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August 18

Blood arc?

Hi,

While shaving over a stopped porcelain sink, i accidentally nicked myself. A few drops fell into the water and I noticed that around the edge where the water met the porcelain, the blood appeared to arc (picture a solar-flare) up the wall on the sink then back down. Is this some form of diffusion? What is this phenomenon called? TIA PrinzPH (talk) 00:52, 18 August 2010 (UTC)

A guess: The drop of blood landed on the edge of the sink, and the edge of the drop left a half circle of blood. The rest of the droplet hit the water and caused the water to splash back up (have you ever seen that in slow motion?) and that water washed some of the blood, leaving the arc. Ariel. (talk) 02:22, 18 August 2010 (UTC)

I'm not a shill, but a modern razer (think of the brand name yourself) wouldn't cut you like that (unless you use the same one for six months or something). 92.230.233.158 (talk) 08:38, 18 August 2010 (UTC)

Oh yes it would. The new ones give you the worst cuts, too, if you're not careful. --Dr Dima (talk) 09:01, 18 August 2010 (UTC)

@Ariel - I distinctly recall the drop(s) landing in the water, in fact the only thing which got me interested about the occurrence was that I saw the 'blood' arc slowly. It took roughly 2 secs to complete a ~1.5 inch arc (from the waterline to the peak of the arc). And as I recall, it wasnt like the 'whole blood', just some particles (could it possible be just the red blood cells?). Maybe it has something to do with the water in the sink having soap while the walls of the sink not having as much? An no, I don't think I was hallucinating... I hope not :P PrinzPH (talk) 20:43, 19 August 2010 (UTC)

Here is a possibility. Take a washable marker and make a strong dot on a paper napkin, then release a drop of water in the middle of the dot. The colors of the ink will spread out and make circles of different colors (you can also try a regular pen and alcohol). Perhaps the blood did the same thing? Ariel. (talk) 01:34, 22 August 2010 (UTC)

Origin of "Global Health"

I'm looking for info on the origins of the term "global health". To my understanding, this is a relatively new term meaning public health on a global scale; i.e. accounting for the threat posed by pandemics, mass migration, climate change, etc. Any idea where the term was first used and what public health/philosophical agenda is behind it? --Whoosit (talk) 03:18, 18 August 2010 (UTC)

This article provides some context, including a statement in the second paragraph of the introduction regarding its origins in the 1970s, and then citing a relevant article on "Global Health" and the WHO (PMID 16322464). The latter, in full text here, provides data and speculation directly addressing your questions (it's a complex issue and the article is freely available, so I won't try to summarize here). -- Scray (talk) 12:15, 18 August 2010 (UTC)

Might this be related to the concept of Gaia's health? ~AH1^(TCU) 13:37, 18 August 2010 (UTC)

Thanks both. That article is a good start. Astro, I think global health is more of a gloabalist extension of public health, i.e. concern for welfare of human populations (which implies human populations are the source/origin of human diseases), where the Gaia health notion is one of ecology and systems biology, i.e. concern for the welfare of the biosphere as a whole and how this affects human populations (which implies an unhealthy environment is the source/origin of disease) --Whoosit (talk) 14:51, 18 August 2010 (UTC)

To give an example, the Global Health Council was named "National Council of International Health" until 1998.[1] Surprising that it took them so long to change a name like that. Wnt (talk) 16:41, 18 August 2010 (UTC)

How does an Epipen helping with an allergic reaction?

How does shooting epinephrine help someone who is allergic to bees and gets stung by one? Does the person still need to see an emergency room after using an Epipen? Thanks! —Preceding unsigned comment added by 76.169.33.234 (talk) 05:57, 18 August 2010 (UTC)

According to Anaphylaxis#Management, epinephrine (aka Adrenaline) is the standard treatment for anaphylactic shock for any allergic reaction, not just bee stings. Since the things about anaphylaxis that can kill you (mainly airway restriction and loss of blood pressure) are directly combated by epinephrine (mainly by opening airways and raising heart rate and blood pressure), its a logical and consistant treatment. To answer your second question, ABSOLUTELY, if anyone has a severe alergic reaction to anything, they should immediately be seen by a medical professional. Epipen is basically designed to combat the immediate, life-threatening aspects of anaphylaxis, but in no way does this mean that the danger has dissapeared or dissipated. --Jayron32 06:04, 18 August 2010 (UTC)

Also, people often carry more than one epipen because the first isn't always enough. If one doesn't always work, there is no reason to think that two will always work. You should always call an ambulance for anyone showing signs of anaphylactic shock. --Tango (talk) 07:09, 18 August 2010 (UTC)

Hell, even if it works the absolute best it can, you still need urgent medical attention. The epipen, like CPR, is just a way of (hopefully) surviving until medical help arrives. 86.164.66.83 (talk) 10:42, 18 August 2010 (UTC)

In many places the epinephrine pen injector requires a prescription; in that situation, the user should follow whatever instructions they were given by the prescribing provider and on the package (rather than ones provided anonymously here on Wikipedia, for example). -- Scray (talk) 12:08, 18 August 2010 (UTC)

Some of the above is straying toward the sort of "medical advice" that Wikipedia editors aren't trusted to give and readers shouldn't count on; but to get back to the question, the reason is that adrenaline (= epinephrine) in the EpiPen is a simple catecholamine hormone that has evolved as part of the fight-or-flight response, which puts top emphasis on maximizing heart and lung function for crisis situations. It's one of the major products of the adrenal glands, two little "epipens" nearly everyone carries. (If you can pay attention when something scares you, I think you can actually feel the adrenals inject their product into your bloodstream, but I might be misattributing the sensation) I think that this means that anaphylactic shock is not one of those situations where the only thing to fear is fear itself, and the victim needs to be calmed with gentle words and reassured that help is coming - rather, the hormones that come with the fear should be a lifeline. But I didn't quickly find a good source for this; here's one perspective about the idea. [2] Wnt (talk) 14:51, 18 August 2010 (UTC)

Whoa whoa whoa! Beware of that article. Not only is it written with a few weird points of confusion, that suggest a layperson trying to summarise things they've read and didn't completely understand, but the bit at the end about fear isn't actually talking about what you were talking about. The end of the article is talking about conquering your fear that you will have a reaction and go into shock so that you can actually take action to avoid the allergen and prepare for if you have a reaction. It acknowledges that some level of fear is rational and necessary to motivate yourself to act appropriately. It is not about conquering or using fear once you have gone into shock. Frankly, if you're going into anaphylactic shock, you probably don't have time to decide what level of fear is appropriate or helpful.

If you have an epipen or similar, you can consult the pamphlet that came with it, your chemist (at least in the UK), and your doctor. There are also various organisations which try to provide accurate and up-to-date information based on medical concensus. An example in the UK would be the NHS or the Anaphylaxis Campaign. 86.164.66.83 (talk) 22:11, 18 August 2010 (UTC)

Voyager 2 propulsion

What kind of propulsion used by Voyager 2? And is it the same propulsion used by Voyager 1, Pioneer 10, and Pioneer 11? How they avoid space debris or asteroids in their way? Do they have wings to steer it? Is it controlled by man or done automatically? What frequency they used for communication? Thanks... roscoe_x (talk) 06:10, 18 August 2010 (UTC)

According to Voyager 2, it is identical to Voyager 1. According to Voyager 1, the probe uses Gravity assist as its main means of propulsion. Voyager Program#Power discusses other power systems on the craft. --Jayron32 06:19, 18 August 2010 (UTC)

As for debris and asteroids, I'm going to make an educated guess that they simply don't need to. Outside of low Earth orbit, the density of space debris is very very small. The dense asteroid fields imagined in Star Wars and countless other movies and video games don't exist. Someguy1221 (talk) 06:25, 18 August 2010 (UTC)

Yeah, there's almost nothing in space. I seem to recall that sometimes spacecraft going through the asteroid belt will have their courses adjusted in order to make them fly by an asteroid close enough to take a picture. Paul (Stansifer) 12:46, 18 August 2010 (UTC)

I think the original poster is imagining that these spacecraft are being continuously propelled, like some science-fiction ones. That is wrong. They were launched by rockets originally, and they carry small rockets that were used to refine their course to reach the relevant planets. But for the most part, and probably all the time since their last planetary encounters, they are just moving in free fall. --Anonymous, 23:41 UTC, August 18, 2010.

Also note that wings don't do anything in space. Wings need air to be functional. - Akamad (talk) 13:44, 18 August 2010 (UTC)

NASA Jet Propulsion Laboratory's official Voyager webpage has technical information. The high-gain antenna received S-band uplink and transmitted X-band downlink. The S-band also participated in the Radio Science Experiment, in which the communication-data radio-signal was analyzed. The RSS website explains the spacecraft radios pretty thoroughly: S-band receiver (2115 MHz nominal frequency) and transmitters at both S-band (2295 MHz nominal) and X-band (8415 MHz nominal). Exact frequency (as received at Earth) was measured to 1/1000th of a Hz and varied with spacecraft/earth relative velocity and plasma-properties in the interplanetary space. As you may recall (those of you who closely followed the Voyager mission sequence - I wasn't quite alive yet) - there was a malfunction in the transmitter on one of the spacecraft in the early 1980s, and it was only by carefully loading new software code into an image-processing computer that the redundant transponder was made to work (I have a whole book on this, I can post more when I get home). Nimur (talk) 18:10, 18 August 2010 (UTC)

I think that the reference to a transmitter failure here may possibly be an erroneous recollection of the Galileo spacecraft rather than one of the Pioneers or Voyagers. Galileo's main antenna, which was stored compactly inside the spacecraft during launch, failed to open properly and they had to use a secondary antenna with a much lower data rate, and I remember they did some special programming to partially overcome that limitation. --Anonymous, 21:15 UTC, August 18, 2010.

There was definitely a PLL failure on Voyager 2. Here's a JPL progress-report that discusses the failure, and workarounds to keep the RSS experiment alive. This transponder failure was also described in Flyby by Joel Davis. Nimur (talk) 00:01, 19 August 2010 (UTC)

Thanks for the correction. --Anon, 16:31 UTC, August 20, 2010.

No real propulsion was on board. For corrections 90kg of hydrazine monopropelant was on board. 16 0.89 Newton and 4 22.2 Newton rocket motors are on board, which used nearly 60 kg of the fuel till 2000.--Stone (talk) 18:43, 18 August 2010 (UTC)

All four space crafts used a very similar propulsion system.--Stone (talk) 18:47, 18 August 2010 (UTC)

the role of condensed milk in the imbibement of coffee?

What is the role, chemically, olfactorily/gustatorily, of the supplementation of condensed milk in the imbibement of coffee process? —Preceding unsigned comment added by 92.230.233.158 (talk) 08:35, 18 August 2010 (UTC)

Adding condensed milk to coffee is said[3] to soften the taste. Wikipedia has articles about Condensed milk and Coffee. Condensed milk has advantages over ordinary milk of indefinite storage life, and less cooling effect on one's hot coffee than adding cold milk. Cuddlyable3 (talk) 10:02, 18 August 2010 (UTC)

I don't think it's a scientific matter, but condensed milk usually includes sugar, and logically it requires less dilution of the coffee (or more in the cup to start with) for the same amount of milk components added. Wnt (talk) 16:48, 18 August 2010 (UTC)

What is the primary purpose of the compression stage in a jet engine?

What is the primary purpose of the compression stage in a jet engine? I can understand the need for compression at high altitude, where the air is thin, but I suspect that it is not the primary reason for having a compression stage. Is there a reason why a jet engine won't work without compression even at low altitude? --173.49.11.120 (talk) 12:12, 18 August 2010 (UTC)

The Turbojet article is a great resource on this, and it has a section on the compressor. Simplistically, I think it's accurate to describe the jet engine as a continuous-flow combustion engine, such that there is no structural barrier to flow in either direction (fore or aft). As a result, the combustion chamber must be preceded by a high-pressure (compression) chamber to drive the combustion products rearward; otherwise, the jet wouldn't eject rearward and provide forward thrust. -- Scray (talk) 12:51, 18 August 2010 (UTC)

The compressoion stage pumps air into the engine to mix with fuel and burn, it also gives the air more energy by heating it up and putting it under greater preasure before being burnt with fuel. Without it the engine would not be able to funtcion at low speed, and would need help reaching a high enough speed so the high speed flow of air into the engine would compress the air itself. This is why ramjets and scramjets require another engine to bring them up to a supersonic speed before they can opperate. If you were to try to start a stationary ramjet or scramjet, you wouldn't get any thrust because they have no means of compressing the air, and the exaust gasses would simply exit out the front and the back of the engine providing no net thrust. In other words, the compressor pumps air into the engine that the engine needs to run and produce thrust out of the nozzle at the end of the engine, you can get rid of the compressor to make the engine simpler and opperate at higher temperatures, but then you need some other engine (conventional turbojet, turbofan, or rocket) to get that engine to the speed (several mach) that it needs for the air to compress itself with out the aid for a compressor.--74.67.89.61 (talk) 15:54, 18 August 2010 (UTC)

See Overall pressure ratio and Brayton cycle. The amount of thrust produced by a jet engine when compared with the rate of flow of fuel into the engine is the engine's thermal efficiency. A high thermal efficiency requires a high overall pressure ratio. If there was no compression of the air going into the combustion chambers the thermal efficiency would be so low the engine would produce little or no thrust, even though it was burning fuel. The same is true of the reciprocating engine in a conventional motor vehicle. Dolphin (t) 23:21, 18 August 2010 (UTC)

It's the same as the reason you'd put a turbocharger (or a supercharger) onto a car engine. The amount of fuel you can burn (and therefore the amount of energy you can extract) is limited by the amount of oxygen in the air. When the oxygen is all used up, combustion stops and no more fuel can be burned. The only way to get more air into the engine is to make the engine bigger or to compress the air to make it more dense. Since there is a limit to how big you can make a practical airplane engine, compressing the air is the only viable approach to getting more power. That's why you can get the same amount of peak horsepower from a 1.6 liter turbocharged car engine as from a 2 liter engine without a turbo. The air compression stage in a jet engine is powered by the outgoing exhaust gasses spinning fan blades at the back of the engine - which also parallels the way the turbocharger in a car is powered by diverting the exhaust gasses through a turbine. SteveBaker (talk) 02:43, 19 August 2010 (UTC)

Life extension versus curing diseases one by one

I have found out just recently, to my amazement, that old age is not a cause of death (in humans), even beyond the age of 100^[4]. At advanced ages it becomes very probable that in some important place the blood will either become solid when it should remain liquid (thromboembolism, infarction) or stay liquid when it should turn solid (ruptured aneurysm, haemorrhage, etc.) i.e. the leading cause of death at advanced ages is "failure of the blood to be in the correct phase of matter", rather than "old age", and if that doesn't finish you off, cancer or an infection likely will. So, purely hypothetically of course, if we cure the diseases of old age and create "smart blood", and subsequently live to 160, is that "life extension"? Why do so many people think "life extension" is unethical but yet trying to treat, prevent, and cure the common diseases of old age one by one is not? 129.2.46.178 (talk) 13:21, 18 August 2010 (UTC)Nightvid

Well, dying from 'old age' is sort of an all-encompassing term, referring to a multitude of things in your body that can go wrong as a result of it. I think the answer of your question (a very good one, by the way) has to do with the way we perceive the concept of 'life extension'. If one does manufacture 'smart blood', that's going to cure a multitude of ailments. If one cures a single disease, many others will still die of other problems. However, if you cure a multitude, you start noticing the life expectancy go up. Life extension is more of a term used to describe extending one's life past the point of when one would have naturally died (for me it is). However, if you cure these diseases, you are extending the natural lifespan (without the support of other modern technologies). Tyrol5 [Talk] 13:48, 18 August 2010 (UTC)

There is a distinction between fighting senescence per se and fighting diseases; some of the more intriguing results in lifespan extension involve not just longer life and protection from disease, but also prolonged vigor.[5] Wnt (talk) 14:56, 18 August 2010 (UTC)

Asking why do so many people think life extension is unethical ... ... ? is not a question that can be answered by science. Firstly, science doesn't even have evidence that any, or many, people think it is unethical. Secondly, any response to this question is only a matter of opinion. It is stated above that this Reference Desk does not provide opinions. Dolphin (t) 23:30, 18 August 2010 (UTC)

This may be splitting hairs, but science could possibly answer why people think it is unethical (social and religious influences, fear of "playing god", etc), given the desire (and funding) to go out and do so. In fact, some poor sociology graduate student is probably doing exactly that right now. It cannot, however, answer whether life extension is or isn't unethical. – ClockworkSoul 00:26, 19 August 2010 (UTC)

While it is true that death by "old age" is always death by the failure of some important bodily subsystem (heart failure, liver failure, etc) - those failures are not happening by random chance - if they were then people would be as likely to die at 100 years as they are at 20 years. But when someone dies in a car accident, it going to be because one or more body-systems failed - yet we still say that the person died because of the car wreck. Hence it's not unreasonable to say that someone died of old age even when we know of some very specific, detailed reason.

At least some of the reason why that happens relates to things called telomeres. When a DNA strand replicates, the last sequence on the end of the strand doesn't get copied - this causes the DNA to gradually shorten as it gets copied over and over as you get older. The body places 'junk' DNA at the end of the strand that doesn't code for anything useful ("telomeres") - and each time a cell divides, you lose a telomere. When you get old enough - you run out of telomeres and on the next cell replication, you have some of the important DNA going missing. That might not kill you - but eventually (and inevitably), you'll lose something critical and perhaps be unable to produce any healthy new heart cells - and not long after, you're going to have heart problems, then death.

If you recall "Dolly" - she was a clone of a 6 year old sheep. Her cells were made from 6 year old cells that had already lost most of their telomeres. Not surprisingly then, despite the best possible medical care, she suffered a bunch of typical "old age" symptoms and died at just 6 years old - when sheep of her breed usually live to age 11 or 12. At age 6, her cells had suffered 12 years of telomere loss (6 years in her "mother" and 6 years in her own life) - and the consequences were entirely as expected.

There is a suggestion (which has been tried in some simple animals) of adding more of these telomeres to the end of DNA strands - and even of using a specific chemical to do that. However, there is a problem. When a cell goes crazy and starts replicating very rapidly (a "cancer" cell) - then the telomere mechanism provides a natural way to shut it down...the very fast replication causes the cancerous cells to lose telomeres more quickly - and eventually die off (that's if they don't kill you first). If we go in and "fix" the telomere problem in order to get longer life - we may cause ourselves to lose all of our natural ability to fight off cancer.

So having people live forever isn't just a matter of fixing individual problems like heart disease, liver failure, etc. When your body is incapable of making any new heart cells, nothing short of a transplant is going to fix that. When no more liver cells can form - you need another transplant. Gradually, more and more parts of your body will run out of telomeres - and soon you're going to need more and more transplants - ultimately, you have to replace every single part of your body...and that is a fundamental problem because at that point you aren't "you" anymore.

It's not impossible that we can fix all of these things - but what our OP suggests isn't enough. We have to figure out how to beat the telomere problem as well as fight off all of the more normal causes of death.

SteveBaker (talk) 02:33, 19 August 2010 (UTC)

Note that the "Dolly" story doesn't match what is said at that article. I think that in the vast majority of cell types, telomere length never becomes an issue - maybe not in any. Well, alright, lymphoid lineages in HIV patients...[6] While telomeres do shorten with aging, and as explained in that article, there is some C. elegans work suggesting that telomerase can oppose aging, we should be wary about jumping to a simple cause-and-effect conclusion. Wnt (talk) 05:38, 19 August 2010 (UTC)

Indeed, New Scientist of 7 August 2010 ran a 7-page feature on cloning by Ian Wilmut, which naturally makes extensive references to Dolly. In part this reads:

"Dolly developed breathing problems and a cough in February 2003 [aged 6½]. We suspected she was suffering from pulmonary adenomatosis, a disease that is not uncommon in adult sheep, which is caused by the jaagsiekte retrovirus . . . . Dolly was sent for a CT scan . . . [which] revealed the full extent of her lung tumors . . . [she] was never allowed to recover from the effects of the general anaesthetic she'd been given for the scan . . . . Although there has been much speculation about how the process of cloning had affected Dolly, the post-mortem revealed nothing particularly unusual for an animal of her age and weight."

Though the feature doesn't go into the telomere issue, this suggests that Dolly did not, at the age of 6, generally exhibit the age-related characteristics of a 12-y-o sheep. Although our own article says she also suffered from arthritis, this can also occur in younger people (and presumably sheep), and it also describes only as speculation by some the suggestion that her shortened telomeres contributed in any way to her death.87.81.230.195 (talk) 17:32, 19 August 2010 (UTC)

Weight of one phytoplankton cell

Yes, I know that this is impossible to determine because it's so small and there are about 5000 species, but I don't need a precise figure. Basically I've followed up my previous question with a bit more research, and I know the scale of plankton generation we were talking about is massively infeasible, but to prove it I need to know roughly how much the stuff weighs. Even if its only a really rough figure, or even just an order of magnitude, that would be enough for my purposes, because it's so infeasible to do this that even a massive exaggeration of their weight would still make it look impractical to generate that much plankton. Anyone know a figure that would help me?

Thanks! Dan Hartas (talk) 13:27, 18 August 2010 (UTC)

I would imagine that only one weighs far less than one microgram (e.g. really, really light). I'm afraid I can't give you a much more definite answer than that. Tyrol5 [Talk] 13:35, 18 August 2010 (UTC)

Heh yeah, "really, really light" is about all I know as well lol. Dan Hartas (talk) 13:52, 18 August 2010 (UTC)

Well, the problem you encounter as you reach these low figures is that the numbers keep getting smaller and smaller indefinitely (in essence, you never hit zero by counting back). Tyrol5 [Talk] 14:08, 18 August 2010 (UTC)

Obviously the answer is "0", just as the answer to the question "what is the thickness of a piece of paper?" is "0". A piece of paper is physically two-dimensional, it doesn't have thickness, and a phytoplankton cell is physically zero-dimensional, it doesn't have depth, breadth, height, or weight. (Unlike the other zero-dimensional object, the black hole, which obviously does have weight). Hope this helps. 92.230.233.158 (talk) 13:42, 18 August 2010 (UTC)

That's a ridiculous answer. A piece of paper is obviously a three dimensional object. Please don't answer questions you don't have the first clue about. Matt Deres (talk) 14:26, 18 August 2010 (UTC)

I'm glad you noticed. The obvious is not always true, however, and string physicists would say that the paper is much more likely to be 11-dimensional. If it is 11-dimensional, the sum of those two digits is 2 (as I said originally), but there is no obvious way to get from 11 to 3. So if either of us is in some sense right, it would be me. Cheers, 92.230.66.177 (talk) 18:53, 18 August 2010 (UTC)

Haha, oh wow. What is that, dialectic physics or something? (e • nn • en!) 04:05, 19 August 2010 (UTC)

To estimate the weight of a phytoplankton cell, have a look at our articles on the different species of phytoplankton. Many of these articles include approximate sizes of these organisms. Using the estimated sizes, calculate a rough volume (note that 1 cubic micrometer is equal to 1 femtoliter), and figure that the density of of these organisms is probably within shouting distance of the density of water (1-2 picograms per femtoliter). Since the size of phytoplankton varies across at least two or three orders of magnitude – depending on species – you're only going to get a very rough estimate anyway.

That being said, for your study, what you're probably more interested in is not the mass of an individual cell, but rather the mass density of phytoplankton which can be cultivated in a cubic meter of seawater. (More specifically, how much carbon is bound within the phytoplankton one can culture in a cubic meter of seawater.) The number of individual cells is virtually irrelevant to the sequestration; one cell gives rise to a billion billion daughter cells after just sixty doubling periods, so once the culture is up and running, maintaining the numbers shouldn't be an issue. TenOfAllTrades(talk) 14:37, 18 August 2010 (UTC)

Using TenOfAllTrades' method for Chlamydomonas reinhardtii gives you a wet weight of 1 nanogram, having a stab in the dark, I'd guess the dry weight would be around 1% of the wet weight - 0.01 nanograms. Smartse (talk) 16:12, 18 August 2010 (UTC)

Even in a good source [7] the wet:dry weight ratio seems remarkably uncertain (10% or 20% by assumption) but I don't know of any living thing that is 99% water. Also see "Net-plankton biomass in the Manazuru Harbor varied from 4.1 to 410 mg m–3 in dry weight; from 2.0 to 200 mg m–3 in ash-free dry weight; from 0.98 to 78 mg m–3 in organic carbon (Fig. 1)." [8] (These are just top two Google hits; serious research may find better data) Also note that one report claims we are making negative progress on your idea.[9] Wnt (talk) 16:24, 18 August 2010 (UTC)

Crowded cell environment anyone? I am pretty sure that water does not make up more than 90% of a cell by wt. It's probably even less. John Riemann Soong (talk) 21:22, 18 August 2010 (UTC)

Another issue: apparently picoplankton and nanoplankton pass right through plankton nets, and only microplankton are usually caught; but it is the former two that make up most of the biomass.[10] Depending on your situation you may care about the total or just the larger cells. Wnt (talk) 16:31, 18 August 2010 (UTC)

Well let's use more feasible units you could use under a microscope. The issue of a mass of a cell is important, when you're say trying to assay one cell culture and differentiate it from another. John Riemann Soong (talk) 19:23, 18 August 2010 (UTC)

Adult male cat being breastfed by another cat

The male is black-and-white. The female is blue. The image might not represent the actual breastfeeding.

The male is black-and-white. The female is blue. The image might not represent the actual breastfeeding.

