nice things about the value of women, for example.) -- Captain Disdain (talk) 06:20, 23 March 2009 (UTC)

Moral teachings as in "The most important thing for anyone to do is to cater to the megalomanic whims of their creator."? No thanks. --Tango (talk) 14:48, 20 March 2009 (UTC)

Just by the way, I can always, always tell when it's SteveBaker who is posting. Your style of writing, it's etched into my memory. Especially with allcaps for EMPHASIS (no pun intended). ~AH1^(TCU) 01:39, 20 March 2009 (UTC)

Never mind the writing style (which is very distinctive, I agree) - you can tell from the length! --Tango (talk) 14:45, 20 March 2009 (UTC)

SteveBaker is not the only one who writes LONG arguments, replies, and questions, you know. :-) ~AH1^(TCU) 17:24, 21 March 2009 (UTC)

A chicken turned into a dog? Here you go.[16] --JGGardiner (talk) 02:46, 20 March 2009 (UTC)

Ah - and I was thinking [17]. SteveBaker (talk) 03:51, 20 March 2009 (UTC)

Evolution does away with God. I know of no serious student of evolution who would postulate such a thing. In fact, evolution ignores God, simply because one is science and the other religion. Or, if you insist on mixing the two, then simply acknowledge that there is nothing at all about evolution that is not compatible with a God. What it is incompatible with is creationism. Very different, unless you're a religious extremist. DOR (HK) (talk) 04:35, 23 March 2009 (UTC)

'I also have read the bible several times.'Some of the old testament reads like health suggestions.' Such as not eating pork.with no refrigeration and not knowing about food poisoning or parasites from uncooked or undercooked food, eating the meat of a scavenger(pig) could be deadly (Gods ultimate revenge)also, marrige would be a way to make the survival of children more likely. With multiple wives because of the high mortality during birth.etc. etc. etc. resource allocation for the in group, and damnation for the outgroup. Furthermore, the origonal poster does not take non Judeo/christina religions into accountHinduism, is older, and creationism according to the Rigveda, only vaguely says"there was nothing,then there was"Crazybearr (talk) 07:23, 23 March 2009 (UTC)

Wow, I have a bad day at school, go hiking for the weekend and come back and ... wow! Thank you to all the people who have contributed to this section, you are the people who make Wikipedia what it is. I have read through all your writing and even went so far as to observe other contributions made by every user. I am impressed. I will address Steve first since he answered me the most. Year 11 Student Perth, Western Australia 60.230.212.29 (talk) 09:03, 23 March 2009 (UTC)

Dear Steve, I studied your answers concerning evolution. However I cannot agree with you for most of it, and nor can my wise, and enjoyable, science teacher.

• Their would of being a lot of what you call incest when there was only a few people on the Earth. But back then it was not considered bad because their was no side effects, with perfect genes there was no problem medically.

• 20 years ago people scoffed at the Hittite civilisation that the Bible describes. Look it up and you will find that they are as real as the brain in your head.

• I vote the the page named Introduction of Evolution should be changed to Introduction of Specialization. Even so, the evolution page is quite confusing.

• Sorry for confusing you on my Volcanoes and Flood thing. What I meant to say is: “Volcanoes and floods can create and destroy what you believe to have taken millions of years?” Your are not telling me that radioactive decay can actually correctly tell me the age of a rock. I have sand and plants in my garden. If, say, I decide to test your experiment in my garden, with unlimited and copious amounts of water, it would go like this. Firstly the plants will be uprooted because the top soil is being washed away. The plants will still survive in the water, almost the same thing as hydroponics. Then the rest of the soil will wash away, causing a massive hole in my garden, likely a few other gardens and houses as well and a large river. A lot of water has been consumed. I am now using a massive hose pouring thousands of litres on my former garden. The water starts to erode the bedrock and has turned into a flood. A canyon, not half the size of your impressive Grand Canyon, has been formed.

• Show me pictures of the in betweens that Evolutionists claim to have existed and did actually exist. Your description of the Dinosaur turning into a bird made sense. But show me some pictures of these dino-gliders. I am interested. But you can also tell me how something as complex as the human eye evolved, just like you told me about the dinosaur evolution. Do not worry about being to scientific for me.

• Evolution says to God “We do not need you to explain how we came into existence” Precisely does away with God.

• About your statement involving the fact that the Bible is the most stolen book in the world. Well, think about this medicine is stolen with out thought that it is wrong, they need to save themselves or someone else from sickness.

• Hitler, Lenon, and Darwin are all people who have used evolution as an excuse for racist ideas. Darwin wanted Australian Aboriginals skinned and sent to him so he could study what he thought mistakenly thought of as a missing link. Hitler thought that his exterminations of Jews and his Master Race breeding program were just helping evolution go faster. Lennon authorised an experiment on African people and monkeys so he could create a half monkey half human slave army because monkeys are “related” to us, and therefore might just be able to breed with us. African people, according to the evolutionary idea are lower on the evolved scale.

• My statement concerning DNA growing on trees was small and was taken light-heartedly. DNA can be copied, mistakenly copied, lost (As in the case of your New York rats and bacteria, which is unfortunate to hear about.), but NEVER found, created or gained. Imagine a computer program, it had to be PROGRAMMED, right? This particular one is programed to copy itself. It is not on a perfect computer so data is lost and corrupted when it copies itself again and again. Sometimes those corruptions and lost data are good for it because the computer is always changing. How can something as complex as even a computer program evolve, how did it get there gradually? It could not.

• Coveting my neighbours ass is disrespecting her. I do hope your child is not disrespectful, just like you were to me. Calling my friends stupid, my religion crap and putting down what I believe in. But I will not hold that against you or Charles Darwin.

• If you believe the Bible, yet say that some of it is wrong, then, how can you believe in the Bible? If the Bible just contained people that were all cherry then would the Bible still be believable. The Bible contains a whole lot of information about David, second king of Israel, not all of it is good, he was not perfect, but the Bible is.

• In telling me that I am just PROGRAMED to live, that evolving and procreation is my only objective, that compassion and being nice to people just evolved, and that I can make up any moral code I like, then you have given me an excuse to commit suicide. But fortunately I have no desire to do so. Being a Christian not only helps me sleep at night but gives me a true purpose, not just something that has evolved and will evolve again. I can see a rainbow and know who to thank. I know that God loves me and made me special, just like he did for you. God would rather you believe in Him because you LOVE Him, not coz of fear or coz He can give you wings.

• Evolutionist - nothing to lose if there is no God
• Christian - nothing to lose if there is no God
• Evolutionist - eternity to lose if there is a God
• Christian - eternity to gain if there is a God

Then can you please show a better answer to why I should continue living. If I believed in evolution that is. Year 11 Student Perth, Western Australia 60.230.212.29 (talk) 09:03, 23 March 2009 (UTC)

I usually refrain from answering questions about evolution because the discussions never seem productive. However, there are several egregious comments that need to be addressed here:

• "African people, according to the evolutionary idea are lower on the evolved scale" -- This is an utter misrepresentation of evolution, and no honest person who truly understands the underpinnings of evolution would say such a thing. This would be like you saying that your 2nd cousins are "lower" on the "evolved scale" (whatever that is) than you are. Where on earth did you get the idea that evolution somehow ascribes a "higher" or "lower" degree of "evolved"-ness? This is utter nonsense.
• "...you can also tell me how something as complex as the human eye evolved" -- This is a common argument by proponents of "irreducible complexity" as some sort of "proof" that evolution does not occur. It may be true that we don't have a complete explanation for every single step in the process (yet), but it is pretty self-evident if you start to actually think about the problem that evolution of the eye is no different than any other part of the body. Others have already addressed these examples in great detail. Read the article on irreducible complexity. Understand what is being argued. There is no "proof" to be offered in simply stating that something is "too complicated to understand". It is lazy, non-scientific nonsense.
• "In telling me that I am just PROGRAMED to live, that evolving and procreation is my only objective, that compassion and being nice to people just evolved, and that I can make up any moral code I like, then you have given me an excuse to commit suicide." - this is a very bizarre interpretation of what evolution teaches us about life. Why do you use the example of suicide? Evolution doesn't give you an "excuse" to do something. It just explains how natural selection might act over millions of years to shape the behaviors exhibited in a species. We have eons of evolutionary history that selected for adaptive features, including fear, aggression, lust, greed, etc. etc. etc., yet our brains have also evolved over millions of years to excel at problem solving and therefore logic, and by logic human societies can arrive at reasonable standards of behavior that allow all of us to thrive and co-exist despite our most base instincts, therefore improving everyone's ability to pass on their genes. That some members of society do not comply with these standards of behavior, and cheat others for their own gain, is part of the evolutionary process as well (and not always rewarded over the long-term). That suicide exists is also part of the evolutionary process. If you know anything about cell biology you will recognize that there are well-regulated programs for cells to commit suicide. This process is fundamental to developmental biology and actually prevents cells from becoming cancer if they are malfunctioning -- cell suicide is therefore quite adaptive at the level of the whole organism. At a higher level, I would argue that evolution has endowed our species with a great aversion to suicide (otherwise we'd no longer exist) and that only under extreme circumstances do people consider this option. How does this conflict with evolution?

Alas, I have spent too much time responding and I fear that I may have been feeding the trolls. You will either spend time using your brain to consider these points, or you will simply be lazy and accept what you are told to believe. Life is yours to do with what you will. --- Medical geneticist (talk) 15:19, 23 March 2009 (UTC)

My pet name for the eye thing is argument from lack of imagination. —Tamfang (talk) 00:17, 24 March 2009 (UTC)

Student:

• About incest, what's your point?
• 20 years ago people scoffed at the Hittite civilisation .... Did your preacher say who scoffed? I have here a dictionary published in 1950 – yup, a rather long entry about the Hittites, their history, their ethnic affinities, and a mention of the decipherment of their language.
• You are not telling me that radioactive decay can actually correctly tell me the age of a rock. Yes, that's what (whoever) is telling you. Would you like to know how?
• Show me pictures of the in betweens that Evolutionists claim to have existed and did actually exist. Yah, so you can demand fossils between those and their neighbors? Show me a picture of the missing link between you and your mother.
• Evolution says to God “We do not need you to explain how we came into existence” Precisely does away with God. Only monotheists, it seems to me, are so hung up on creation. Polytheists have their creator-gods, but the creator usually isn't the most important one in the pantheon. Does evolution do away with their other gods too?
• Hitler, Lenin, and Darwin are all people who have used evolution as an excuse for racist ideas, bla bla bla. Can you point to any belief of any kind – religious, scientific, political, aesthetic – so pure that no wicked or misguided person ever adhered to some version of it?
• Imagine a computer program, it had to be PROGRAMMED, right? ... How can something as complex as even a computer program evolve, how did it get there gradually? It could not. You might find genetic programming interesting.
• I do hope your child is not disrespectful, just like you were to me. Calling my friends stupid, my religion crap and putting down what I believe in. Why should anyone be more respectful to your religion than you are to science?
• Then can you please show a better answer to why I should continue living. If I believed in evolution that is. Well, I continue living because I haven't seen all the beauty that I might see – or make.

—Tamfang (talk) 00:17, 24 March 2009 (UTC)

Technically, I should put this on Steve Baker's talk page but I can't figure out how.

Anyway, I enjoy Steve's responses and find them most informative. HOWEVER, his attitude toward the original poster was rude and condesending. I found it hard to focus on his arguements when his disrespect was so blatant. Steve: you owe the guy an apology. I guess you must have had a bad day.

Soami Oil?

I was at a trendy restaurant yesterday and they served a salad dressing made of balsamic vinegar and "Soami Oil". Surprisingly, no one could tell me what Soami Oil is. And there is no entry for it on Wikipedia. Any idea what it is? And is it even legal to serve a substance that no one can define? --67.66.110.148 (talk) 15:15, 19 March 2009 (UTC)

Just a wild guess, but there is Radha Soami Satsang Beas. It might be the newest fad, sort of Ayurveda used to be "in" and every marketing department tried to get it on their label.76.97.245.5 (talk) 15:38, 19 March 2009 (UTC)

Another very long shot, there's a company in Pune, India called 'Swami Oil Industries', that appears to make edible oils. Mikenorton (talk)

Laser safety

Is there something wrong with the graph at the start of Laser safety#Maximum permissible exposure? As I am interpreting it, the longer that you are exposed for, the higher the dose you are allowed to receive. That seems completely backwards. The second graph looks much more sensible. Should I just delete the first one? -- SGBailey (talk) 15:57, 19 March 2009 (UTC)

I haven't checked to see if it agrees with the source, but it seems to make sense. It's a graph of total energy absorbed (per square centimetre of eye) against time, so it's saying that the more total energy you absorb, the more time this dose has to be spread out over for it to be safe. Algebraist 16:14, 19 March 2009 (UTC)

Indeed. The difference between the two graphs is that the first is talking about energy density (J/cm²) and the second power density (W/cm²). The same amount of energy over a longer time is less dangerous because it corresponds to lower power. The same power over a longer time is more dangerous because it corresponds to more energy. --Tango (talk) 16:23, 19 March 2009 (UTC)

Ahh. OK. Thanks -- SGBailey (talk) 17:03, 19 March 2009 (UTC)

String theory

I've often heard that the mathematics behind string theory is really, really, really complex and that few can interpret the equations, let alone understand it. Could anyone provide an example of where I can see this stuff? I don't intend to try and understand it, I'm just curious to see how complicated we're talking here. —Cyclonenim (talk · contribs · email) 17:46, 19 March 2009 (UTC)

You can read some of it in this Google Books entry: [18] --Sean 17:57, 19 March 2009 (UTC)

What's that smell?

Hi. Recently on the non-residential sub-urban streets, especially those with lots of large trucks and side-road sand, I've noticed a particular strong and intermittent smell. It smells rather like three parts glue, two parts rubber, one part latex, one part chlorine, one part automobile exhaust, half a part paint, half a part sand and asphalt, half a part vinegar, a quarter part garbage, and a quarter part gasoline, co-mingled together. Sorry about my confusing decription, but I find it easiest to compare unidentified olfaction to other smells, and idea what it is or what causes it? Thanks. ~AH1^(TCU) 17:54, 19 March 2009 (UTC)

Where do you live?--Shantavira|^{feed me} 18:13, 19 March 2009 (UTC)

In S. Ontario, in the GTA. Does that help? ~AH1^(TCU) 18:30, 19 March 2009 (UTC)

It could be the asphalt they use to plug potholes. Is there a lot of black patches on the road that look like shiney black glue mixed with rocks? Livewireo (talk) 19:51, 19 March 2009 (UTC)

It may not be entirely out of the realm of possibility that you are smelling exactly what you have described depending on the surroundings. Truck exhaust, asphalt, garbage haulers, and any typical manufacturing facility (if there are any close by) can all be adding to the mix. cheers, 10draftsdeep (talk) 20:27, 19 March 2009 (UTC)

Here in North Carolina, lots of trees are in bloom right now, and many, like the Dogwood and Bradford pear trees in my neigboorhood have a rather pungent smell. It reminds me of methylamine sorts of smells (mildly like rotting fish), but lots of blossoming trees do give off odors that many people find unpleasant, like this one. Or it could just be all the stuff noted above. --Jayron32.talk.contribs 00:02, 20 March 2009 (UTC)

Are you talking gravel roads or paved? And what's your current thaw state? It could be patch asphalt (per Livewireo, you will see the patches), it could just be a winter's worth of crap melting and starting to rot/vapourize. And they may be putting non-clumping agents in the sand spread all winter too. I always found in Ontario that you could call up the local Works Department and they would be happy to answer questions and/or go check it out. Franamax (talk) 21:36, 20 March 2009 (UTC)

Pharmacological naming convention

I was wondering if there was any convention/rule/guideline for naming new medicine? I see there is a nomenclature for enzymes. Is there anything similar for drugs, such as anesthetics, etc.? --BorgQueen (talk) 18:38, 19 March 2009 (UTC)

Check out International Nonproprietary Name for the various systems available. --Sean 19:50, 19 March 2009 (UTC)

sinus operation......

My friend is suffering frm sinus infecion.....he drinks a lot of cold drinks..but at d moment he is suffering frm hi fever nd head ache. he consulted a doc. nd he said he has got cough depostied in his head. the doc. has given him medications. and said if these dont work....he needs an operation. i m a bit scared .is it something serious or is it ok....????????? pls suggest me wid something......... —Preceding unsigned comment added by Sweetgirl290608 (talk • contribs) 18:39, 19 March 2009 (UTC)

We are not medical professionals here and we can't give medical advice regarding how serious your friend's case may or may not be. For general information about sinus infections, you should read the article on Sinusitis. - Eron^Talk 18:45, 19 March 2009 (UTC)

Specifically, see here. We cannot offer you anything more than this, please tell your friend to see a doctor, and if you're interested, ask to go with him too. —Cyclonenim (talk · contribs · email) 18:46, 19 March 2009 (UTC)

Focalin shortage?

I've been trying to get a prescription of focalin refilled for about three weeks. They pharmacies say they haven't been able to get it and no one else has either. I asked if it had been recalled and they said no. Is there a shortage? Did they quit making it? Why aren't they able to get it?