I've seen an adult male cat being breastfed by a cat whose kittens had just stopped suckling. The two did not know each prior to the breastfeeding and that did not occur only once. The tomcat was certainly adult; he was larger than the female who was breastfeeding him. This lasted for several days, until the tomcat disappeared. I'd like to know:

1. What made the cat breastfeed another adult cat?
2. What made an adult cat suckle another cat?
3. How (un)common is this behaviour? The Spy Who Came in from the Cold (talk) 17:25, 18 August 2010 (UTC)

Maybe they had sex just after that. I have seen this behavior in horses. Sometimes just before the male starts fucking he causally licks the tits of the mare (though there is no milk there). And of course we (human) do it too.  Jon Ascton  (talk) 20:23, 18 August 2010 (UTC)

They did not mate. But thanks for not helping. The Spy Who Came in from the Cold (talk) 22:32, 18 August 2010 (UTC)

This is both a little surprising and a little unsurprising. If the momma cat's kittens weaned a little ahead of schedule, she may have become engorged with milk - which can be quite uncomfortable. The male cat may have been doing her a favor in that case. However, in most mammals (but not most humans) adult animals are naturally lactose intolerant and their digestive systems cannot handle milk. Of course everyone knows that cats like milk...right? Well, maybe - but it's not that good for them. SteveBaker (talk) 01:58, 19 August 2010 (UTC)

My experience of cats (and I'm not a fan), is that it's not unusual for adult cats to attempt to breastfeed and they aren't fussy about the target species either e.g. it could be a large primate watching TV for example. I should add that I also think it can be triggered by visual cues i.e. seeing and recognising a nipple. Perhaps you could ask Anne Corwin, who carries out marvelous experiments on her cats, to investigate it. Sean.hoyland - talk 03:50, 19 August 2010 (UTC)

Car mirror -- "closer than they appear"

Why would the passenger side mirror show objects farther than they actually are -- isn't it just a regular mirror? DRosenbach ^{(Talk | Contribs)} 19:45, 18 August 2010 (UTC)

As curved mirror#Uses notes "The passenger-side mirror on a car is typically a convex mirror. In some countries, these are labeled with the safety warning "Objects in mirror are closer than they appear", to warn the driver of the convex mirror's distorting effects on distance perception." This paper is very relevant. -- Finlay McWalter ☻ Talk 19:51, 18 August 2010 (UTC)

but aren't all objects closer, since the ray from the object describes two sides of a triangle (object to mirror, mirror to your eye) where the direct view from your eye would be the third side of the same triangle? As long as the lengths of two sides of a triangle have to add up to more than the length of the third side, objects in mirror will be closer than they appear. 92.230.66.177 (talk) 20:05, 18 August 2010 (UTC)

The label is imperfect. It should be interpreted, "Objects are closer than they would appear if viewed through a flat mirror." The purpose is simply to remind drivers that the curved mirror has affected depth-perception differently than a flat mirror would. Nimur (talk) 20:10, 18 August 2010 (UTC)

• I think you mean, "Objects are closer than they would be if they were seen in a flat mirror and appeared the same size." Which I think we can agree is not a very practical wording. --Anonymous, 21:18 UTC, August 18, 2010.

In other words, the driver, when he sees through back-mirror is under illusion that vehicle behind is quite far away, but really it is not as far away as it seems  Jon Ascton  (talk) 20:18, 18 August 2010 (UTC)

The reason why objects are made to look further away is so that you can see more of them within the narrow field of view provided by the mirror. It's just like a microscope, which lets you see an object very close, but only a tiny portion of it - just in reverse. Wnt (talk) 20:27, 18 August 2010 (UTC)

How a 3-year-old might participate in sharing his "knowledge" on Wikipedia: Deep Sea Tube Worms

I'm writing on behalf of my 3-year-old son. Somehow I got him all excited about the fact that wikipedia is an encyclopedia to which everyone on the planet can contribute. He kinda got the wrong idea. So, he loves to review the article on Giant Tube Worms (http://en.wikipedia.org/wiki/Giant_tube_worms ) and wants to contribute this bit of fiction. Obviously, there's not really a place for that, so I guess our question is: are there any discussion pages on Wikipedia where people can have casual discussion on a topic? (we already think the answer is "no" after listening to "what Wikipedia is not," but I don't want to totally discourage him from participating in the future in a genuine way, so I'm wondering if there might be a way to validate his interest in participating, not just reading, but also to not just create junk. Maybe there's a kids' website along these lines that somebody knows about and can direct us to?!) Anyway, here's his bit of story: 'After deep sea tube worms disappear, the other animals come back and don't see the deep sea tube worms and think, "Huh, the deep sea tube worms aren't here." They aren't there!' --24.22.93.88 (talk) 23:10, 18 August 2010 (UTC)

I think he might be more welcome over at the Simple Wikipedia. He can contribute here but the populace over there tends to be much younger. It's good to know we have toddlers interested in the site but one concern of mine is that his age will be known if he just pops up and people connect the dots. I'm off to something right now but if you have any concerns, please feel free to pop by my talk page. Kevin Rutherford (talk) 23:21, 18 August 2010 (UTC)

You are welcome to go to the Wikipedia Sandbox and select Edit. If there is already some text there, just delete it. You can write it up in as much detail as you like and hit the Show preview button. You will then see your work previewed on the screen. Alternatively, you can hit the Save page button and see it in a slightly different format. Either way, it can stay on your screen for as long as you like, so long as you don't select a new page. (Within minutes the sandbox will be refreshed by someone else's experimenting.) If this will satisfy your son it is a quick and simple way of beginning to interact with Wikipedia. Best wishes! Dolphin (t) 23:42, 18 August 2010 (UTC)

Well, young contributors are welcome to Wikipedia! But we do not make special exceptions to our rules about encyclopedic content & style or verifiability. I hope the young contributor will understand - this is not meant to discourage imagination and enthusiasm for interesting things, but to modulate those ideas by reality and verifiability. Other internet sites, (ones that are not encyclopedias), will be a better place to submit pure works of imaginative fiction. Obviously, a 3-year-old's "knowledge" about deep-sea tube-worms is severely limited by a lack of experience - so it's probably best to have him or her learn about tube-worms before contributing to our encyclopedia article. You can make this a very educational project: consider going to the library or researching in other reliable sources - and then process through the information you learn together, and finally contribute (factually correct, verifiable content) to the articles. Nimur (talk) 00:07, 19 August 2010 (UTC)

I think the answer may be this:

• First, create an account for yourself and/or your son on the system. When you do that, you get a web page called "User:yourname" where you can put stuff about yourself. It is acceptable to create a "sub-page" from there, for the purpose of doing test editing. So you could create: User:yourname/Tube_Worms - and copy into that page as much or as little of the tube worm article as you'd like. Then you and your son have your own private copy of the article that you both can edit it to your heart's content - add stories, go nuts. In the unlikely case where someone complains that you have no right to do that, point them to Wikipedia:USERPAGES#Common_uses_of_userspace which explains that you can have 'working drafts' of articles there - and use them for editing practice.

Sadly, this doesn't give you a place to discuss tubeworms with other Wikipedians. The way we're set up here doesn't really provide anyplace like that.

• Sometimes you will find this kind of discussion on the 'discussion' tab of the article itself - but that's not strictly what that is for. That space is for discussion of the article itself (how it could be improved, what is wrong with it, etc) - and not for discussion about the subject of the article. However, that rule is very often breached and people are generally fairly relaxed about it...although that might change if you let a 3yr old loose with the keyboard in there!
• This reference desk is a fine place to ask questions. We don't encourage random discussions here - but if you should find that your son has a question about tube worms (or anything else for that matter) then you both can ask it here and we'll do our best to answer it. If you wish us to use simpler language to describe the answer, then you should probably mention that in the question.
• If your son gets very deeply into Wiki's in general, you can get yourself a web site someplace (I use 'DreamHosts.com') for between $5 and $10 per month and create your very own Wiki! I've done that (http://www.sjbaker.org/wiki) and my son (who is now 19 years old) and I make stuff there free of all of the Wikipedia rules and regulations - and what goes in there is entirely at my own whim! (Check out http://www.sjbaker.org/wiki/index.php?title=Measuring_hard_things_with_easy_experiments for stuff your kid will one day have fun with and one day http://www.sjbaker.org/wiki/index.php?title=A_Year_of_Learning_Fractions_in_Ten_Simple_Rules which will one day save him no end of grief in math class).

Good luck! The world needs more parents who can get their kids interested in tube-worms...or whatever!

SteveBaker (talk) 01:33, 19 August 2010 (UTC)

Wow -- thanks so much to all of you who offered these very helpful suggestions! I think he would, in fact, love to start his own experimental wiki, as Steve suggested, and now we know how! I wanted to walk that fine line between encouraging him and respecting everyone else's expectations not to have inappropriate material/discussion posted on the site, and all of these help give me a great framework within which to do that. This whole business today of him wanting to contribute to the tube worms page has helped initiate a great family conversation about "fact" versus "fiction," the roles and importance of each, and how they intersect (he wanted to cite some material he learned about tubeworms from a Magic Schoolbus kids' book, and we're still scratching our heads about appropriate citation sources, but we're figuring it out!). Thanks again! --24.22.93.88 (talk) 01:50, 19 August 2010 (UTC)

If your son is still looking for a place to host/expand on his Giant Tube Worm story, you can explore the various collaborative fiction sites with him. For example:

• Protagonize
• My Baby Monsters (this is geared towards kids)

If you create a personal wiki, or post your son's fiction online, do drop us a link (on the Reference Desk talkpage in case this thread has already been archived). Cheers. Abecedare (talk) 03:40, 19 August 2010 (UTC)

As Abecedare suggests, Wikipedia isn't the only collaborative site on the Web. There are also Wikis on videogames and popular tween TV shows. Your 3-year-old probably isn't interested in either of these categories (and if he's smart enough to grasp the concept of reliable sources, then these places might not be the best, since they hardly get that concept themselves), but the Web is full of Wikis on a variety of topics, and they can be a great way for kids to improve their writing and reference skills while focusing on what they're passionate about in a collaborative environment. I imagine our future Wikipedians are on these sites right now!--el Aprel (^facta-_facienda) 03:58, 19 August 2010 (UTC)

I think that young children have a special talent for remembering facts precisely - for example, retelling a story just as they've heard it like a bard, or drawing a scene just as they've seen it like an artist. I do not know how this will play out in the modern age of Internet and Wikipedia; nonetheless, it seems possible that very young children who have recently been exposed to detailed facts from other sources may well be able to come forward and point out things that are missing in our articles, or provide acceptable original artwork. I think that the history of the past fifty years speaks to a remarkable improvement in the maturity of children - so much so that one wonders whether the college students of the 1950s would have the maturity expected of 7th-graders today. We should consider seriously that in time even three to five year old children may come to be valued contributors, no matter how impossible it might seem to us. Wnt (talk) 05:14, 19 August 2010 (UTC)

In all seriousness Wnt, have you had much interaction with children since you ceased being one yourself? I don't think they've changed much at all in the last few decades, and past writing on children still seems to fit. The areas of their expertise have changed, but their basic development hasn't. And have you looked at typical child art? Children tend to go through set phases in drawing, and I don't think you could call any of the young child phases 'drawing a scene just like they've seen it', assuming you meant something photorealistic here. The youngest make scribbles, round and round, which are then said to be things. Older toddlers - preschool drawers tend to draw symbolically and in a predictable manner: they will draw a person as a face, when slightly older they will add arms and legs directly to the face. By the time they're about 8, if asked to draw a still-life exactly as they see it the average child will produce something vaguely cubist: they will include information from different angles in a single drawing. Children only really tend to start drawing realistically what they actually see when they're about 10, and even then most children need some sort of training or explanation to do this. Left entirely to their own devices, most continue to draw more iconically. 86.164.66.83 (talk) 09:50, 19 August 2010 (UTC)

Ah, while not terribly well referenced, we do have an article Child art, complete with pictures. 86.164.66.83 (talk) 10:34, 19 August 2010 (UTC)

I suppose I should have stuck to science here... Children aren't really my calling, but I'm amazed at the level of restraint required today of young teens, under penalty of law, by contrast to the drunken brawling wild oats-sowing antics of young adults of previous eras. Not all child art is suitable for Wikipedia, yet in the examples from the article and elsewhere it is apparent that some can be. (Speaking of cubism... [11]) And children certainly are capable of taking up facts from a museum, book, or other source and telling them to whoever wants to listen (or not). I don't mean to suggest that you should loose young kids on Wikipedia unsupervised (whether you're concerned for our benefit or theirs), but I think they have capabilities yet to be known. Wnt (talk) 11:53, 19 August 2010 (UTC)

Where you live young adults aren't getting drunk, getting into fights and having sex? Nil Einne (talk) 15:01, 19 August 2010 (UTC)

There have always been gifted and precocious children, and of course what an individual can contribute or enjoy will vary based on the individual. That isn't because anything has changed, and it isn't because children as a group are ready to contribute earlier, it is simply a result of human variation. Which is a good thing. And of course if an individual child produces a useful image, and licences it properly, we'll be delighted to use it. But most children, particularly young children, won't produce something suitable to illustrate anything except as an example of what children draw: when they are older, and have developed their talent, they may well do. And we won't use an image that is good for the age of the person who made it, but not better than the other images available. In any case, the drawing discussed in that link is an entirely private, storytelling thing, not concerned with creating a useful graphic. Of course many children are capable of more than they are given to do, but that should not be confused with them having mystical abilities or astounding self-control. Having a bit of slack where they don't have to be achieving anything 'worthwhile' is an important part of childhood, and I would be worried more than impressed by a child who showed too much maturity in some ways. 86.161.255.213 (talk) 20:33, 19 August 2010 (UTC)

Wikiversity might be another option. They do have a Marine Biology Lesson Plan but it appears to be designed for 11th grade students. Nevertheless, you might ask around at their Help desk since their goals include being devoted to learning projects, unlike Wikpedia whose main goal remains writing an encyclopedia (reference desks notwithstanding). ---Sluzzelin talk 15:19, 19 August 2010 (UTC)

If you actually do decide to start your own Wiki - I'd be happy to help you set it up. It's not difficult - but you will want to take care over the security aspects of the thing...an unguarded Wiki rapidly gets spammed into oblivion - mostly with things you wouldn't want your son to be concerned about for at least another decade! If you go to my user page (User:SteveBaker), you'll see a link to my email and we could discuss it offline. SteveBaker (talk) 00:02, 20 August 2010 (UTC)

August 19

Cocaine for numbing and other uses

I saw a picture online of a bottle of topical cocaine. Do they use it anymore for numbing (or any other purpose) or do they use other drugs now? Also, what other medical purpose would it be used for? —Preceding unsigned comment added by 76.169.33.234 (talk) 01:46, 19 August 2010 (UTC)

According to Cocaine#Cocaine_as_a_local_anesthetic, it looks as though it still has some limited, approved medicinal uses, but its use is not widespread. --Jayron32 02:04, 19 August 2010 (UTC)

Glass Graffiti

I was eating in a fast food restaurant today, and I noticed that one of the exterior windows had been graffitied by someone who had etched a name into the pane. The etch was done very smoothly, as if someone were writing on the pane in large cursive letters, but one could clearly see that the pane had been scratched and not merely written on. Now, three questions: 1) What are store windows generally made out of these days? (e.g. plate glass, laminated glass, plexiglass, etc.), 2) What implement(s) might the vandal have used to scratch such smooth cursive letters? (It seemed smoother and more fluid than I might expect from a knife or similar large object.), and 3) Given the other answers, is vandalism like this quick and easy or slow and hard? Dragons flight (talk) 02:33, 19 August 2010 (UTC)

It might have been etched with acid. Vandalizing etchers do seem to exist, see here, for example. ---Sluzzelin talk 02:38, 19 August 2010 (UTC)

I'm very surprised to read about this. Apparently the "glass etching acid" really is the nasty old hydrofluoric acid that has been around for centuries.[12] In academia, the stuff has acquired a nasty reputation for seeming to be harmless on the skin, but actually proceeding to kill nerves, tissue, and eat all the way down to the bone. The notion of vandals running around with it... well, one's reaction either has to be horror or mirth, or both. Unless the reputation has been exaggerated, anyway...

According to the reference I cited, they used a "Bingo dabber" (a swab of some sort, I assume). Since the acid does the work, there is no reason for it to take long at all.

It would seem to me that shopkeepers should have some method to prevent this - if an outer layer of plastic can somehow be applied to the glass, however thin, either as a laminate, coating or by some method of spraying, then the etcher could be left disappointed. Wnt (talk) 05:28, 19 August 2010 (UTC)

Bingo dabbers, at least, I can speak of. They are generally a plastic tube filled with ink, ending in a broad flat sponge tip, such that you can press down and leave a solid circle of ink. Presumably they empty the ink out and fill them with acid. They also, of course, have a plastic cap to protect the sponge end, which would protect you slightly from acid when you weren't using it. 86.164.66.83 (talk) 09:28, 19 August 2010 (UTC)

It is not hard to scratch standard window glass with a steel implement like a nail or a knife. Googlemeister (talk) 13:09, 19 August 2010 (UTC)

...or with a diamond ring. That is easier to conceal and less incriminating if detected. Cuddlyable3 (talk) 14:15, 19 August 2010 (UTC)

Or with a rock or a pebble. Really, it's not that hard to scratch regular glass. It doesn't take special tools, it just takes the will to do it and the reasonable possibility of getting away with it. --Mr.98 (talk) 16:11, 19 August 2010 (UTC)

Abyss of time

I seek the definition of "abyss of time" Center39 (talk) 04:08, 19 August 2010 (UTC)

See HERE. Dolphin (t) 04:26, 19 August 2010 (UTC)

I'm curious, what happened to Centre34 - 38? Richard Avery (talk) 17:39, 19 August 2010 (UTC)

Human body fat vs. modern synthetic clothing

Past a certain amount, accumulation of additional body fat seems (to me) to benefit the owner (if at all) via better resistance to cold. So I'm now wondering if there is any hard data out there regarding the "performance" of a given thickness of human body fat versus modern synthetic clothing. Is there any equivalence at all? Will X cm of body fat provide the same level of comfort as Expensive Fleece Y ? Note - I have been trim and fit my whole life and have no personal experience to draw from. Note 2 - let's assume a windless environment to simplify things a bit. Thanks! 218.25.32.210 (talk) 07:29, 19 August 2010 (UTC)

you should assume a windless environment with a thin man who is covered in a thick paste of whale blubber. 92.230.66.177 (talk) 07:34, 19 August 2010 (UTC)

I thought there were different kinds of body fat, brown fat and umm...something else, that perform differently and people have different amounts. Yes...Body_fat#Brown_fat has something, so it's probably even more complicated. Sean.hoyland - talk 09:01, 19 August 2010 (UTC)

It won't provide the same comfort level in any case, because the skin is outside the fat. It may save you from hypothermia, but it won't protect you in the slightest from frostbite. Looie496 (talk) 20:03, 19 August 2010 (UTC)

I did a search for "Thermal Conductivity of fat". The only one I could read for free[13] said 0.0004 cal/cm/s/°C maybe someone with more access could do some more searches. Ariel. (talk) 02:08, 20 August 2010 (UTC)

Isn't comfort commonly associated with sensations? I'm thinking since fat occurs beneath the skin wouldn't the sensation of temperature be the same? But then I know we have to factor in the individuals internal temperature etc so its not quite as simple right? PrinzPH (talk) 22:43, 20 August 2010 (UTC)

Is my brainwave re: Joining Interplanetary Federation genius or loony?

Please tell me if this is a goer. I dreamt it up last night, after I was thinking of Star Trek, and how sad it was that the vast distances of space mean that there never will be space ships visiting other forms of life. There is no such thing as “warp drive” and “hyper drive” and so on, and that means we are all alone, SETI will never find others out there. But we will still conquer space, and we may find very primitive life (there are possibly a million planets with life to every one with technological beings.) What a sad disenchantment! To come to a realization like that must be how a religious man feels when he finally accepts atheism and the finality of death. Then I had this strange idea. I am assuming you are an intelligent and resourceful person. Suppose you and another person like you (but not one you know personally) are dropped into a vast jungle at random spots. You both have the job of finding each other, and you are not permitted to make fire or noise. What would you do? The only thing that stands out is a single mountain. Now you reason thus: this mountain is the only thing both of us can see. So, I will go towards it, in the hope that the other person will reason similarly. And you end up finding each other through the use of logic and intelligence.

Now let us use an extension of this idea for our (Star Trek-like) Interplanetary Federation. We can’t ever meet any of the other members of this Federation, will never know much about them. Yet we can be a fully-fledged member of that august group. How? Simply by affirming and being committed to certain fundamental principles of logic, reason, ethics, science and compassion. On this basis, we can DEDUCE what the other members of the Federation are doing, and how they behave, regardless of what they look like. The Federation we belong to would never impose itself on or otherwise colonise other worlds if it found them. It exists to serve and help sentient life wherever it finds it, even if that is only on their own home planet and the space ship itself. It is a champion of scientific research and explores to find out how the Universe works. We can make crests and logos and uniforms and write logs and documents concerning this Group, and it matters not if members in other “sectors” have slightly different regulations, and the paraphernalia looks different to ours. We will never know that, but here is the beauty of the Federation. We don’t need to ever meet. That’s a primitive concept: we don’t need to hold hands for comfort. They know that they are not the only ones and they know, too, that there are logical, scientific and ethical beings somewhere out there and that they belong to the same Federation. We and they are just like those two persons who made their way to the same mountain, even though neither has ever communicated directly with the other.

Paradoxically, those two isolated people can work together for a common end. As a species becomes ever more advanced, the paths of logic, ethics and science become ever clearer. In consequence, we can work together with other members of the Universal Federation more closely and with greater empathy and respect as we learn more and more about each other. How can we learn ANYTHING about them, let alone MORE about them? you ask. Because as we advance historically and culturally, we learn more about ourselves, and this makes us knowledgeable about the other members of the Federation.

Does anyone think there is anything in my brain wave? Myles325a (talk) 09:06, 19 August 2010 (UTC)

I think you've derived religion. Congratulations! Let the Star Trek Wars commence! You have a lot of assumptions, such as that ethics become simpler and clearer as you advance scientifically and technologically, that a lot of what a society does is logically and consistently derived rather than being cultural, that an intelligent species arising in a completely different situation will have a great deal in common with us. Even in Star Trek, the Vulcans and the Humans do not have identical ethics.

But that's okay. I'm sure you can fiddle with it and redefine terms to make it work. Enjoy your religious peace! 86.164.66.83 (talk) 09:20, 19 August 2010 (UTC)

There's not really a science question here that I can see, but I should point out that Alcubierre drive and such are legitimate topics of speculation, and there's certainly no way to prove that a warp drive (or some other way to exceed speed of light) will never be invented. There are many other possible explanations for the lack of visible alien activity (painted stellar backdrop, sentients innately nuke themselves, universe is one of many short-term simulations of culture formation de novo etc.). Wnt (talk) 12:04, 19 August 2010 (UTC)

How do you know SETI will never find others out there when by your own estimate there are technological extraterrestrial beings? Your idea of joining a philanthropic Federation of mutually unknowable alien beings sounds like a longing for imaginary friends, which is a need that a TV space drama can feed for a few minutes. Cuddlyable3 (talk) 14:03, 19 August 2010 (UTC)

Your mountain example fails because you are using two humans. The other "alien" is not going to be a human, even if they are very clever. Imagine you and a very smart chimpanzee are dropped into the jungle. Does the chimp care about going to the mountain? Does he care about meeting up with you? Does he get distracted by a banana? If he does meet up with you, does he see this as a good thing or a bad thing? Once you throw out the "everybody wants to be like Star Trek" assumption as being universal — which it is not, even amongst human beings, it is just a catchy cultural product that happens to appeal to various wooly human notions about what a world without limitations would look like — the whole thing crashes down. You can't assume anything of that sort. Even the idea that uniforms and crests are a good idea — that's a very human notion, built up from centuries of human obsession with heraldry and particular notions of power and authority and so on. It's an utterly human-centric idea masquerading as something that has a universal basis. It does not. --Mr.98 (talk) 16:07, 19 August 2010 (UTC)

I agree - this suggestion isn't going to work. We drop you and an alien into a forest. You see the mountain and think that this is "obviously" the way to go. The alien, meanwhile, has no eyes but an acute sense of hearing. It can tell from the sound of lapping waves that there is a lake off in the opposite direction to the mountain and heads off that way and you never meet up. Using the exact same logic as you, it comes to the opposite conclusion. But suppose it doesn't use the same logic? You can easily imagine a very nervous alien might see the mountain and conclude that all of the violent predators would think like you do and head toward the mountain - so it concludes that walking AWAY from the mountain makes the most sense. A super-intelligent alien might both see the mountain AND hear the lake - and reason that either of these could equally well be the destination you'd choose - so its best bet is to walk to a point midway between the two and hope to meet you walking towards either one or the other. Another kind of alien just sits still and yells really loud using it's 1MHz radio-wave voice in the sure and certain knowledge that your 1MHz antenna ears will be able to pick up the sound of it's voice from up to about 100 miles away...There are just too many possibilities.

I'm also not so sure that mankind can never reach the stars. There seems to me to be at least a couple of possibilities:

• One is to build craft several miles across with onboard fusion reactors and ample supplies of helium-3 (or whatever) and the ability to sustain a comfortable life-style for around 1,000 people. Given the prospect of a life of leisure, wanting for nothing, you'd have no problem getting volunteers to spend their lives aboard the ship. It could head out at 1% of the speed of light and take ten human generations to get to the next star. People live their entire lives on board the ship - have children and grandchildren. This is the slow way - but it's certainly within the realms of possibility.
• Another is to develop computers powerful enough to accurately simulate all of the neural pathways in a human brain. When you get old and frail, you transfer your brain's neural network into the computer and let your body fail. Everything that make you be intellectually "you" is still there, your thoughts and feelings are all very much the same as they ever where...except that now you are immortal. When you wish to travel to another star, you sent out a small spacecraft containing a computer of sufficient power. When it arrives at the star you wish to visit, you transmit your brain "data" via radio waves to the spacecraft and "you" travel at the speed of light the whole way there...not getting bored or consuming valuable resources like fuel and power along the way. By use of robotic landers, you can explore and even colonize the new star system. When you get bored, you can transmit yourself back via the radio link to Earth and be back in a reasonable number of years after you left. Going back and forth to your new home is instantaneous as far as you are concerned.

Either of these approaches is technically feasible (nobody said "easy" though!) - and both have the capability to take humans out to the stars. If those approaches are possible for us - then they are possible for any alien cultures out there - and hence we may safely assume that the universe has a lot of aliens in it...unless there is something else that we've somehow misunderstood about the nature of the universe.

SteveBaker (talk) 23:43, 19 August 2010 (UTC)

The first idea you've put there is called a generation ship. The main problem with this idea is that technological progress makes such a ship pointless. Let's take your 1% of the speed of light ship. It sets out for Alpha Centauri 4.24 light years away in 2100. At 1% of the speed of light it will take 424 years to get there, arriving in 2524 Meanwhile back on earth, after 100 years we develop a ship that can do 2% of the speed of light. This launches in 2200 but will only take 212 years to get there so will arrive in 2412, 112 years BEFORE the first ship! Given the accelerating rate of technological progress which is not a linear increase but an exponential one, it's very easy to see that launching ships with journey times of hundreds of years is pointless - a faster ship can be built using improved technology during the journey's lifetime that will easily overtake it. There will come a point when the travel time will become feasible - that will be when it's fast enough that there's not likely to be any major leap forward in starship speed within the timeframe. You only have to look at how far technology has advanced in the last 50 or 100 years to see how rapidly things change. Exxolon (talk) 00:59, 20 August 2010 (UTC)

Taking the mountain idea a little more literally - how about we hang around near a prominent feature of the galaxy, such as Sagittarius A* in the hope that someone, or something else also takes an interest in prominent features of the galaxy? --Kurt Shaped Box (talk) 01:14, 20 August 2010 (UTC)

Myles, you can go to the mountain, but I am going to find water, since I do not want to die of thirst on top of a mountain. Googlemeister (talk) 13:10, 20 August 2010 (UTC)

OP Myles325a back to finish this up. Thanks 86.164,66.86 even if your comments do sound a just a WEE bit patronising. Yes, there is a good analogy between what I am proposing and a religion; an unseen sky pilot who theoretically determines how we should behave. Some might say that such notions are regulative fictions that allow society to flourish. In the case of my Interstellar Federation, it will guide us to being responsible intergalactic citizens, mentors and allies, even if there is nobody we can actually mentor or ally with. Btw, your number is a good serial number for one of the peace troopers on my vessel. Welcome aboard!!

Thanks, Wnt, but what is a “painted stellar backdrop”? Your criticism that “there’s certainly no way to prove that a warp drive...will never be invented”, puts the onus on the wrong party. There’s no way to prove that the world was not created by a gorilla wearing hot pants. It is the job of those putting forward notions to show why such are superior to what is currently known. Einstein’s theories are very well corroborated by experiment and observation, Alcubierre drive is little more than speculation.

Thanks Cuddlyable3. (There are 3 of you cuddly ones? That’s cool!). Don’t underestimate imaginary friends – they can have a life of their own. I had a couple of them when I was a kid, but they used to leave me alone and go and play with each other....But you can come journey with us and be the resident “asteroid hugger”.

Thanks Mr.98. Sorry about that chief, but I think my mountain analogy holds up pretty well, speculative though it may be. Don’t forget that we start with 2 sophisticated, intelligent and rational beings, say, like us two. These are members of technologically capable societies, who have survived through millions of years of evolution. They did not do this, and build space ships and so on, by being “distracted by a banana” when there is a vital task to be accomplished. I am assuming, but I believe reasonably, that a being who belongs to a race than can reason well enough to attain such levels will be able to see that the mountain is the ONLY thing that can be known to be in common. Of course, if the two subjects are from different planets, (as for instance in our case, where I am from Earth) then they must be able to make some guesstimates of what the other one can do. I don’t think I’m being overly anthropocentric here. But for being a rational sceptic, you can be one of our resident scientists. Welcome aboard, Mr. 98!

Thanks, SteveBaker. You are always good value. I am drafting you to be the resident historian on the Ship, as you are so gifted in the production of many words. I would do the job myself, but being in charge is a massive workload. You are extending my analogy, which, as a formal logician you must know is not permitted in logical exegesis. The experiment deals with two subjects given a task to accomplish. My overriding conception is that logical rules are the same everywhere in the Universe, just like basic physical laws, in fact even more so. For example, I can imagine a time when the speed of light was different, but I CANNOT imagine a time when there was a number 2 and 4 but no 3. Or a time (or place) where the Aristotelian syllogisms we use here do not apply elsewhere. An advanced civilization may have very different ideas to us, they might regard mathematics or sexual sadism as the ultimate in poetry, but I cannot see how an advanced society could assume for instance that if A > B, and B > C, then A is not > C. So I am asserting that these beings DO use the same logic as we do, and that is why the IF can exist. As for your sci fi notions about interstellar travel, they might be the case, but on any impartial standard, what we know now strongly argues they are not the case. My own idea is that it may be the case that there is perhaps only 1 or 2 human-like species in each galaxy. That figure would explain the absence of Von Neumann machines.

Thank you Exxolon. The idea of generation ships is a necessary part of any notion of non- sci fi interstellar (or even interplanetary) travel. Even if a ship was just exploring the solar system on a thorough basis, the mission would take hundreds of years. I like your scenario about Earth inventing a new and faster space ship which gets to the target before the original one does. But you have neglected to mention that the 2nd ship would be overtaking the 1st one, and so would be able to give the passengers a lift, while sending the obsolete ship home. But you are now Exxelon the Mighty on our Ship, and you have the perfect name for a warrior ready to defend us from all invaders. Cushy job, as there will be none.

Kurt Shaped Box, Thanks, and yes, your idea has been well canvassed in SETI circles. I think that when 1986a supernova occurred, there were thinkers who advised us to train our radio telescopes in that direction for decades to come, as an advanced species trying to discover others would station transmitters beaming in all directions from the vicinity of that nova, knowing that any other species with telescopes etc would be training them on that patch of sky from millions of light years around. It is my landmark mountain all over again. It makes perfect sense to do just that, although if Steve Baker is right, there is no point in trying to second guess another species’ logic and they would be thinking completely differently. I don’t know what you will be doing on the ship, but with a name like that, you have earned your passage. Welcome aboard!

Thanks Googlemeister Yes, I will go to the mountain, and tell it there, like it is. You can be dressed in black, like the hypocrites turning back. I didn’t say you had to CLIMB the mountain. Circling around it would be just as expeditious (nice word that, haven’t used it for a long time, expeditious hmmm...) Welcome aboard, Googlemeister, you will be peeling potatoes in the scullery, and as a generation ship, you will be doing it for the next 90 years. And that’s just practice, because we won’t be taking off before then.

In relation to other comments, I DO realize that other advanced civilizations may be colonisers and sadistic exploiters. Look at what Rome did to so many of its colonies, and only a few decades ago, the culturally and technologically superior Japanese inflicted the most brutal atrocities on the peaceful and simple Pacific Islanders. But the IF would not allow a Japanese or Nazi culture to join the Federation. Even today, we are excluded from formal entry to this body on the grounds of the conflict that still stain our current affairs. But we will shortly be admitted, as I have made numerous recommendations to that effect, necessarily written to myself until the day (if that ever comes) when there will be another party to peruse them. Myles325a (talk) 11:07, 21 August 2010 (UTC)

chemistry

When an iron object rusts its mass increases. When a match burns its mass decreases. Do these observations violate the law of conversation of mass? Explain. —Preceding unsigned comment added by 112.206.151.82 (talk) 10:08, 19 August 2010 (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. Someguy1221 (talk) 10:12, 19 August 2010 (UTC)

When I fill a cup with water, its mass increases. Does this violate conservation of mass? Why or why not? There's your answer (though your teacher may want it in a more formal format -- consider showing the chemical equations for rusting and burning, since this is a chemistry class). — Lomn 12:27, 19 August 2010 (UTC)

When I spit, my mass decreases. Does that violate the law of thermodynamics? --Chemicalinterest (talk) 13:51, 19 August 2010 (UTC)

When an iron object rusts, it absorbs oxygen. When a match burns, it releases sulfur dioxide, phosphorus pentoxide, and several other chemicals. --Chemicalinterest (talk) 13:53, 19 August 2010 (UTC)

Destroying an ailanthus

How do I do it? Would copper nails or copper sulphate work? Where do I get the latter in UK? Kittybrewster ☎ 12:13, 19 August 2010 (UTC)

I thought a good old saw would work the best. Isn't copper sulfate for algae and scum on pools? --Chemicalinterest (talk) 13:52, 19 August 2010 (UTC)

Copper salts are usually used as fungicides rather than herbicides, and their use in the open is strictly regulated in the UK because they are a potential pollution problem. If you want a chemical solution to the problem, I would gthe quoto for sodium chlorate, which is a cheap broad-spectrum herbicide that doesn't stick around in the environment: you should find it in your local garden centre in the UK, although you have to look at the small print on the labels to see which commercial herbicides are effectively sodium chlorate. Physchim62 (talk) 14:20, 19 August 2010 (UTC)

Sounds to me that a lot of salt will be needed if the roots go everywhere. Kittybrewster ☎ 16:09, 19 August 2010 (UTC)

Just curious... did you always intend to kill the tree, or did Wikipedia convince you? Wnt (talk) 14:50, 19 August 2010 (UTC)

No, not until I saw the links. Kittybrewster ☎ 16:09, 19 August 2010 (UTC)

So, let's think about this. I assume you are referring to the large tree you sought info about recently. You are going to need unfeasibly large amounts of herbicides of which the best - sodium chlorate is not available in useful quantities in the UK. If you put whatever useful or useless chemicals on your tree and it dies you are then left with this great big dead tree in your garden. Hmm, very attractive. What then? wait for it to fall down slowly? Your only reasonable method is to get a competent person to get rid of it for you. Richard Avery (talk) 17:48, 19 August 2010 (UTC)

Maybe I could drill holes in it and then pour in the chlorate? Kittybrewster ☎ 18:12, 19 August 2010 (UTC)

There's no specific disclaimer that Wikipedia does not give horticultural advice, but maybe there ought to be. The tree grew this tall without causing you any bother; it's not known for being so invasive in the UK; whatever links you may have read here, you should reevaluate most skeptically. Wnt (talk) 00:32, 20 August 2010 (UTC)

Wouldn't glyphosate be more effective? Sodium chlorate (not chloride) is an effective weedkiller, but it kills everything and remains for at least a year. I agree that it would be best to use a saw first. Dbfirs 17:51, 19 August 2010 (UTC)

What about "Unfortunately for those trying to tackle the plant, Ailanthus is also fiercely resistant to human intervention and will respond to cutting by throwing out underground suckers which can damage pavements, drainage systems and building foundations."? Kittybrewster ☎ 18:04, 19 August 2010 (UTC)

I agree with Richard Avery. You should ask a professional. If you're worried about paying, the damage you might cause following random replies here might be costly too. I would first call the municipality, and ask them to refer you to somewhere competent. If Alianthus really is considered to be a plague where you live, perhaps you won't have to carry all the expenses. ---Sluzzelin talk 21:02, 19 August 2010 (UTC)

It depends how near the tree is to drains and buildings. I agree that professional advice is advisable if there is a risk of damage. Some trees can be killed by painting a herbicide such as 2,4-dichlorophenoxyacetic_acid and 2,4,5-Trichlorophenoxyacetic_acid (possibly still available as "SBK Brushwood Killer" in the UK) mixed with oil on the bark, or in drilled holes, but I don't know how effective this would be with ailanthus. Dbfirs 21:46, 19 August 2010 (UTC)

I would consult DEFRA as to whether they consider it invasive in the UK. They would also be able to advise on its destruction. An old farming friend of mine told me the only way to kill a laurel tree was to hammer copper piping into it, by the way. --TammyMoet (talk) 09:29, 20 August 2010 (UTC)

Effect of Humidity on visibility

What effect, if any, does humidity have on visibility?Smallman12q (talk) 15:44, 19 August 2010 (UTC)

Humidity often decreases atmospheric transparency, which can have an effect on visibility. High humidity is also often associated with fog or with high levels of particulate matter and smog. ~AH1^(TCU) 19:10, 19 August 2010 (UTC)

This falls into the realms of Mie theory and Rayleigh scattering depending on the size of any droplets that might form (the 'Mie' bit) or on the size of the molecules present if they aren't formed into droplets (the 'Rayleigh' part). So, yes, the humidity affects how light is scattered - and therefore the visibility. SteveBaker (talk) 23:21, 19 August 2010 (UTC)

How large/nominal is the effect? Let's say the humidity is 80%...by how much would visibility be reduced on an otherwise clear day?Smallman12q (talk) 23:13, 21 August 2010 (UTC)

List of operational spacecraft in lunar orbit

Where can I find a list of spacecraft which are still receiving and capable of transmitting in lunar orbit? Ginger Conspiracy (talk) 13:51, 19 August 2010 (UTC)

nowhere: the military satellites of most countries will be classified. 92.229.13.215 (talk) 18:09, 19 August 2010 (UTC)

Right, the military satellites defending the moon, which has no people and no strategic value to anyone at this time. TastyCakes (talk) 18:14, 19 August 2010 (UTC)

Hmm well I think Wikipedia could probably use an article like this one but for the moon. Looking at thisit seems that only 1 is currently active, the Lunar Reconnaissance Orbiter. The rest have either been crashed into the surface or are broken. TastyCakes (talk) 18:27, 19 August 2010 (UTC)

Oops, this page led me to the THEMIS article, another active orbiter. TastyCakes (talk) 18:32, 19 August 2010 (UTC)

THEMIS is not in lunar orbit, it's in Earth polar orbit! Berkeley has a THEMIS Orbit page and NASA has a standard Mission Page. They are quite large orbits (12 Earth radii), but nowhere near the Moon, let alone orbiting it. Nimur (talk) 22:38, 19 August 2010 (UTC)

Ah so it is, don't know how I misread that one so badly ;) It looks like the plan is to put Themis B and C into lunar orbit though, but they are not there yet, as stated in this section. TastyCakes (talk) 14:47, 20 August 2010 (UTC)

Excellent! I was hoping that the answer was three or more, and very glad to see that it will be. Frank Drake and his colleagues have grown frustrated with radio interference from Earth, and it is good to know that there will soon be the opportunity to perform space radio VLBI from the far side of the moon. Ginger Conspiracy (talk) 19:35, 20 August 2010 (UTC)

If you're in Mountain View, the SETI institute is seeking privately-funded researchers... Nimur (talk) 21:13, 20 August 2010 (UTC)

quantum mechanics

when light will behave like a wave and when light will behave like particle? —Preceding unsigned comment added by 122.178.184.204 (talk) 14:06, 19 August 2010 (UTC)

See the Wikipedia article on Wave–particle duality. Cuddlyable3 (talk) 14:11, 19 August 2010 (UTC)

the answer is "always". For example, when it is a particle, it interferes with itself like a wave. (and the particle might never hit a spot that is dark in its wave's interference pattern). 92.229.13.215 (talk) 18:08, 19 August 2010 (UTC)

Try this on for an example. Consider a lemon. If I look at a lemon, it is yellow. If I taste a lemon, it is sour. We don't say that the lemon sometimes behaves yellow, and sometimes behaves sour. It is always sour and it is always yellow. The difference in whether or not a lemon is sour or yellow depends not on the lemon, but on whether I look at the lemon or whether I taste the lemon. Light is like a lemon here. Just as we can organize an experiment which highlights the "yellowness" or the "sourness" of a lemon, we can organize an experiment which highlights the "particleness" or the "waveness" of light. The deal is, just like the lemon isn't less sour just because I am looking at it rather than tasting it, light isn't any less of wave just because I am doing an experiment which highlights its particle properties. --Jayron32 04:35, 20 August 2010 (UTC)

The genius of your analogy is that you can't both look at and taste a lemon at the same time (without some device, at least). --Sean 17:56, 20 August 2010 (UTC)

You can't see your tongue then? I can so could probably semi taste a lemon and semi see it at the same time. Nil Einne (talk) 09:48, 21 August 2010 (UTC)

Mystery ship mutilates seals

According to [14], a seal team at St. Andrews' is appealing to members of the public to submit ideas as to how a seal could be sliced in a helical pattern from head to toe.

It's obviously not the usual propeller injury - it's as if it passed through some kind of tube with a slicing point rotating, or spiraled through the tube past a fixed sharp object.

I wonder if some fancy submarine propulsion system like a magnetohydrodynamic drive could do it, or maybe even some colossal sort of ballast system? But I have no idea. Any guesses? It's for a good cause! ;) Wnt (talk) 14:46, 19 August 2010 (UTC)

I too have been waiting for further news about these curious injuries (in part because I used to live in St Andrews, and in part through general interest in marine biology.) A couple of notions sprang to mind:

(i) harpooned whales are or were sometimes manipulated and cut in such a fashion as a prelude to further processing, so perhaps someone with a grudge against seals is employing similar handling techniques;

(ii) perhaps such injuries would result from the seals passing through a tube-enclosed turbine of some sort - perhaps one associated with a conventional water-cooled nuclear power station (would Torness be the nearest?), or a new/experimental tide- or current-utilising setup, such as a Gorlov helical turbine. Your suggestion of a submarine propulsion system, Wnt, is also a good one. 87.81.230.195 (talk) 17:05, 19 August 2010 (UTC)

That's bizarre. I wonder what would happen if a seal twisted itself up in a semi taut cable (maybe attached to a fishing net) while trying to escape and that cable was subsequently pulled tight by a trawler or something. Would that produce a cut like that ? Very odd. Sean.hoyland - talk 17:42, 19 August 2010 (UTC)

Once, maybe, but apparently several seals have been found with these injuries over a period. 87.81.230.195 (talk) 17:52, 19 August 2010 (UTC)

The seals have gone Emo! Googlemeister (talk) 18:10, 19 August 2010 (UTC)

Did it look like Spiral sliced meat? Edison (talk) 19:18, 19 August 2010 (UTC)

I could imagine this being some ghastly propellor accident - if the propellor were rotating clockwise and hit the flank of the seal - the force of the impact would apply an anticlockwise rotation to the seal - and the angle of the propellor blade would drive the seal's body towards the back of the boat. So we have the body spinning and moving backwards - so a spiral cut doesn't seem impossible. SteveBaker (talk) 21:09, 19 August 2010 (UTC)

Megaflow Heating Systems

There is no entry under this title. Google searches do not list readily accessible or 'layman's' information. Plumbing forums have many questions as to what a Megaflow system is. Thus there is a need for a straightforward article.

Please could you find a plumbing contributor to define precisely what the system is, how it relates to other Hot water/Central Heating systems, and how it works!

Many thanksChallca (talk) 18:20, 19 August 2010 (UTC)

I'm not a plumber or an expert on heating systems, so I originally thought it just referred to a large bore diameter (as opposed to microbore), but it appears that the term refers to a system that supplies hot water from an unvented tank at mains pressure (or at least three atmospheres), without using a header tank. A good reliable high-pressure mains supply is required. I think it is the same as our brief description at Central_heating#Sealed_water-circulating_system, but perhaps an expert can check this. Dbfirs 21:15, 19 August 2010 (UTC)

Mixture of energy and matter

To me entropy means that matter and energy (like the salt and pepper analogy) can never be completely separated. Is this a postulation upheld by the law of entropy or am I missing the point? By completely I mean all the energy in the universe and all the matter in the universe. —Preceding unsigned comment added by 165.212.189.187 (talk) 18:29, 19 August 2010 (UTC)

Missing the point, you are. Entropy characterizes the number of states in which the system can be at the given energy. What do you mean by separating energy from matter? Energy can be transferred between systems, but it cannot exist as a non-matter. Particles -- elementary or composite -- that mediate the energy transfer by carrying the forces of the fundamental interactions are matter. Entropy has nothing to do with this inseparability; it is just a number to begin with, and is not even well defined in many cases. --Dr Dima (talk) 19:19, 19 August 2010 (UTC)

Yeah, the OP is completely off WRT entropy. Entropy is a tricky idea. Let me try to explain it how I teach it to my students. Picture you have a house that is completely insulated: nothing gets in and nothing gets out. Inside the house, you have two rooms at different air temperatures: One room is at say 30 C and the other is at say 20 C. Now, imagine there is a window between these rooms. If you open the window, what happens? Well, air begins to move between the two rooms, making a breeze. As that air moves, you could, say, place a wind turbine in the window to do work. How long will the turbine be able to do work? Until the two rooms equilibrate; eventually both rooms will be at 25 C, and thus air will stop moving, and thus your turbine will stop. OK. Do you have the entire scenario in your head now? OK. So here's the deal, call the house BEFORE opening the window "State A" and the house AFTER the two rooms are the same temperature "State B". Since the house lets nothing in or out, the total energy in the house in State A is identical to the energy at State B. And yet, House A does work, and House B does not do any work, even though they have the same amount of energy inside of them. How do we explain the difference between the two houses? Well, there are several ways, and the related concepts of Entropy and Free energy are both numerical answers (and rather esoteric numerical answers) to the question of "What is the difference between the two houses" We can say that House A has less entropy than House B. or we can say that House A has more free energy than House B. Now, the actual, mathematical definitions of Entropy or Free Energy are actually several degrees removed from the house example, but roughly speaking they mean the same thing: The ability of a system to do work based on the organization of that system. --Jayron32 03:37, 20 August 2010 (UTC)

Dima, do heat and sound energies have matter? If all energy is matter then why do we have E=MC^2? OK So let me rephrase my question: Lets say matter and energy are like two states of the same thing like ice and water. Is it possible for all the energy and matter in the universe to be all matter or all energy at the same time? Does this have to do with entropy? —Preceding unsigned comment added by 165.212.189.187 (talk) 14:03, 20 August 2010 (UTC)

"Lets say matter and energy are like two states of the same thing like ice and water" - but they are not. Matter has mass, and mass is energy - see our article on mass-energy equivalence. So you can't have matter without energy. But you can have energy without matter - a light wave has energy and mass, but its constituent photons are not (in most definitions) classified as matter. So if all the mass/energy in the universe were in the form of electromagnetic radiation then you would have a universe with mass/energy but without matter. Gandalf61 (talk) 14:34, 20 August 2010 (UTC)

Is that possible or is there something preventing that absolute from occurring in actuality? —Preceding unsigned comment added by 165.212.189.187 (talk) 14:51, 20 August 2010 (UTC) What about the mixture of matter&energy with dark matter&dark energy? —Preceding unsigned comment added by 165.212.189.187 (talk) 15:50, 20 August 2010 (UTC)

Well, we can certainly envisage a model universe filled with a low density of photons and no matter, and I don't think this breaks any physical laws. In fact, one of the unsolved problems of physics is to work out why our universe is not like this - this is known as the baryogenesis problem. If the initial hot dense conditions of the Big Bang produced equal numbers of matter and antimatter particles, and if there is an exact symmetry between matter and antimatter, then all these particles should have eventually annihilated each other as the universe cooled, leaving only photons. But the universe we see is not like that at all, and the most likely explanation is that the interaction between matter and antimatter is not exactly symmetric. What we don't know is exactly where this asymmetry is found. Gandalf61 (talk) 15:51, 20 August 2010 (UTC)

Isn't that where entropy would come in? Energy forever caught up in matter and dark energy forever caught up in dark matter? Or something like that. —Preceding unsigned comment added by 165.212.189.187 (talk) 17:34, 20 August 2010 (UTC)

No, that's not entropy at all. And if dark energy exists it has nothing to do with dark matter. Ariel. (talk) 19:06, 20 August 2010 (UTC)

That bold statement discredits everything I would ever see you write! Don't you know by now that in this universe everything has to do with everything?! —Preceding unsigned comment added by 165.212.189.187 (talk) 19:34, 20 August 2010 (UTC)

No, Ariel is correct, it seems you have an incorrect understanding of dark matter and dark energy, because even though they have similar names they are completely different ideas. Dark matter isn't the opposite of matter and dark energy isn't the opposite of energy, dark matter is matter that isn't visible or doesn't interact with light (hence the name dark) but contributes to the motions and arangments of stars and galaxies by it's gravitational effects. Dark energy is a proposed explanation to why the universe's rate of expansion is increasing. —Preceding unsigned comment added by 74.67.89.61 (talk) 20:39, 20 August 2010 (UTC)

And, of course, that means that they do not interact with each other, whatsoever!?!? All I want to know is if everything in the universe can be in one form: all energy or all matter or all dark matter or all dark energy, yes or no?