I tried to find out who makes Focalin so I could ask them, but I could not find it. Bubba73 (talk), 18:48, 19 March 2009 (UTC)

I don't know the answer to your main question, but the first line of our focalin article says that this company produces it. —Cyclonenim (talk · contribs · email) 19:32, 19 March 2009 (UTC)

Also this company according to our Dexmethylphenidate article. Mikenorton (talk) 19:48, 19 March 2009 (UTC)

You should ask your doctor for help. S/he probably has samples of the drug that can tide you over until you can get a supply, and also contacts in the drug industry who will be very motivated to get you back on their product. You can also legitimately order scheduled drugs online after doing some paperwork. --Sean 19:42, 19 March 2009 (UTC)

I did call them today, they are supposed to get back to me. Sorry I missed the manufacturer in the article. Bubba73 (talk), 21:14, 19 March 2009 (UTC)

I couldn't find a pharmacy that had the medication, but the doctor found one. Bubba73 (talk), 16:38, 20 March 2009 (UTC)

doors

I had always assumed the huge old wooden doors with the rusty metal hinges were made of oak and iron, but I recently discovered these two materials don't work very well together. What actually happens if they are put together, and what do people use instead? 148.197.114.165 (talk) 21:16, 19 March 2009 (UTC)

Brass is a possibility. Wrought iron surface is different from cast iron. Annealing doesn't mention it, but this article does [19]. Not sure whether that would affect how it interacts with oak. Since oak was used for tanning presumably before it was used for doors, people probably knew about it's properties. AFAIK oak was often soaked and dried before it was used in construction. They also used pitch as surface treatment. My money would be on the Tannins in the oak wood eating your iron. Some of them are acids. 76.97.245.5 (talk) 22:26, 19 March 2009 (UTC)

I'm not familiar with the details about how they would react, but I would note that common writing ink until very recently was iron gall ink, made from iron compounds and tannin rich oak galls. -- 76.201.156.15 (talk) 03:32, 20 March 2009 (UTC)

Iron through wood accelerates the decomposition of the wood by feeding bacteria an essential element in short supply. Also you get the black staining due to the iron tannin compounds. Graeme Bartlett (talk) 05:22, 20 March 2009 (UTC)

So what could be used instead to have a similar appearance without any of these problems? And would steel have the same effect as iron? 148.197.114.165 (talk) 22:35, 22 March 2009 (UTC)

Synthesis of Vanillin from Benzene

I am currently studying organic chemistry, and I was curious how this particular synthesis could be accomplished. These are the steps I used, and I would like someone to tell me if they are correct. No, this isn't a homework problem, I was just curious how this could be accomplished. I know it's not the most economical way to synthesize it; I was just curious.

1)I used Friedel-Crafts alkylation (CH₃Cl & AlCl₃) to add a methyl group.
2)I added a diazonium group to the para position using NaNO₂ and HCl.
3)I added PCC to oxidize the methyl group to an aldehyde. I'm not sure if I used the right oxidizing agent here.
4)I brominated the compound with Br₂ and FeBr₃.
5)I replaced the bromine with a methoxide group by adding sodium methoxide.
6)Finally, I converted the diazonium group to a hydroxyl group by adding an aqueous acid (H₃O⁺).
CalamusFortis 21:59, 19 March 2009 (UTC)

PCC may not work. PCC generally is specific for taking alcohols to carbonyls. I don't think it is strong enough to take a simply alkyl group all the way to the carbonyl. The other steps look OK, so long as the methoxide will not also substitute the diazonium. You may also want to protect your aldehyde once it is made; else you may end up with unwanted side reactions like the Aldol condensation. See Protecting group for more info on this. --Jayron32.talk.contribs 23:47, 19 March 2009 (UTC)

I see a few problems here, especially if this needs to be any sort of practical (vs "looks possible on paper") approach:

1 Getting a methyl electrophile is probably pretty hard (think about stability of carbocations). Might work, but would be easier to put on...well anything else. Given that you're going to oxidize it, could even be an ethyl or isopropyl, since those additional carbons can be cleaved in step 3.

2 To get diazonium (Ar-N₂⁺), you use those reagents starting from Ar-NH₂. For a simple aromatic, those give you the nitroso (Ar-NO). Which could be reduced to the amine.

3 Jayron is right...PCC only oxidizes alcohols well. Need something stronger and mechanistically different for benzylic position (I think KMnO₄ is standard).

4 Your ring is *very* electron-deficient at this point (diazonium and aldehyde are electron-withdrawing) so doing another electrophilic aromatic substitution is probably too slow to be practically useful. And I don't think you would get good positional control. Diazonium is probably a strong meta-director and you want to Br go ortho to it.

5 Given how electron-poor the ring is (now with 3 inductively withdrawing groups!) an addition/elimination mechanism for this substution might work, but it's clearly *not* an S_N2-type displacement and you have the risk of forming benzyne and then getting the nucleophile adding at a different position. Heck, you've got the diazonium too, which is a much better leaving group. Although it might be unlikely for it to have stayed attached this long.

Overall, might be better to activate the ring first as aniline, then put the para and then ortho substituents on (the NH₂ would make the electrophilic reactions go faster whereas diazo and carbonyl each make it go slower), and last diazotize and convert to the hydroxyl. DMacks (talk) 00:04, 20 March 2009 (UTC)

It should also be noted that synthesizing ANYTHING from benzene is pretty much a pointless exercise; benzene is fairly chemically inert, and substituted aromatic compounds are readily availible. It's about as useful as synthesizing anything with only methane as a starting material. It is theoretically possible, but practically pointless. Our article on Vanilin gives numerous other synthetic pathways to make it, and none are as convoluted as taking it from unsubstituted benzene. If this is a homework problem, I sympathize with you, and say that you should have enough between your initial ideas and those of myself and Dmacks excellent additions to put together a workable synthesis; just know that this is a purely academic exercise; no real chemist would do it this way... like, ever... --Jayron32.talk.contribs 02:54, 20 March 2009 (UTC)

Free will

Everything is life is subject to the laws of physics, and therefore act accordingly. If you drop a rock it will fall down, if you flip a coin it will fall with some outcome. My question is, isn't everything predetermined? Because everything I do, every action every human being and object does in the world is because of the laws of physics. Am I right in saying that if you flip a coin, flicking it with your thumb with a specific amount of force in a specific environment (something like wind, no wind, rain) everything happens because of physical interactions (e.g. a drop of rain falling on the coin) and could only happen in one way. What I wanted to know, is this true? Is there anything in nature that's random? Is there anything that, given the same environment, given the same forces and objects at the same time- would result in something... else? Can two occurrences that are completely the same in every possible metaphysical (I don't know what that word means, it just sounds smart) manner end up.. not being the same?

I hope I've gotten my point across, what I basically mean to ask "is there anything in life that is really random". I don't have much knowledge of quantum mechanics but I've heard that on a quantum level random things do occur, but my question is whether they are really random? To someone like me who doesn't know much about quantum mechanics, it seems impossible that two coin flips that are the same and are affected by the all the same forces and hit the exact same table on the same place should produce different results. If so, how can there be free will if every action we take is because of some chemical or physical reaction in our environment or bodies? --BiT (talk) 22:31, 19 March 2009 (UTC)

You might find the articles about chaos theory and the butterfly effect interesting. They show that even in a truely deterministic world there is still room for unpredictability. With respect to your question about quantum mechanics: Yes, in the standard interpretation of quantum mechanics there is true randomness in many situations, radioactive decay for instance. Dauto (talk) 22:56, 19 March 2009 (UTC)

I would like to add that despite the fact that your line of thought is quite common, I find it very puzzling. I see free will as a sentient being's ability to make good choices given the circunstances. Good choices are more often based on logic than on randomness. Dauto (talk) 23:15, 19 March 2009 (UTC)

No - there are at least two or three reasons why things aren't predetermined...firstly there is quantum randomness - secondly there are chaotic systems. Both of these things guarantee that at least in some situations you can't predict the outcome of some future event with perfect certainty. At least once during the infinite life of an infinite universe, all of the molecules in your rock will spontaneously leap 6" to the right and not fall as you expected. Well, OK - that's pretty rare - but there are certainly 'macro-scale' things that you can't predict. There IS perfect randomness.

However, I don't think you can parley "randomness" into "free will". I don't think we have free will...quantum randomness and chaos theory notwithstanding.

SteveBaker (talk) 23:20, 19 March 2009 (UTC)

SteveBaker, I agree with you that quantum randomness is a red hearing in discussions about free will. What I don't understand is why so many people equate determinism with lack of free will. As I see it, exactly the opposite is true. Total randomness destroys free will and determinism preserves it. Dauto (talk) 05:50, 20 March 2009 (UTC)

I find it rather difficult to define "free will". It requires a concept of conciousness that is somehow outside of science in order to make any sense. --Tango (talk) 23:37, 19 March 2009 (UTC)

It's a common misconception that true randomness can be found in chaos theory. In fact it cannot. A quick read of our own article will show that these systems "appear to be random" and "this happens even though the system is deterministic". Chaos theory is about systems where the tiniest deviation in the starting condition can produce huge changes in the end condition, which makes them practically impossible to predict, but they are in principle predictable. DJ Clayworth (talk) 23:38, 19 March 2009 (UTC)

I strongly disagree. Chaotic systems might be predictable in principle - but only if you have literally infinite precision in the measurement of initial conditions....but you don't...you CAN'T - you don't have enough paper to write down all of the digits of data to put into the calculations - and there isn't enough energy in the visible universe to crunch the numbers. Even without resorting to "oh no - you can't measure things that accurately because that nice Mr Heisenberg said 'No'."...a completely classical system can be literally impossible to predict. SteveBaker (talk) 03:32, 20 March 2009 (UTC)

When we're talking about a philosophical subject like Free Will, the question is "is the future determined" not "can we predict the future". Chaotic systems are determined, whether or not we can predict them. I would submit that to deny that the future is determined we have to invoke Heisenberg and quantum; chaos theory won't do it. DJ Clayworth (talk) 14:13, 20 March 2009 (UTC)

Well - I suppose at that extreme (both of logical position and linguistic interpretation!) - you are right for truly 'classical' systems when you are only talking about predetermination and not prediction. But - of course - there are quantum effects that are truly random (in the not-predetermined sense). What chaos theory does in the real world is to magnify the true uncertainty of the quantum world into macro-scale uncertainty. In a system such as when the ultimate position of a metal-tipped pendulum swinging over two strong magnets is determined by it's starting position in a 'fractal' manner, and for some regions, the initial position of the pendulum has to be known to literally infinite precision - but for quantum/heisenberg reasons, we know that's impossible. Hence the final position of the pendulum is indeed both entirely unpredictable (even in principle) and not predetermined (in the sense that quantum effects are not predetermined). The chaotic nature of that system magnifies quantum uncertainty to macro scales. So even something as 'classical' as a pendulum over two magnets is affected by quantum randomness - and that's enough to bust open predestination. However (as I said before) I don't think that opens things up to "free will" since we cannot influence either the macro-scale chaotic system that is our brain or the quantum randomness that drives that unpredictability. I suppose if you want to equate free will with some quantum-scale randomness, then you have your "get out clause" - but it's not very convincing. SteveBaker (talk) 14:45, 20 March 2009 (UTC)

Thanks. I completely agree with you. I guess we can summarise as "quantum effects generate true randomness at the microscopic level, and chaos theory says that those microscopic causes can have macroscopic effects". DJ Clayworth (talk) 15:18, 20 March 2009 (UTC)

i think that evry thing run with aperfect order ... random theories is a sily way to avoid looking for answers , evry action on this universe will affect the whole universe by the way under the same conditions.

the problem that we are trying to explain the whole universe while we're still ignorant about alot of the world basics,even in the most trustable theories in science we have to assume that the light travel with qunstant velocity , while its not, but this assumption could twist the theory so much in ahigher level , and thats why as the science keep going we try to come up with a more accurate theories .

when you try to build lets say a 1000 mile\ hour car you will need more accurate calculations than the ones you will use to build a 150 mile\hour car .

we always try to simplefy evry thing so we can predict it , and there were evry thing goes wrong . and when evry thing go very very complex for our minds we start to use this randomness theories . —Preceding unsigned comment added by Mjaafreh2008 (talk • contribs) 02:01, 20 March 2009 (UTC)

Well - you're in good company. Albert Einstein refused to believe it too - but sadly, the fundamental randomness of the subatomic world is all too real. If your computer has flash-memory in it - then it only works because of quantum randomness. This is more than just some maybe-true theory - we can do real engineering using it and produce real products that depend on it. SteveBaker (talk) 03:35, 20 March 2009 (UTC)

I apolgose for sounding arrogant, but most people here (except Tango) are missing a very important point because they are so used to the determinism of physics being the unviolable constant in natural science. Let's start at the beginning... the determinism of physics was discovered through the efforts of various scientists like Galileo and Newton who deciphered various physical laws that governed the behaviour of physical bodies. Determinism wasn't always the accepted (or intuitively correct) principle. The discovery of physical laws went up to make up the edifice of physics which was governed by fixed laws. These laws, until the discovery of quantum processses, meant that you could predict the behavious of any physical system accurately as long as you know the state of the system (position and velocity of particles) at a given point. Now here comes the important part... at some point people (like our OP) make the mistake of extend the determinism of PHYSICS to humans as if humans were nothing more than physical systems. The difference is that there is an entity called the will, which comes into the picture to decide how we will behave. This entity of the will lies outside the purview of Physics. I am not talking matphysical mumbo jumbo here. It is an important question in the study of the philosophy of mind - extending to the concepts of materialism/dualism/idealism. In short, the determinism of the physical world does absolutely nothing to undermine the existence of free will - and you don't need quantum indeterminism or chaos theory to account for that. The question of free will is fundamentally a philosophical one, not physical. --ReluctantPhilosopher (talk) 07:28, 20 March 2009 (UTC)

What was the arrogant part - that you claim humans are more than just "physical systems" with no evidence to back it up? To me all the evidence points to humans being organisms, with which our "will" helps us maintain homeostasis and ultimately reproduce. Although the physical system can act differently, i.e. in suicide. Depression is still a very complex disorder which isn't well understood and many brain regions are involved, so I can't say specifically what is wrong which would lead to a human to kill itself. --82.21.28.65 (talk) 11:11, 20 March 2009 (UTC)

"you claim humans are more than just 'physical systems' with no evidence to back it up" - well there is no evidence to the contrary either. You are basically arguing the case for materialism. Materialism states that everything is fundamentally physical, with "will", "conciousness" etc. just being words we throw about to account for our experiences. Well it's not a settled question - and the debate is very much alive on it. Dualism and Idealism are other alternatives. I personally believe in a sort of dual aspect theory --ReluctantPhilosopher (talk) 11:55, 20 March 2009 (UTC)

Well, you're the one positing an extra-physical "will", so you're the one obliged to do better than saying "there's no evidence to the contrary". --Sean 14:11, 20 March 2009 (UTC)

Well I am not the only one positing an extra-physical will - as I said it's a subject of philosophical discussion. Will, consciousness, mind - do they exist independent of the physical - it is the subject of philosophy of mind. --ReluctantPhilosopher (talk) 14:38, 20 March 2009 (UTC)

Btw, I would perform the gargantuan feat of solving the mind body problem if I could "do better than" just stating what the different viewpoints are :D --ReluctantPhilosopher (talk) 14:51, 20 March 2009 (UTC)

Einstein only refused to believe in it until there was an overwhelming amount of evidence for it. Once that evidence was provided he accepted it, as any good scientist would. --Tango (talk) 12:39, 20 March 2009 (UTC)

I'm not sure that that is correct. My understanding is that Einstein never accepted quantum mechanic's indeterminism and tried until his death to find a deterministic model. A Quest For Knowledge (talk) 13:09, 20 March 2009 (UTC)

Well, yes, I guess you are right - he accepted most of QM, but not the Copenhagen interpretation of it. As I understand it, it was about 17 years after his death that experiments were performed that conclusively showed things like the EPR paradox should be resolved in favour of QM. I don't think he disagreed with anything that was firmly supported by experimental evidence that was available to him (although I could be wrong - I haven't studied the matter in any depth). The point I was trying to make (rather unsuccessfully, perhaps) was that arguments to authority along the lines of "Einstein didn't believe in QM, so neither do I" are seriously flawed since we have access to more experimental data now than Einstein did when he made those statements. --Tango (talk) 14:42, 20 March 2009 (UTC)

Unfortunately, my knowledge of physics only extends to one college physics class and whatever's on the Discovery and Science Channels, but apparently some people are still trying to come up with a deterministic model. [20] A Quest For Knowledge (talk) 15:18, 20 March 2009 (UTC)

There are always a few people on the fringes that disagree with everyone else. Without them we wouldn't have paradigm shifts, so they have an important role in the scientific community, but until other scientists start agreeing with them it's best for us non-scientists that don't understand the subject well enough to pass judgement on their theories to just assume the majority are right. --Tango (talk) 17:20, 20 March 2009 (UTC)

Carbon Fiber

What exactly is the tensile strength for carbon fiber? And how much does it cost? I can't find the information anywhere. I thought this might be a good place to ask. <(^_^)> Pokegeek42 (talk) 22:42, 19 March 2009 (UTC)

Our article gives a value of 5650MPa or 820,000 psi for the tensile strength, but note from this source "Overall, the strength of a carbon fiber depends on the type of precursor, the processing conditions, heat treatment temperature and the presence of flaws and defects"[21]. Mikenorton (talk) 23:01, 19 March 2009 (UTC)