You still seem to not understand what dark energ and dark matter are, they are a form of energy and matter not the opposite of energy and matter, so asking if everything can be dark matter vs. matter or dark energy vs. energy is completely pointless and doesn't even really make sense. As for energy vs. matter, it has already been answered above by Gandalf61, the big bang should of produced equal amounts of antimatter and matter which should have annihilated to leave just photons, or in other words just energy, no matter. This would have occured if there was an exact symmetry between matter and antimatter, but it is believed that there isn't an exact symmetry which would lead to the production of more matter than antimatter and the formation of the universe we observe today from the left over matter. And no to the entropy part, entropy has nothing to do with the left over matter which is known as baryogenesis. There is no need to get snappy, exspecially when the question has already been answered and we are simply correcting a misunderstanding on your part.--74.67.89.61 (talk) 00:29, 24 August 2010 (UTC)

Its funny instead of just giving an answer that you know will shut me up you give answers that cause me to reply ( you must like conflict). So Ariel says that dark matter and dark energy do not interact with each other. If they are both proved to exist in the SAME universe how can they not interact??? I'm through asking you people who just want to keep all the knowledge to yourselves. Wikipedia doesn't really care to enlighten all people just select people. I didn't ask whether everything can be dark matter vs matter or energy vs dark energy I asked whether everything could be 100% of one of the four. Can't you read english!? Regardless if its pointless or not can't you just answer the question or am I not worthy?

-Actually its questionable if you can read english. This is becasue you are taking what Ariel and I said and changing it into something it is not, we never said that dark energy and dark matter do not interact at all, we said they have nothing to do with each other, meaning they are different ideas, different theories, not related to one another, they are completely different like for example the electromagnetic force compared to quark qluon plasma. The second reason is because your question has been answered atleast twice above. Ohh and aslo dark energy hasn't been proved to exist, it is a proposed solution to a problem in cosmology.

-To try to answer your question another time, the reason we can't give you a yes or no answer is because your question has errors in it that are misleading if we gave you a yes or no answer. Let me give you an example, imagine I have a basket and I ask you if it is possible to have just oranges, carrots, fruit, or vegetables in it, which corresponds to your question can you have a universe filled with just dark energy, dark matter, matter, or energy. The answer to that exact question is no, because even though the basket can be filled with just fruit vs. just vegetables or just carrots vs. just oranges, it is impossible to have a basket filled with just oranges and no fruit because oranges are a type of fruit so if you have oranges, you have fruit, the same applies to carrots vs. vegetables. Likewise dark matter is a type of matter, so it is impossible to have just dark matter and no matter because dark matter is matter. The same applies to dark energy and energy, dark energy is energy so you can't have dark energy but no energy, just like you can't have a basket filled with oranges but no fruit because oranges are a type of fruit. However just saying no to your question is misleading, lets clear it up by getting rid of the part about dark energy and dark matter and just talking about energy vs. matter becasue dark enrgy and dark matter are a type of energy and matter respectively (corresponding to our basket example, get rid of the part about oranges and carrots and talk about only fruit and vegetables because oranges and carrots are a type of fruit and vegetables). Now because of E=MC^2, mass is energy, and and matter has mass so matter has energy, which means no, you can not have matter but no energy. But, you can have energy but no matter, if you take equal parts matter and antimatter and mix them for example, they will completely destroy each other into pure energy. In fact why this didn't happen and why all of the universe isn't simply composed of photons (energy) and no matter was actually a problem in cosmology, baryogenesis is the beleived reason of why this didn't happen.

-And finally NO THE REASON THERE IS ENERGY AND MATTER IN THE UNIVERSE (BARYOGENESIS) IS COMPLETELY DIFFERENT FROM ENTROPY,YOUR UNDERSTANDING OF ENTROPY IS WAY OFF.--74.67.89.61 (talk) 19:35, 24 August 2010 (UTC)

Puberty and menopause throughout history question

Do puberty (and menopause if female) occur at different times in people's lives than they did, say, in the 1200s? I.e., is puberty earlier/later, and is menopause earlier/later? Also, does the onset of puberty and menpause differ between developed and third world countries? Does it even differ between sub-cultures of a developed country (for example, will a middle class girl destined for university hit puberty and menopause at a different age than a lower class girl from a sub-culture that looks down on education and success?) —Preceding unsigned comment added by 92.251.179.48 (talk) 18:34, 19 August 2010 (UTC)

I don't know the answer to your question, but I do know that some female athletes hit puberty at a much later age than most teenage girls due to the endorphins and hormones produced by increased strenuous exercise. ~AH1^(TCU) 19:05, 19 August 2010 (UTC)

To the general question, yes, it varies. Here's a writeup on a recent study regarding the increasingly early onset of puberty in the US. Many factors with correlation are noted, but bear in mind that correlation is not causation. — Lomn 19:23, 19 August 2010 (UTC)

For the other perspective, here's a refutation. — Lomn 19:25, 19 August 2010 (UTC)

It's difficult to tell, because we don't have historical records for a good sample of the population: that is, we can guess when certain historical figures went through puberty, but we don't know if that sample is representative of humans in general. My guess would be that ten-year old mothers and fathers have always been very rare, because there's little or no reliable mention of them: beyond that, there is also the fact that puberty occurs at different ages in different individuals, and always has done. Physchim62 (talk) 19:44, 19 August 2010 (UTC)

According to this article, Aristotle, Hippocrates, and Roman authors agreed that most women entered menopause in their early 40s. Medieval authors gave 50s as the age. The article points out some of the difficulties in determining this even today (people "round up" their recollections), and discusses rates in different societies. Probably a pretty useful article for your question all around. --Mr.98 (talk) 19:44, 19 August 2010 (UTC)

And what's the age today? 50 something?--92.251.179.48 (talk) 20:04, 19 August 2010 (UTC)

If we're going to talk about menopause, we should probably also mention menarche (which is not the same thing as puberty). Mitch Ames (talk) 02:19, 22 August 2010 (UTC)

Signs > and < with tilde below

Where I can copy-paste math signs "<" and ">" with tilde below them? 213.154.18.72 (talk) 19:30, 19 August 2010 (UTC)

Those probably aren't in most character sets, so copying and pasting may be difficult (but poke through the character map program in Windows if you've got a suitable font). On Wikipedia, it can be done with the TeX-based math markup as follows (documented at WP:MATH):

$\lesssim \lessapprox \gtrsim \gtrapprox$ — Lomn 20:36, 19 August 2010 (UTC)

Right here: Unicode mathematical operators and symbols. Ariel. (talk) 21:23, 19 August 2010 (UTC)

setting up of a SOLAR POWER PLANT to meet the requirements of a college campus

hii...

I am Gaurav Sharma, a final year student of B.Tech-Civil. I got a project of setting up of a Solar Power Plant for my college campus.

I don't have any idea about where to start from. Can anyone please help me by providing me with some info about what types of plants can be installed under which conditions, their advantges & disadvantages, costing etc. & also the steps to be followed or factors to be kept in mind while installing a plant.

Any type of info will be helpful.

Gaurav —Preceding unsigned comment added by Sharmagaurav89 (talk • contribs) 19:59, 19 August 2010 (UTC)

I think the best place to get started would be to determine how many hours of sunshine you get in an average year, and also, what the peak power consumption and average power consumptions of the college are so that you can have a basic idea of how much power you need to generate. Then you can say something like, what kind of power plants would make sense given that I have 220 sunny days per year and I need 50 MW average and 220MW peak. Googlemeister (talk) 20:26, 19 August 2010 (UTC)

Obviously your project would have to provide power at night and when the sun goes behind a cloud - so you need to consider whether you need a gigantic stack of batteries to store the energy when there is sunlight in order to provide power when there isn't. Perhaps, as in many countries, you can sell your excess daytime power to the local electricity company and use that money to buy conventionally generated electricity at night (that's a very common approach in the US and UK) - I have no idea whether the power companies where you live are open to that way of doing business. You can think of it as driving your electricity meter backwards during the day and then forwards at night - hopefully not using more than the excess that you generated during the day. All of this requires that you understand the day lengths in summer and winter and the pattern of energy usage on a 24 hour basis during summer and winter. Are there any times when the usage is likely to 'spike'...maybe at lunchtimes when the campus food outlets do more cooking...maybe there are peaks on the first day of school or when there is a local sports event on TV or something? SteveBaker (talk) 21:03, 19 August 2010 (UTC)

I'm unfamiliar with your geographic surroundings, but would solar air conditioning methods be within your purview? I would hope that they might be more efficient, quieter, and cheaper than expanding a fully photovoltaic system to cover the load, for example. Wnt (talk) 00:40, 20 August 2010 (UTC)

You also need to consider how much space you got available. A solar plant for the campus doesn't have to be on campus; you can always buy the land elsewhere, build a bigger and more efficient plant, and sell the excess power to offset the capital investment and transportation costs assuming the economics add up. Physchim62 (talk) 03:19, 20 August 2010 (UTC)

It's also worth mentioning that there are other ways to use solar energy than to generate electricity. For example, you can use roof-mounted panels with water flowing through them to heat water and use that for room heating or to replace hot water heaters in bathrooms and such. You still have the problem of keeping things warm at night - but having a large reservoir of water that gets heated during the day may suffice for nighttime use. SteveBaker (talk) 13:03, 20 August 2010 (UTC)

Please see also Concentrated solar power. Why Other (talk) 20:49, 23 August 2010 (UTC)

abyss of time

This follows-up my very recent queery "Please define "abyss of time". I realize the question as put was not as focused as I wished. Please let me indicate the full context of my inquiry.

A recent play written by me uses “the abyss of space”. Its use is important. However I want to emphasize time as also being contained in an abyss. Therein my problem; confusion between early and recent understandings. Although I think I have resolved the matter I seek expert opinion to eliminate any uncertaintly. (An important disclaimer here. I am not a professional scientist. My life's work was in the commercial and performing arts world. )

I’ve recently seen written, “the abyss of Time”, “Time abyss”. This accords with my lifelong understanding of space as all alone in a boundless abyss, with time an add-on, a separate construct (so many ways of representing times). So: if one said “Time abyss”, or the “abyss of Time” it would mean an abyss within an abyss.

More recently, from readings, lectures, discussions with astronomers and other experts, I understand and accept the concept that it is not space and time but a single entity, space-time. That means I can consider time as an equal component of space, one of its four dimensions

If this is so, and I strongly believe it is, then there is only one abyss which same is occupied by three space components and a time component.

If you will, we now have a mixture. Before, it was a compound.

This presents no problem for me. Wherever I now use abyss I will use “space time abyss”. What I have to be satisfied with is the accuracy of the idea that time always existed with the other three space dimensions; nameless at first then identified with names and so considered an equal member of the abyss called “space-time”, not occupying its separate abyss.

In my play I emphasize "Time past". I may still use the idea of Time past located in an Abyss waiting to be found, ergo contrary to what I indicate above. If I do, its use will be poetic

Would appreciate your thinking.

PS: A lingering thought. It seems that most people still think of Space as three dimensional with time not usually considered an integral part. I suppose 50 to a hundred years from now common usage will usually reflect four dimensional thinking.

In advance, many thanks.

Center 39Center39 (talk) 20:01, 19 August 2010 (UTC)

Time and space are not the same thing. They have different properties. The are used together in certain situations because it can make the math or the physics elegant, but they will always be separate. One obvious difference is you can not go backward in time. Time is not a place, you can not go there, time is a way of defining how "fast" things happen. Space is a place, and you can travel freely to all points in it. One example of how time and space are used together is a particle traveling in a straight line: As you move in time, you also move in space. If you move in space, you also moved in time. But this is just a mathematical construct, it does not mean that space and time are the same thing. I don't see how "Time Abyss" means an abyss within an abyss. Ariel. (talk) 20:17, 19 August 2010 (UTC)

(e/c) "Abyss of ..." is inherently poetical. The word literally means 'bottomless pit', and so when you say "abyss of ..." you are merely referring to something that extends on and on and on, usually in darkness. When applied to space the 'darkness' is usually literal; if applied to time the 'darkness' bit would translate as 'unknown' or 'historyless'. 'spacetime' does not carry the same connotations as 'time' (it's a physical property - one does not talk about the passage of spacetime, and that phrase would in fact be fairly meaningless). --Ludwigs2 20:22, 19 August 2010 (UTC)

It's an entirely valid poetic/literary phrase - but to try to seek some kind of scientific meaning is kinda pointless. We can talk about how big space is, whether it's truly "empty" or not - how long time extends and what it's properties are - but the word "abyss" isn't likely to pop up in that discussion other than as a poetic/literary matter. Wiktionary defines "abyss" as:

1. A bottomless or unfathomed depth, gulf, or chasm; hence, any deep, immeasurable, and, specifically, hell, or the bottomless pit.
2. Infinite time; a vast intellectual or moral depth.

So, yeah - you can use the word for either space or time. A depth, gulf or chasm that's deep, immeasurable, hellish or bottomless - could be the chasm between stars and galaxies - it's also bottomless (as well as endless, topless and side-less!) - it's unfathomed because "fathoming" means measuring the depth of - and we can't measure the 'depth' of space. The second Wiktionary definition has time covered - and time certainly seems to modern science to be infinite. I don't quite see where "a vast intellectual or moral depth" might come from - scientifically speaking - but I don't have a problem with that as words spoken in a book or play.

I'm sorry but I don't think we can illuminate your search in any useful manner - but I don't see why you shouldn't use those terms if you wish. SteveBaker (talk) 20:55, 19 August 2010 (UTC)

This is an aesthetic question, but consider Cronus, who devours his children. Time can be viewed as an abyss in the sense that all things sink into it and pass away, and there is always room for more. While the conception of spacetime might seem beyond ancient authors, the metaphor of time as a river (and I suppose a waterfall, falling into an abyss) has been around for a long time. Wnt (talk) 00:48, 20 August 2010 (UTC)

Cronus is not the same god/character as Chronos. Cronus was the one who ate his kids; Chronos was the personification of time. Matt Deres (talk) 01:09, 22 August 2010 (UTC)

car key gets hot

I have noticed that after driving, even over relatively short distances, my ignition key gets quite warm. The other keys are quite a bit cooler. Why would this be happening? Googlemeister (talk) 20:33, 19 August 2010 (UTC)

Well, there are a bunch of fairly chunky wires going from inside the engine bay up to the ignition switch - those wires are made of copper - which conducts heat very well indeed. The inside of the engine bay is really hot (especially on a hot summer day)...so heat from the engine warms up your ignition switch - and hence that key gets a little warmer too. I'm surprised it's enough to be noticable - but this is a perfectly valid explanation. It's not entirely unreasonable that for some make of car with some kind of ignition switch and some kind of key that this might happen. SteveBaker (talk) 20:44, 19 August 2010 (UTC)

Our article on immobilisers says that some cars induce a current in the ignition key to check that it matches the car's ECU. This would cause the key to heat up. Brammers (talk/c) 21:10, 19 August 2010 (UTC)

No way. That's a very tiny signal indeed - and it's only done once, briefly when you stick the key into the lock. There is nowhere near enough energy to make a noticable difference to the temperature of the key. Plus if the key became hotter than the ignition switch, the heat would just flow into the lock and pretty soon the key would have cooled down again. This cannot possibly be the correct answer. SteveBaker (talk) 23:11, 19 August 2010 (UTC)

Yes, Steve's original explanation is more likely, but I think even more probable is that there is a bad connection (i.e. a spade terminal with a significant resistance) that is generating heat at the ignition switch. (I'll check my key next time I drive!) Dbfirs 23:34, 19 August 2010 (UTC)

You haven't said what kind of car, but in many of them there is a lot of electrical current that flows through there. I don't think it's engine heat flowing through the wires, but rather the wires heating from all the electricity passing through them. In mine for example the full current of the headlights passes through the turn signal switch. The key cylinder is a central switch for the entire car - I wouldn't be surprised if lots of current flowed through it. If this is a new issue (or getting worse, or it's an older car) I would open it up and clean the switch, it's probably making a faulty contact. You might not need to fully disassemble it, you should be able to to clean it by soaking it in alcohol (unless it's greased). Ariel. (talk) 01:02, 20 August 2010 (UTC)

This forum suggests that heating effects could be down to a solenoid that unlocks the steering wheel being energised, although they don't provide any corroboration for that. It seems to have affected a few people with 2003 CR-Vs. Brammers (talk/c) 07:33, 20 August 2010 (UTC)

I'm kinda horrified that they'd send the entire headlamp current through the stalk switches - headlamps pull a lot of juice and need fairly chunky wires - which wouldn't fit well when threaded through those skinny switches. Are you 100% sure about that? Every car I've worked on has had a relay or something like that so that a low current signal from the switch trips the relay and that switches the high current to the headlamps. If high current through skinny wires is enough to make things heat up than that's a really nasty piece of design work! I'm similarly horrified about the steering lock theory. Are they saying that the steering lock mechanism is reliant on power going to that solenoid? So if the fuse blows or the solenoid fails then your steering could lock while you're hurtling down the freeway at 80mph?! I don't think they work like that - I believe these are usually dual solenoids - activate one coil to lock the steering and another one to unlock it - rather than having one solenoid that pulls the pin out against a spring or something. SteveBaker (talk) 12:58, 20 August 2010 (UTC)

I'm sure about the headlights because it failed, and I had to fix it. It started getting VERY hot, and the lights would flicker and dim, and eventually would not turn on unless you jiggled it a lot. I removed it, opened and cleaned it, and now it works just fine. I suppose there could be a relay, but I'm pretty sure there isn't. The stalk has a "press to pass" button on it that flashes the high beams (and turns off the low). 1998 Mercury Sable. The solenoid failed does sound horrible though. And actually doesn't totally make sense - can't you unlock the steering without turning on the car? Ariel. (talk) 17:40, 20 August 2010 (UTC)

Canards

The article on canards says that they are not very stealthy "because they present large moving surfaces forward of the wing". Could a stealth aircraft use a non-moving canard, such as on the Rockwell B-1 Lancer? --The High Fin Sperm Whale 21:51, 19 August 2010 (UTC)

Your objective is unclear because your question is ambiguous. Any canard aircraft, even a stealth aircraft, can be designed with a non-moving canard. The laws of physics apply just as much to a stealth aircraft as a non-stealth aircraft.

On the other hand, if you are asking if an aircraft can have a non-moving canard and still be stealthy the answer is no. The difficulty in making a canard aircraft stealthy applies just as much, perhaps more, to an aircraft with a non-moving canard as with a moving canard. (A moving canard can be swept backwards in cruising flight and the sweep provides reduced radar reflection.) Dolphin (t) 22:36, 19 August 2010 (UTC)

Most of the time, "stealth" aircraft are designed to have small RADAR cross-sections. Sharp angular surfaces, like tail-fins, wings, and so on, are undesirable because they usually act as radio-frequency corner reflectors (to some extent). The trouble is, everything acts as a radio-reflector, (to some extent) - so the engineers need to make a design-tradeoff: to what extent do they need to minimize RADAR reflectivity? (They've already tried removing everything from the plane except the wings!) In the case of the B-1, the forward canards probably stick out like a bright shiny scintillating beacon, (exactly like these, but in the radio spectrum instead of in visible light). Stealth aircraft try to avoid being "bright and shiny" at all frequencies, especially in the range of radio-wavelengths that anti-aircraft systems are likely to operate in. But, the engineers decided that it needed those canards (probably for flight stability), and that it was worth the impact to stealthiness. Nimur (talk) 22:51, 19 August 2010 (UTC)

The article specifically says that Control Canards are not very stealthy. It doesn't say anything about fixed Canards. Nimur's probably right that a Canard can act as a corner reflector to some extent, but I would imagine that if they didn't move around, the problems would be largely alleviated. I'm not sure why Dolphin asserts so assuredly that an aircraft could not have a fixed canard and still remain stealthy; I see nothing in any of the related articles that would lead me to believe this. All else being equal, maybe a canard-ed aircraft is less stealthy than a canard-free one, but I would be quite surprised if canards made stealth flight impossible. And to be clear, the B-1 was not designed as a stealth aircraft. My impression is that it's (relatively) small radar cross section was achieved with only modest modifications in the B-1B (mostly a change in the engine intake shape to shield the moving parts in the engine from radar), and that most of it was designed with other priorities (mostly being fast and carrying a lot of bombs). Buddy431 (talk) 03:33, 20 August 2010 (UTC)

My comment that a stealth aircraft can [not] have a non-moving canard and still be stealthy is based on the following thought process. The HFSWhale began by quoting the article and stating that canards are not very stealthy. Next, he asked if a stealth aircraft could use a non-moving canard. One of the interpretations of this ambiguous question is that he is asking whether a stealth aircraft could be made more stealthy by use of a non-moving canard instead of a moving canard. There is no reason to expect a non-moving canard to be any more stealthy than an equivalent moving canard so my answer was no.

I see your observation that the quotation applies to control canards and therefore not necessarily to lifting canards. Whether a canard is a control canard or a lifting canard is dependent primarily on the location of the aircraft’s CG and how much of the aircraft’s weight is supported by the canard. A lifting canard must generate significantly more lift than a control canard so it will have a greater angle of attack. For this reason, perhaps a lifting canard is less stealthy than a control canard, rather than more.

I still think the problem of canards on stealth aircraft cannot be alleviated by changing the moving canard for a non-moving canard. Intuitively, I assume the radar-reflective properties of the canard depend on its leading edge radius, thickness and sweep angle. In the cruise, a moving canard will actually move very little so, from the radar perspective, it will be almost indistinguishable from a non-moving canard. Dolphin (t) 06:17, 20 August 2010 (UTC)

I don't think "moving" or "non-moving" is the issue - it's whether to have a canard at all. The difference between a moving- and non-moving one might mean more mechanical parts exposed, or other constraints on the design; and it would be more effort to characterize and test the RADAR-properties for all possible configurations; but overall, fewer things sticking out of the airframe mean fewer things to reflect radio. The original question specifically asked about a line in the article: checking the cited source for that line resolves the issue: the original paper says, very bluntly, "Canards have poor stealth characteristics." That section does not actually mention anything about moving- or non-moving canards. I have fixed our article. Nimur (talk) 20:58, 20 August 2010 (UTC)

There is another source. The Eurofighter article notes how they use software to make their canards more stealthy. Hcobb (talk) 21:27, 21 August 2010 (UTC)

Calculating Rising and Setting Times of Stars

If you know your latitude and longitude and the declination and right ascension of a star, is there a formula that can be entered into Microsoft Excel that will calculate the rising and setting of that star on a given day of the year? Thank You. —Preceding unsigned comment added by Fleanorradbeast (talk • contribs) 22:13, 19 August 2010 (UTC)

Yes, and it is called an ephimerides calculation. You can also find our List of observatory software useful - such software already has the formulae, plus corrections for minor details like Earth wobble, and usually have large built-in databases of stars, planets, and deep-sky objects. Nimur (talk) 22:53, 19 August 2010 (UTC)

Here are several source-codes, mostly in the C language (but you can easily translate the calculations to Excel, if you prefer that tool). The equations can get fairly messy if you want to be very accurate, and the result is complicated mathematical software. If you don't much care about accuracy, you can make dramatically simplifying assumptions; the relevant article is Equatorial coordinate system. Nimur (talk) 21:08, 20 August 2010 (UTC)

Cats and dogs

You always here about cats' good eyesight and dogs' good hearing and sense of smell. How are a cat's hearing and sense of smell? 76.230.224.114 (talk) 23:47, 19 August 2010 (UTC)

We actually have an article on this: Cat senses. It's of note that it's not really fair to compare any other senses of smell to a dog's. Dogs have an amazingly good sense of smell — it's really what they bring to the table, in terms of animal specialties, sort of like what cognition is for human beings. --Mr.98 (talk) 23:58, 19 August 2010 (UTC)

As humans, perhaps we single out the dog's sense of smell rather than other animals because early man's attempts to domesticate the bear were fraught with difficulties on account of them eating all of the food, some of the children and the dogs. :) Sean.hoyland - talk 06:45, 20 August 2010 (UTC)

Canine sense of smell isn't really all that remarkable in the animal kingdom. If you consider the molecular genetics, most rodents—certainly mice and rats—can probably smell better (in that that have a greater olfactory receptor repertoire). Plenty of other terresterial, non-primate mammals can probably smell just as well as dogs. However, what dogs "bring to the table" is their obedience and ability to be trained for olfactory tasks. A mouse can discriminate between odors at a incredibly small concentrations, a threshold of between 0.001 ppm and 0.0001 ppm, but you're are not going to have much luck using it to search for people trapped in a collapsed building. Rockpocket 12:57, 20 August 2010 (UTC)

That and vultures were too heavy to nicely sit on ones shoulder. Googlemeister (talk) 12:59, 20 August 2010 (UTC)

The male silkworm moth is even better, being able to detect single molecules of bombykol - [15]. Smartse (talk) 10:12, 21 August 2010 (UTC)

Wow i guess wikipedia does have an article on everything ;) Does this change between domestic cats and wild felidae (ie pumas lions tigers leopards etc) 76.230.224.114 (talk) 00:54, 20 August 2010 (UTC)

This is a little bit interesting — about dogs sniffing out bedbugs. Bus stop (talk) 14:55, 20 August 2010 (UTC)

August 20

Car antenna

A mechanical question: I recently purchased a 2001 Ford car, and the antenna on it is very short. I've found the radio reception to be tenable but overall very poor. How can I go about upgrading my antenna? Or is it the antenna at all that needs the upgrade? I am not at all familiar with either radio or car radio technologies, so apologies if my question is off base. Magog the Ogre (talk) 00:01, 20 August 2010 (UTC)

The visible part might not be the entire antenna, and there is more to good reception than just the antenna - but it certainly helps. The first thing I would do is find a forum with other people who have the same car and see how their reception is. That can help you distinguish a bad design from a problem of some kind. And BTW how short is short? Ariel. (talk) 01:18, 20 August 2010 (UTC)

About a foot on the exterior. It's a 2001 Ford Echo, there aren't a lot of those around anymore. Magog the Ogre (talk) 03:09, 20 August 2010 (UTC)

Interesting. We normally have an article (or redirect) for every model of car but I can't seem to find one for the Ford Echo. What is it called elsewhere from where you live? By the way, my Subaru Forester has a stubby antenna as well and while it's not bad, I have noticed that the reception is slightly less than other vehicles that I've had. Dismas|^(talk) 03:36, 20 August 2010 (UTC)

I've also noticed that my recent cars with short antennas have poorer reception. Presumably car manufacturers don't consider drivers who live in areas of poor reception. I haven't tried replacing the antenna. Can one still obtain old-style aerials? Dbfirs 07:24, 20 August 2010 (UTC)

Dear goodness I'm an idiot, it's a Toyota Echo. Magog the Ogre (talk) 07:28, 20 August 2010 (UTC)

I doubt you'll improve matters much by changing the antenna - and indeed length isn't everything. Antenna design is an arcane and horribly complicated business. I switched out the foot-long bendy antenna on my MINI Cooper'S convertible for a stiff four inch 'billet aluminium' antenna (because that car has the antenna mounted just above the windshield in the center - and the bending and bouncing of the thing distracted the heck out of me when the roof was down). I expected worse reception - but in fact, there was no difference at all...I know this because I regularly to the same 180 mile freeway trip and I have to tune to a different radio station roughly halfway there...so I know exactly where the FM reception starts dropping out - and it didn't change measurably with the shorter antenna.

If your reception is substantially worse than many other cars in your area then it may be that the antenna connection is faulty - either at the radio end - or at the antenna end - or possibly as the wire goes through some hole in the bodywork.

SteveBaker (talk) 12:37, 20 August 2010 (UTC)

Given the age of the car I would check the antenna route for bad connections or broken insulation.

ALR (talk) 12:43, 20 August 2010 (UTC)

Electronic front-end amplifier design is so complex nowadays that the (external) antenna may actually be irrelevant to the final signal quality (even in things like FM radios- but especially in things like iPods that operate at much shorter wavelengths - despite recent media hype). In any case: for your car question, I vote "no" on a mechanical antenna solution, "yes" on an electronics replacement. The quarter wave antenna for a dipole whip at 100 MHz (FM radio) is about 75 cm; so a good, long antenna wire should "theoretically" make a big difference. But as described in this 2007 EE Times article, modern AM/FM mmics are so good, your "antenna" is probably the wire-lead between the circuit edge and the chip! (Anything sticking out of the car is just for show!) The MAX2180 automotive AM/FM LNA seems to be a pretty standard model in cars these days - it's a low noise pre-amp that gives 30dB of gain with built-in gain control. If your loudspeaker-amplifier even knows it's connected to an antenna, I'd be surprised! So, as the end-user: you might consider upgrading to an after-market stereo - this will replace the AM/FM radio component as well - and pick out one that has a reputation for good FM reception (i.e. uses good quality tuner and amplifier circuits). That will make a much bigger difference than changing the physical antenna-wire. Nimur (talk) 20:50, 20 August 2010 (UTC)

Thanks for the advice, Nimur; you advise a complete upgrade of the radio? I looked and I'm using the Toyota a56814 that came with the car; does your advice remain the same? Magog the Ogre (talk) 01:14, 21 August 2010 (UTC)

Well, it depends on how much you want to spend. You can probably buy a new antenna much cheaper than an aftermarket stereo; but you can buy replacement radios for as low as $50 or $100 (though theoretically, more expensive units will use better parts; in actual fact, many brands and models probably use the same ASIC on the front-end). Compare to a new antenna, which can be as low as ~ $10. Installation costs are where they'll get you, if you choose not to attempt the installation yourself. Here's a replacement parts for Toyota Echo models for comparison; it looks like if you buy a part specifically for an older Echo, the antenna is a little longer. I actually don't know how standard/non-standard these antennae are; there are parts specifically listed as "Toyota Echo Antennae" in a lot of these online catalogs, but I suspect they're the same parts as most other antennas. Nimur (talk) 05:19, 21 August 2010 (UTC)

Cats' whiskers...

Inspired by the above cat question and my subsequent reading of Cat senses... Is it actually true that the whiskers of domestic cats are usually as wide across (when measured across from one side to the other, tip to tip) as the widest point on the cat's body, in order that the cat may easily determine whether it will be able to fit through a space/hole by first attempting to place its head through? So, fat cats will have longer whiskers than skinny cats?

It's one of those 'everyone knows' factoids that you hear as a kid that I've never really thought much about until now. --Kurt Shaped Box (talk) 00:09, 20 August 2010 (UTC)

OR warning: After having had cats pretty much my entire life, I would say that it's false. Just looking at the cats that currently rule my house, they each can fit through much narrower places than their whiskers would have you believe. Dismas|^(talk) 00:30, 20 August 2010 (UTC)

Children can often use their ears for the same purpose. As one gets older, the proportions change! Some fat cats might have a similar problem. Dbfirs 07:08, 20 August 2010 (UTC)

It's my understanding, and I can't find a good source at the moment (sorry), is that they don't literally use them as a yes/no "Can I fit" check, but one of their uses is to help judge near-face distances while crawling through close spaces. As you might imagine they rely on them much more in total darkness than in the light. APL (talk) 14:37, 20 August 2010 (UTC)

Web Bot predicting the future

How exactly does web bot predict the future? According to the article it searches the internet for words and phrases. But surely that just means it reports what everyone is talking about, rather than predicting the future?--92.251.179.48 (talk) 01:23, 20 August 2010 (UTC)

It doesn't. It's fiction. I doubt they even have a search spider at all. In fact I bet they don't - if they do what is the user agent of the bot? Ariel. (talk) 01:35, 20 August 2010 (UTC)

Reading the article suggests to me the owners follow the typical behaviour of people that claim to predict the future in some way. Make very vague claims and then fit whatever happens (the more major the better) to your vague claims (alternatively put out a bunch of nonsense and then find some way that you can get something to support a major event in said nonsense). When you really can't either ignore it or just say you were wrong for some reason. I find it funny how the Columbia Shuttle Disaster is a 'maritime disaster' (and they ignored real maritimes disasters). Anyway my predictions for next month are 'airplane, meow, iraq, dollar, natural disaster, iran, people, un, many deaths, tiger, disease'

Oh snap "From July 11, 2010 onward, civil unrest will take place, possibly driven by food prices skyrocketing, and the devaluation of the dollar". Maybe they got a little too worried by teapartiers?

Nil Einne (talk) 01:54, 20 August 2010 (UTC)

Has anyone ever observed their web-bot in action? If you run a web page it's easy to spot most web spiders in your log. If their claims are true they ought to be one of the web's most common spiders, on par with the Google bot. APL (talk) 14:28, 20 August 2010 (UTC)

If it's ever shown up on my webserver, it's never hit more than two or three pages per month. My server sees a very low level of human traffic, so web bots stick out like a sore thumb. --Carnildo (talk) 01:54, 21 August 2010 (UTC)

A similar "Delphi" function, polling the opinions of a large number of actually uninformed people and arriving at actually meaningful odds of future developments, (and also soliciting pooled advice for personal problems) is depicted in John Brunner's pre-web 1975 SF novel The Shockwave Rider, which I happen to be currently re-reading. Perhaps that's where the idea came from. (87.81 posting from . . .) 87.82.229.195 (talk) 14:01, 20 August 2010 (UTC)

Mathematical computation, Symbol, Electrical check on circuit board

Mathematical computation symbol for counting the number of pin to pin checks on a circuit board needed to be done without duplicating already checked pins. For instance; I have 1000 pins to do an ohms check on. I check from pin 1 to pin 2, then 1 to 3, then 1 to 4 … and so on until 1 to 1000. That was 999 different checks. Now I have to check from 2 to 3, then 2 to 4 … and so on until 2 to 1000. That was another 998 different checks. Then on to pin 3, then 4, then all the way to pin 999 to pin 1000.

I have already figured out the answer for what I need in Excel, but there has to be an equation for this problem without using excel at all, I just can’t seem to find it.

Now for the real question AFTER the equation…What is the ‘name of this equation’ and if it has a symbol ‘what is it’ and ‘what is the name of the symbol’?

Much appreciated and thank you for your time. v/r cg 65.28.249.47 (talk) 01:48, 20 August 2010 (UTC)

It sounds like you want to read the combinatorics article. The mathematical notation for calculating "all possible combinations" are binomial coefficients - commonly referred to as "n choose k" or "choose" functions. Nimur (talk) 01:56, 20 August 2010 (UTC)

It's probably Summation, and it's this symbol: Σ. Ariel. (talk) 01:57, 20 August 2010 (UTC)

It's a special case of a mathematical series, and a well known one (because it's really easy to prove the result). Let's say you have (N+1) pins to check, and S (for sum) is the number of checks you have to do; the series is given by

$S=\sum _{n=0}^{N}(N-n)$ :

if N is an even number,

$S={\frac {N}{2}}(N+1)$ ;

if N is an odd number,

$S={\frac {(N-1)}{2}}(N+1)+{\frac {(N+1)}{2}}$ .

The proof is left as an exercise for the readers ;) Physchim62 (talk) 02:27, 20 August 2010 (UTC)

For the practical application, be careful that I said there are (N+1) pins, that is N spaces: this gives the equations in a form that you should find them in any decent high-school algebra textbook. Physchim62 (talk) 02:44, 20 August 2010 (UTC)

The symbol for this is ${\binom {n}{k}}$, by the way. Looie496 (talk) 03:08, 20 August 2010 (UTC)

Specifically ${\binom {n}{2}}$ (read n choose 2) for n pins. ${\binom {n}{2}}={\frac {n!}{(n-2)!2!}}={\frac {n(n-1)}{2}}$ for n either odd or even. Note that Physchim62's two formulas above for S with even and odd N (with N+1 pins) are equivalent to each other. The traditional visualization is to do the pairing suggested by SteveBaker, but to overcount and then divide by 2, obviating the need to worry about a lone middle pin. -- 115.67.45.89 (talk) 13:08, 20 August 2010 (UTC)

The easy way to think about this is as follows: For the first pin, you have to do 999 checks 1-2, 1-3, ...1-1000. For the second pin, you only have to do 998 checks and for the third, 997...and so on until the second to last pin where you only have to do one check (999-1000) and the last pin for which you have nothing to do. Now, here is the clever twist: if you add the number of checks you have to do for the first pin (999) to the number you have to do for the last pin (0) - then you get 999. If you add the number of checks for the second pin (998) to the number for the second-to-last (1) then you get 999. Add the third to the third-last and you get 999 again...all the way up to pin 500 (500 checks) and pin 501 (499 checks). You can imagine this process as writing down the number of checks for each pin on a long sheet of paper - then folding the paper in half so that each number is match with it's opposite. Every one of those pairs adds up to 999. Do this 500 times and you get 500 pin pairs x 999 checks for each pair = 499,500 checks.

You have to be careful about cases where there are an odd number of pins to check because there is then one pin in the middle with no buddy on the other side!

SteveBaker (talk) 12:20, 20 August 2010 (UTC)

Cooking wine?

Why do people use cooking wine if the alcohol evaporates in a few minutes? Would it dissolve some unpleasant flavors from food and leave them in the food as it without changing anything? Many commercial cooking wines are salted. Isn't it going to make cooking even more difficult? -- Toytoy (talk) 04:01, 20 August 2010 (UTC)

For the flavor of the wine. Wine has a lot of flavor which isn't due to the alcohol, which typically only makes up about %16 of the wine. Vespine (talk) 04:13, 20 August 2010 (UTC)

Also, the alcohol does not cook out completely. This is a fallacy sadly spread by some cooking shows (but not all, see Good Eats for one that gets it right). Ethanol and water form an Azeotrope, which basically means that you cannot completely seperate a mixture of ethanol and water by heating alone. When you cook with alcohol much of the alcohol cooks off, but a small amount does not. This alcohol can act as a solvent which will dissolve certain flavor components from foods that water by itself does not; which is part of the reason why cooking with wine or brandy causes a different flavor profile than cooking with, say, grape juice would. There are compounds in foods which are more soluble in ethanol than in water, and thus the small amounts of alcohol that are left in the dish after cooking actually bring these flavors to your taste buds in ways that water by itself does not. It should be noted that this is still a pretty small (but not zero) amount of alcohol left in the food; most people should be safe, but if you have any concerns (small children, people with religious objections or health concerns) then you should leave the alcohol out of the recipe because it never cooks out 100%. --Jayron32 04:22, 20 August 2010 (UTC)

Quibble about azeotropes: it means you cannot separate an alcohol/water mixture that is at the azeotropic ratio and you cannot boil off anything except that if both alcohol and water are present (i.e., distill out just the alcohol, leaving the water). But you certainly can "remove the azeotropic mixture until there is none of one component left"--the whole topic deals primarily with what's vaporizing, not so much whatever else may be in the pot. You can (assuming ideal conditions, etc etc) evaporate (nearly) all of the alcohol from the wine, you just also lose a little water in the process too. DMacks (talk) 14:40, 20 August 2010 (UTC)

Sure, there are traces of alcohol that can be detected with sufficiently sensitive equipment. But listing small children as a concern??? That's just silly. There's not enough left to worry about from that point of view. I have never heard of a health condition (in the ordinary sense of the word) that would be sensitive to it either, though I haven't heard of all possible health conditions. I think only the religious objections would really hold water, or possibly you'd want to avoid it for some recovering alcoholics, not because they would notice any actual neurological effect but simply because it might trigger problematic memories. --Trovatore (talk) 20:25, 20 August 2010 (UTC)

Yes I know that there will be a little residual alcohol in the gravy. How does it differ from adding just a little diluted wine+juice after cooking is done? I think it is a waste to let most of the alcohol vaporize. -- Toytoy (talk) 05:52, 20 August 2010 (UTC)

There's a lot of complex things going on in cooking. Two important elements in cooking are heat and time. With any recipe, screwing with these can mess up a dish drastically. Its not just the alcohol in the dish, its the alcohol being present during the cooking process which produces the desired flavor profile the alcohol is producing. While most of the alcohol will cook out, the stuff that does remain needs to be present during the entire cooking process to do what it needs to do to affect the flavor of the dish in the way that you want it to. In other words, adding a cup of wine to a dish before cooking will NOT yeild the same results as adding a few drops of wine after you are done cooking. The alcohol needs to be present during the cooking process itself. It is not only evaporating. On the way towards evaporation, it is also doing other stuff, which is desirable. --Jayron32 05:58, 20 August 2010 (UTC)

One doesn't drink wine merely for the alcohol.

ALR (talk) 09:00, 20 August 2010 (UTC)

You can always position your head above the pan and breath in the vapours if you don't want the alcohol to go to waste. Something no one has mentioned yet is that esterification will occur if you add alcohol to a dish and heat it, producing more flavour compounds. Smartse (talk) 10:24, 21 August 2010 (UTC)

The Universe

Is the universe infinite or finite? How do we know this? —Preceding unsigned comment added by 67.149.29.45 (talk) 04:51, 20 August 2010 (UTC)

It could be either, and we don't. See Shape of the Universe for some discussions over various hypotheses which are in their own ways consistant with existing theories and models. --Jayron32 05:21, 20 August 2010 (UTC)

I'm a Galactic Zookeeper. What are the conditions of my human habitat?

I'm curious if there is any scientific consensus about what constitutes "ideal environmental conditions for human life" ? For a start, I figure my human habitat must have the standard day/night cycle. But do the lengths of the days need to change? Would I need to include equinoxes? How about air pressure? Would my humans be more productive at slightly more than 1 atmosphere? Temperature seems easier - hovering around 80F would allow them to pretty much be naked all the time, right? 218.25.32.210 (talk) 04:53, 20 August 2010 (UTC)

You could ask Billy Pilgrim and Montana Wildhack about their stay on Tralfamadore. --Jayron32 05:15, 20 August 2010 (UTC)

Humans are very adaptable and can handle a wide variety of habitats, and conversely humans vary a lot and like a wide variety of habitats. So there is no single ideal. To your specific questions: you do not need to vary the day length, except your humans might get bored. Humans like to be able to control the light at will, so please provide some method of local light control. A higher air pressure will increase stamina to some degree. Humans like to cover themselves while sleeping, and 80 degrees is a bit hot for that, so it would be good to vary the day/night temperature. For the infants of the species 80 degrees is too cold for no clothing. Ariel. (talk) 05:27, 20 August 2010 (UTC)

One question that comes to mind is whether humans in any truly constant environment will be damaged by long-term breeding. Logically, humans possess a considerable genetic diversity, but if maintained under truly homogeneous conditions, some genes are good and others bad, even though in nature they were each best suited to a certain niche. As a result, I think genetic diversity should be lost within tens to tens of thousands of generations. The resulting humans may seem as well suited to the zoo environment (better, no doubt), but they would not thrive on Earth. (I'm not sure precisely how to source this, though certain "lab strains" of bacteria come to mind - nobody on Earth has such long-term data for long-lived vertebrates) Wnt (talk) 13:55, 20 August 2010 (UTC)

Were you planning on your humans being born in the zoo, or were they going to be "wild caught"? I suspect you will have a ton of problems with the humans that previously were not in your zoo since most humans would resist. And humans are quite clever, so it might be very expensive to hold them in a natural appearing environment. Googlemeister (talk) 14:50, 20 August 2010 (UTC)

Don't worry, humans have already figured out a number of clever ways to keep even clever, desperate humans locked up with reasonable success. --Mr.98 (talk) 16:26, 20 August 2010 (UTC)

Certainly, but a prison in no way mimics a human's natural habitat. Googlemeister (talk) 16:44, 20 August 2010 (UTC)

I wouldn't expect an intelligent alien species to have that much trouble confining a group of humans to a zoo habitat. It's not like in John Campbell stories, where humans always turn out to be much better than all other possible aliens. Particularly given these are aliens with the means to take the humans and bring them to the galactic zoo in the first place, so they obviously are more technologically advanced than us in some ways. And, unlike a prison, the zookeepers aren't too worried about maintaining contact between the captured humans and their friends and family outside, or about preparing the captured humans to be released into the wild. The problem would be more likely to involve keeping the humans relatively happy and healthy, a necessary task for a good zoo. The danger of them going on hunger strike, or settling into depression, will be difficult to avoid. I would suggest a large enclosure with at least 10 genetically-diverse humans, set up so that each has a private enclosed space that they can choose to retreat to or exit whenever they want (you'll want to put one-way mirrors, or similar, in these so that you can observe them). This gives the humans some choice over their surroundings and the company they keep, and should also reduce genetic problems for the next few generations. If keeping the population per enclosure low, and keeping your humans for more than a few generations, you will need to allow mixing with other human populations, possibly from another enclosure. I think allowing the humans to breed will probably help with some of the issues. 86.161.255.213 (talk) 18:29, 20 August 2010 (UTC)

Technological superiority and breaking all contact with friends and family works really well. See e.g. Haitian Revolution. --Stephan Schulz (talk) 18:56, 20 August 2010 (UTC)

Ah, but again that didn't involve sealing humans off from the outside: they were interacting with their captors, and they were also enduring appalling conditions. The death rate was higher than the birthrate. It would be an extremely bad idea for the keepers to enter the humans' enclosure when the humans were conscious, certainly, and keeping them in anything close to the conditions slaves experienced in Haiti would be a recipe for disaster for a zookeeper. The humans in the zoo aren't going to have any outside contacts to bring them information or equipment, they aren't going to have access to any of the keepers or anything the keepers care about (except themselves, which is why a hunger strike is a real threat). If prisons weren't trying to be humane or lower reoffending rates, but simply contain people, they would have much easier jobs. Much less useful jobs, but easier. And a zoo only tries to recreate a habitat to a point: a large (building-sized) cell with appropriate set-dressing would be fairly easy to secure. 86.161.255.213 (talk) 19:40, 20 August 2010 (UTC)

If they're captured humans, with their own control over the temp, that 80 degrees will be nonsense to the vast majority. Best you learn about the metric measurement system used by most of them. HiLo48 (talk) 18:20, 20 August 2010 (UTC)

I'm sure the humans will be smart enough to figure out what it means. Temperature units were not given by god, C is not better than F in any way. K might be, but C is not. Ariel. (talk) 18:50, 20 August 2010 (UTC)

There are quite a number of companies which are happy to supply Christians, per Google: [16]. It is harder to find companies which supply adherents of other religions or of no religion. Edison (talk) 20:37, 20 August 2010 (UTC)

For humans living on earth closish to sea level that's questionable. Given how important water is, a temperature scale where water freezes at roughly 0 degrees C and boils at roughly 100 degrees C makes more sense where then one where zero is set at the value which happened to be the lowest the person designing it could come up with Nil Einne (talk) 21:43, 20 August 2010 (UTC)

My point about metric was simply one about what 95% of humans are most familiar with. HiLo48 (talk) 21:52, 20 August 2010 (UTC)

While I understood your point your specific claim '95% of humans are most familiar with' is questionable as well. A significant proportion of humans are almost definitely not familiar with either. If you can't read or write and need to struggle to survive, understanding or being familiar with temperature scales isn't likely to be the most important of things Nil Einne (talk) 22:03, 20 August 2010 (UTC)

Just mark one end of the temperature control blue and the other red. Also make sure that neither extreme is immediately fatal. Problem solved. APL (talk) 22:34, 20 August 2010 (UTC)

Is the blue cold or hot? Why not say black and white? Nil Einne (talk) 09:34, 21 August 2010 (UTC)

Red is hot because it is the color of fire, hot metal, etc. Blue is cold because it's on the other end of the scale.

Of course, captive-born humans might not have experience with fire or hot metal, but they would have grown up with the temperature knobs, so that would just work itself out. APL (talk) 00:45, 22 August 2010 (UTC)

Why do humans cover themselves when they sleep?

My humans are covering themselves when they sleep even if I give them total control over the temperature (so they can't be doing this because they're just cold) and total security. Why do they keep doing this? It makes them harder to observe as they sleep. 92.230.69.80 (talk) 08:19, 20 August 2010 (UTC)

Your humans? You're observing them? What are you running there - some nightmarish laboratory with human guinea pigs? -- Jack of Oz ... speak! ... 10:43, 20 August 2010 (UTC)

You're not AM, are you? As in "I Have No Blanket, and I Must Sleep"? Clarityfiend (talk) 10:46, 20 August 2010 (UTC)

I think it's the OP from the thread above. I've smallified the sub-heading for clarity. Ghmyrtle (talk) 10:58, 20 August 2010 (UTC)

No, this OP has only made two edits. The IP address bears no similarity to the IP address of the OP in the thread above. I assumed this OP might be running a sleep clinic. Dolphin (t) 11:28, 20 August 2010 (UTC)

That would be a remarkable coincidence, given the last comment in the previous thread. I agree they are not the same person - but are they playing the same game or something? Or just trolling? Ghmyrtle (talk) 12:26, 20 August 2010 (UTC)

I think we might be over-analyzing the situation here. The OP's first title says "Galactic Zookeeper" which to my knowledge is not an actual job description ;) and they seem to be asking questions "in character". --- Medical geneticist (talk) 12:53, 20 August 2010 (UTC)

Dr. Moreau? Darigan (talk) 12:36, 20 August 2010 (UTC)

"I assumed this OP might be running a sleep clinic" - what a spectacular assumption of good faith!!! In actuality, I just read the above question and decided to add one of my own... 84.153.204.126 (talk) 15:41, 20 August 2010 (UTC)

He's just asking hte question in an interesting way, no need to go so crazy.--178.167.163.66 (talk) 22:45, 20 August 2010 (UTC)

Whatever it is you are doing, it must be force of habit. Unless you've raised them from birth without blankets, they will be used to having them; without, and they would feel wrong. - Jarry1250 ^{[Humorous? Discuss.]} 13:07, 20 August 2010 (UTC)

Some humans like to sleep with their heads colder than the rest of their bodies, possibly as a result of using blankets for sleeping since birth. In addition, blankets reduce heat loss from convection and breezes, which cannot be replicated by simply increasing the air temperature, as well as offering some sense of protection from crawling insects, which are common in most natural human habitats. In the behaviour of young humans, hiding under the blankets when afraid, you can also see evidence of the use of blankets as camoflage, hiding the humans from predators when they are most vulnerable. Most humans will feel as uneasy sleeping without a blanket as most rodents feel sleeping in the open. Personally, I think you should be using this as an example of their natural behaviour, and bring it to visitors' attention. You could always produce some sort of soft, warm, but transparent blanket, although I suspect they will still feel uneasy, especially the young. 86.161.255.213 (talk) 15:18, 20 August 2010 (UTC)

I think it is an excellent question the OP poses. (My humans do this too.) Bus stop (talk) 15:43, 20 August 2010 (UTC)

There may be greater heat produced by the head while sleeping than the rest of the body. The head is likely to sweat at a lower temperature than the rest of the body, in general. The greatest overall comfort may thus result from a sheet over the body and the head uncovered, even when the person has control of the thermostat. Edison (talk) 15:47, 20 August 2010 (UTC)

yeah, core body temperature drops during sleep. it would be natural to cover up to prevent further loss of body heat. Not to discount the psychological aspects, of course, which are probably also significant

By the way, anyone know where I can get some humans of my own? I checked eBay, but no luck so far... --Ludwigs2 17:23, 20 August 2010 (UTC)

Have you tried your local orphanage? Googlemeister (talk) 19:32, 20 August 2010 (UTC)

There are also "do-it-yourself" kits if you want to make them from scratch. Nimur (talk) 20:06, 20 August 2010 (UTC)

Make sure you buy the equipment outright; soliciting for rental is illegal in many jurisdictions. Matt Deres (talk) 20:36, 20 August 2010 (UTC)

The do-it-yourself kit is fun, but with a wait time measured in months at a minimum, if you want fast results, that is not the way to go. Googlemeister (talk) 20:44, 20 August 2010 (UTC)

Outright purchase of the equipment is also illegal in many jurisdiction, so you might just have to borrow it. Physchim62 (talk) 20:56, 20 August 2010 (UTC)

LOL. *Ahem* This is merely a habit. Many individuals in western cultures enjoy sleeping in the nude in warm weather, and doing so is the mode in other cultures including many if not most aboriginals without textiles. Even warm areas with mosquitos or other biting insects will naturally lead to a preference for sheets. Ginger Conspiracy (talk) 00:51, 21 August 2010 (UTC)

Speaking only for myself, I have difficulty sleeping well when the air is warm enough that I don't need covers. Somehow cool air produces deeper and more restful sleep. Looie496 (talk) 01:08, 21 August 2010 (UTC)

Bad dentist?