Also, the tensile strength for carbon fiber will depend on the orientation of the fibers, as well as the matrix you use to bond the fibers. It is entirely possible for the tensile strength for a force in one direction to be 2x that in another direction. Also, the manufacturing process will introduce errors that can weaken the carbon fiber, so there is not really a simple answer to this question. As far as cost goes, I am not sure, but I believe a lot of the high costs associated with carbon fiber is not so much the cost of materials, but the cost of labor. It is time consuming to manufacture if you want quality stuff.65.167.146.130 (talk) 13:30, 20 March 2009 (UTC)

hair drug tests

would washing your hair with aloe vera,chlorine,bleach and other cleaning chemicals gaurenty passing a hair drug test?? —Preceding unsigned comment added by 76.14.124.175 (talk) 23:08, 19 March 2009 (UTC)

Probabily not. It might make it obvious that you tryed to hide your past drug use though. Dauto (talk) 23:18, 19 March 2009 (UTC)

No - the drug residues are inside the hair - not on the outside where it could be washed off. I guess you could shave it all off...that would make it kinda difficult to test! But don't forget it would have to be ALL of the hair on your body....hmmm - I guess that also might make it obvious that you tried to hide your past drug use. SteveBaker (talk) 23:27, 19 March 2009 (UTC)

(EC with SteveBaker) Hey... My wife did her master's thesis research on drug testing in hair, so she is uniquely qualified to answer this. According to her, the drugs are bound in the structure of the hair itself, and any topical washing is going to have no effect on this. Even treatments like bleaching and the like will not remove it; it may reduce the concentration slightly, but there is no way to remove all traces of the drugs from your hair. According to her (who spent two years studying this exact thing, mind you) the only way to get rid of the drugs is to get rid of the hair. Good luck with that! --Jayron32.talk.contribs 23:29, 19 March 2009 (UTC)

Our article on drug testing notes that hair testing can be done on just the follicle, so shaving won't, er, cut it either. Better hope for a case of this instead. - Eron^Talk 23:31, 19 March 2009 (UTC)

Wouldn't that only detect very recent drug use, though? The idea of testing hair is that it can detect drugs that were in the system when that hair was grown, which could have been some time ago. I think shaving your head would work as long as you haven't used drugs in a long enough time that the hair anywhere else on your body isn't long enough (and therefore old enough) to contain traces of them. --Tango (talk) 23:35, 19 March 2009 (UTC)

Indeed, detectable compounds only remain in the folicle for a short while. Folicle testing could, in theory, tell if you recently smoked a j... But hair testing can show that you smoked one last year... Or last month, or smoked most of last year and stopped six months ago. Its pretty neat stuff... --Jayron32.talk.contribs 02:48, 20 March 2009 (UTC)

March 20

Supernova confusion, and the fate of nearby/bright stars

Hi. The article on Supernovae states that type Ia supernovae are the result of star-dwarf interactions, type Ib and Ic are the result of truly massive stars, possibly Wolf-Rayets, and that type II supernovae have a mass of at least 9 solar masses. However, this causes a contradiction. The article on the Chandrasekhar limit states that stars with masses greater than 1.4 solar masses will collapse into a neutron star rather than a white dwarf, therefore initiating a supernova. Or, is this defined by the mass of the star in the late phase of its life, when it has burned the hydrogen and helium and begins to swell, thereby losing some of its mass? I see that most stars visible in the night sky do have masses greater than 1.4 Sol. Why are there not more supernova explosions in our own galaxy, then? Is it possible for stars to gain significant mass during their lifetime, other than by ingesting material from a companion? The article on black holes does not mention this, but I read somewhere that a star having a mass over 6 Sol is a good indication it may collapse into a black hole (assuming that any core remnant is not destroyed). Also, when two medium-mass stars with similar masses in a very close binary system collide (due to gravity in the system shrinking their orbits, not a by-chance collision), is the result a supernova or a hypernova? The article on supernovae does not mention this category, and apparently hypernovae refer only to hypergiants collapsing.

If the limit for a star to end as a supernova is indeed 1.4 Sol, then looking at the top ten brightest stars in the sky, it looks like that Arcturus and Vega will explode as supernovae; Sirius and Procyon will also explode as supernovae, but interactions with their companion dwarf star could initiate a type Ia instead; Canopus and Achenar will explode as supernovae, and are just massive enough to perhaps end as black holes, Rigel and Betelguese will be especially energetic supernovae resulting in black holes; Rigil Kentarus will have one star swell to red giant first, probably star A, then shed its outer layers, and if the explosion doesn't significantly disrupt the second star, then possibly its remaining material will migrate towards the remnant of star A; Capella appears to be a binary system of two stars massive enough to generate supernovae, perhaps the explosion of one will disrupt the other, or else we could have stellar matter being drawn towards a neutron star. Most of these stars will probably be well away from Earth, though, by the time the explosion occurs, because a positive radial velocity would cause the star to be farther away, and a negative one probably means the star will have long receded by the time the explosion occurs. Or, is there something I'm missing here? Would this mean that supernova explosions are likely to be common near Earth, and would they significantly affect our atmosphere?

Also, what exactly are the evolutionary phases of higher-mass stars (those heavier than 1.4 Sol, specificly)? Does a blue giant evolve to a red supergiant, does a blue supergiant evolve any farther before exploding, what about white and yellowish-white stars in this category, are they still the young versions of red giants or red supergiants? Also, in the case of supergiant-black hole interactions, such as with Cygnus X1, what is expected to occur when the supergiant itself goes through the end of its life cycle? Thanks. ~AH1^(TCU) 01:29, 20 March 2009 (UTC)

Wow, so many questions... I won't tackle all of them. The gist of most of what you are asking seem to boil down to "what happens to stars that are heavier than chadrasekar's limit but are lighter than 9 solar masses? Some of them will end their lifes as Planetary nebula. This page has a nice explanation. Dauto (talk) 03:18, 20 March 2009 (UTC)

Nothing ends up as a planetary nebula - as that article says, it's a short-lived phenomenon. --Tango (talk) 12:35, 20 March 2009 (UTC)

My point was that after shedding the outer layers on a planetary nebula the 5 sol star isn't a 5 sol star no more. So that's the end of the 5 sol star. Dauto (talk) 13:38, 20 March 2009 (UTC)

Hi. OK, so it appears middle-weight stars usually end up with a much lower mass. What happens, however, with binary systems like Sirius and Procyon, does the white dwarf absorb the extra material and end up as a type Ia supernova? Also, is it possible to predict whether a star such as this will lose most of its mass or not? Thanks. ~AH1^(TCU) 17:14, 20 March 2009 (UTC)

hair tests again

thanks for the aswers. but i'm confused...if ur hair takes in drugs....does that mean almost any chemical put in our bodys go in the hair? or is God just getting back at stoners? —Preceding unsigned comment added by 76.14.124.175 (talk) 02:03, 20 March 2009 (UTC)

ps. doea ethnicity affect hair tests? —Preceding unsigned comment added by 76.14.124.175 (talk) 02:19, 20 March 2009 (UTC)

Asking my wife again. It's not that everything you take in ends up in your hair, but most drugs have chemically very similar chemical compositions, and those compounds do tend to accumulate in the hair. After all, the basic idea of drugs is that they mimic chemicals in your brain, and those chemicals also tend to accumulate in certain places like hair and fingernails. It isn't that ONLY drugs do, its that drugs are one of the things that do accumulate there. There are many other things that do, like heavy metals and arsenic, and hair tests can be used to show that a person has been poisoned over a period of time. The deal with hair is not that it magically absorbs drugs; its that it lasts a LONG time, so it carries a record of things you have taken in over a long time. And, ethnicity does effect hair type; your ethnicity can be positively identified by microscopic analysis of your hair... however no person or ethnicity is immune from these hair tests. Again, your only option is to shave your head; however if you shave it after being told that you need to give a hair sample for a drug test, then they will likely know exactly why you did so. Your options are a) don't do drugs or b) don't apply for jobs where it matters... --Jayron32.talk.contribs 02:46, 20 March 2009 (UTC)

I don't believe shaving your head will do the trick. We don't have hair only in our head. There are also other ways of testing for drugs - read drug test for more, but they don't have a long detection period like hair test.--80.58.205.37 (talk) 12:54, 20 March 2009 (UTC)

Are humans the fastest long distance runners?

When it comes to the fastest on land, everyone bows down to the sprint of the cheetah. But beyond the sprint, what is the fastest land animal over a substantial distance, let's say 50 miles or so? I've recently heard an assertion that we, as a species, were very successful in our infancy because we evolved to be the best at tracking herds over very long distances. Sappysap (talk) 02:37, 20 March 2009 (UTC)

I've heard that said, many times. It may be true...but I don't think so. Marathon runners can do 26 miles without a break. However, in the Man versus Horse Marathon - the race was won by horses in the first seven years although a human did win on the eighth event - but on a bicycle (which, IMHO, is cheating). The race was run for 25 years before the first human won on foot. In 28 years of running the event, only two humans have ever won on foot. For some reason that's only a 22 mile race, but it's cross-country - which may give the horse an unfair advantage. But then consider that they horses are HEAVILY handicapped by having to run with a human rider on their backs! If the runners had to carry a 40lb backpack - I think it would slow them down too!

So it's abundantly clear that 22 miles isn't enough to give the human a winning advantage. I had a neighbour in England who was a big time long-distance runner. He did the London-to-Brighton foot race (which I think is 50 miles or so) - also several double-marathons (52 miles) and the South-Downs-Way run (I believe 70 miles) and the Isle-of-Wight race which is also some crazy long distance. But I don't think an average human can do that - even with training.

I dunno - I think it's a tough sell. SteveBaker (talk) 03:04, 20 March 2009 (UTC)

Yes, true. But may be the 'Man versus Horse Marathon' isn't the best way to test the hypothesis. Horses, after all, are pretty good long distance runners themselves. May be we would do better against animals more adept of short bursts of very fast sprints like impalas? Dauto (talk) 03:54, 20 March 2009 (UTC)

Harvard anthropology professor Daniel Lieberman claims we are "the animal world’s best distance runners."[22] Clarityfiend (talk) 04:20, 20 March 2009 (UTC)

26 miles is a single marathon. Many people can do it - probably most healthy adults after a year or three of training. See Ultramarathon for really dedicated runners. --Stephan Schulz (talk) 09:12, 20 March 2009 (UTC)

But to find out if we're the best we need to compare ourselves to others that are very good. --Tango (talk) 12:26, 20 March 2009 (UTC)

Humans can run 3,100 miles over the course of 41 days. Does anyone know if a trained horse could do the same? --Sean 14:16, 20 March 2009 (UTC)

But here is my hypothesis in a nutshell: We know that most people (my wife, for example) can more or less run 26 miles - with a bit of training (she's never run a race over any distance in her entire life - she trained over two months - and finished the London Marathon in a hair over 5 hours - although she did walk some of the way). It's not unreasonable to suppose that pre-soft-living-modern-civilisation-humans could all run at least 26 miles if they had to. But we also know from the Man-vs-Horse thing that AT LEAST the one species we've seriously tried this against can beat us easily over 22 miles WITH A HUGE LOAD ON THEIR BACKS. So I'm betting that horses without riders would have no problem whatever in whipping our asses out to at least a few miles beyond the regular marathon distance. However, we have these ultramarathon loonies who run 50 mile races. It's perfectly possible that the horse gives up at about 30 miles...and that SOME humans can make it out to 50 miles. But if we're taking about maybe 1000 people in the world who run ultramarathons - that's the top 0.00001% of humans. I'm pretty sure we couldn't all do that - even with training. And what if we picked the very best long-distance horse out of all the horses in the world - and trained the heck out of it. Gave it really nice Nike running horseshoes and a digital heart-rate monitor with integrated pace timer - no rider, no saddle - and made sure it had specially formulated 'rehydration' stations every few miles...wouldn't the best horse manage equal amounts of improvement over the general population of horses? I don't think there is any evidence whatever that a 'typical' human could out-run a 'typical' horse over any significant distance...and I don't believe that the top 0.0001% of humans with the best training and support facilities could beat the top 0.0001% of horses if they were given fair training and support (and no riders!). And that's just horses. What about all of the other long-legged runners of the world? I think this one is busted...unless there is some solid evidence to the contrary. SteveBaker (talk) 14:22, 20 March 2009 (UTC)

Wait, that's not a fair comparison at all! Horses have been bred for centuries for speed, endurance, carrying capacity, etc. How would a horse's pre-domestication ancestors fair in a human-vs-Equus ferus marathon? APL (talk) 01:09, 21 March 2009 (UTC)

How is that fair either thought? Prehistoric humans were probably quite fit but I doubt they compared to modern professional marathon runners at running such long distances. Nil Einne (talk) 14:05, 22 March 2009 (UTC)

There are other animals besides horses to consider as well. What about wolves? 65.167.146.130 (talk) 14:57, 20 March 2009 (UTC)

Let's play devil's advocate for a bit... Okay, so an average horse could beat an average human in a single race of 50 miles. How soon until it can go another 50? I imagine it would take a lot longer to refuel a horse than a human; in fact, if the human slowed to a walk here and there, it could refuel on the run to some degree, or at least take in some water. Quadrupeds can't do that. The horse is going to need enough energy to haul its 1,000 lb carcass across the plain, while the human only needs to haul its ~150 lb carcass, and gets to take in higher calorie foods to boot (including, er, horse, but that's a bit rude to your opponent...). Sooner or later the issue of fuel quality and fuel consumption are going to overwhelm any short-term equine superiority. Maybe. Matt Deres (talk) 20:14, 20 March 2009 (UTC)

Interesting point - I hadn't thought about it that way. However, horses are capable of eating grass, which is generally more readily available in large quantities than food suitable for humans. --Tango (talk) 20:34, 20 March 2009 (UTC)

See Persistence hunting. Wolves quite probably could beat humans as they also do something similar, I don't know. It would only need a good fit person to run down a horse without a rider though, they wouldn't need to be Olympic standard or anything like that. And by the way I've run longer than that 50 miles of those 'ultramarathon loonies' ;-) Dmcq (talk) 22:40, 20 March 2009 (UTC)

Why do you say that? As SB has mentioned given the conditions the horse with a rider is subject to, it seems resonable a horse without a rider would be capable of being faster. The question is would it ever actually run that fast if there isn't a rider edging it on? Well it's difficult to say IMHO. As I've mentioned below, in general we can expect most animals wouldn't. But if you are chasing a horse as a prey and the horse realises you are a predator it seems to me easily possible the horse will actually run that fast Nil Einne (talk) 14:33, 22 March 2009 (UTC)

I just had a good read of the Nature article referenced at the end of the wiki article on the evolution of endurance running in humans and it says some dogs and horses that have been bred for endurance would probably beat humans. The wolves article says they normally give up chasing after a fairly short distance but one was observed hunting a moose for 35km. Another animal that possibly would beat humans is the kangaroo. Dmcq (talk) 17:46, 21 March 2009 (UTC)

The refueling thing is an interesting point. It's worth remembering many (not all obviously) marathons don't involved the runners bringing their own water. Nil Einne (talk) 14:07, 22 March 2009 (UTC)

IMHO one issue we're not addressing is the difference between what can be done, and what is done. Personally, it wouldn't surprise me if a number of animals can beat humans in general. However many of them are never going to do it in practice. Similarly while humans may have evolved endurance for long hunts, what sort of distance are we talking about here? Did humans really chase animals by running after them non stop for 50 miles? Nil Einne (talk) 14:11, 22 March 2009 (UTC)

Without having read the article that Sappysap is referring to, I wonder if it's solely referring to our endurance or it may also refer to our intelligence etc. I presume one advantage humans have is that they have endurance and also intelligence. Let's say you are chasing something. Perhaps it's about the same speed as you so you don't really catch up to it and it doesn't escape. Eventually you tire and slow down (or perhaps you could go on but decide the current run is pointless). It 'escapes' and then slows down itself. Trouble for it is you may rest and 'refuel' and then go on. You can see it's tracks so you can easily still go after it. It doesn't know this so it's not necessarily running away from you any more. Eventually you may get close and it sees you and runs away again. Perhaps you repeat the same thing. It's easily possible you will ultimately win because you are chasing it in a direct line and wearing it down successful. It's not necessarily the case you have more endurance then it, you have good endurance sure but you are also smarter. Nil Einne (talk) 14:33, 22 March 2009 (UTC)

Plenty of animals are far better trackers than humans. Humans may have an advantage in a race to a pre-determined finish line because we can pace ourselves. I'm not sure any other animal would understand the concept of a long distance race well enough to do that. In a chase, though, pacing yourself doesn't really help unless you know how fast you and your opponent can run and for how long at various speeds and can work out a strategy to win, which would be rather difficult (an maybe impossible, depending on the respective abilities of the predator and prey). --Tango (talk) 14:40, 22 March 2009 (UTC)

You'd have to watch the episode in David Attenborough's series 'The Life of Mammals' where a Bushman runs a kudu to death to really appreciate what can be done. They typically have to run 25 or 35 kilometers which is nothing to a trained long distance runner. Dmcq (talk) 00:06, 23 March 2009 (UTC)

What is your point? So humans are better long distance runners than kudu, that doesn't answer the question. We knew humans weren't the worst, we're asking if they're the best. --Tango (talk) 00:12, 23 March 2009 (UTC)

You seemed to think it required special pacing. It doesn't. To win against other humans does. As to the best long distance runner I don't know but my best guess would be the kangaroo, I'd be surprised if humans actually are the best but they're very good rather than not the worst. I haven't a citation but I believe people in America in the past have run down wild horses rather than doing the sensible thing and creeping up and lassoing them. Dmcq (talk) 14:49, 23 March 2009 (UTC)

When the sun becomes a red giant...

About how long will it take for it to expand from its current size to red giant size (following the collapse of its core once the hydrogen there is used up)? 69.224.37.48 (talk) 03:09, 20 March 2009 (UTC)

See Stellar evolution which has words and pictures... --Jayron32.talk.contribs 04:31, 20 March 2009 (UTC)

Thanks! I should have thought to look there, as I looked at some related articles but couldn't find quite what I wanted. 69.224.37.48 (talk) 17:11, 21 March 2009 (UTC)

whats the origin of universe

its the biggest question ever ... what's the beginning , what's the source of evry thing .. if i said god is the source, atheistes will be angry.but if i said it's avery powerfull elian had created the earth ... i think they will buy that.

i just need to know whats wrong with god theory ... it might be right . but i think that humans dont like the idea of being a lower cretures ... we are so pride to be god slaves,we need so much to belive that there's no destiny ,so we can make our own.

human evolved from monky...monky evolved from (whay ever)...all the way to the creation of the universe ... from where did the universe came from ... from where that gas came from ... what is the first thing ... what is ground zero.

and if there is no god , and all this religion thing is just acrap,then i think the best thing that happened to the earth is hetler...we must let the smartest,the strongest , the healthiest ones to survive .who cares about moral standards ,we invinte these standards,and we can change them ,i think it's inmorale to leave the weak alife so they can multiply and reduce the chances of our survive,we should eliminate them.

and why do we evolve to have this huge power of thinking ... were we to needy to find answers for the question we had before we have the mind to ask.whats the need driven us to evolve to have this huge brain ... food ..???

will .. after all evry thing could be true , just leave the door open. —Preceding unsigned comment added by Mjaafreh2008 (talk • contribs) 04:19, 20 March 2009 (UTC)

There are two (implied) questions you are asking, even if you don't realize it. They have different answers. Question 1 is "What is the process by which the universe was created" or "what went on when the universe came into being". Its a procedural question. The answer, as far as we can tell, is that some form of the Big Bang brought it about, somewhere in the neighborhood of 13-14 billion years ago. Now, while this satisfactorily answers your first implied question, it does not answer your second which is "What is the cause of the Universe coming into being" or "What is the purpose for which the universe was created". The answers to THOSE questions are ultimately unanswerable via direct observation or by inferences from those direct observation. Assigning meaning and purpose to creation isn't really the realm of observational study, so one must derive their own personal answer to the question. Did God make it so? Is it all random? Any answer you arrive at must be arrived at via faith, even if your answer is "The universe has no purpose at all". You may be interested in looking into the field of Cosmogony which discusses the philosophical (as opposed to the procedural) questions of the creation of the universe. --Jayron32.talk.contribs 04:28, 20 March 2009 (UTC)

Let me point out one thing you said that reveals you haven't thought about that long enough.

You said "i just need to know whats wrong with god theory ... it might be right . but i think that humans dont like the idea of being a lower cretures ..." If that was true, most people wouldn't believe in God. We know that that's not the case.

Now, if we skip all the senselessness about eliminating week people (not a very moral thing to say), we get to the only thing in your rant that actually sounds like a science question:

You asked "why do we evolve to have this huge power of thinking?"

To outwit one another in matters of love and war. Dauto (talk) 04:59, 20 March 2009 (UTC)

Oh, someone who concludes that if there is no God, Hitler is awesome because without God there's no morality! Why, sir, you have unintentionally created an argument for belief in God! What an amazing coincidence! -- Captain Disdain (talk) 10:53, 20 March 2009 (UTC)

As far as I understand it, evolution doesn't say that humans evolved from monkeys. Instead, it says that humans and monkeys evolved from a common ancestor. This common ancestor no longer exists (i.e. it is extinct). 12:59, 20 March 2009 (UTC) —Preceding unsigned comment added by A Quest For Knowledge (talk • contribs)

Well, yes, that's true. It's accurate to say we evolved from apes, but monkeys are a separate class of primate - it wouldn't be accurate to describe the most recent common ancestor of modern monkeys and humans as a monkey. (The most recent common ancestor of humans and non-human apes was an ape, though.) --Tango (talk) 13:12, 20 March 2009 (UTC)

Here we go again...

• its the biggest question ever - maybe - but I think I have bigger ones. Abiogenesis is one. Is there intelligent life throughout the universe is another. Are there parallel universes is a third. But this is right up there.
• ... what's the beginning , what's the source of evry thing - that's an easy one - the Big Bang. We're really very sure about that now. We know pretty much exactly what happened from about the first millisecond of existance. We still need to fill in some details about dark-matter and dark-energy - but we're definitely getting there.
• .. if i said god is the source, atheistes will be angry. - No, not angry. Saddened perhaps. Exhausted maybe.
• but if i said it's avery powerfull elian had created the earth ... i think they will buy that. - No, we wouldn't. That's really not what the science says and it wouldn't explain how the moon was formed from a collision between early earth and another Mars-sized planet. We don't need 'aliens with godlike powers' as a substitute for 'god' - we have strong evidence for a relatively mundane explanation that centers around stellar remnants, gravitation, that kind of thing.
• i just need to know whats wrong with god theory ... - it's "Unfalsifiable". That means that there is no conceivable experiment that could be done to either prove or disprove the theory. The "god theory" is (scientifically) no more and no less probable or provable or credible than that I made the earth and have been keeping quiet about it all these years. There are literally an infinite number of unprovable ("wild-assed") claims you could make - they all have equal status with the "god theory" - and we can't go around believing in an infinite number of random things. On the other hand - we have an exceedingly good 'conventional' theory that works perfectly well without hypothesising supernatural causes. God simply isn't necessary for our explanation of the universe. You might like to read about Occam's Razor.
• it might be right. - well, it might but so might be the theory that the Invisible Pink Unicorn (mhhbb) did it...or that roaming gangs of green furry fish did it. I can keep coming up with these stupid suggestions from now until doomesday - they are all just as valid as the "god theory" - there is the same amount of evidence that they are true (ie NONE) and just as easy to prove or disprove (ie IMPOSSIBLE). So why should we give the "god theory" a moment's more attention than the IPU (Invisible Pink Unicorn - mhhbb) theory - at least the incomprehensible but undeniable existence of pineapple and ham pizza provides at least a shade of evidence for the IPU? (I'm kidding - OK?)
• but i think that humans dont like the idea of being a lower cretures ... - that's true. When I was a kid - the text books said "Humans are superior to the animals because we have language and use tools." - but then we discovered that bees have a language (involving dancing and wiggling their butts) - and lots of animals use tools (watch a starling breaking open a snail shell by hitting it with a pebble). So the next generation of textbooks said "Humans are unique because we MAKE and use tools."...but then we found that chimpanzees strip the leaves off of thin branches to make tools for getting ants out of termite mounds...and there is a fish that cuts and shapes leaves to make a disguise that it holds over it's body so that birds can't see it swimming by. We are clearly at the 'top of the heap' - but reality keeps reminding us that we're really not that much more superior to the "lower" creatures.
• we are so pride to be god slaves,we need so much to belive that there's no destiny ,so we can make our own. - I certainly don't want to be a "god slave". I couldn't imagine what it would be like to believe in all that stuff. To have to continually bow down to an infinitely superior being? Urgh! We have not made up all this stuff we've found out about the universes. We've investigated what the universe has to tell us. We know the Big Bang is true because (in a sense) we sent up a spaceship to take a photo of it! The cosmic microwave background is the clearest proof that the Big Bang really happened. If you take the time to understand the science behind it - you'll be convinced too!
• human evolved from monky...monky evolved from (whay ever)...all the way to the creation of the universe ... from where did the universe came from ... from where that gas came from ... what is the first thing ... what is ground zero. - Ground Zero is the Big Bang. We're pretty solidly clear on everything that happened from then to now. What we don't know - and what (if you must) you could attribute to a "God" is what actually caused the Big Bang in the first picosecond of the life of the universe. I don't think we need a supernatural explanation for that - but if you must, you could imagine a god who decides to make the universe and after about a picosecond - steps back and lets it all roll out without touching anything after that. This makes a sort of sense I suppose. It's a "God of the gaps" argument. Wherever we don't yet have a scientific explanation - you can stick God in there. Sadly, those gaps are getting smaller every year. Science is making huge leaps in figuring this stuff out - and every time we plug a hole, there is less need for a god to make a workable explanation. Give it ten years and the role of god will have shrunk from a picosecond to an attosecond. But this raises a bigger question for me. You aren't prepared to accept that the "Big Bang" came from nowhere (despite good evidence pointing that way) - yet you are entirely happy to accept that God "just is" - nobody asks "what is the origin of god?"...but if we were (as scientists) to accept the god-theory, that would have to be the first and biggest new question. "Where did God come from?" When I ask that question, I get some vague hand-wavey thing about him always having been there - or "He's outside of time and space". But when I say that time actually started with the big bang - and that it's meaningless to ask what came "before" - you get all huffy about it and start demanding why I don't have an explanation. Your theory is certainly no better than mine - and Occam's razor says it's a lot worse because it involves a whole extra step that my explanation doesn't need.
• and if there is no god , and all this religion thing is just acrap,then i think the best thing that happened to the earth is hetler...we must let the smartest,the strongest , the healthiest ones to survive - but that's not true. Hitler's actions were not acceptable to the majority of humanity - or even to his own people when they finally realised what was happening. So Hitler was attacked from all sides - Europe, Russia, the US...and driven to extinction. He died because the majority of humans could not accept his behavior. That's because we've evolved a mental capacity to reflect the feelings of others - that capacity means that we can put ourselves into the positions of the poor people in those death camps - and we become outraged and belligerent - and we fix the problem. That's an evolutionary response to a failed genotype. Religion had very little to do with that. Plenty of atheists fought against Germany.
• who cares about moral standards ,we invinte these standards,and we can change them - some we can - others are so inbred into our genetics that we can't. You can't just decide to do something that's morally repugnant to you. I could no more kill my son than I could kill myself. That's not a matter of logic - it's a matter of what my brain chemistry has made me be. We are like we are because of the genetics of being a "pack animal".
• i think it's inmorale to leave the weak alife so they can multiply and reduce the chances of our survive,we should eliminate them. - you say that, but I doubt very much that you'd be able to carry it through. I have no god commanding me not to do that - and I certainly give money to help the needy - I volunteer to help out underprivilaged kids - I donate my time free to answer people's questions here on the Wikipedia reference desks. Without a god - your claim is that I should have no reason to do those things...yet I do! Gladly. For the betterment of mankind - for the survival of the species - for the survival of my genes into future generations. This is a moral standpoint for sure...but one that does not in any way rely on religion to prop it up. I actually agree with most of the more important of the Ten Commandments (although one or two of them are a tad nutty). "Thou shalt not kill" works very well for me! In fact, I'd prefer to avoid the weasel-words added to that that say "oh...unless it's a war or something...or maybe murderers could have the death penalty...and in Texas it's OK to shoot burgulars". No - for me, "Thou Shalt Not Kill" actually means what that bloody stupid book says it does. Not because there is some old white guy up in the clouds somewhere telling me to...it's because my brain tells me that killing (in general) is not a good thing. I have moral principles...pretty strong ones actually. They just don't derive from religion.
• and why do we evolve to have this huge power of thinking ... - it helped early humans to be smart. The smartest ones didn't get eaten by the sabre-toothed tigers - so they had more kids - who inherited their parent's smarts - and gradually, via the relentless force of evolution we evolved to what we are now. It's not in any way a mystery.
• were we to needy to find answers for the question we had before we have the mind to ask.whats the need driven us to evolve to have this huge brain ... food ..??? - Sex, actually. But food also.
• will .. after all evry thing could be true , just leave the door open. - No. It's ridiculous. I don't have the time to go around believing in green furry fish that MIGHT have created the universe - I don't have time to believe that there MIGHT be a teapot orbiting Mars right now. I don't have time for any of the hundred or so wildly different supernatural claims for a "god" or "gods" either. It's unnecessary and (frankly) ridiculous.

209.163.180.6 (talk) 14:01, 20 March 2009 (UTC)

Wow! What an inciteful reply! I think you should have used more CAPITAL LETTERS for EMPHASIS though. SteveBaker (talk) 14:04, 20 March 2009 (UTC)

OK - look I'm not playing sock-puppet-master here - I really didn't notice that my 30 day login period had expired on this PC.SteveBaker (talk) 14:04, 20 March 2009 (UTC)

Green furry fish? What happened to the aardvarks (mtasnro)? Algebraist 14:26, 20 March 2009 (UTC)

In the Cyclic Model, the universe follows an infinite number of Big Bang / Big Crunch cycles, first cause isn't an issue because there is no beginning and no ending, just an infinite loop. "All this has happened before and will happen again." A Quest For Knowledge (talk) 14:03, 20 March 2009 (UTC)

I thought the whole universe was in a hot dense state and then nearly 14 billion years ago expansion started? Wait...have i been misinformed? 194.221.133.226 (talk) 16:14, 20 March 2009 (UTC)

Yes, that's right, although we have little or no idea what was going on just before that expansion started (or even immeadiately after it - there is a fraction of a second at the beginning during which our physics breaks down). --Tango (talk) 17:46, 20 March 2009 (UTC)

Is it too much of a sidetrack to ask what "mhhbb" and "mtasnro" stand for? Franamax (talk) 18:52, 20 March 2009 (UTC)

'mhhbb' stands, I believe, for 'may Her Hooves be blessed' and is a standard phrase when referring to Her. 'bbhhh' ('blessed be Her holy Hooves) and 'mhhnbs' ('may Her Hooves never be shod') are also in use. 'mtasnro' is a new coining standing for 'may Their ant supply never run out' and is a phrase used to propitiate the pink aardvarks who run the universe. Algebraist 19:02, 20 March 2009 (UTC)

In case mtasnro ever catches on, as of March 20, 2009, a Google search on the term returns exactly 2 hits neither of which are about the Pink Aardvark religion. A Quest For Knowledge (talk) 19:19, 20 March 2009 (UTC)

Thanks much for the info, faithfully recorded in my notebook! After Steve's analysis on the chances of being killed in a meteorite strike a while ago, I'm taking no chances on suddenly being called to the "undiscovr'd country from whose bourn no traveller returns". 'Scuse me now, I have to run out and find a goat, a virgin, a 100-foot tall flammable man-like structure and some chicken bones before nightfall. Oh yes, a box of ants too. :)

And to get even more sidetrack-ey, what's the name for when you find only one instance of a Google search term? Of course, when you report it, it then shows up twice. You were oh-so-close there! :) Franamax (talk) 22:43, 20 March 2009 (UTC)

Googlewhack, although it needs to be two dictionary words, random sequences of letters aren't allowed! --Tango (talk) 23:44, 20 March 2009 (UTC)

I get the feeling a lot more evolving of this power of thinking is needed. Or perhaps by then we'll all have evolved so the muslim faith or whatever is bred into our genes. Then nobody will have to ask - we'll all 'know' without any evidence just like the OP. Wouldn't that be a grand fate for our descendants. Dmcq (talk) 15:30, 23 March 2009 (UTC)

the iron content in steel wool lab queries

for an important lab we're doing titled "percentage of iron in steel wool", a sample of steel wool is placed in excess dilute sulfuric acid, and this supposedly converts the iron present in the steel wool into Fe2+ ions......then, the Fe2+ ions in the solution are titrated against a standard permanganate solution, and thus are further oxidised to Fe3+ ions, while the permanganate ions are reduced to Mn2+ ions..

do you have any idea of the kind of questions that are likely to be asked of me in this lab? also, i'm assuming my teacher will give a 'manufacturer's value of the % Fe'. do you know the equation to figure out the % difference between your value and the manufacturer's claim?

thanks heaps —Preceding unsigned comment added by Mtsa37 (talk • contribs) 04:45, 20 March 2009 (UTC)

Percent difference? That's a pretty technical article, but the essence is in the "Percent error" formula and the intro: it's a ratio of the difference between the values to the values themselves. You might take one value as "correct" and thus compare to it, or you might just take them both as "someone's data" and consider the average of them to be the value to compare. I would ask a student to write the net ionic equations for the redox reactions involved in this experiment. DMacks (talk) 04:56, 20 March 2009 (UTC)

You're likely to do stoichiometry calculations somewhere to figure out the mass of iron in your original sample. This can be done any number of ways, but since Fe3+ ions are colored, you could use a spectrophotometer, a series of standardized Fe+3 solutions, and Beer's law to calculate the concentration of Fe+3 ions in your unknown solution. Then, knowing that concentration and volume, you can find moles of Fe3+, which should ALL have come from the steel. You could also do the same via titration with a standardized KMnO4 solution; if you know the volume and concentration of the KMnO4, and have a balanced chemical reaction for the Fe+2/Fe+3//Mn+7/Mn+2 redox reaction, you can also quantitatively find the moles of iron in your unknown, and then its the same calculation as above. --Jayron32.talk.contribs 05:03, 20 March 2009 (UTC)

potential energy

I was watching TV where i saw a man working in a high way project , this man was trying to crack a big rock , he kept hitting the rock with a hummer until and suddenly it just split into half , i asked about it and get some opinions like a potential energy is being stored in the mass until its enough to crack the mass, but i think that the hummer is producing a hairy cracks at aspecified plan until its reach that critical edge where it to weak to resist that hit energy , so it jut crack down,what did you think....? —Preceding unsigned comment added by Mjaafreh2008 (talk • contribs) 10:24, 20 March 2009 (UTC)