Why is it that most dentists almost never prescribe drugs like prevident toothpaste, prevident mouthwash, MI paste, and other similar ones? I was reading that its even possible to re-mineralize small cavities with these drugs. Do most dentists just want to drill them and make money? Rather than help you fix the small cavities and help prevent them in the future? I never heard of any of these until my pharmacist friend told me about it, none of my other friends have heard of this stuff from their dentists too. —Preceding unsigned comment added by 76.169.33.234 (talk) 08:59, 20 August 2010 (UTC)

In the UK my dentist recommends fluoride toothpastes and mouthwashes every time I see him, and has described the benefits of re-mineralisation to me. Gandalf61 (talk) 10:04, 20 August 2010 (UTC)

I suspect practice varies according to whether (in the UK) one can/is willing to agree to and pay for private treatment or can/will not go beyond NHS provision (most dentists treating under the NHS offer additional private treatment). Although I've been at the same practice for some 15 years, my most recent dentist there has been very reluctant to carry out any (currently free-to-me) NHS-only treatments, even including scale-and-polishing, filling new cavities and replacing those that have fallen out (often after only a couple of months) but often tries to persuade me to pay for unaffordable-to-me (and doubtless more lucrative to him) private crowns, etc. I am tempted to suspect that preventative treatments might cut down on his potential earnings. I'm also suspicious that when I do have a checkup and/or NHS treatment, I'm always asked to sign a blank NHS form with the actual treatment not yet filled in. (87.81 posting from . . .) 87.82.229.195 (talk) 13:45, 20 August 2010 (UTC)

Any chance of looking for another NHS dentist in your area, or even another at the practice? Personally, I never sign anything with blank spaces that will be filled in: that's just a bad idea. What do they say if you refuse to sign it before it's filled in, and draw a line through the rest of the space? Every Primary Care Trust should have a complaints procedure easily accessible, like this one. Alternatively, your local Citizens Advice Bureau can offer help navigating the systems and services in place to try to improve your care. What you are experiencing is not normal, and you don't have to take it. 86.161.255.213 (talk) 14:59, 20 August 2010 (UTC)

I do hear what you say , but NHS dentists are thin on the ground around here (as in most of the UK), and I was previously dubiously bumped out of a nearby practice that wanted to go fully private. I agree that signing blank forms is a bad idea and ordinarily I avoid it, but making an issue of it in this instance (which is an interaction with the Practice admin staff, and in my experience is a widespread dentistry habit) seems potentially more trouble than it's worth, as I could be left without a dentist at all - at least now I can get some treatments when I bother to put my foot down. I know I should try to do something more about the situation, but currently I have more pressing worries and, frankly, I'm indolent where my own affairs are concerned :-). —Preceding unsigned comment added by 87.81.230.195 (talk) 20:16, 20 August 2010 (UTC)

Remineralization isn't a very well studied realm of tooth physiology and there are so many variables that research results don't hold much weight in real life. Many aspects of operative dentistry are applied empirically. Most dental literature is related to periodontics and then there's some pedodontic literature as well. That being said, once the surface contour of the proximal surface of a tooth has cavitated (broken inward), all hopes for remineralization are gone. You can ask your dentist to show you the radiographic different between cavitated and non-cavitated lesions. DRosenbach ^{(Talk | Contribs)} 18:22, 20 August 2010 (UTC)

According to the toothpaste article, toothpastes in the UK have more flouride in them than those in the US, and its difficult to find a toothpaste without flouride, so recommending extra flouride may not be necessary. 92.15.3.131 (talk) 20:23, 20 August 2010 (UTC)

Niggly pedantic correction: it's fluoride, not flouride :-) 87.81.230.195 (talk) 09:25, 21 August 2010 (UTC)

Reminding people to brush after meals and floss regularly is so much more important, and meets with so much resistance among people ashamed of themselves for not following that advice, I suspect much of it has to do with the fact that dentists and their assistants can become socially exhausted just trying to convey those basics and performing delicate, tedious, and stressful dental work may not leave them much psychological energy to discuss the details of the latest experimental home treatments. Consult reviews on Pubmed before a visit so you can talk with your dentist and hygienist intelligently on the subject. Ginger Conspiracy (talk) 00:24, 21 August 2010 (UTC)

Nootropics, Ampakines

Hello clever people, can someone here guide me to some good reading about Nootropics/Ampakines, Wikipedia's article is a bit small, I would like to know more info about this topic, specially about their syntesis, but not only, i googled it but didnt find good sites on the web. TY muchDSTiamat (talk) 09:40, 20 August 2010 (UTC) —Preceding unsigned comment added by DSTiamat (talk • contribs) 09:39, 20 August 2010 (UTC)

There are a large number of ampakines described here. Could you be more specific about which synthesis interests you? It's not hard to run down some syntheses.[17] Wnt (talk) 13:41, 20 August 2010 (UTC)

While Wikipedia can't give you medical advice (positive or negative), I think you may find AMPA receptor and especially excitotoxicity to be interesting reading. Wnt (talk) 14:00, 20 August 2010 (UTC)

CX-717 synthesis, CX-7139 would interest me, they dont look that complicated. TY DSTiamat (talk) 18:35, 20 August 2010 (UTC)

Maybe this will be helpful. Ariel. (talk) 19:43, 20 August 2010 (UTC)

Patents on secret compounds?

Alright, now I'm pissed. According to the Wikipedia article CX717 and borne out by at least early sources, somehow Cortex Pharmaceuticals has kept the actual structure of CX717 secret - while patenting it and referencing it extensively in several patent applications! [18] I thought one of the very few redeeming qualities of the patent system was that you couldn't patent a trade secret - that you had to publish what you did. If they (or some affiliate) go back in 2020 and patent another compound, how do we know it isn't the exact same thing? If someone else tries to patent something, how does he know it isn't already invented? Then there's the part about scientific journals publishing experiments on this unknowable substance, and the FDA approving tests on it, and no one knows what it is, nor has any way to do research on it without company authorization.

Does anyone know what brilliant legal innovation allowed this to happen? Should we expect that discussion in a scientific paper about any future drug will say no more than "This is Good Stuff^TM. The Company says it is Safe", and move on? Wnt (talk) 20:09, 20 August 2010 (UTC)

That patent you reference appears to be for a method of doing something rather then a specific substance. Cortex is likely to have the rights to any substance which does what's covered in that patent be it CX717 or something with a completely different structure. If someone developed CX717 and uses it for something not covered in that patent then that patent you mention would be irrelevant. Nil Einne (talk) 21:12, 20 August 2010 (UTC)

In theory it is like having a patent that says, "I have patented a use for Coca-Cola as a means of curing cancer" (or washing the baseboards, or attracting ants, or whatever). You don't have to disclose what the formula for Coca-Cola is (or even know!) to get a patent like that. Presumably you could also do tests to see whether Coca-Cola was safe to consume, or cured some disease, without knowing exactly what it was made out of. I do agree that the FDA approving things that it doesn't know the formula for sounds a little dodgy, though they may have some means of disclosing it in such circumstances. (They do have a policy on protecting trade secrets.) --Mr.98 (talk) 23:10, 20 August 2010 (UTC)

I don't find this persuasive. As I understand it, patents were supposed to allow "one skilled in the art" to duplicate the procedure, not "one associated with the parent company". Every other time I've looked at a patent, I've gotten to the compound in question. But why would any company have revealed such information if they're not required to? Admittedly, I'm not an expert in patent law, but something here smells.

However, on consideration, the application does give formulae for two compounds, without, so far as I could tell, saying whether either is CX717. I wonder if they are pulling a smaller fast one here - publishing the formula to claim the patent, but not admitting that they did so? Wnt (talk) 14:34, 21 August 2010 (UTC)

Is there any kind of claim as to the formulae given? If someone comes up with a substance that just happens to be the same, I would guess that it could be patented as the patent office will not be able to tell that it was already covered. The suggestion is that DARPA has suppressed it. Because of a lack of jurisdiction in other countries it could be patented elsewhere without the intervention of US government. The company is risking not having a patent on the substance, however it is possible that there can be no patent just on a substance, just on ways of making it or using it. DARPA may hold the IP rights to the substance. Graeme Bartlett (talk) 06:05, 22 August 2010 (UTC)

Dilute HCl

Is very dilute HCl toxic? Can it be used as a vinegar replacement? Does it taste bad? --Chemicalinterest (talk) 16:17, 20 August 2010 (UTC)

Your stomach acid is primarily HCl, so it certainly makes sense that at a similar level of dilution it wouldn't be toxic. On the other hand, swallowing it would put it into the same places that gastroesophageal reflux disease does, perhaps producing similar damage. And I think any statement beyond those points of fact would constitute medical advice, which is an area that we are not allowed to get into here. --Anonymous, 16:48 UTC, August 20/10.

It's not toxic - it's in your stomach acid. However, any acid drink can cause acid damage to tooth enamel if the pH is low enough. The cooking uses of vinegar are beyond my competence, but I should note that acetic acid in vinegar is a weak acid, meaning that vinegar placed into a recipe may have a higher pH than dilute HCl, but even so it will bring down the pH of the food to which it is added via a buffer (chemistry) much more effectively than the HCl would. Wnt (talk) 16:49, 20 August 2010 (UTC)

I mean very very very dilute HCl, where the pH is around 3. Not likely to give heartburn any more than soda. I don't want to try my own hydrochloric acid because it is contaminated with cobalt, copper, iron, manganese, nickel, chromium, lead, etc. ions from my sloppy experimenting. --Chemicalinterest (talk) 17:05, 20 August 2010 (UTC)

Yes, you can use it as a food additive – it is INS 507 on the Codex Alimentarius list as an "acidity regulator". I've never tasted it (and have no intention of trying!), but I would guess that you only get the "sharp" acid taste, rather than the fuller flavour you get from decent vinegars of the same pH. Physchim62 (talk) 18:22, 20 August 2010 (UTC)

I have, and your guess is correct! 87.81.230.195 (talk) 20:04, 20 August 2010 (UTC)

Odd calculation for Percent Daily Values figures

I recently acquired two containers of spices: both are produced by the same company, but the contents of the containers are slightly different. Among other things, a ¼-teaspoon serving of container 1 has 135mg of sodium, while a ¼-teaspoon serving of the container 2 has 110mg. What's odd, however, is the Percent Daily Values figure — I'm told that a serving of container 1 equals 6% of the PDV daily amount, while a serving of container 2 equals 7% of the PDV daily amount. Is this a simple mathematical error, or do the other contents somehow affect how much of the sodium is absorbed by the body? Nyttend (talk) 16:31, 20 August 2010 (UTC)

Incorrect labels would cost the company some fairly hefty fines from the FDA if they got caught at it, so companies are usually pretty careful about them. Still possible that it's an error, of course, but I'd start by looking to make sure the serving sizes are what you think - if container 2 has a larger serving size, that might account for the difference. it's unlikely that the contents of the spice affect the sodium absorption rates - sodium dissolves readily in water, so unless the spice is packages in little tiny latex balloons (what kind of spice is this, exactly?) you can be pretty sure that any salt in the spice will make it into the system. you might also check other wordings: for instance, if one of the spices uses sea salt instead of refined salt it may contain higher percentages of of other ions which reduce the actual sodium content but leave the salt PDV values higher. --Ludwigs2 17:16, 20 August 2010 (UTC)

As I said above, each container specifies that a serving is ¼ teaspoon. There are very few ingredients listed; the entire brand is based on a secret-recipe collection of spices. Container 1 specifies simply "salt" in its ingredients list, while Container 2 specifies three kinds of salt: potassium chloride, sodium chloride, and silicon dioxide. Nyttend (talk) 17:26, 20 August 2010 (UTC)

The brand is Tony Chachare's, by the way. Nyttend (talk) 17:27, 20 August 2010 (UTC)

It might be a case of UK vs US recommendations. In the US, the RDA is 2.4 g, while in the UK, it is 1.6 g. --Polaron | Talk 17:44, 20 August 2010 (UTC)

Hmm. Interesting suggestion — the calculations work out to a PDV of 2,250 mg for container 1 and 1571.42857142857142857... for container 2. However, it's a Louisiana-based brand, and the containers were bought in Louisiana, so I can't see why they would have British measurements included. Wouldn't the EU fine them bigtime for including a non-metric serving size, anyway? Nyttend (talk) 21:51, 20 August 2010 (UTC)

[unindent] All the numbers given are only quoted to the nearest whole number (excepting the rather imprecise ¼-teaspoons) so the difference between the resulting 6% and 7% could easily be due merely to rounding errors in the calculations. 87.81.230.195 (talk) 20:01, 20 August 2010 (UTC)

"¼ teaspoon" is a metric measurement, anyway, or at least based on SI, at least in the US, according to Title 21, section 101.9(b)(5)(viii): "A teaspoon means 5 milliliters". Marnanel (talk) 22:07, 20 August 2010 (UTC)

So, a nutritional-unit teaspoon is now a (slightly) different volume than a teaspoon in a recipe or cookbook. Nimur (talk) 22:12, 20 August 2010 (UTC)

Yes, but I vaguely remember reading of some EU bureaucrats trying to fine greengrocers for selling in customary units, so either the UK didn't legally define customary units in metric terms, or the bureaucrats don't care. Nyttend (talk) 01:49, 21 August 2010 (UTC)

I'd want I cite for that, as it's the sort of thing certain journalists perpetuate without factchecking. I've only seen reliable stories of the so-called metric martyrs, whose real crime is not putting the price in Imperial, but in not including a price in metric. I'm pretty sure you can sell by the teacup as long as you put the price in metric, with a way to measure the quantity in metric. 86.161.255.213 (talk) 02:32, 21 August 2010 (UTC)

The article suggests you do need to have the metric more prominent then other units although it's uncited. Of course it also mentions the case of someone who got in trouble for selling beer in litres instead of the required imperial units so it would be misleading to suggest it's only those who wish to use imperial units who suffer. Note that I'm not commenting on whether I agree or disagree with any of it Nil Einne (talk) 16:23, 21 August 2010 (UTC)

Well yes, there are standard units for different situations, but the point is I would be very surprised by anyone being taken to court for selling in teaspoons, as long as they defined the quantity in grams or mils as well. Why would a greengrocer be using teaspoons, anyway? Where 'customary units' differ from the defined legal units of the land, it has been illegal to sell only or primarily in those customary units for centuries, in the UK. Beer in glasses in pubs must be sold in units of pints, just as spirits in pubs must be sold in standard shot sizes, to prevent customers being swindled: the law could, instead, demand that beer be sold by the litre, but people generally don't want that, and actually care quite a lot. If you buy it by the bottle, you can buy and sell it in any size, and it will always have the quantity printed in metric units.. 86.161.255.213 (talk) 20:03, 21 August 2010 (UTC)

Origin of Life on Earth, compared to other planets

One of the theories states that amino acids may have been brought to Earth through comets and their impact with the earth caused these amino acids to form peptides which can eventually form into proteins correct? Well if this is true, shouldn't we expect to see peptides, and amino acids on other planets such as Mars, Venus or moons? Have we discovered such things? ScienceApe (talk) 17:38, 20 August 2010 (UTC)

They haven't been discovered yet, but the Moon is too arid, and the remaining water reserves on Mars have not yet been investigated. Dbfirs 19:19, 20 August 2010 (UTC)

Bear in mind that the conditions in the early Solar System, both on other planets, etc, and on the early Earth, were very different from what they are today, so it's dangerous to make assumptions about what could have occurred then based only on what conditions are like now, some 4 billion years later. 87.81.230.195 (talk) 19:56, 20 August 2010 (UTC)

Sarah Horst has determined that the atmosphere of Titan (moon) plus small amounts of oxgen results in amino acids and all five nucleotide bases. Let me see if I can find that reference. Ginger Conspiracy (talk) 19:29, 20 August 2010 (UTC)

This is one or another Urey Miller experiment in the lab or a calculation. There are experiments showing that UV radiation can change the material of comets to form amino acids. This all does not help at all. The rosetta mission to a comet will determin what the comet is made of, even amino acids can be determined by the GC-MS onboard. Although the viking experiments showed no organics on mars although the instruments were the best what you can built at that point of time there have been a few martian meteorites here on earth which contained amino acids. The MSL11 and ExoMars mission to mars will search for organic material and both are capable to determine amino acids so after these missions we will know more about mars. The Hyugens probe to Titan was not capable to determine amino acids or peptides so at that planet we will have to wait another 20 or 40 years. Venus might be the wrong place to look, because of the temperatures and the chemical composition of the atmosphere, which makes any organic material short lived. There is only limited knowledge and in a few decades an answer might be possible to your question, but up to now you only can read the hypothesis papers of a lot of astrobiologists.--Stone (talk) 21:32, 20 August 2010 (UTC)

This says that amino acids are found in interstellar gasses and in meteorites - that is not so surprising - after all, Miller-Urey shows that these are not exactly difficult chemicals to produce. What's most interesting about that is that these extra-terrestrial amino-acids are all left-handed - just the same as the ones found here on Earth. It's odd that there isn't a 50/50 mix of left and right handed versions. However, what's even more weird is that the Miller-Urey experiment - and other similar efforts at producing amino-acids from basic chemicals always produce a 50/50 mix of handedness. This is a rather deep mystery...exactly the opposite of what you'd expect! This is at least circumstantial evidence that life may have originated far away from the earth. SteveBaker (talk) 23:47, 20 August 2010 (UTC)

I think the new result from Sarah Horst's very recent Titan+O2 variant of the Miller–Urey experiment was production of all the DNA and RNA bases, beyond just the amino acids. I have asked for that citation and I will try to put it here as soon as I get it. I agree the chirality of the Martian amino acids is very profoundly interesting and provides evidence in the opposite direction, but these lines of inquiry are ongoing and we may learn more about chirality distributions as they continue. Ginger Conspiracy (talk) 23:59, 20 August 2010 (UTC)

Will atheists go to hell?

Note: You cannot answer questions? Only discuss improvements? That's what WT:RD is for! --Chemicalinterest (talk) 11:19, 22 August 2010 (UTC)

What percentage of them are rapists and murderers? What about sociopathy?12.40.220.253 (talk) 18:29, 20 August 2010 (UTC)

Probably less than 1% . The answer to your first question is not really a Science Desk question, and you will get different answers from different religions. Personally, I think that they will have the choice! Dbfirs 18:55, 20 August 2010 (UTC)

Not all religions believe in hell. Ariel. (talk) 19:03, 20 August 2010 (UTC)

From [19]:

But when it comes to more serious or violent crimes, such as murder, there is simply no evidence suggesting that atheist and secular people are more likely to commit such crimes than religious people. After all, America’s bulging prisons are not full of atheists; according to Golumbaski (1997), only 0.2 percent of prisoners in the USA are atheists – a major underrepresentation. If religion, prayer, or God-belief hindered criminal behavior, and secularity or atheism fostered lawlessness, we would expect to find the most religious nations having the lowest murder rates and the least religious nations having the highest. But we find just the opposite. Murder rates are actually lower in more secular nations and higher in more religious nations where belief in God is deep and widespread (Jensen 2006; Paul 2005; Fajnzylber et al. 2002; Fox and Levin 2000). And within America, the states with the highest murder rates tend to be highly religious, such as Louisiana and Alabama, but the states with the lowest murder rates tend to be among the least religious in the country, such as Vermont and Oregon (Ellison et al. 2003; Death Penalty Information Center, 2008). Furthermore, although there are some notable exceptions, rates of most violent crimes tend to be lower in the less religious states and higher in the most religious states (United States Census Bureau, 2006). Finally, of the top 50 safest cities in the world, nearly all are in relatively non-religious countries, and of the eight cities within the United States that make the safest-city list, nearly all are located in the least religious regions of the country (Mercer Survey, 2008).

Dragons flight (talk) 20:15, 20 August 2010 (UTC)

There is a legitimate question in the percentage of self-described atheists who make up various criminal populations. Unfortunately the data is rather muddied on this, and both the pro- and anti-atheist sites distribute some dodgy data. This page goes over a lot of the various data out there. Of note in particular is the importance of distinguishing between a self-defined "atheist" and someone who has "unknown/no answer" when asked about religious preferences. The data from the US Federal Bureau of Prisons, from 1997, indicates that only .2% of federal prison inmates self-identify as "atheists", as compared to 39% Catholics, 35% Protestants, 7% Muslim. The statistics get a little more dodgy when you consider prison conversion, though — some religions (in particular Islam, Nation of Islam, and Scientology) recruit quite heavily amongst prison populations, which is going to skew such things a bit.

There are other class issues that confound this as well. To self-identify as "atheist" or "agnostic" (rather than just saying, "I don't know" or "nothing" or "whatever I was raised with") requires generally some education, and studies have shown (I don't have them on hand, unfortunately) that, say, people who self-identify as "agnostics" and "atheists" tend to have higher levels of education. This is not necessarily because being educated makes you non-religious, at all. Some of this is simply a matter of knowing the vocabulary: "agnostic," for example, is not a word that people who have skipped out on school generally know, or have thought to identify themselves with. But in any case, if you have a class (and probably race) bias in terms of those who identify in this category, then that is obviously going to show up in prison percentages, which are also heavily skewed in class and racial directions.

As a side note, as an agnostic-atheist myself, I have always been completely dumbfounded by the sincerely-held belief by many religious adherents that without worship of God, people would just run around and kill and rape each other. There are two major flaws with this idea. First is that one needs God to have cultural ideas of morality. I certainly know "right" from "wrong" in a visceral way, not because I was taught to believe in a book (or divine punishment), but because I was raised with a heathy diet of ethical consideration and empathy for others. Second, we don't rely on God-based deterrence in any case in civil society. If belief in God was all it took to make people not be criminals, we wouldn't need an extensive police and penal system. Obviously relying on religion alone to deter crime has never worked, so why should anyone assume that religion is necessary to deter crime? --Mr.98 (talk) 20:16, 20 August 2010 (UTC)

One common argument given to explain the disproportionate number of religious people who are in jail is that atheist-prisoners are often converted to religion while in jail - or that the nature of prison life somehow encourages atheist-murderers to "convert" to religion - and hence (so the argument goes) the prisons are full of criminal-atheists who have "seen the light" and are therefore now religious. However, one very significant fact discounts that - all of these surveys are based entirely on the forms prisoners fill out when they enter the prison system. What happens to them as a result of the prison experience is therefore not represented by those statistics. It truly is the case that religious people in the USA are about 70 times more likely to wind up in jail than atheists. SteveBaker (talk) 23:14, 20 August 2010 (UTC)

_{If there are 70 times more religious people than athiests. --Chemicalinterest (talk) 11:20, 21 August 2010 (UTC)}

You seem to not be understanding the statistics here. What he's saying is that it is not equal for either — atheists are underrepresented based on their numbers in the population. You are implying that it is an identical rate. --Mr.98 (talk) 15:20, 21 August 2010 (UTC)

If most murderers are religious, then most religious people must be murderers. 92.15.3.131 (talk) 20:26, 20 August 2010 (UTC)

That is a stupid statement 92. It is equivalent, logically to saying "If most cars are red, then most red things must be cars" which is absurd. Googlemeister (talk) 20:40, 20 August 2010 (UTC)

See joke. 92.29.119.106 (talk) 22:29, 20 August 2010 (UTC)

See crickets. Marnanel (talk) 22:33, 20 August 2010 (UTC)

I've no idea what that is supposed to mean. 92.28.255.53 (talk) 09:45, 21 August 2010 (UTC)

He's saying it wasn't funny — the "joke" fell flat. --Mr.98 (talk) 15:21, 21 August 2010 (UTC)

See satire. I wrote it to draw attention to common fallacious reasoning: There are a lot of {minority-X) in prison, therefore a lot of (minority-X) will do bad things. 92.29.124.61 (talk) 23:28, 21 August 2010 (UTC)

A person has to feel more secure to identify as an atheist than a member of a religious group. Prison inmates I think feel insecure due to their situation in life. It could be argued that religious identity in a prison population aims to compensate for insecurity—real and perceived. This would tend to skew statistics coming from prison populations concerning religious/atheistic self-descriptions. The reason I say that people need to feel secure to identify as being an atheist is because atheists have fewer or weaker organizations binding their group together than do coreligionists. Coreligionists generally have the bonhomie deriving from a shared weltanschung.Bus stop (talk) 20:59, 20 August 2010 (UTC)

_{Since you think my opinion is minority, I will make it smaller. According to the Bible, man has a sin nature. No matter how religious you are, man has a natural impulse to sin. That would mean that no matter what your religion is, you still sin. Religion does not prevent sin in any way other than a possibly stronger feeling of remorse in most people.--Chemicalinterest (talk) 21:09, 20 August 2010 (UTC)}

I'm sorry, but that is not true. The bible does NOT hold that view. Christianity does. Ariel. (talk) 21:14, 20 August 2010 (UTC)

Bibles are books, and are unable to formulate opinions, voice their opinions, or issue decrees and edicts. Nimur (talk) 22:09, 20 August 2010 (UTC)

_{But the bible was written by God, so it is God's word and has god's views in it. --Chemicalinterest (talk) 11:20, 21 August 2010 (UTC)}

This question is impossible to answer and only leads to a simple discussion about theology. ... It really depends if you believe in hell, how to get there and what happens when you die really. Tommy! [message] 21:26, 20 August 2010 (UTC)

Read the top of this page - Do not start a debate; please seek an internet forum instead. This is not a question that the science desk is able or indeed intended to answer. --Cameron Scott (talk) 21:27, 20 August 2010 (UTC)

Assume good faith please, I'm aware. And as I explicitly stated, this question is impossible to answer (and should be closed). Tommy! [message] 21:31, 20 August 2010 (UTC)

If you believe in heaven and hell and all that stuff - then surely you have to believe that 100% of atheists would wind up in The First Circle of Hell (or the Asphodel_Meadows) just because they are atheists? But this is indeed not a scientific question - because the scientific answer is that the existence of Hell is an unfalsifiable hypothesis and therefore not worthy of inquiry. SteveBaker (talk) 23:14, 20 August 2010 (UTC)

The "Do not start a debate" injunction applies just as much to respondents as to OPs. Apart from the OP's original question, the entirety of contributors to this thread are other editors. It really should say "Do not start a debate; and if someone does try to start one, do not engage them". -- Jack of Oz ... speak! ... 23:15, 20 August 2010 (UTC)

If you guys read the text of the question rather than the header, there is a legitimate sociological question in there which presumably modifies the header. (E.g. the OP is implying that rapists, murderers, and sociopaths go to hell, and is asking whether atheism in particular contribute to higher percentages of those.) That's perfectly answerable from a sociological point of view. From a theological point of view it depends what you consider "going to hell" to require. Obviously if the OP just assumed, say, that people who violate the first commandment in the Bible as people who are going to tell, atheists by definition fall into that category. --Mr.98 (talk) 23:05, 20 August 2010 (UTC)

Actually - if we're being handed the existence of hell and the truth of the Bible as axioms, then the scientific view must be that atheists are actually marginally better off going to hell because it's cooler than heaven. (This is an old calculation - but I can't find it's origin - so I'll explain it in my own words).