The rock is certainly not storing significant energy from the hammer blows. It's much more likely that each blow (or even only some of the blows) create and propagate cracks and fissures, gradually weakening the rock. At one point the rock is weak enough that the last blow splits it. --Stephan Schulz (talk)11:12, 20 March 2009 (UTC)

As a professional rock splitter, I concur with that. When trying to break up a rock down to a size that you can take back as a specimen you generally concentrate your hammering on any obvious existing weakness such as a crack or a weathered zone. Normally you can see, feel (from the change in the response of the hammer handle) or hear (a change in the sound of the blow) when you've started to propagate a crack just before it finally splits. Mikenorton (talk) 11:24, 20 March 2009 (UTC)

You could argue that a rock with cracks in it has higher energy that one that doesn't (in the same way that two separate atoms have higher energy than when they are bonded together), but there is no way easy way to get that energy back so I'm not sure I'd call it "potential energy". --Tango (talk) 12:17, 20 March 2009 (UTC)

When you're propagating a crack through a material, bond-splitting is what you're doing, so some of the input energy is converted to fracture surface energy. Mikenorton (talk) 12:27, 20 March 2009 (UTC)

I'd bet that you're actually releasing energy in the rock by breaking bonds - but the biggest part of what your hammer blows are doing ends up as heat or sound energy (which in turn is going to be heat energy pretty soon). When you hit the rock - you are causing it to vibrate or accelerate (briefly) - and that's getting turned into heat by friction. So to the extent that the rock gets a bit warmer (and most certainly the hammer does - you can feel it!) you are storing energy in the rock - but not usefully. SteveBaker (talk) 13:14, 20 March 2009 (UTC)

I'm sticking with using up energy to propagate a fracture, it's the basis of the Griffith approach to fracture mechanics. Mikenorton (talk) 14:06, 20 March 2009 (UTC)

Breaking bonds requires energy, it doesn't release it. That's the same for rock as for anything else. --Tango (talk) 17:11, 20 March 2009 (UTC)

During the recent gasoline price spikes, I imagine quite a few people "kept hitting a rock with their Hummer until suddenly it just split in half". I'm not sure if the junkyard would take half a Hummer, though. :-) StuRat (talk) 04:13, 22 March 2009 (UTC)

pls help...

what are the similarities and dissimilarities between prokarotic and eukaryotic replication,transcription and translation.59.92.238.182 (talk) 12:49, 20 March 2009 (UTC)

Please do your own homework.

Welcome to the Wikipedia Reference Desk. Your question appears to be a homework question. I apologize if this is a misinterpretation, but it is our aim here not to do people's homework for them, but to merely aid them in doing it themselves. Letting someone else do your homework does not help you learn nearly as much as doing it yourself. Please attempt to solve the problem or answer the question yourself first. If you need help with a specific part of your homework, feel free to tell us where you are stuck and ask for help. If you need help grasping the concept of a problem, by all means let us know. SteveBaker (talk) 13:08, 20 March 2009 (UTC)

Also, use a descriptive title. --ReluctantPhilosopher (talk) 13:17, 20 March 2009 (UTC)

Do you mean prokaryotic and eukaryotic? DJ Clayworth (talk) 14:16, 20 March 2009 (UTC)

Transcription (genetics), Translation (genetics) look promising and weren't that hard to find. (Click on words in blue in a text on wikipedia and it will get you to the relevant page.) If the assigned textbook for your class doesn't give you good enough answers it might be useful to check if you have a well stocked library in the area. 76.97.245.5 (talk) 14:32, 20 March 2009 (UTC)

DNA replication and the sub-articles prokaryotic DNA replication and eukaryotic DNA replication would also be a good place to start. After digesting the information, if you still have specific questions, re-post them and I'm sure we'd all be happy to help. --- Medical geneticist (talk) 14:52, 20 March 2009 (UTC)

does anyone know??

what are the advanced drug delivery systems? 59.92.238.182 (talk) 12:50, 20 March 2009 (UTC)

Please do your own homework.

Welcome to the Wikipedia Reference Desk. Your question appears to be a homework question. I apologize if this is a misinterpretation, but it is our aim here not to do people's homework for them, but to merely aid them in doing it themselves. Letting someone else do your homework does not help you learn nearly as much as doing it yourself. Please attempt to solve the problem or answer the question yourself first. If you need help with a specific part of your homework, feel free to tell us where you are stuck and ask for help. If you need help grasping the concept of a problem, by all means let us know. SteveBaker (talk) 13:08, 20 March 2009 (UTC)

Also, use a descriptive title. --ReluctantPhilosopher (talk) 13:18, 20 March 2009 (UTC)

Yes, wikipedia knows. Here's how you can find out what: copy your word into the white box underneath where it says "search" in the left hand sidebar near the top of this page. Then click on "search". If you can't find a relevant page or have trouble understanding some of the content, please feel free to come back with a specific question. 76.97.245.5 (talk) 14:23, 20 March 2009 (UTC)

can anyone help...

what is physiology pharmacokinetic model? 59.92.238.182 (talk) 12:52, 20 March 2009 (UTC)

Please do your own homework.

Welcome to the Wikipedia Reference Desk. Your question appears to be a homework question. I apologize if this is a misinterpretation, but it is our aim here not to do people's homework for them, but to merely aid them in doing it themselves. Letting someone else do your homework does not help you learn nearly as much as doing it yourself. Please attempt to solve the problem or answer the question yourself first. If you need help with a specific part of your homework, feel free to tell us where you are stuck and ask for help. If you need help grasping the concept of a problem, by all means let us know. SteveBaker (talk) 13:09, 20 March 2009 (UTC)

Also, use a descriptive title. --ReluctantPhilosopher (talk) 13:19, 20 March 2009 (UTC)

Yes, wikipedia can help. Here's how: copy your word into the white box underneath where it says "search" in the left hand sidebar near the top of this page. Then click on "search". If you can't find a relevant page or have trouble understanding some of the content, please feel free to come back with a specific question. 76.97.245.5 (talk) 14:19, 20 March 2009 (UTC)

Start with the pharmacokinetics article. If that doesn't answer your question, re-post a more specific question and I'm sure we'd be happy to help. --- Medical geneticist (talk) 14:54, 20 March 2009 (UTC)

Solar Panels

If you put solar panels on windmills, could they help increase the energy given to the town or city or whatever the windmill's powering? What would you connect the solar panels to? <(^_^)> Pokegeek42 (talk) 17:38, 20 March 2009 (UTC)

I think putting the panels on the ground would be the best way to use the same space for solar and wind power. The alternative is putting them on top of the turbines (thus avoiding shadows being cast on them), but I suspect that would mess with the aerodynamics of the turbines and make them less efficient (whereas the shadows should be a mini\mal concern - turbines are pretty thin). --Tango (talk) 17:44, 20 March 2009 (UTC)

In terms of an individual windmill, its probably not all that efficient, but in terms of a national energy policy; diversifying one's energy sources is a sound idea. Generally, solar power is most productive at times and places quite different from the times and places where wind power is productive. Thus, they tend to complement each other as a source of power, but mostly so on a national rather than individual scale. In general, one windmill or a single solar panel running a single house, or even one of each, is a fantastically wasteful and inefficient way to do things. It would be far more efficient use of resources to provide power via Wind farms and Photovoltaic power stations. --Jayron32.talk.contribs 17:54, 20 March 2009 (UTC)

What an impressive generalisation, but it just squeaks through as accurate but very misleading. In general a small number of solar panels in a house is a pretty efficient way to provide thermal water heating as a top up to other energy sources. Solar for the summer and a wood chip boiler in winter is fine for all year domestic heating. Plenty of people use wind and wood for heating too (but not city ants). Local solar panels are also very efficient to provide local summer heating for things like domestic swimming pools. Only if you convert solar or wood to electricity (at massive inefficiency) does it look very uneconomic at home and equally it looks uneconomic for most climates as Photovoltaic power stations. The trade off between economic of scale and transport cost and loss depends on many things and is not obviously one way or another. --BozMo talk 18:37, 20 March 2009 (UTC)

When you consider transmission losses, local generation starts to look much better. But one windmill, even a utility scale one does not provide much area for the very inefficient photovoltaic power panels. You might get enough panel on the nacelle to get power one home. Rmhermen (talk) 19:25, 20 March 2009 (UTC)

However, covering the ground at a wind farm with solar panels might work quite well - wind farms are generally quite spread out and the area is often not used for anything else, as far as I know. --Tango (talk) 19:49, 20 March 2009 (UTC)

The windmill farms I've seen in the desert are not used for much, but the ones I've seen in the plains are used for cattle. Replacing their grazing land with solar panels will mean that the cattle need to graze elsewhere. Also, windmills require a lot of maintenance. It will be hard to work on one if you have to move a lot of solar panels out of the way first. -- kainaw™ 20:46, 20 March 2009 (UTC)

In Denmark, on-land wind turbines are quite commonly located on rural land and farming happens right up to the footprint of the turbine foundation itself which I believe is between 12 and 20 feet square. (And obviously the pathway needed to bring the maintenance equipment in counts as footprint too, but farmers need laneways for tractors anyway).

More desolate land, esp. deserts are good candidates for solar and mountains for wind - but yes, transmission losses, construction expense and bio-effects for the transmission lines come into play. There is a lot to be said for generation near to consumption, not least of which is grid stablization. If clouds pass over a remote solar plant or the wind calms at a wind-farm, everything in between supply and demand will see voltage effects, possibly quite severe. Franamax (talk) 22:54, 20 March 2009 (UTC)

The problem is that this idea is solving a non-problem. The problem with solar panels isn't in finding land to put them on. In all the places with the largest amount of sunshine, land is cheap. Deserts and prairie is easy to get for a couple of hundred bucks an acre. Compared to the cost of an acre of solar panels, the cost of the land is quite utterly negligable. So there is no need to make special considerations for putting them near windmills. To the contrary - you place windmills where the wind is good - you place solar panels where the sun is good - going out of your way to put one in the same place as the other is unlikely to be optimal. SteveBaker (talk) 23:35, 20 March 2009 (UTC)

The solar panels on windmills idea would be more of a benefit to home windmills, where space might be limited and trees and the house may cause shadows to fall on panels placed on the ground. If the windmill is on a tall mast, solar panels near the top would get more sunlight (the additional weight and wind-load might require a stronger mast, though). They could also be placed on the blades. In this case, the electricity could be transmitted from the moving blades to the rotating mast via brushes or some other method. StuRat (talk) 04:06, 22 March 2009 (UTC)

But that's a dumb idea...the windmill has to face into the wind - and the solar panels have to face towards the sun. Since there is little correlation between the two - you'd expect that either your windmill or your solar panels would be pointing the wrong way at least half of the time! Again, the limiting factor with solar panels isn't available area. Almost all houses have FAR more available roof area than the owner can afford to populate with panels. Going to all that grief to put a handful of solar cells onto the blades of the windmill (making them heavier - and therefore harder to get spinning in a light wind - requiring brushes to extract the power - which will inevitably add to the frictional forces - worse still - you are incurring all of those penalties during the night when the solar panels aren't paying for those additional costs!)...and all for what? About another three square feet of panels that's hardly ever pointing optimally? When did you last see a roof so packed with solar panels that another 3 square feet of them would be so urgently needed?! This is a STUPID idea....period. SteveBaker (talk) 19:39, 22 March 2009 (UTC)

Sure, there's a correlation. Just build your house somewhere where the prevailing winds are roughly southerly. (That doesn't affect your main point, of course.) --Tango (talk) 19:50, 22 March 2009 (UTC)

Then there's the problem that the house roof may be in shade in areas with tall trees (like my house), so not at all suitable for solar panels. Also, there may be a minimum amount of electricity required for a house, and any beyond that may be wasted (if there's no way to sell it back to the power companies in that location). In such a case, pointing the blades either at the wind or Sun may be enough. When there's no sunlight, point it into the wind. When there's no wind, point it into the sunlight. When there's neither, you're out of luck. StuRat (talk) 03:43, 23 March 2009 (UTC)

You've still greatly added to the complexity of a device that already is unlikely to pay for itself. If your solar panels need to be up on a pole, it'd probably be better to put them on their own pole.

You probably could think up some contrived hypothetical situation where a solar windmill would make sense, but you'd really just be searching for a problem to your solution. APL (talk) 12:52, 23 March 2009 (UTC)

Russell Watson Brian Tumor

Hi

Do you know the name of the surgeon who performed Russell Watson's brain tumor operation at the Alexadra Hospital in Cheadle (Greater Manchester) in 2007? Many thanksCarlchester (talk) 18:34, 20 March 2009 (UTC)

I couldn't find a specific answer to your question, but it will be one of the surgeons listed here. You might want to make further requests at the hospital itself. —Cyclonenim (talk · contribs · email) 19:13, 20 March 2009 (UTC)

Assuming of course that the surgeon has not moved on in the meantime and / or that the list is otherwise up to date - I note that a surgeon who operated on me is still listed on the hospital (I went to) pages, despite being suspended from the GMC :( 78.151.212.201 (talk) 21:59, 21 March 2009 (UTC)

Should I add this to an article? Electrolyzed water applications

This Reuters article caught my eye because I was just reading about other uses for Electrolyzed water. (Just ignore the snake-oil bits, I'm talking about mainstream uses like hospital disinfectants)

The Reuters article talks about using "electrolysis and ultra-low frequency waves" to raise sea water pH to 10 then spraying it in a scrubber stack to knock down soot, SoX, NoX and CO2 in ship exhaust. I wonder if it would also knock down heavy metal emissions, bunker oil being about the dirtiest thing in the world. The method described sounds very much like the process for producing electrolyzed water in commercial applications. (Again, I'm not talking about bottling it and scamming people into drinking it)

My request here is for some sage observers to look at the Reuters and wiki articles and tell me if it would be appropriate to add some verbiage and source to our wiki article to describe this use. And/or feel free to add it yourself!

And what the heck would ultra-low frequency waves have to do with this? Thanks! Franamax (talk) 21:48, 20 March 2009 (UTC)

I can't figure out the ultra low frequency wave bit. About the only thing I can think of is an ultrasonic cleaning effect, but the frequencies used for ultrasonic cleaners are far from "ultra low." (unless they're comparing sound frequency to light frequency but that doesn't make much sense). If the correspondent doesn't have a strong background in science (I have no clue about this guy), another possibility is that he could have messed up somewhere in the terms or facts so ultra low frequency waves refer to something else. Without putting too much thought into this, the alkaline electrolyzed sea water is basically a bleach solution. Perhaps the concept is to oxidize the NO₂, N₂O, and NO to NO₃^- and the SO₂ to SO₄^-2? The CO₂ I suppose would be removed when it dissolves in the alkaline water to form Na₂CO₃. I'm a little surprised because the calcium present in sea water would produce CaCO₃ which would build up as scale over time which wouldn't seem good for a ship. I am not sure about heavy metals. If they dissolved into the alkaline bleach water it would need to be treated to remove the metals before dumping it back into the ocean. Sifaka ^talk 23:15, 20 March 2009 (UTC)

There is some more verbiage on the website of Ecospec, the company that is marketing this thing. It sounds suspiciously like those gadgets that you attach to the fuel line in your car, that are claimed to improve your fuel efficiency, and has a familiar lack of any numbers or measurements. Caveat emptor. --Heron (talk) 12:30, 21 March 2009 (UTC)

March 21

Olaflur

What exactly is olaflur and how effective is it compared with the other forms of fluoride for teeth? Any disadvantages (human toxicity, environmental, etc)? —Preceding unsigned comment added by 79.107.234.164 (talk) 01:25, 21 March 2009 (UTC)

Our article olaflur will tell you exactly what it is (it is N,N,N'-tris(2-hydroxyethyl)-N'-octadecylpropane-1,3-diaminium difluoride) but will not, alas, answer your other questions. Algebraist 01:33, 21 March 2009 (UTC)

Thank you Algebraist, I have read that, as I have searched in many different sites all of which have the excactly same info as in the article you mentioned. I am particularly interested in the advantages/disadvantages that it has, how it compares with the othe fluoride forms for dental use, it's hazard-toxicological profile and any concerns/other issues about its use. Thanks again though! —Preceding unsigned comment added by 79.107.234.164 (talk) 01:41, 21 March 2009 (UTC)

Google coughed this up which might help. [23] Particularly the PubMed study list link. - 76.97.245.5 (talk) 10:44, 21 March 2009 (UTC)

sweetness equivalent of the Scoville scale?

Is there a scale that measures how sweet something tastes, similar to how the Scoville scale measures heat? The closest thing I found is the Brix scale, but that doesn't seem to directly measure sweetness. --Ixfd64 (talk) 02:11, 21 March 2009 (UTC)

For the sweetness scale see e.g. this. I don't think the scale is named after anyone, though; or at least I am not aware of such a name. --Dr Dima (talk) 09:20, 21 March 2009 (UTC)

See Brix. For grapes there's Oechsle scale. - 76.97.245.5 (talk) 10:35, 21 March 2009 (UTC)

Balling, Brix, Oechsle scales all measure specific gravity, and do not measure sweetness directly. In other words, they only indicate concentration of the sugar (sucrose) in the solution, and do not indicate how sweet other substances are compared to sucrose --Dr Dima (talk) 06:46, 22 March 2009 (UTC)

cacti

Can anyone identify these cacti? Scale is that they are about 2.5" across, and the flowering one is 3.5" tall. Also, would these do ok with only office florecent lights, or do they need actual sunlight?

http://i671.photobucket.com/albums/vv76/nod2003/DSCN0034.jpg http://i671.photobucket.com/albums/vv76/nod2003/DSCN0035.jpg

Oh, the not flowering one has cobwebs on it. 12.216.168.198 (talk) 02:31, 21 March 2009 (UTC)

A Mammillaria sp. perhaps? If I remember correctly the species in this genus can sometimes be tricky to identify. One website suggests partial shade (Filtered sunlight or direct sun for only a few hours) and watering it weekly. Sifaka ^talk 06:04, 21 March 2009 (UTC)

The first one is almost certainly Mammillaria, right. The second one looks like a young Melocactus or Cereus, something in the Cereus tribe; but I'm not sure really. --Dr Dima (talk) 09:39, 21 March 2009 (UTC)

[24] looks similar. (Lots of other cacti pix when you click on the sidebar.:-) 76.97.245.5 (talk) 10:29, 21 March 2009 (UTC)

I was thinking maybe the second one was a Echinocactus. That one really has me stumped. 12.216.168.198 (talk) 12:45, 21 March 2009 (UTC)

Depth of Field vs. aperture diameter

Why does the depth of field depend on aperture diameter of a lens? I am a bit confused. Aperture is to control the amount of light entering the lens. If I make my aperture smaller, the less light should enter, but focal length is still the same, so how does it affect the depth of field? Thanks. - DSachan (talk) 16:27, 21 March 2009 (UTC)

It's because aperture appears in the formula for Hyperfocal distance. I have no idea why that is, though! (Our article doesn't seem to explain the formula much.) Hopefully someone more knowledgeable will come along soon... --Tango (talk) 16:40, 21 March 2009 (UTC)

Actually, after thinking about it, I think I have it - the circle of confusion is going to depend on aperture (in fact, I suspect it is proportional to it), since that confusion is caused by light passing through different parts of the lens ending up at different points on the screen. How far apart those points are is going to depend on how far apart the bits of lens in question are, and a bigger lens allows for greater distances between parts of the lens and so greater confusion. --Tango (talk) 16:44, 21 March 2009 (UTC)

Yes, sounds like a good argument. I should have thought about it. Thanks - DSachan (talk) 16:51, 21 March 2009 (UTC)

The diameter of the circle of confusion is proportional to the aperture diameter, and there's an easy way to see that. Assuming an ideal lens, all light rays emitted from a point in the focal plane and passing through the aperture will be focused onto a single point of the detector. Any light emitted elsewhere along the path of that ray, in the same direction, will end up at the same point. So that point on the film will show features lying within a double cone whose base is the aperture and whose apex is the point in the focal plane. A flat object at a certain distance from the focal plane will be blurred by convolution with the aperture scaled by (distance from object to focal plane / distance from aperture to focal plane). This also shows that the "circle" of confusion is really an image of the aperture, and is only circular if the aperture is. -- BenRG (talk) 18:10, 21 March 2009 (UTC)

With a pin-hole camera - which is a lot easier to think about that the ones with lenses and mirrors and stuff - the smaller you make the pinhole, the better the depth-of-field (but the less light you get in - so the longer the exposure times you need). In the limit - if you imagine a pin-hole camera with an infinitely small hole then every ray of light from everywhere in the world would have to pass through that infinitely small hole in order to hit the film. But only ONE path for that ray is possible. Light (basically) travels in straight lines - but you can only draw one line that goes from some point in the world, through that infinitesimal hole and onto the film. So a perfect pinhole camera has perfect focus from zero to infinity for an infinite depth-of-field. But now imagine a pinhole camera with a 1cm "pinhole" (more like an "ice-pick-hole camera!") - now, the light from a particular point in space can go through the extreme left side of the hole, the extreme right, the top, the bottom, through the middle - or anywhere inbetween. Each of those rays hits the film at a different place - so you get a fuzzy image. If the film is very close to the hole - then a 1cm hole will produce a roughly 1cm blur around a point-sized object in the world. If the film is further away from the hole, then the blurry region will be even bigger. But a perfect pinhole camera has perfect depth of field and everything is always in focus...it just takes you an infinite amount of time to capture the image because you have an infinitely small hole for the light to pass through!—Preceding unsigned comment added by SteveBaker (talk • contribs) 14:14, 21 March 2009

Thanks people, it is clear now. - DSachan (talk) 18:17, 21 March 2009 (UTC)

Actually, you are limited by diffraction with smaller pin holes and the amount of detail that is resolvable. Noodle snacks (talk) 07:22, 22 March 2009 (UTC)

True - I was trying to keep it simple for the OP...but yes, you're absolutely right. SteveBaker (talk) 19:32, 22 March 2009 (UTC)

Now you know about that blow your mind out trying to understand Qinitiq's system desribed in [[25]] which can keep the information from different distances sharp. Dmcq (talk) 23:47, 21 March 2009 (UTC)

High Pressure lighting fixtures

Moved from WP:RD/M#High Pressure lighting fixtures, 19:05, 21 March 2009 (UTC)
My question has to do with lighting fixtures. Can a ballast,ignitor & capistor for a high pressure sodiumn light also be used for a metal halide (Ceramic) light if they are the same rated wattage. —Preceding unsigned comment added by 52.129.12.48 (talk) 18:11, 20 March 2009 (UTC)

No, a metal halide light does not need a high voltage pulse to ignite it, but may need a transformer to convert to the correct voltage. Metal halide lamps may work off the full mains voltage. Graeme Bartlett (talk) 21:20, 21 March 2009 (UTC)

That is not correct, Graeme. All HID lamps require a ballast, including HPS and MH/CMH lamps, and all require a high-voltage pulse to strike (initiate) the arc. They do not operate directly off mains voltage. Different ballasts are generally required for MH vs. HPS, because of the different run-up and operating voltage requirements; mixing and matching makes problems ranging from the costly and inconvenient (early failure of lamp and/or ballast) to the extremely dangerous (catastrophic lamp failure). However, there are now on the market various "smart" ballasts compatible with more than one type of lamp, usually HPS and CMH. They detect the current draw characteristics of the lamp during run-up, and since these characteristics are peculiar to the different lamp types, the ballast is thus able to "know" what the lamp wants to see in steady-state operation. We presently have two relevant articles, High-intensity discharge lamp and Gas-discharge lamp, though a merger has been proposed. —Scheinwerfermann ^T·_C22:07, 21 March 2009 (UTC)

Is this Munchausen, or...?

Okay, so if a person knowingly fakes/exaggerates illness/distress, they would be described as having Munchausen disorder; if they create or fabricate illness/distress in a dependent, Munchausen by proxy; do either over the internet, Munchausen by internet. But if a person who engages in all three of the above also mimics real diseases/distresses of their dependents, does that also fall under Munchausen? What if they are a parent who is chronically negligent to an extent that their child(ren) encounter numerous, potentially life-threatening accidents, yet makes no attempt to be less negligent and revels in the attention that results from the child(ren)'s accidents? And what would you call it if said parent, in a fit of new-found religion, demanded that medical personnel announce a miraculous recovery (in the same manner that a standard Munchausener might demand medical treatment), which resulted in the continuation of an injury of the patient that would have otherwise been corrected or at least improved, as a way to self-confirm their religious ideas (note, this would not be in absence of the Munchausen/by proxy/by internet, but rather alongside it...and the treatment avoided by the "miraculous recovery" ultimately causes the injured party permanent disability)?

Thanks in advance for any and all ideas on this. Even if you don't know for sure, please do share your thoughts. bcatt (talk) 19:21, 21 March 2009 (UTC)

Munchausen's, and related diagnoses, are extremely controversial - it's not at all clear what (if anything) distinguishes between someone who abuses themselves or others in a medical context and someone who has Munchhausen's. (In other words, couldn't a diagnosis of "Bank Robber Syndrome" be assigned to anyone who robs banks). There are certainly those who claim that Munchausen's simply does not exist, and others that it is greatly overdiagnosed. At best we can say that empirical diagnostic tools for making even a tentative diagnosis are pretty dismal, so parsing the more complex examples you cite seems beyond current analysis. 87.114.29.204 (talk) 20:20, 21 March 2009 (UTC)

The bible of mental disorders (the DSM-IV) doesn't even list Munchausen - let alone all of these complicated variations. I agree with '87 - this is controversial at best. SteveBaker (talk) 00:36, 22 March 2009 (UTC)

DSM calls it "Factitious Disorder" 87.114.29.204 (talk) 00:40, 22 March 2009 (UTC)

Ah! Thanks - so they have one listing with three sub-classes for the main deal - and one that rolls in all of the "By Proxy" stuff:

• Factitious Disorder with predominantly psychological signs and symptoms.
• Factitious Disorder with predominantly physical signs and symptoms.
• Factitious Disorder with combined psychological and physical signs and symptoms.

...then there is...

• Factitious Disorder Not Otherwise Specified.

...which includes the 'by proxy' thing - and is a vague 'catch all' for things that it describes as "suggested research".

So the answer to our OP is that there is no official term for all of these complicated variations. SteveBaker (talk) 04:09, 22 March 2009 (UTC)

Thanks Steve, do you think the refusal of medical treatment in order to force confirmation of religious beliefs would also fall under that category, though? bcatt (talk) 05:50, 22 March 2009 (UTC)

No! The diagnostic criteria is that the person with the disorder wishes to be treated as if they were sick - or in the "by proxy" version wishes someone they care for be treated as if sick. Refusing treatment to someone who actually IS sick (for whatever reason) doesn't sound to me like the same kind of thing at all. I agree with the subsequent posters - sometimes a jerk is just a jerk. SteveBaker (talk) 19:31, 22 March 2009 (UTC)

Basically we're talking about where you draw the line between a "bad person" and a "mentally ill person that does bad things". I've never really known how that is supposed to work... --Tango (talk) 01:12, 22 March 2009 (UTC)

People who are rich enough to afford doctors who can make a diagnosis are mentally ill. Everyone else are just healthy people who make bad choices. --Jayron32.talk.contribs 02:22, 22 March 2009 (UTC)

That would seem to suggest that everyone who behaves badly in countries with "free" medical care is mentally ill, and there are no healthy people who have made bad choices in such places. One might conclude then that socialized medicine causes mental illmess, or even that it cures choosing badly. // BL \\ (talk) 04:45, 22 March 2009 (UTC)

I am personally in Canada, and we have universal health care. I can assure you that many mentally unstable people access the free health care here. Doctors make money from the pharmaceutical companies every time someone fills a prescription, so it's really not that hard to find a doctor who will play along with a mentally unhealthy person's imaginary problems. Also, BL makes a very good point. And to Tango, I would think that all "bad people" have some sort of mental disorder, no? I don't understand the distinction you're trying to make. bcatt (talk) 05:50, 22 March 2009 (UTC)

Well, you don't have to be sick to be a jerk, you know. -- Captain Disdain (talk) 12:57, 22 March 2009 (UTC)

When people are mentally ill we don't punish them for their actions or put them in secure mental facilities. When people are just bad we throw them in prison. (That's an oversimplification, obviously, but you get the point.) I'm not the one making the distinction. I agree with you that such a distinction doesn't make much sense - that was the point I was trying to make. --Tango (talk) 13:14, 22 March 2009 (UTC)

Of course, my response above was somewhat of an oversimplification, but it comes from a basic problem with the mental health industry, indeed one which Tango has aluded to. The deal with most mental illness is that there is a lack of mechanistic explanation for it. If I have diabetes, its because my pancrease doesn't work right. If I have AIDS, I have a virus in my system which is causing it. If I have ADHD, it means I display a set of behaviors, but what is the underlying physical cause of this?!? See, there's the crux of the problem. Diseases have causes which can be identified. Mental diseases, mostly, are about a set of causeless symptoms; so what sepereates a person who chooses to behave badly from one with a mental illness is simply the existance of a doctor willing to provide the diagnosis. Now, don't get me wrong, there are real mental illnesses. I understand this; however there are also a vast number of people who are overdiagnosed with them, because there is no way to distinguish between people who make bad choices and people who are incapable of making good ones. It;s a shame, because it swamps the system with people who don't need treatment, and reduces the quality of treatment to people who really need it. So people with access to the doctors to make the diagnoses get labeled "unable to make good choices" and those people without get labeled "people who make bad choices". It is unclear what is wrong inside of their bodies that distinguishes one group from the other... --Jayron32.talk.contribs 01:07, 23 March 2009 (UTC)

Ok, I have a lot easier time agreeing with you on these points. Coincidentally (or not), ADD/ADHD appears to be one of the favourite diagnoses of the type of parent that I've described, as well as of every damn teacher out there who expects a child to engage in the completely abnormal behaviour of sitting at a desk for 7 hours 5 days a week...it's simply unnatural. bcatt (talk) 16:19, 23 March 2009 (UTC)

March 22

Pick on somebody your own size...

Why is it that the largest animals, both on land (elephants) and in water (whales), don't have any natural predators (other than man, that is). I'm talking about adult animals here. So, why isn't there a predator (or group of predators) large enough to take on an adult elephant or adult blue whale ? Somehow the upper size limit for predators seems to be lower than for other animals, but why exactly is this ? StuRat (talk) 04:23, 22 March 2009 (UTC)

If the largest animals in the world were predators, they would quickly outstrip their food source, and then ensure their own demise. The situation is not unique to modern times, Tyrannosaurus, one of the largest predators ever, was still dwarfed by contemporaneous herbivorous dinosaurs; probably on a scale similar to the size difference between the largest predators and herbivorous animals today. Incidentally, Blue Whales are technically meat-eaters; they subsist on Krill, which is definately not a plant. --Jayron32.talk.contribs 04:41, 22 March 2009 (UTC)

Why couldn't there just be fewer in the predator species than their prey species ? I believe this is the normal situation in any predator-prey relationship. StuRat (talk) 04:47, 22 March 2009 (UTC)

Well, we could invent any situation we want to; except that time and time again, over history, the same patterns have emerged. We can justify these repeating patterns, by offering explanations as I have done, but offering counterexplanations (like "we SHOULD have really huge predators") doesn't make much sense, since it just appears to not work that way. Except that, as I noted above, the largest animal ever to have lived, IS A PREDATOR. Blue Whales eat other animals, live, which seems to me to be what a predator does... Even if you don't want to include that as a predator, you must admit that predators just AREN'T the largest critters in any environment and at any time, so explanations that attempt to say they should be must be flawed from the start, no? --Jayron32.talk.contribs 05:09, 22 March 2009 (UTC)

Keep in mind that the larger the animal, the longer it takes to grow a replacement. In general, anyway. Preditors can eat rabbits all day long and the population will rebound quickly. If a theoretical uber-hunter ate all the elephants within its range in could be decades before they replenished. It seems like that would leave a very low margin of error for the predator-prey balance.

In general predators prefer animals that reproduce quickly and grow up quickly. APL (talk) 06:34, 22 March 2009 (UTC)

Incidentally, while adult elephants have no natural predators other then humans, juveniles are general vunerable to big cats although the social herd nature helps to protect them.. The same appears to be the case for mammoths and saber-toothed cats and one common believe is the demise of the mammoths may have played a role in their extinction, take a read of Homotherium and Smilodon for example. Homotherium in particular says

Friesenhahn cave in Texas contained the remains of over 30 H. serum individuals, which were discovered along with the remains of between 300 and 400 juvenile Columbian Mammoths (Mammuthus columbii).[6] Besides mammoth, very few other potential prey species were found in the cave - it is therefore unlikely that Homotherium carried scavenged carcasses of already dead animals to the cave. Such specialization on prey of a particular species and age structure is not covenant with a scavenging lifestyle. For the same reason it is also unlikely that the dire wolves carried the mammoths into the cave.