• Isaiah 30:26 says: "Moreover, the light of the Moon shall be as the light of the Sun and the light of the Sun shall be sevenfold, as the light of seven days." So it appears that the Bible is telling us that in heaven the sun produces 49 times as much radiation as it does here on earth - and moreover the moon is as bright as our sun. So heaven gets 50 times the amount of insolation as we get here on earth. That would make the temperature in heaven about 520 degC. Actually, that's a low estimate. Another way to read that Biblical statement is that here on earth, the moon is 450,000 times dimmer than the sun - if the heavenly moon is the same brightness as our sun - then the heavenly sun must be 450,000 times brighter in order to make shine so brightly. I leave it up to you to come up with the likely temperature of heaven under that interpretation!
• Revelation 21:8 says: "the fearful, and unbelieving...shall have their part in the lake which burneth with fire and brimstone." Brimstone is just another name for sulphur - and if it's a "lake" then it must be molten and that means that the temperature in hell is below the boiling point of sulphur - which is 444.6 degC. We don't know how much less it is - but the melting point of sulphur is 115degC - which is hot...but survivable.

So...while neither place is very comfortable, you'd obviously want to go with Hell. Well, that's the scientific view! SteveBaker (talk) 23:34, 20 August 2010 (UTC)

_{The first verse is not referring to heaven; it is referring to the brightness of Jesus as he descends from heaven to reign the earth. The sulfur thing may or may not be correct, but the verse states about a lake of fire, not sulfur. The main punishment in hell is the eternal separation from God. --Chemicalinterest (talk) 11:15, 21 August 2010 (UTC)}

I'm pretty sure I'm OK with the eternal separation thing. If that's the worst thing, then I'm definitely hoping for hell. SteveBaker (talk) 19:44, 21 August 2010 (UTC)

This reminds me of an old joke: "Everyone goes to heaven, because god knows there's no worse punishment for an evil-minded person than to force them to sit around listening to harps all day." --Ludwigs2 23:50, 20 August 2010 (UTC)

_{That's not what you do in heaven. --Chemicalinterest (talk) 11:17, 21 August 2010 (UTC)}

_{It was my understanding that it is the dearth of humans in heaven that made it so pleasent.Smallman12q (talk) 13:20, 22 August 2010 (UTC)}

Getting off topic, but i disagree that 115 DegC is survivable. Maybe for a short while, but then again, you're already dead so it's a moot point really. Personally, I'd rather go to Hell too, but my reason is the same as what Bill Hicks' used to say: Hell would have much better music. Vespine (talk) 11:08, 21 August 2010 (UTC)

We have an article on the World Sauna Championships, where competitors start at 110°C. Marnanel (talk) 19:56, 21 August 2010 (UTC)

_{You can make a hell of your own with music (its called a party), but the hell mentioned in the bible does not have any music, just the anguished screams of those eternally separated from God. --Chemicalinterest (talk) 11:17, 21 August 2010 (UTC)}

If you want to avoid hell, you can always try and follow this guys [20] example Nil Einne (talk) 13:23, 21 August 2010 (UTC)

I could mention that there's mention of discourse, which presumably is in addition to any anguished screams. But even though the medievals called theology "the queen of the sciences", that doesn't mean a discussion of soteriology belongs on the Science Desk, edifying and written in small letters though it may be. Can we stop it now? Marnanel (talk) 19:56, 21 August 2010 (UTC)

Renewal alkaline batteries recharged in NIMH charger

I have some dead AAA"Rayovac Renewable alkaline" rechargeable batteries, and a charger intended for NIMH Nickel metal hydride batteries. What ill effects are likely to result from recharging the batteries in the charger? How do the charged voltages compare? Edison (talk) 20:00, 20 August 2010 (UTC)

IIRC, the renewable alkaline cells are 1.5V and the charger is made to charge 1.2V. Is it a fast (30 minute) charger or a slower (6 hour) charger? The fast one may overload the batteries. --Chemicalinterest (talk) 20:26, 20 August 2010 (UTC)

Do not charge alkaline batteries in a regular charger!!!!! It's not just voltage, the charger needs to send a pulse of current, then wait for the hydrogen gas in the battery to recombine, then do it again. It's a totally different process than for a regular battery. These two pages may help: Rechargeable alkaline battery Recharging alkaline batteries. Ariel. (talk) 21:11, 20 August 2010 (UTC)

It can be dangerous to charge batteries in the wrong kind of charger - they can get hot, the contents boil and then they explode - or hydrogen gas can build up and cause the battery to catch fire. I wouldn't want to risk doing this without being REALLY certain. SteveBaker (talk) 22:47, 20 August 2010 (UTC)

The best-case scenario is that the charger will recognize that you've stuck something other than an NiMH battery in it and will shut off; the worst-case scenario is that the battery will explode and start a fire. --Carnildo (talk) 02:12, 21 August 2010 (UTC)

The worst-case scenario is that the battery explodes violently just as you are near it, blinding you and causing you massive wounds and a slow and painful death. Seriously, Murphy's law man. 84.153.204.126 (talk) 09:15, 21 August 2010 (UTC)

I agree that it is best not to try this because the charge current will be too high by a factor of more than ten (though I did build and use a recharger for zinc batteries nearly fifty years ago without explosions, but with only minor success). It is possible to charge NiCad rechargeable batteries in a NiMH charger, though this might shorten their life marginally. Dbfirs 22:53, 21 August 2010 (UTC)

is all jerky salted?

or can it be smoked and dried but at no point salted? 92.230.70.110 (talk) 21:19, 20 August 2010 (UTC)

Salt is a natural preservative, so yes. In fact, historically salt has been used as a preservative, as it removes water content, in which bacteria and viruses live in. Tommy! [message] 21:23, 20 August 2010 (UTC)

sorry, let me rephrase: Does ANY jerky not contain salt? (is there at least one which has no salt in it). 92.230.70.110 (talk) 21:19, 20 August 2010 (UTC)

Without salt, it would probably not be called "jerky", but this is a matter of word style/preference. Smoked meat has its own name. Nimur (talk) 21:29, 20 August 2010 (UTC)

Without salt (and no refrigeration) it would be unsafe to eat... and you'd get sick. Tommy! [message] 21:32, 20 August 2010 (UTC)

so salt is the only suitable preservative? what if it were sealed properly after being dried and then in a clean environment "pasteurized" or flash heated to kill bacteria? 92.230.70.110 (talk) 21:41, 20 August 2010 (UTC)

It can't be pasteurized because you can't boil meat. There is irradiated meat, though. But not for jerky. Jerky is known for its salty and smoky taste. Tommy! [message] 21:46, 20 August 2010 (UTC)

What do you mean by "you can't boil meat"? I've eaten boiled hot dogs. Nyttend (talk) 01:53, 21 August 2010 (UTC)

Hot dogs are already cookied. Generally, no you can't boil, say a steak... sure it'd cook, but it'd taste like **** Tommy! [message] 12:23, 21 August 2010 (UTC)

I had the same initial reaction, but I think he means you can't boil meat like you can boil water or milk, rather than the culinary sense in which the meat is cooked in a boiling liquid. 86.161.255.213 (talk) 02:23, 21 August 2010 (UTC)

Yes. Meat doesn't boil. I should have said that. Tommy! [message] 12:25, 21 August 2010 (UTC)

Of course pasteurisation usually doesn't involve boiling anyway Nil Einne (talk) 09:29, 21 August 2010 (UTC)

Sorry for being misleading. Tommy! [message] 14:40, 21 August 2010 (UTC)

By salt do you mean sodium chloride only, or the nitrate and nitrite salts which are also used to preserve jerky? If you smoked meat heavily and packed it under nitrogen or in vacuum, it would keep for a while, but not as long as jerky with one or more varieties of salt. If you irradiated it first you could probably get away with zero salts and still have it last for years potentially. I guess it depends on how strongly you want to irradiate it. Ginger Conspiracy (talk) 00:06, 21 August 2010 (UTC)

The reason jerky needs to be salted is that it isn't completely dry. If you make pemmican by drying lean meat until it is crispy, grinding it to a powder, and mixing it with hard beef fat and berries, the product will last indefinitely without any added salt, as long as you keep it from getting damp. Looie496 (talk) 00:54, 21 August 2010 (UTC)

Bakkwa is another form of meat which will keep for some period of time ([21] suggests 30 days stored outside the fridge but in decent conditions). While it usually contains salt [22] [23] sugar is the more important prevervative I think, you could potentially adjust the recipe to eliminate sodium although I can't say I think it will taste very good. Of course you can also use canning to preserve meat Nil Einne (talk) 09:27, 21 August 2010 (UTC)

Bird identification?

Can anyone identify this bird for a friend? Thanks :) FT2 ^{(Talk | email)} 22:39, 20 August 2010 (UTC)

Well, the back end of it looks exactly like a Canada Goose - but it doesn't have the characteristic black head and neck. I wonder whether it is a juvenile that hasn't quite gotten it's adult plumage. SteveBaker (talk) 22:44, 20 August 2010 (UTC)

can't get the image to load. --Ludwigs2 23:52, 20 August 2010 (UTC)

Same here. ~AH1^(TCU) 01:34, 21 August 2010 (UTC)

... and here. Dbfirs 11:44, 21 August 2010 (UTC)

Here too. --The High Fin Sperm Whale 17:59, 21 August 2010 (UTC)

It's vanished for me too - and I could see it when I answered the question yesterday. SteveBaker (talk) 19:41, 21 August 2010 (UTC)

The subjective experience of dementia

Do people ever realise themselves that they are becoming demented, or are sufferers always unaware? Regarding psychosis, do sufferers simply think that other people have become more disrespectful? 92.29.119.106 (talk) 22:54, 20 August 2010 (UTC)

Yes, they often are aware. People in the early stages of Alzheimers are usually informed they have this condition, and that there is support available should they become unable to manage their own lives/affairs. Whether they choose to accept this is actually happening to them is another matter. -- Jack of Oz ... speak! ... 23:08, 20 August 2010 (UTC)

After Ronald Reagan was diagnosed with Altzheimer's disease, he gave a famous speech to announce it to the nation; it was very widely publicised, at least in the USA. The full text of the speech is available online. Nyttend (talk) 01:51, 21 August 2010 (UTC)

I believe this varies from person to person. I've worked with dementia sufferers, and some of them have lucid moments when they are fully aware of their gradual loss of capacity. Others (such as a lady I'm currently working with) have no awareness of what's happening to them, even if they are told repeatedly. I suppose that the actual variety of dementia has a bearing on which experience happens. --TammyMoet (talk) 08:36, 21 August 2010 (UTC)

You could look at Terry Pratchett - he has early onset Alzheimer's disease and has done many interviews regarding the condition and it's effect on his life. Exxolon (talk) 11:03, 21 August 2010 (UTC)

Hazel Hawke also gave interviews, wrote books and did other fund raising for Alzheimers when her condition was first diagnosed; I believe it's now advanced to the stage where she is no longer capable of doing this. -- Jack of Oz ... speak! ... 11:12, 21 August 2010 (UTC)

Alzheimer's disease#Characteristics doesn't list anosognosia as being a characteristic of Alzheimer's until the moderate dementia stage. Red Act (talk) 03:44, 22 August 2010 (UTC)

S-duct

The article on the Lockheed Martin F-22 Raptor says it has S-shaped intake ducts. Is this related to an S-duct (even though the S-duct article says it is "used only on trijet aircraft")? And what is an S-duct (the article explains it very poorly)? --The High Fin Sperm Whale 23:44, 20 August 2010 (UTC)

It is a duct that is s-shaped. In the simplest jet-engine design, the air basically flows through a straight cylinder; the various compressors and fuel injectors (and turbos and all the other fun things) are all axially aligned. In an s-shaped configuration, the air intake is offset from the main axis of the jet engine (for mechanical layout reasons - it's less efficient, but it allows the engines to "fit" in ways they otherwise would not fit). In the 727, the "S" was vertical; the intake was above and forward of the tail and ducted down to the rear of the tail. In the F22, the ducts are lateral, and duct in from the front and sides of the airframe, and then to the interior of the airframe, finally to the jet exhausts at the rear of the aircraft. Nimur (talk) 01:03, 21 August 2010 (UTC)

Then why does the article say they are only used on trijets? --The High Fin Sperm Whale 03:45, 21 August 2010 (UTC)

Good point. I have amended the article by removing the word only. It no longer says S-ducts are only used on trijets. Dolphin (t) 04:53, 21 August 2010 (UTC)

The article on the F-22 Raptor says that it has s-shaped ducts, but it doesn't actually say it has s-ducts. I don't know the exact requirements for an intake system to be classified as a s-duct, but I am geussing that the term s-duct was ment to be applied to the use of the design in trijets and larger aircraft, not fighterplanes, but in reallity there isn't really any difference between a s-duct and what is used on the raptor (besides that most aircraft utilising the design implement it vertically and the raptor implements it horizontally). In other words I think there really isn't a difference, the term S-duct was ment for commercial aircraft and no one thought of applying the term to a fighter aircraft. Although as mentioned above this is only a geuss, so if I am incorrect please anyone feel free to correct me. —Preceding unsigned comment added by 74.67.89.61 (talk) 04:55, 21 August 2010 (UTC)

August 21

Noah's Ark

Now, before I start, I'll just state now that I don't really want to start a debate here about whether Noah's Ark was actually real, or whether the Flood happened or not. What I'm actually curious about is this - supposing that one wanted to construct a great ship, capable of housing two members of every extant species of land animal (we can include species that were present in Biblical times but not now, if you wish) for a year or so, with enough space to store the food and fresh water required to keep them alive throughout... then how big would the ship actually have to be? I seem to remember that someone actually tried to work this out once and came out with a rough estimate that (assuming no physics-bending divine intervention) would put the Ark at several times larger than the largest supertankers and aircraft carriers ever constructed - and the amount of raw materials and time required for construction would be utterly staggering. Does this sound familiar to anyone? --Kurt Shaped Box (talk) 00:13, 21 August 2010 (UTC)

Yes, but can't remember who did the math, either. I think the conclusion was that he stored the genetic material and not the actual animals :) . Besides, most extant species (that is, invertebrates) have a natural life span comparable with the duration of the Flood, if not smaller -- not to mention predation and such -- so they wouldn't have made it alive anyway. Another problem is the narrowing of the gene pool: if a species is down to just one breeding pair, its chances of survival are not too good; inbreeding is a Bad Thing. --Dr Dima (talk) 00:44, 21 August 2010 (UTC)

Are you including insects and other invertebrates? I'm assuming you want birds. And do you want to limit yourself to animals from a given area, or do you really want it for all species in the entire world? And are you thinking of this article? 86.161.255.213 (talk) 00:45, 21 August 2010 (UTC)

That wasn't the specific article I read (I think I read mine in a newspaper) but that is a really good read. It covered a few things that I'd never considered. Nice find. I suppose that an argument could be made for limiting the number of species (including birds and invertebrates, as I think that is specifically stated in the Bible) to those present in the *known world* at the time of Genesis, to tie in with the 'it wasn't a global Flood - but a large Flood in the Near/Middle East' theory that some expound... --Kurt Shaped Box (talk) 01:51, 21 August 2010 (UTC)

I don't think predation would be a problem, since anyone with some common sense would take aboard young animals (taking up much less space). As for smaller animals, such as mice, you would need very little space (or just let them run around free). They were only to take animals "that lived on dry land and breathed through their nostrils", so you would not need to take fish, invertebrates, amphibians, etc. And since the Bible says "every species after its kind", not "every animal after its taxonomically separate species", I think they would have considered elephants, for example, to be just one kind (meaning you don't have to take aboard all three species that existed at the time, just one). And to KSB's earlier comment, the source says it took 120 to build! For a 450 foot long boat, I think it would be quite possible. --The High Fin Sperm Whale 04:00, 21 August 2010 (UTC)

That is a challenging idea from the High Fin Sperm Whale. If it wasn't necessary for the Ark to carry a pair of each of the two or three separate species of elephant that existed at the time, only one pair, that begs the question how is it that we now see at least two separate species of elephant - African and Indian? How did two separate species spring from just one breeding pair of elephants on the Ark? Could they have evolved from that one breeding pair? Unlikely, since evolution and the story of the Ark are incompatible. Could the two or more separate species have sprung from the one breeding pair by a miracle of God? If God was into performing miracles as a means of populating the world from the animals in the Ark why did there need to be a breeding pair - God could have used miracles to populate the world starting with just one animal. That would have required an Ark only half the size. And pursuing that line of thought a little further, why bother with the Ark at all - just use miracles to populate the world with animals, starting with just fish or microbes. If God could manufacture Eve starting with nothing more than one of Adam's ribs He would have no problem creating a breeding pair of elephants starting with nothing more than a couple of tuna or trout or perhaps a pair of Elephant seals, and they would all have survived the flood without any trouble.

Another possibility is that the whole flood story is just a story that grew with the telling, passed on from one generation to the next until it was eventually committed to writing in what we now know as the Old Testament. This is the Science Reference Desk where people confine their ideas to things that can be supported by information gathered by observation, and without recourse to intuition. Outside the Bible there is no evidence to support the story of the Ark and the flood. Many people have attempted to shoe-horn various observations into the Biblical story but those attempts have never won support outside the group of like-minded people. Consequently the Ark and the flood have no place in science, unless and until someone finds evidence that will objectively support the Biblical account. Science must examine the facts and draw the most consistent conclusion, not search for facts that will support a preferred or pre-determined conclusion.

Answers to questions about the Ark and the flood don't belong on the Science Reference Desk. Dolphin (t) 04:36, 21 August 2010 (UTC)

Why not? The question encompasses both history and science. --The High Fin Sperm Whale 05:55, 21 August 2010 (UTC)

I agree that KSB's question encompasses science and a little recent history (someone actually tried to work this out once), but I think your first reply strayed from the scientific a little. My comment about answers to questions on the Ark and the flood was intended to be a general comment and not one directed solely at this thread. Dolphin (t) 07:41, 21 August 2010 (UTC)

(after edit conflict) ... and the story has been investigated by both scientists and historians. I don't think they have come up with a definitive conclusion yet, but the best explanation I've read that explains both the biblical story and the similar account in the Epic of Gilgamesh is that of the catastrophic flooding of the land around the Black Sea around 5600 BC as a result of the sudden breaching of the Bosphorus. Scientific evidence for this is set out in Ian Wilson's book Before the Flood (ISBN0752846353). Dbfirs 07:48, 21 August 2010 (UTC)

Unfortunately I haven't read Wilson's book. I doubt an account based on the sudden breaching of the Bosphorus could be found compatible with the Biblical version, because the Biblical version speaks only of continuous rain for 40 days and 40 nights. I have seen a documentary about ancient flood and Ark stories abounding in the vicinity of the Euphrates River. Dolphin (t) 07:56, 21 August 2010 (UTC)

There are many flood stories from around that time because of the climate change and the scientifically documented rise in sea levels. The continuous rain would only add to the sudden rise of the water in the lake that subsequently became the Black Sea. Wilson presents a convincing explanation, but does not try to justify the "Noah's Ark" story word-for-word. A suspiciously similar story is that of Atra-Hasis Dbfirs 11:37, 21 August 2010 (UTC)

You should bear in mind that there weren't just two of each kind. According to Genesis chapter 7, There were seven of each bird, and of each "clean" animal (presumably as defined by Jewish dietary law), and two of each of the "unclean" animals. Rojomoke (talk) 10:04, 21 August 2010 (UTC)

Was there one extra male and two of the males had to fight for the females or was there an extra female and one of the males got two females? Or some other combination like 1 male, 6 females? If it were either of the later two options, what happened to those animals (a number of birds for example) that practice pair bonding? Incidentally, wasn't it lucky Noah was so good at sexing so many different kinds of animals. Nil Einne (talk) 11:07, 21 August 2010 (UTC)

I have heard that Noah took only the kinds. So he wouldn't take 2 of each species of dog, but just the one original dog. Then the original dog "evolved" to the many species of dogs. But this evolution does not go out of its kind naturally. --Chemicalinterest (talk) 11:33, 21 August 2010 (UTC)

I've heard such claims before, but all they do is reveal how little people who make them know about evolution or even basic taxonomy. The idea we could get the level of diversity of life we see nowadays from this supposed 'restricted' evolution in a few thousands years, but it's impossible humans evolved from a common ancestor with chimpanzees in several million years is clear cut nonsense. (I wonder is the general idea only one kind of Simiiformes was chosen, excluding humans, which then underwent this limited evolution into Catarrhini and Platyrrhini or did these different 'kinds' already exist?) Being able to compare the increasing number of whole genome sequences is further proving the point. And we're not even getting into the other things people have discussed like the absence of any evidence of a genetic bottleneck for most species Nil Einne (talk) 12:50, 21 August 2010 (UTC)

Well, we could certainly take a shot at this.

Using numbers from too many articles to list: There are 10,000 species of bird, 5,400 mammals, 5,600 frogs, 7,900 snakes & lizards - and much smaller numbers of other kinds of larger animal...but to be honest (in terms of species count), that's all largely irrelevant compared to the between 5 and 10 million species of arthropod (most of which are insects). A good fraction of those would be marine arthropods - which one assumes wouldn't need a ride on the ark - but if we make a guess at 2 million land arthropod species - then even if each pair needed a 10cm x 10cm x 10cm cage (pretty spacious for, say, an ant!), you're only up to 2,000 cubic meters of space. You could keep a pair of birds in maybe 30x30x30cm (on average - ostriches take more, but love-birds less) - so we're looking at another 1000 cubic meters of birds. Some mammals are much bigger - but 1,100 of those species are bats (100 cubic meters), 2,200 are rodents (maybe 200 cubic meters). Even if the rest are things like dogs and cats and cows and such, there are lots of voles and other tiny mammals to counteract the elephants and giraffes. Let's guess at an average of 1 cubic meter per non-rodent/bat mammal species, so we need maybe 4,000 cubic meters for the mammals. Frogs snakes and lizards would probably consume another 10x10x10 cm cage per species - so we'll need a mere 8 cubic meters for them.

I'd say that for a VERY rough estimate, the living space alone would consume something like 8,000 cubic meters. Let's quadruple that to allow space for food and water, add another 8,000 meters for corridors, access, exercise areas, etc. So perhaps we need 50,000 cubic meters for the entire ship.

The Seawise Giant (the largest cargo ship ever built) is 458m long, 68m wide with a draft of 24m - so a volume of 750,000 cubic meters is easily attainable in a modern vessel. A more typical large cargo ship would be more like 150,000 cubic meters - so we can get away with a relatively small ship. Could this be a wooden ship? You'd be looking at something about five times the size of HMS Victory (10,000 cubic meters). Is that possible? Well, yes! The Greeks built the Tessarakonteres in about the 3rd century BC - it was (very, very roughly) 200m x 30m x 30m - 180,000 cubic meters. Plenty enough to hold one pair of every land animal!

The bible says that the ark was 300x50x30 cubits...there are many definitions of a cubit - but they mostly come out at around a half meter - which makes the ark about half the size of the Tessarakonteres. So the ark (as described) was evidently well within the technology of the 3rd or 4th century BC. The ark could hold 56,000 cubic meters...plenty big enough for 8,000 cubic meters of animals, food and water.

Of course we can be very sure (from fossil evidence, DNA analysis, etc) that Noah's ark is a myth. Doing this is so far beyond the capabilities of the people of the time that it's completely laughable - there are a crazily large number of reasons why this is obviously bullshit.

I don't think the size of the vessel is (in principle) an obstacle...I'm very surprised about that...someone had better check my math!

SteveBaker (talk) 19:32, 21 August 2010 (UTC)

The article I linked suggests a lot of the animals will die if you try to keep them in those conditions for weeks on end. 86.161.255.213 (talk) 19:51, 21 August 2010 (UTC)

I've always thought that the story works much better from God's point of view if you assume that the flood was local, but God told us it was global. After-all, human civilization lived almost entirely in river valleys at the time, no need to flood all the way up to the mountain tops.