Nil Einne (talk) 13:44, 22 March 2009 (UTC)

Killer Whales have been known to hunt blue whales. — DanielLC 16:55, 22 March 2009 (UTC)

Wow, they are 1/25th the mass, so that would seem rather ambitious. That's worse than a house cat hunting an adult human. StuRat (talk) 17:22, 22 March 2009 (UTC)

I think that they only go for the calves and they do hunt in packs, so maybe not so ambitious, although such attacks are said to be rare in our article. Mikenorton (talk) 17:37, 22 March 2009 (UTC)

Still, there have been cases where a dog of a similar size to a housecat has managed to kill an adult human. I'm not entirely certain - but I think that killer whales are much faster and more manoeuvrable than blue whales, and they are (obviously) much more aggressive. Blue whales are huge, yes - but I'd imagine that taking a chunk the size of a killer whale's mouth out of the body of one would cause it to die. --Kurt Shaped Box (talk) 22:33, 22 March 2009 (UTC)

There are plenty of ecosystems where the dominant predator is also the largest animal. The Killer Whale eats penguins and seals - and is easily the biggest animal that lives (continuously) in those areas. I doubt that in regions where the Great White Shark lives has any animals that are any larger. Ditto Polar Bears, ditto Grizzly Bears. I think there are plenty of ecosystems where the predator is the biggest creature around - and plenty of others where it isn't - it seems fairly random to me. As for the evolutionary pressures - I agree with the earlier respondant - if an easier living can be had hunting rabbits - why go after elephant? If the only herbivore was the elephant - then probably the carnivores would evolve to take it down. But generally a pack of animals is better at doing that...and for that, size isn't everything. SteveBaker (talk) 19:26, 22 March 2009 (UTC)

Are you sure no whales live in those oceans ? And how about large land herbivores, such as elk and moose ? They seem like they might be too big to be prey for bears, at least the adult males. As for your "if an easier living can be had hunting rabbits - why go after elephants ?", the point is that the rabbit-hunting niche is already filled by well-adapted predators, while the whale- and elephant-hunting niches are wide open. StuRat (talk) 03:34, 23 March 2009 (UTC)

Not any more, they ain't. We got there first and did it better. :) --Kurt Shaped Box (talk) 03:40, 23 March 2009 (UTC)

FYI: Biggest land animal to ever live = sauropod = 80 tonnes [26] 141.14.245.244 (talk) 15:52, 23 March 2009 (UTC)

Pyrethrins

I have sprayed a Kaffir Lime tree with a pyrethrin product to eliminate a heavy infestation of red spider mites. Since I use the leaves in cooking, IS IT SAFE to eat the food cooked using these pyrethrin-sprayed leaves? Is there a period of time after spraying not to use them, and then it is OK?

Thank you very much for your answer. Yvonne Stinson —Preceding unsigned comment added by Rajahstein (talk • contribs) 12:15, 22 March 2009 (UTC)

Pyrethrins are amongst the safest pesticides available. Having said that I'm loath to pronounce anything completely safe. You should judge for yourself from the published information about them, here are a couple of links that discuss both direct exposure [27](i.e. during application) and safety as residue in food [28]. The conclusions seem to be that there are few definite health implications but the possibility of carcinogenesis has not been ruled out. Mikenorton (talk) 12:43, 22 March 2009 (UTC)

If you do use them, I would recommend you rinse the leaves well Nil Einne (talk) 13:39, 22 March 2009 (UTC)

Next time spray the Kaffir Lime with plain water more frequently, two or three times a day if possible. Red spider mites hate moist conditions and will find it hard to survive let alone flourish. Richard Avery (talk) 08:30, 23 March 2009 (UTC)

Metal spoon in microwave

Hi. Sometimes we leave a metal spoon in our food when we put it in the microwave, and nothing happens, and the spoon is barely hot afterwards. Of course, the food must be full, solid, and in a bowl, and most of the spoon is immersed in the food so the microwave isn't heating *just* the spoon. Are there any risks that are unforseen with this practice, such as radiation being emitted outside of the microwave, or the spoon or the food storing excess radiation or an electric current, etc? Thanks. ~AH1^(TCU) 14:56, 22 March 2009 (UTC)

Microwave oven#Hazards contains language that makes me not want to repeat your experiments... 88.112.62.225 (talk) 15:10, 22 March 2009 (UTC)

It does however say "Microwaving food containing an individual smooth metal object without pointed ends (for example, a spoon) usually does not produce sparking". There is a risk of shorting if the handle gets too close to the side of the oven. I can't see how any excess radiation or electric current could be stored. Mikenorton (talk) 15:25, 22 March 2009 (UTC)

Well, there are certainly situations when this practice is "A Bad Thing" - sharp metal objects concentrate the charge at their tips and can arc - that produces all sorts of nasty, toxic gasses that you really don't want in your food - also, metal objects positioned "just so" with respect to the microwaves resonant cavity can concentrate the heat in small areas resulting in food that's cool in some areas and dangerously hot in others - that can result in small explosions when heating liquids - it can also "short out" the magnetron to some degree which will shorten it's life and might even outright destroy it. However, there are other times when none of these terrible things can happen. However, the precise reason you get one outcome versus another depends critically on exact placement of the metal, its exact shape and the precise nature of the food (if any) around it. Since we mere mortals have ZERO 'gut-feel' for what's right and what's not when it comes to invisible & intangiable things like microwaves - putting metal that was not designed specifically to be there into your microwave - is just a dumb thing to do. It says that right there in the instruction book for your oven - and there is probably another sticker someplace on the door frame that says it again...they don't do that without a reason...so just don't do it - OK? SteveBaker (talk) 19:17, 22 March 2009 (UTC)

Let me reword the OP's question a bit to understand it a bit better... "See, this one time, I crossed a busy street wearing a blindfold and blasting my I-pod. I could see nothing, I could hear nothing, and there were like 100 cars crossing the street in front of me. And yet, I didn't get hit. Doesn't this mean that all the things I read about looking where I am walking and only crossing with the light are bullshit? Like, if I managed to cross the street with a blindfold and nothing bad happened, why is there all this fuss?!?". Seriously, putting metal in a microwave is ALWAYS contraindicated, even if occasionally nothing bad happens, it is NOT a habit you want to get into... --Jayron32.talk.contribs 00:49, 23 March 2009 (UTC)

When I was a little kid, I saw a wildcat (Bobcat) in a cage at a roadside zoo. I stuck my finger through the chickenwire of the cage to tease the cat, and suffered no ill effects. Around the same time, I stuck my finger in a live electric socket, and suffered only momentary pain.Around this same time, while walking in high weeds in the southern U.S, I stepped on a snake (of unknown species) which thrashed around dramatically. Can we conclude from these anecdotal reports that these actions were a good idea? Edison (talk) 02:25, 23 March 2009 (UTC)

, still a spoon is a heck of a lot safer then a fork, so maybe the ipod was not on full blast and the blindfold let you get a glimpse of shadow vs light.65.121.141.34 (talk) 14:03, 23 March 2009 (UTC)

ATTN Steve Baker - do we really have complete dinosaur dna like in Jurassic Park?

Dear Steve Baker,

My question is: have we really got complete dinosaur dna like in Jurassic Park? Eventually, does it look like there is any reason we couldn't really hatch little dinos?

Thank you for your time!

Yours sincerely,

94.27.132.205 (talk) 15:27, 22 March 2009 (UTC)

I'm not sure why you are specifically asking Steve, he wasn't a palaeogeneticist (is that a word?) last time I checked. I'm pretty sure we don't have a complete genome for any dinosaurs - they didn't even have one in Jurassic Park, they had to fill in the blanks with frog DNA (why they didn't use bird DNA, I don't know... probably because the plot wouldn't have worked!), or something, which is what caused all the problems. Our article, Dinosaur#Soft tissue and DNA, suggests we haven't even got a reliable partial genome from any dinosaurs (a couple of unreliable ones, though!). --Tango (talk) 15:33, 22 March 2009 (UTC)

Hey! I have advanced degrees in palaeogenetics with all four of the universities that offer the course - paelaeogeneticists come to me when they have problems with spelling the word! {{citation}}: Empty citation (help) and because of that, I have all fourteen alternative spellings of the term tattooed on places I'm not going to mention. {{citation}}: Empty citation (help) SteveBaker (talk) 18:57, 22 March 2009 (UTC)

I stand corrected and humbly and deferentially beg for forgiveness, O Omniscient One! --Tango (talk) 19:45, 22 March 2009 (UTC)

I'm asking Steve Baker because he's the smartest and best-informed paleogeneticist in existence -- paleogeniticists might not exist as a profession, yet Steve Baker would be the best qualified of them all (if not best-credentialled). Thank you for the link. However, with the above points in mind, I will wait for Steve Baker's verdict. Thank you! 94.27.132.205 (talk) 15:46, 22 March 2009 (UTC)

Steve is very well read and an excellent researcher, but what gives you the idea he's a well qualified palaeogeneticist? --Tango (talk) 16:20, 22 March 2009 (UTC)

(edit conflict)Even with an animal as geologically recent as a mammoth, paleogeneticists (6660 ghits BTW) have only assembled part of the genome and in this BBC article [29] Dr Gilbert of Copenhagen's Center for Ancient Genetics says that even if we had the whole genome "technology does not currently exist to turn that biochemical information into a live animal". Mikenorton (talk) 15:50, 22 March 2009 (UTC)

If you really are only interested in answers from Steve Baker, then you should ask this Q on his talk page, not here. If you want answers from everyone, then post here, but don't address those Q's to any particular person. StuRat (talk) 16:02, 22 March 2009 (UTC)

No, we do not have complete dinosaur DNA. For full details see Bully for Brontosaurus (1991) by Stephen Jay Gould (who was a paleontologist), and well worth the price. (Sorry for not being SteveBaker.)  —B00P (talk) 17:07, 22 March 2009 (UTC)

We barely have a complete human genome, and there's no shortage of fresh, brand new, human blood. Only very tiny, and (obviously) very old samples of dinosaur blood and soft tissue have been recovered. It's not clear if it's even theoretically possible to extract a complete dinosaur genome from these samples (It's possible that the information we'd need simply doesn't exist anymore.), but even if it is, we'd need technology much more advanced than we've got now. APL (talk) 17:10, 22 March 2009 (UTC)

1. No.
2. Yes.

SteveBaker (talk) 18:57, 22 March 2009 (UTC)

I certainly feel like Moses and maybe shouldn't be asking back, but although I understand #1, could you explain the reasoning for #2? I mean, "eventually" is a long time, even if we had to combine 100,000 bits of DNA, there ARE that many in total waiting to be unearthed, no? Couldn't they be combined? If all you have is a very poor (less than VGA) webcam and want a super-super high-resolution scan of something -- couldn't you get it through 100,000 passes? Or in this case, you would have 100,000 deteorated photographs, coudln't you come up with the original based on all that? —Preceding unsigned comment added by 94.27.132.205 (talk) 19:16, 22 March 2009 (UTC)

Maybe. The problem with DNA is that, while you may have all the bits necessary, you wouldn't have any way to know what order to put them together in. Your photograph analogy doesn't quite work - a better analogy would be a puzzle for which we don't know the image we are supposed to be putting together. --Tango (talk) 19:45, 22 March 2009 (UTC)

But we do know the image! A T-Rex! 94.27.132.205 (talk) 19:47, 22 March 2009 (UTC)

I mean the image of the DNA. We are far from being able to backwards engineer DNA from observations of fossilised bones. --Tango (talk) 20:22, 22 March 2009 (UTC)

The problems with making a creature from scratch goes a long way beyond just assembling a viable DNA strand. You've also got to implant it in a suitable cell (ie one that has the right chemical environment, etc) - that has to be provoked into replicating by the right chemical setup in the mother - in the case of Dinosaurs, something has to create a huge egg - and lay it and hatch it. The way we clone animals right now is to take the egg from a closely related animal, wipe out its DNA and replace it with the new DNA. Then you implant the cell back into the female of the closely related species and wait for nature to take its course. However, we don't have any extant animals that are anything remotely like a Dinosaur. So we have no egg to implant the DNA into - and no mother dinosaur to implant the egg into. Worse still, it's very likely that all of the food that a baby dinosaur would be able to eat has long gone extinct - so you have a problem feeding it. Because we have no live dinosaurs to study - we don't even have a way to know what nutrients they need. Also, the world has changed quite a bit - different amounts of oxygen in the air - that kind of thing. Most animals get resistance to disease from their mother's antibodies - no chance of that happening here. The obstacles are spectacular...even if you could get an intact DNA strand - which isn't looking very possible from the amounts we've been able to extract. Remember that you can't just collect random DNA snippets from 500 different species spread over 160 million years and expect to be able to stitch them all back together! You need DNA from a single species...perhaps even a single sex of a single species...and over a few thousand years or so. That's asking a lot! SteveBaker (talk) 19:56, 22 March 2009 (UTC)

It doesn't need to be a huge egg, there were plenty of small species of dinosaur we could try and bring back. We don't have the technology now, but I don't see any theoretical reason why a synthetic egg wouldn't be possible to construct eventually. I think the DNA is the biggest problem, the rest can be overcome with effort but if the DNA doesn't exist, then it doesn't exist. --Tango (talk) 20:22, 22 March 2009 (UTC)

I'm no SteveBaker, but here's my take.

1.) Not yet, but theoretically possible given a well-preserved specimen. There has been some progress in sequencing the Neanderthal genome but there are still considerable gaps. Another concern is that even if you could piece together a "complete" genome for a given dino species it would almost certainly be a patch-work of pieces from different individual specimens and would utterly fail to capture the degree of genetic variation that would have existed within a population of that particular species. This would lead to considerable trouble with part 2 and any future breeding of your little dinos (which would all be genetically identical to each other -- not good for the health of the species).

2.) Without extraordinary advances in molecular biology, NO. One reason is that even if you knew the complete DNA sequence based on sequencing fragmented pieces of dino DNA, you'd still have problems assembling it into the proper chromosomes that would enable the putative dino cells to replicate. The way the sequencing of the human genome was done, large fragments of DNA contained in bacterial artificial chromosomes were sequenced and mapped to their proper chromosomes, then overlapping fragments were pieced together to generate a computational "assembly" of the genome that is now an advanced draft stage (there are still bits that haven't been sequenced due to their complexity or repetitiveness). We know the structure of human (and mouse, and fly, and dog, etc.) chromsomes because of cytogenetics, fluorescence in situ hybridization, and other such techniques -- which require intact cells and in some cases cell culture. Mapping the fragments of dino DNA to their proper locations within the dino chromosomes would essentially be impossible because of the inability to perform cytogenetic techniques. Furthermore, even if you knew where each piece was supposed to go, we don't currently have the ability to stitch together an entire chromosome "de novo" and somehow get it to assemble into its proper macromolecular structure, complete with histones and all the other DNA binding proteins that endow the DNA with the ability to be replicated in a living cell. Now, it is theoretically possible that you could get enough of the dino DNA to make a "complete" sequence and somehow "splice" it into existing chromosomes from a modern-day species (as was the plot in Jurassic Park) but this would be extraordinarily challenging (dare I say "impossible"?) for today's molecular biology. --- Medical geneticist (talk) 20:25, 22 March 2009 (UTC)

What about this iterative proposal: put the large species in a small species so that it's cramped and deformed, but alive, at birth. Then put the DNA straight back into the new girl once she's an adult (no CHANGE in the dna). It might still be cramped because of the deformity but basically should be normal. A final few generations the same way will result in a perfectly fit dino -- raised in as good a womb as you get (or whatever cold-blooded lizards have instead of wombs). What do you think of this proposal? 94.27.132.205 (talk) 20:40, 22 March 2009 (UTC)

See ALL of my objections above. You might maybe be able to get around needing a big egg that way - but you still have no cell to put the DNA into, no parent animal to implant the egg into, no food for the hatchling, no knowledge of how young dinosaurs have to be treated by their mothers - whether the temperature of the egg has to be varied during development (this turns out to be a CRUCIAL factor in the development of Turtles and Crocodiles...so it's probably critical in Dinosaurs too)...there are a million things we don't know (and arguably, cannot know) about raising a dinosaur. When you consider how many species have proven impossible to breed in zoo's - and that's with full knowledge of diet, parenting, etc, etc...this is so far from being possible. Heck, your first step would have to be in assembling lots and lots of plant DNA from species of that era and figuring out how to grow that BEFORE you even start on the actual Dinosaur. SteveBaker (talk) 21:02, 22 March 2009 (UTC)

I, for one, am very comfortable leaving it to Steve to determine whether paleogeneticists have access to complete dino DNA at this point. Edison (talk) 02:20, 23 March 2009 (UTC)

Birds are considered the modern descendants of dinosaurs so just hatch an egg and you've got yourself your own little baby dinosaur. It may be possible to get something like a dinosaur by seeing what's common between birds and crocodiles say and then cutting out a selection of those changes which are specifically for bird like features like beaks and putting in some of the more dinosaur like things that have their remnants in the junk dna and occur in crocodiles.

Falling

I was watching videos of cats falling and being okay--but some of the heights impressed me! If I fell from the same height, I'd be seriously hurt, how do they do it?!24.91.161.116 (talk) 15:48, 22 March 2009 (UTC)

See our article Cat righting reflex, it looks like it has everything you need to know. Mikenorton (talk) 15:56, 22 March 2009 (UTC)

The lighter the animal the farther it can fall without injury. With a small enough animal, like an insect, it could fall from an airplane and survive, as it's terminal velocity is too low to be, well, terminal. StuRat (talk) 15:56, 22 March 2009 (UTC)

I don't think it's just mass that's a factor, it's the ratio of mass to the area of animal projected onto a plane. Since mass is roughly proportional to volume (different animal have similar densities), which is proportional to the cube of linear size, whereas area is proportional to the square, smaller animals have an advantage over larger ones. With cats there is more to it, though, since they can self-right so their legs hit the ground first, allowing them to absorb the impact better. --Tango (talk) 18:25, 22 March 2009 (UTC)

This is of course covered in the classic essay On Being the Right Size. Algebraist 19:16, 22 March 2009 (UTC)

1 Milkshake, 2 straws

If I drink something with 2 straws in my mouth does it take more or less sucking power to get the same amount of liquid as with 1 straw. How about with 15? I'm looking to find out the most effective number of straws, where I exert the least amount of energy for the most amount of liquid pay-off.24.91.161.116 (talk) 15:51, 22 March 2009 (UTC)

I'd say one straw is best. Two would at first seem to be the same, but there is likely to be an air gap between the straws which allows some of the suction to be wasted by sucking in air. The more straws, the more likely you will have air gaps. StuRat (talk) 15:58, 22 March 2009 (UTC)

I wonder what the efficiency of sucking through a straw is... if it's very efficient to start with (and I have a feeling it might be) then adding more straws won't be able to help. The only losses I can see would be from an imperfect seal around the straw (which is probably negligible with one straw) and the usual losses associated with any muscle usage (in this case, the diaphragm). --Tango (talk) 16:40, 22 March 2009 (UTC)

It's a simple matter of conservation of energy. The liquid is raised to some height - so it gains gravitational potential energy in proportion to (mass x :height) - that's the amount of energy it costs you to lift it through that height. So, neglecting friction and such - there is no difference in the energy required. That's certainly a reasonable assumption for drinking (say) water - but milkshakes are non-Newtonian fluids and their viscosity doesn't behave in a simple way. But in any case - assuming the two straws could be said to be independent - moving X amount of liquid through one straw ought to take the same amount of energy as X amount through two. So this is really a question of efficiency - can your mouth muscles (or rib muscles or diaphragm) produce that energy more efficiently in short-high-power sucks or better in slower, low-power sucks. Think of how your car uses more gasoline if you drive around all day with the tachometer pegged at 6,000 rpm instead of 2,500 rpm. Sadly, the human body is ridiculously complicated - and so that's an insanely difficult question - so probably you need to do a series of serious (albeit delicious) experiments to figure it out. SteveBaker (talk) 18:47, 22 March 2009 (UTC)

I believe that the viscosity of a milkshake is the main factor limiting flow rate, not the potential energy between the top and bottom of the straw due to gravity. The flow should be approximately proportional to the pressure differential created by sucking (atmospheric pressure minus intra oral pressure) divided by the resistance to flow through the straw, analogous to Ohm's law for linear electrical resistances. The lips, being flexible in the normal person, can seal around two straws as well as around one, especially if they are a short distance apart so there is not a failure to seal between them. Two straws=twice the milkshake per second, with the same suction created by the mouth. Two straws is like a larger straw (but wall effects may prevent a simple relation to the area of the straw opening). The failure to linearly keep increasing the flow with more and more straws would be due to the inability of the mouth to maintain the same high suction when a high flow rate enters, as well as leakage between adjacent straws. Edison (talk) 19:06, 22 March 2009 (UTC)

WP:OR: (I couldn't help it) with 8 oz of low viscosity liquid (water) and there is a learning curve:

Trial #	Seconds, 1 straw	Seconds, 2 straws
(was 1) 1 & 2	19	19
(was 2) 3 & 4	15	15
(was 3) 5 & 6	13	13
(was 4) 7 & 8	12	11

I'm not tempted to do any high viscosity testing tonight. -hydnjo (talk) 23:59, 22 March 2009 (UTC)

Since there is, as you say, a learning curve, we need to know what order you did the trials in in order to interpret the data. --Tango (talk) 00:02, 23 March 2009 (UTC)

• I have altered the table above to provide clarity as to the trial counting:

Would the trials be numbered for some reason other than chronological sequence? // BL \\ (talk) 00:20, 23 March 2009 (UTC)

Unlikely, but the ordering of the two sets of trials is not clear at all. Algebraist 00:21, 23 March 2009 (UTC)

You can tell I am not a scientist. From the layout by itself, I assumed Trial 1 was first one straw and then two straws; Trial 2 was one straw and then two straws. You are right that it doesn't say that, though. // BL \\ (talk) 00:39, 23 March 2009 (UTC)

• I have altered the table above to provide clarity as to the trial counting: hydnjo (talk) 01:13, 23 March 2009 (UTC)

I recruited an independent referee to do the timing with a one second resolution timer. My challenge was to empty a measuring cup filled with 8 ounces of water with either one or two drinking straws by sucking the water into my mouth and then spitting it out into the adjacent sink in the fastest time. We then practiced a few times withan empty cup to be sure of the cues.

Show time: When she started the timer and said "go" I did the best I could to empty the cup as fast as possible and then declare "stop" while putting the cup down onto the counter (where it started) and then she stopped the timer. I then recorded the elapsed time. The testing trials alternated between between using one and two straws starting with one straw and finally ending with two straws (eight trials in all). The "spitting out" time seemed to go much faster than the "sucking" time that I attribute much of the "learning curve" to the "sucking" part. The apparatus consisted of a 12 ounce graduated clear glass measuring cup with a handle and "squash-proof" plastic drinking straws 7.75 inches long by 0.25 inches diameter. The water was about 48ºF. The referee thought I was nuts! -hydnjo (talk) 01:07, 23 March 2009 (UTC)

I've replaced the other responses to this question that you removed and moved your latest reply to the bottom - you managed to completely mess up the section!! (We've all done it, don't worry!)

So the conclusion we should draw from this extremely scientific and reliable experiment is that there is no significant difference between one straw and two for drinking water. Thank you for sacrificing your reputation for sanity for the sake of science - I salute you! --Tango (talk) 01:16, 23 March 2009 (UTC)

I'm enjoying your saluto in the most libationious of ways, maybe russians or something more viscous next. ;-) -hydnjo (talk) 02:38, 23 March 2009 (UTC)

Oops, Edison (below) is suggesting not spitting out! -hydnjo (talk) 02:38, 23 March 2009 (UTC)

USE A MILK SHAKE! Don't spit it out, to avoid lots of wasted time. SWALLOW IT! Water is very low viscosity, so the limiting factor is likely the ability of the tongue and jaws to pump liquid, rather than the rate of flow of a viscous liquid through one or two tubes at constant pressure. Edison (talk) 02:14, 23 March 2009 (UTC)

Whilst generally in favor of the scientific method - I can't help thinking that our most dedicated test subjects may have trouble maintaining a uniform performance after consuming approximately 8 milkshakes...and that's before we begin to concern ourselves with control groups for the influence of extra chocolate on the viscosity. SteveBaker (talk) 12:36, 23 March 2009 (UTC)

And that's before we get started in ice cream milkshakes which you end up having to "drink" with a spoon. --Tango (talk) 13:24, 23 March 2009 (UTC)

The low flow rate with a thick shake might allow consumption of a small amount per trial. 3 ounces, maybe? There would probably be lots of volunteer experimental subjects outside a malt shop/McDonalds on a nice day. Edison (talk) 18:41, 23 March 2009 (UTC)

Injuries causing memory loss

Hi all I am researching injuries that can cause memory loss. By this I mean memory loss that occurs as a result of an accident, most likely a head injury in this case, as opposed to the likes of Alzheimer's or Parkinson's disease causing memory loss. I have read about the likes of chronic traumatic encephalopathy (punch drunk syndrome), subarachnoid haemorrhage, skull fractures and concussion causing memory loss. (Only temporary with regard to concussion). My question does anyone know if I have missed out any injuries which can result in memory loss? If so could they give me some pointers as to where I can find out more information on them? Many thanks. —Preceding unsigned comment added by 139.222.240.10 (talk) 20:45, 22 March 2009 (UTC)

We have an article, Post-traumatic amnesia, which may help. --Tango (talk) 21:13, 22 March 2009 (UTC)

March 23

zero point energy questions

Hello

Apologies, I know you guys must get stupid questions like this alot, but I cant get a straight answer anywhere else. From this quote "A potentially promising area for research is the fact that if particles become more energetic as they are heated or accelerated their gravitational field increases. Changes in gravity can perhaps be attributed to a change in a spherical zpf energy density gradient surrounding an accelerated or decelerated massive particle." It seems to suggust that the zero point field can effect gravity, and the casimir effect moves objects, would it be possible , If we had better tech than we do now, to make a device that can manipulate zero point energy to move objects like the gravity gun if halflife 2 for example. I know this is stupid question but i cant get a strait answer from anyone about this, if not thats fine , if so thats fine too, if opinions are devided who current has the strongest case scientifically.

Thank you so much —Preceding unsigned comment added by 80.6.41.111 (talk) 00:37, 23 March 2009 (UTC)

The Casimir effect is a fairly weak force equivalent to van der Waals bond. It's potential energy must be very low and contribute very little to a measured mass. Its effect will be the greatest on the smallest scales, such as between nucleons. However this mass would already be measured when the mass of nuclei is determined, so there should not be lots of spare energy there for the taking. This force is what gives grease its strength. Graeme Bartlett (talk) 04:24, 23 March 2009 (UTC)

protonation of the alcohol group in 2-methylcyclohexanol

In order to protonate the OH group with phosphoric acid to weaken the C-(H)OH bond so a dehydration elimination reaction can occur to yield 1-methylcyclohexene, does this mixture need to be subjected to heat? At what stage of the mechanism for the elimination reaction is heat needed? John Riemann Soong (talk) 01:42, 23 March 2009 (UTC)

Heat probably doesn't affect the extent of protonation much. However, heat probably does promote loss of water because that is a fragmentation reaction, and increasing temperature makes this change in entropy an increasingly important part of the overall energy of the reaction. Heat also makes all reactions faster, so you'll be able to get out of lab in time for the next class:) DMacks (talk) 01:49, 23 March 2009 (UTC)

Well, I'm a bit confused by my lab manual. It seems to imply that the thermodynamic stability difference between 1-methylcyclohexene and 3-methycyclohexene is greater than the stability difference between 1-methylcyclohexene and 1-methylcyclohexanol. If I look at it a certain way, it almost seems that the 1-methylcyclohexene product is lower in energy than the alkane product! I'm wondering at what point the heat input is critical for what must be an endothermic reaction (reversal of saturation/addition of an alkane). And the protonation of the OH group appears to require the greatest activation energy in the reaction. I know heat aids in reactivity, but surely it can't be just that (as well as yes, the steam distillation of my product?) According to the energy diagram, the loss of the water molecule after the alcohol has been protonated is exothermic so heat would only appear to aid in speed of the fragmentation step. John Riemann Soong (talk) 02:15, 23 March 2009 (UTC)

If you have the actual energy diagram, then you know exactly where energy needs to be added to make the reaction go:) I assume that it is ΔG, so steps where ΔS changes are generally the ones that are the most affectable by T. You always need energy to get over the activation barrier, but once you have "at least that much", the equilibrium will always be establishable. And no matter what the role of heat may be in the chemistry or where each equilibrium lies, "removing the product as soon as it's formed" is going to drive an even fairly unfavorable (by product stability) reaction, thanks to Le Chatelier. Once you're steam-distilling the product out, that's all that really matters for accomplishing this reaction in practice. DMacks (talk) 02:29, 23 March 2009 (UTC)

I'm not sure if the diagram is being held at constant temperature though. Fragmentation generally would be exergonic yes? It wouldn't be that elevated temperature between the protonation and fragmentation steps allows fragmentation to proceed, e.g. s*dT exceeds a positive dH? I'm confused about energy flow -- e.g. whether the diagram includes the phosphoric acid in the system or not. The lab manual says the phosphoric acid "catalyses" the reaction so would it be that the H+ is what injects free energy into the system before the mixture is heated? Removing the product sounds really promising as a "drive" for the reaction, except I think the methylcyclohexanol is being distilled too (along with the aqueous components). Is this where volatility and vapor pressure would start to be important as well? I'm trying to finalise my understanding of this process. Thanks for all the help anyway! John Riemann Soong (talk) 05:19, 23 March 2009 (UTC)

Also, I note interestingly that methylcyclohexanol has a boiling point of 165-168 degrees Celsius. It's miscible with water, so it would probably form some kind of azeotrope and I'm correct to assume it wouldn't boil at significant amounts at 96 degrees Celsius compared with the methylcyclohexenes (bp 104-110)? John Riemann Soong (talk) 05:19, 23 March 2009 (UTC)

Folic acid

I'm currently working on a spoken version of folic acid. However, as I was going through it for a quick copyedit, I ran into a problem; the equation at the end of the section Biochemistry of DNA base and amino acid production seems, to me, to be nonsensical. I'm having difficulty determining what it's actually supposed to be. Is it wrong, or is it just my sight beginning to blur from too much editing? If someone could take a look at it, I would be much obliged. Thanks! Sophus Bie ^(talk) 10:00, 23 March 2009 (UTC)

I simplified the equation and added an image from Commons. Axl ¤ [Talk] 12:21, 23 March 2009 (UTC)

Scaled Drawing

For my science class on a project, we have to draw a scaled drawing showing improvements we made to a windmill. How would I show that I made the turbines out of carbon fiber? <(^_^)> Pokegeek42 (talk) 13:13, 23 March 2009 (UTC)

By writing "carbon fibre" next to them. Technical drawings are often annotated to include information on construction materials and lots of other stuff. --Tango (talk) 13:23, 23 March 2009 (UTC)

Maybe you could copy (as in make a similar drawing not photocopy) a micrograph or show how the fiber reinforces the material [30]. Then compare to other materials and say why carbon fiber is better. or do s.th. like Crystal structure. You could also do a drawing of the windmill shaded with areas showing high strain and how your carbon fiber would be an improvement there. S.th. like this would be over the top. [31]. Just get some colored pencils and shade in a turbine image.76.97.245.5 (talk) 13:51, 23 March 2009 (UTC)

Tango's absolutely right. Use any method that makes your intention clear. I've recently been involved in a rather large construction project and, besides the sheer volume of drawings required, which is staggering, I've also noticed that formality tends to go out the window if there's a more clear way of expressing what you need to. Matt Deres (talk) 19:56, 23 March 2009 (UTC)

mirlodermabration

can microdermabration application cause purging ?70.216.81.127 (talk) 13:20, 23 March 2009 (UTC)

Did you mean Microdermabrasion? What do you think is being purged? 76.97.245.5 (talk) 14:01, 23 March 2009 (UTC)

Probably "purging of toxins". In this case, no, not to any significant degree. Also, it's a mistake to believe that we are all suffering from mysterious unnamed "toxins" in the first place. This is just a marketing scam. StuRat (talk) 15:53, 23 March 2009 (UTC)

Another possible interpretation is that they are asking if microdermabrasion can cause vomiting. I sure hope not. If so, I'd never do that again. StuRat (talk) 15:55, 23 March 2009 (UTC)

Monophyly of amphibians

Nowadays, the consensus is that amphibians form a monophiletic group. Nonetheless, in the past there was much debate over whether they were paraphyletic (i.e., amniotes descend from them). I have looked in Amphibian articles on Wikipedia and I have done google searches, but I haven't found much; does anybody know some place where I might find an in-depth discussion of the taxonomy of amphibans over the last few decades? Thank you. –Leptictidium (mt) 19:43, 23 March 2009 (UTC)

Expansion of Space

I have a hard time understanding what we mean when we say our universe is expanding. What exactly is expanding? Is it the distances between all cosmological objects? (Are these objects themselves expanding?) If it is, where is it expanding to? Where does this extra space come from? If I get it right, it is the space itself which is expanding. If it is so, is it expanding into its own dimension? I mean in 3 dimensions or something else is going on here. If we assume a hypothetical picture of seeing the universe from 4th dimension, we will see its edge. is this edge moving outside? If yes, what is this outside and what is this outside composed of? Please clarify. - DSachan (talk) 20:11, 23 March 2009 (UTC)

We have an article Metric expansion of space. Algebraist 20:13, 23 March 2009 (UTC)

Does that mean I have to go and learn the Metric system, now ? :-) StuRat (talk) 20:40, 23 March 2009 (UTC)

"What exactly is expanding?" pace itself is stretching

"Are these objects themselves expanding?" Objects that are gravitationally bound like galaxies and solar systems are not expanding. Larger objects like galaxy super clusters may still have some residual expansion but could possibly complete their gravitational 'colapse' in the future and become bound, after which the space within them would have stopped expanding (Only at a very large scale the universe can be considered to have a uniforme rate of expansion).

"If we assume a hypothetical picture of seeing the universe from 4th dimension, we will see its edge. is this edge moving outside?" There is no evidence that the universe has an 'edge'. 71.203.58.148 (talk) 21:05, 23 March 2009 (UTC)

Wren diet

Hi. I've got another bird question, this one about Thryothorus ludovicianus.

So, there's a mated pair of Carlina Wrens that frequent my backyard, foraging together. They're quite cute. Now, I read in our article that: "They eat insects, found in leaf litter or on tree trunks; they may also eat small lizards or tree frogs. In winter, they occasionally eat seeds, berries, and other small fruits." This doesn't quite agree with my observation.

Both of them come to my feeder, in which I've got a variety of seeds and nuts, and also a container of delicious mealworms on top. The smaller member of the pair eats only mealworms, never nuts, and the larger eats only seeds and nuts, never mealworms. Sometimes the larger one will bring the smaller one a bite of peanut, and pass it between their beaks, but it just ends up getting passed back, and the smaller wren goes back for more yummy beetle larvae.

Does anyone know what's going on there? I wonder if the smaller one is the female, loading up on bugs to feed to some chicks back at home? Why is the other one (male?) an apparent vegetarian? -GTBacchus^(talk) 20:51, 23 March 2009 (UTC)