Anyway, with the ark story as written you'd need some good climate control systems too. Polar bears and Komodo Dragons are not going to do well in the same climate. I wonder which would be easier with the technology of the time : Sailing the ship in arctic waters and using some sort of solar heating rig to keep the tropical animals happy, or sailing in a warmer climate and rigging up some sort of evaporative cooling system. APL (talk) 01:03, 22 August 2010 (UTC)

There was probably a canopy of water vapor or something that produces the greenhouse effect, making the heating almost equal. --Chemicalinterest (talk) 11:17, 22 August 2010 (UTC)

That makes it worse not better. If, as you say, the air was saturated with water vapor and the world was globally warm, then Noah would have had a tremendous difficulty with keeping cold-weather animals cool. The cooling technology they would have had back then would have been very primitive evaporative coolers, not only would those not have been powerful enough to reach anywhere near arctic temperatures, those only work properly in very dry weather. A globally warm humid climate would have killed off many species that have clearly survived to this day. Polar bears.

The only way he's going to keep arctic animals happy is if he goes some place really cold, then warms the rest of the boat with solar power and fires. (Fuel for the fires adds to the boat's cargo requirements.) APL (talk) 21:01, 22 August 2010 (UTC)

Regarding the flooding of the Black Sea, see Black Sea deluge theory. ~AH1^(TCU) 01:08, 22 August 2010 (UTC)

Steve Baker has done an excellent job of estimating the order of magnitude of the size of the ark. Well done Steve! I think the next step to challenge our minds is the human resource necessary to feed all these creatures. It might go something like this. One trip by one person to carry enough food for 20 species of bird. That is 500 trips to feed all 10,000 species of bird. Distance from feed store to aviary - 200 metres; with a round trip taking 5 minutes. One minute to feed one species so each trip involves 20 minutes actually dispensing the feed. That is 208 hours to feed all the birds once. Let's assume Noah's family members worked 20 hours a day, so if all the birds were fed once every 2 days it would require 5 people working full time just to feed the birds on the ark, without considering any cleaning of the aviaries or carrying away the droppings.

Now let's consider the mammals. No! I'm exhausted. Dolphin (t) 02:11, 22 August 2010 (UTC)

Your estimate for birds is very low. You should be able to carry enough for more than 1000 birds in one load (a budgie eats 2 teaspoons a day, which is about 10cc, and weights maybe 12g or so). BTW the Talmud discusses this topic, and concludes that the whole thing is impossible for a person to do (for pretty much the same reasons as listed above), and that the story is a miracle. Ariel. (talk) 02:30, 22 August 2010 (UTC)

Natural science relates a point in the present to a point in the past by natural laws, which are assumed to be constant. Any variation of the rules of nature by a divine entity invalidates the predictions of natural science. More generally, it is possible that a number of parallel universes exist, each related within itself by natural science, but relatable to one another throughout their extent by a different set of rules. Thus I think it could be meaningful to speak of multiple dimensions of time, each representing a different ruleset - however, scientists can only study the one that affects laboratory experiments as they perceive them.

The story of the Ark is utterly absurd in our universe as we understand it. Yet we should be sensitive to the consideration that there could be some other universe (perhaps one with fewer species...and fewer barriers to inbreeding) where the events make some sense. We cannot rule out that such a universe might have been created "before" our own, whether according to the biography of an Author of universes, or by the operation of a physics ruleset that we have not ourselves observed. In this way, we should recognize that our science cannot disprove the actions of a creator capable of creating and changing physical laws. Wnt (talk) 12:56, 22 August 2010 (UTC)

The whole thing is obviously ludicrous to the modern mind. Consider the plight of the Granulated Tasmanian snail which lives only in Australia. That means it would have had to travel about 10,000km to get to the location of the Ark - at a peak speed of 1mm per second - taking about 7 years to do so (if it could do it in a straight line overland without coming across any insurmountable obstacles - which for a Granulated Tasmanian snail doesn't take much!). However, how could it cross the ocean? Clearly a lot more than one pair of snails would have to set out in order to be sure that they'd arrive without being eaten by a bird along the way. Worse, those snails don't live for 7 years - they'd have to treat this as a multigenerational trip. Worse still, we'd have to consider animals that live in cold climates that would have been unable to survive in the middle east...animals like the Giant Panda that can only eat bamboo - which didn't grow in that part of the world. What about those hundreds of species of cave-dwellers who are completely blind - how do they find their way there? Species of animal like the Ichneumon wasp that doesn't live long enough to survive the 10 month trip without reproducing - and which requires a living host for its pupea to develop within. I could keep on coming up with problems like this for as long as anyone would be prepared to listen. There are a simply insane number of little problems that would have to be overcome at every step of the way:

• How could these animals all be assembled at the right time?
• How could predation and sort life-spans ensure they'd all survive?
• How could their wildly varied diets have been handled? Even modern zoo-keepers with the benefit of years of study find some species to be impossible to keep in captivity. (How did the Noah crew find bamboo for the Pandas?)
• Why is there no evidence of a lack of genetic diversity such as would be expected if just one breeding pair of each species survived the mass-extinction event claimed here?
• There is no actual solid definition of a "species" - how exactly did all of the subtle variations between two species that blur together come to be represented in the Ark?
• Where did all the water come from to flood the earth to that depth? Where did it all go to afterwards? How did it disappear so insanely quickly?
• How come there is no geological evidence for all of this? We ought to at least find a thin layer of salty alluvium at the same geological age over the entire planet.
• How did plants survive the inundation? 10 months underwater would have eradicated every terrestrial plant species and likely made the soil so salty that nothing would grow in it afterwards.
• What did the animals eat when they were released from the ark?
• Were there two of every kind of bacterium present on the ark? If not - then how did the ones that require animal or plant hosts survive?
• What about communal species like ants and bees - one male and one 'queen' isn't enough to raise the first generation of pupea after the flood. Even if they could recover, how would the newly regrowing plants get pollinated in the meantime.
• ...etc, etc, for another few hundred obvious questions...

Clearly this was a story written for a local audience. People who had never gone beyond the next village in their entire lives - who perhaps only knew of a few hundred animal species. For someone like that, this would be a rather believable story. But in the light of modern knowledge, it's just plain silly.

What is sad is that when people like our very own resident fundamentalist have to resort to patently ridiculous "explanations" for a story that should never be taken literally. In response to the tricky issue of how the ark would have provided ranges of temperatures suited to everything from the polar bear to the desert tortoise we are told: "There was probably a canopy of water vapor or something that produces the greenhouse effect, making the heating almost equal."...um...words fail me! Noah's ark is a cutesy story for little children - there is no conceivable way it could be real.

The only answer that can possibly work here is "It's magic...God waved his magic wand and it all came out like the big book says...then (for some unaccountable reason) he did this amazing cover-up job to make all of the evidence point to it never having happened."...and if that's the answer, then it has no place here on the science desk.

SteveBaker (talk) 19:17, 22 August 2010 (UTC)

All these estimate

Space related

Sir, I am just an ordinary person. I am not a scientist. Stephen Hawking in his book namely " A BRIEF HISTORY OF TIME" published during 1988 has narated in his conclusion topic that ' we shall all. philosphers,scientists,and just ordinary people, be able to take part in the discussion of the question of why it is that we and the universe exist. Hence, being an just ordinary person, i would like to express my views to my indian scholars. —Preceding unsigned comment added by Kannappanvelu (talk • contribs) 07:26, 21 August 2010 (UTC)

• I'm not sure I understand your question. If you are asking for an analysis of Hawking's statement, he's commenting on the difference between the nature of science (which is about describing what the Universe does), and other analysis of the Universe, such as its purpose and reason for being. He is stating that all people, not just physicists as himself, have a role in defining for themselves why the universe exists, that is assigning a purpose or meaning to its existance. It is a similar sentiment, from the opposite direction, that Cardinal Cesare Baronio expressed when he stated "The Bible teaches us how to go to heaven, not how the heavens go". In other words, there are seperate domains for Science and for Religion/Philosophy to occupy in the human existance. Hawking is merely reminding us that, while his (Hawkings) domain is the description of "how the universe goes", he isn't going to tell you "why" or "for what purpose" the universe goes. Ordinary people can do that for themselves. --Jayron32 07:40, 21 August 2010 (UTC)

Hawking expresses that Freedom of speech about existential subjects shall not be limited to those with particular qualifications, such as scientists or philosophers. Viewpoints on these subjects often constitute a Belief system. The rules stated at the top of this page do not allow starting a debate here about such questions. Cuddlyable3 (talk) 14:50, 21 August 2010 (UTC)

Free speech is not a surrogate to "qualification" - it's a totally independent matter. I think India is a pretty progressive place; so if the OP wants to express his/her views to scholars, he/she can probably write a book, a letter to a major newspaper, or even visit a university and try to meet with a scholar. If I understand correctly, no government regulators will try stop you. But if you voice your opinion, it might not be taken seriously unless you have established credibility - in many cases, this means "an advanced degree in the subject you're interested in." It really depends on the community that you want to participate in - if you have opinions about physics, most physicists will expect you to have a well-rounded background in the "core subjects" of modern physics. If you only want to express philosophical ideas, most philosophers will equally-well expect a solid training (informal or otherwise) in the basic philosophical arguments that have historically been laid out before - so that you don't waste time their repeating other ideas that have been elucidated previously, and instead build new ideas. These are sort of "pre-requisites" for serious discussion in certain communities - it proves that you have invested the time, and been vetted for basic competency by a trustable institution. Nimur (talk) 15:46, 21 August 2010 (UTC)

Hawking mentions all people, not just those meeting pre-requisites. The OP spoke about "my indian scholars" (from Latin schola school) which may mean the OP is a teacher. Cuddlyable3 (talk) 21:20, 21 August 2010 (UTC)

That's a completely silly conclusion to reach, and a nonsensical way of reaching it. --Mr.98 (talk) 00:34, 22 August 2010 (UTC)

Please explain clearer if there is a problem with my post. Cuddlyable3 (talk) 11:37, 22 August 2010 (UTC)

IMHO, the most logical reading of the OP's post which I think 98 is getting at, is that the OP is an ordinary person who's job is indeterminate and largely irrelevant, who wants to communicate with scholars (meaning learned people or researchers, most likely scientists given the specific question) in India (where they likely live) about their views of why the universe exists apparently because they believed Hawking was encouraging it and/or suggesting they would be interested Nil Einne (talk) 13:56, 22 August 2010 (UTC)

"My Indian scholars" does not imply, in any way, that the OP is a teacher. Falling back on the Latin roots of "scholar" is a ridiculous way to interpret the word in context. --Mr.98 (talk) 14:30, 22 August 2010 (UTC)

[24]scholar n.

1.A student; one who studies at school or college.

2.A specialist in a particular branch of knowledge.

3.A learned person.

4.One who educates themself for their whole life.

I make no assumption about which meaning the OP may intend. With respect, neither should you. Cuddlyable3 (talk) 19:20, 22 August 2010 (UTC)

Hawking is not suggesting that scholars want to listen to you or care about what you say. What he is saying is that the overall question of the origins and purpose of the universe should not be limited to astrophysicists, that it is a broader question, that some of it is deep philosophy. He's trying to encourage you not to defer to scholars just because they are scholars. --Mr.98 (talk) 00:36, 22 August 2010 (UTC)

In the extract given, Hawking does not say the question is deep anything. One may deduce that he encourages ordinary people to take part in discussing the question, though his actual statement is worded as a prediction ("we shall..."). Cuddlyable3 (talk) 11:37, 22 August 2010 (UTC)

I'm pretty sure the OP wants to communicate with scholars from the country of India regarding the nature of the universe and share his ideas. He seems to have taken Professor Hawking's ending sentiments quite literally rather than distant future figuritively. 24.177.120.57 (talk) 14:11, 22 August 2010 (UTC)

Fishbone getting stuck in throat

A fishbone is getting stuck in my throat, and if I leave it there without doing anything for I have been told that fisbone is calcium which can automatically be decayed (though it is quite bothersome), will this be dangerous?

203.131.212.36 (talk) 12:21, 21 August 2010 (UTC)

We are not allowed to give out medical advice. See WP:MEDICAL.

SteveBaker (talk) 17:12, 21 August 2010 (UTC)

I don't think deleting my comment was called for. It's not like I told the poster what to do. Wnt (talk) 23:18, 21 August 2010 (UTC)

Adjusting the cost of energy for using carbon

Template:Cost of energy sources

How would you adjust Template:Cost of energy sources for the external, weather-related cost of using fossil fuel?

Carbon pricing is not much help. Here is a diminishing-returns chart; does that help?

What do we need to learn to answer this question? Why Other (talk) 17:53, 21 August 2010 (UTC)

A major part of the problem here is that we don't know the full cost of global climate change. We know it's happening - and we know that it's largely caused by fossil fuels and things like the large scale farming of herbivores (specifically "Cow farts"). However, even if we did know that, it's not a flat-rate kind of a thing. Think of it this way...X amount of CO2 in the atmosphere might have almost no effect because it might not cause the polar icecaps to melt - but twice X might be enough to melt the icecaps, create dark water where there was bright ice and therefore much more solar absorption. Twice X worth of CO2 could easily cause ten X worth of warming. So there is no price we can put on X amount of CO2 in the air.

That means that the price that's put on this is a matter of deterrence, politics, economics - not science. SteveBaker (talk) 18:21, 21 August 2010 (UTC)

Good point, we need cost information per emitted carbon, with which this source-sink flowchart might help, in addition to the source information from livestock. Why Other (talk) 18:30, 21 August 2010 (UTC)

Cow farts aren't a major contributor to climate change. Cow burps may be. Note that contributions from livestock also come from things like land cleared (a one time thing usually) both for the cows and for the feed due to increasing production are also usually considered a factor. Nil Einne (talk) 19:10, 21 August 2010 (UTC)

I asked about that on Talk:Climate change mitigation#Low carbon diet. Why Other (talk) 19:20, 21 August 2010 (UTC)

I just found Economics of climate change mitigation and I am having trouble understanding some of it.

Can we just move all the fossil fuel subsidies to wind and water power subsidies? That's $500 billion a year. How could we determine whether it would be too much or not enough? Why Other (talk) 18:48, 21 August 2010 (UTC)

Why only wind and water? What about solar? Nuclear? Biofuels? (Incidentally does water include geothermal? Wave?) Nil Einne (talk) 19:09, 21 August 2010 (UTC)

Solar is good, but does it play much of a role? Nuclear looks expensive to begin with, and I'm not sure it can be built out fast. Some of the storage and transmission energy developments look much more important than geothermal generation. 71.198.176.22 (talk) 19:16, 21 August 2010 (UTC)

Depends where you're referring to surely. Iceland already gets about 24% of their power from geothermal. Also how/why have you determined solar doesn't play much of a role if you're trying to expand usage by subsidies anyway? Nil Einne (talk) 19:20, 21 August 2010 (UTC)

Agreed; something like File:Extreme-weather-cost.gif is necessary to approximate the financial value of reducing atmospheric carbon. 71.198.176.22 (talk) 19:32, 21 August 2010 (UTC)

Wind, water, and solar are certainly all good, but definitely in that order long term. Water includes both hydroelectric and tidal, and geothermal is certainly more important than tidal (which is only used in 2010 to recharge the batteries a few electric yachts with on-board regeneration at anchor.[25]) Why Other (talk) 19:29, 21 August 2010 (UTC)

Again, how have you made that decision on what's important and what order? Particularly since you talking about using subsidies and considering in many countries the level of usage of all (except nuclear and to a lesser extent hydroelectic) are rather small. Are you sure your suggestions apply everwhere? What about say in the Middle East or tropical countries? Nil Einne (talk) 19:33, 21 August 2010 (UTC)

That is the order they appear by magnitude in Jacobson, M.Z. and Delucchi, M.A. (November 2009) "A Plan to Power 100 Percent of the Planet with Renewables" (originally published as "A Path to Sustainable Energy by 2030") Scientific American 301(5):58-65 and so that is the order I put them in energy development. Why Other (talk) 19:42, 21 August 2010 (UTC)

That appears to be one group?'s ideas and while it may be legitimate to present such ideas in the article (something which is not up for discussion here, if you want to discuss what goes in an article that should stay in an article talk page), this doesn't mean that their ideas are the only valid ones as you seem to imply here. In fact, the fact it's presented in a popular science journal somewhat suggests is justs a simplified public proposal rather then a robust peer reviewed scientific analysis. BTW I forgot to mention this earlier. I'm not that familiar with nuclear power developmental time frames but if your suggestions are hinged on some significant developments in energy storage systems then it's not clear to me if you can reasonably dismiss nuclear as taking too long. P.S. From a quick read of the article you mention, it doesn't even seem to agree with your suggestions. In fact their proposal seems to be 51% wind and 40% solar, so I don't see how you can dismiss solar as not playing a role as you did early on. And in fact in their proposal solar appears to play a far bigger part then water. Wind may be more important then solar in their proposal but only by about 20% and it's difficult to imagine that they are really claiming their proposal is so robust that a change from their proposal to say 46% solar and 45% wind is impossible. Nil Einne (talk) 03:06, 22 August 2010 (UTC)

Identify this animal

Hello Science Desk! I just saw a creature, about the size of a small woodlouse and similar in shape, but light blue in color and with an outer body that looked hard and spiny. What might it have been? 82.44.54.4 (talk) 18:18, 21 August 2010 (UTC)

We can answer these questions much more easily if you could tell us roughly where you live. Which country, which state? (I also gave your question a more useful title "Question" doesn't really help much!) SteveBaker (talk) 18:23, 21 August 2010 (UTC)

If the IP address is any help, the questioner is located in the UK. Woodlice normally aren't spiny, though they can appear to be blue. Could it have been a short blue spiny caterpillar or other larva? (Sometimes, the caterpillar's appearance is even described as "woodlouse-form". --Sluzzelin talk 18:42, 21 August 2010 (UTC)

Sorry, I missed the "hard" part in your question, which make caterpillars and other larvae seem unlikely. For woodlice, we have a list of woodlice of the British Isles. "Blue" isn't mentioned, but Philoscia muscorum looks blue on that picture, though its color is described as "mottled and greyish-brown". I was perhaps a bit quick claiming that woodlice normally aren't spiny. Stenophiloscia glarearum is described to have "a distinctly spiny dorsal surface", but it is also long and white, not short and blue. Another one from that list, Styloniscus spinosus, has a name suggesting spininess, but the entry lacks any description whatsoever. I wasn't able to find photographs of either of the potentially spiny species. ---Sluzzelin talk 14:50, 22 August 2010 (UTC)

Not a woodlouse, but a silverfish might be what you're referring to from the description. Mikenorton (talk) 15:39, 22 August 2010 (UTC)

Callus

When you develop a callus, is it there for good (permanent) ... or is there a way to make it go away (i.e., reverse the process of the skin hardening)? I am referring to a small callus on the palm of the hand, as the result of constant (daily) use of a gym treadmill. Once I noticed the callus, I started wearing weight-lifting gloves. But will these small calluses (calli?) eventually go away and disappear on their own? Or can I do something that will make them go away? Or am I stuck with them permanently now that they have arrived? Thanks! (64.252.34.115 (talk) 19:10, 21 August 2010 (UTC))

Pretty sure a doctor (presumably a dermatologist?) could answer these questions. Medical advice it outside the remit of the Ref Desks, but our article callus has a few ideas - it seems calluses are removed, rather than reversed. 90.195.179.233 (talk) 19:30, 21 August 2010 (UTC)

Anecdote from personal experience: fifteen years ago, I used to carry a heavy case into work every day. A long and tough callus built up across my palm from the handle. Today, I can still feel where it was, but it's only a soft bump, difficult even to notice. I assume that it vanishes as the skin is constantly renewing itself. Oh, and the Latinate plural is indeed calli, though I think as it's a common English word you'd be fine saying "calluses". Marnanel (talk) 20:13, 21 August 2010 (UTC)

See Callus#Treatment. They may go away on their own, they may not. You can use pumice to grind it off if you wanted to, if you are not diabetic. There are also chemicals you can use to dissolve them. They sell things like this in the "foot care" section of your local pharmacy. You might talk to a pharmacist about this, if not a doctor. --Mr.98 (talk) 00:28, 22 August 2010 (UTC)~

Callous care advice and warnings. (video) Cuddlyable3 (talk) 11:25, 22 August 2010 (UTC)

Not sure how much advice I'd take when the authors can't even spell it right. --Trovatore (talk) 17:57, 22 August 2010 (UTC)

The Brain

What part of the brain is imagination synthesized, specifically art, music, literature, ect. Maybe someone can satisfy my insatiable desire for knowledge by adding some interesting facts? Like maybe how does someone come to "enjoy" certain representation of art yet not others as much or not at all (e.g. music like deathcore compared to RnB?). 99.114.94.169 (talk) 22:03, 21 August 2010 (UTC)

There is no definitive understanding of exactly how one derives pleasure. Have a look at Pleasure#Neurobiology, Pleasure center, Emotion#Neurobiological_theories, and Perspective (cognitive).Smallman12q (talk) 22:54, 21 August 2010 (UTC)

Is that the best of Wikipedia can give me? I was hoping for some discussion on theory? Are there any theory on why people njoy certain types of music/art/literature, while other may prefer something completely different? 99.114.94.169 (talk) 23:52, 21 August 2010 (UTC)

You usually have to wait more than 2 hours on a weekend. People have lives, you know, and we're just volunteers. But I do suspect that Smallman12q's answer is probably about as good as it gets. You seem to be assuming there are distinct, known, physiological structures responsible for different types of cultural appreciation. I'm not sure there's any evidence of that, at least with out current understanding of the brain. The neurological domain may be a bit too fine-grained for the level of analysis you are talking about. --Mr.98 (talk) 00:30, 22 August 2010 (UTC)

Harsh? Well, by the tone I was assuming that was the best answer I was going to get, but I was hoping otherwise. Well maybe if I tried something different... What part of the brain processes music, would it be the same part that processes other auditory stimuli, and art likewise? Then what of literature? Or maybe does it starts there and then what part of the brain says its "enjoyable." The I guess i can do some reading on the associated article. 99.114.94.169 (talk) 00:53, 22 August 2010 (UTC)

Take a look at music-related memory, artistic inspiration, creativity, sleep and creativity, lateralization of brain function, reading comprehension, and imagination. ~AH1^(TCU) 01:02, 22 August 2010 (UTC)

There is still a lot of argument about how imagination works, but one popular view, backed especially by Stephen Kosslyn, is that the sensory parts of the brain play a major role in imagining things in a given sensory modality, especially the higher-level sensory areas. So when you imagine music, your auditory cortex is active; when you imagine a painting, your visual cortex is active; and so on. Other areas are active too, though, including parts of the frontal lobes. Looie496 (talk) 01:07, 22 August 2010 (UTC)

Thank you, I did some looking around and found some more interesting reads. Such as Cognitive Neuroscience of Music, Music and the brain, and Amusia, a disease affecting perception of music. So it is commonly believed that each individual sensory area specializes and forms its own cognitive imagination? Or would it be more likely they all go to a certain part of the brain? And what part of the brain is the picture seen at the top of Amusia? 99.114.94.169 (talk) 01:16, 22 August 2010 (UTC)

The section highlighted in that image is a portion of the temporal cortex. You could also do a search on google for "audio perception theories", or if you're more determined/interested, go through "theories+of+audio+perception" relevant books. The process of Perception#Theories_of_visual_perception is not yet well understood...though you might like to read Philosophy of perception. Sensory neuroscience is a fairly modern field and currently does not currently offer an in-depth explanation for how senses are perceived. That aside, you are welcome to debate the theories behind perception and pleasure, (as well as Nature vs nurture and stereotypes). Just a friendly FYI, you'll probably get more responses during the week so stick around. Hope I've at least somewhat satiated your otherwise noble unquenchable thirst for knowledge. Cheers!Smallman12q (talk) 02:07, 22 August 2010 (UTC)

Here is a recent paper entitled "Towards a neural basis of music-evoked emotions", which may be of interest. --Mark PEA (talk) 10:22, 22 August 2010 (UTC)

August 22

Strange shadow

Shadowing the bottom edge of the light source shifts the position of the lower edge of the umbra/upper edge of the penumbra. Wnt (talk) 12:23, 22 August 2010 (UTC)

I observed few years ago that when one shadow nears another they start to merge, but before they do they appear to ”reflect” each other. I figured description wouln't make much sense, so I took a picture of shadows casted by my fist and pipe - observe how an extra fist appears to be coming out from the pipe (the shadow also shows a welding on the pipe which was behind my hand). I noticed this ilusion again tonight and since I didn't find any explenation the first time around, I decided to ask here - what exactly causes this ? ~~Xil (talk) 01:14, 22 August 2010 (UTC)

I think this would be an example of an Umbra. 99.114.94.169 (talk) 01:39, 22 August 2010 (UTC)

I don't think so - as far as I understand umbra is the darker part of shadow, which you can see, but it is not what I want. In case it is hard to see shadows in first pic (I chose it because you can see what is going on with the objects in case placement is important), here is another one which might ilustrate the ilusion itself better ~~Xil (talk) 02:03, 22 August 2010 (UTC)

What you have photographed is an elementary diffraction pattern. Diffraction accounts for many visual anomalies that exist in our daily lives but that we mostly take for granted. Dolphin (t) 02:19, 22 August 2010 (UTC)

I don't think you understand what I am asking. Lightwaves bending around small objects still appears to be related to color of the shadow not the shape and as for ”our daily lives” - I have never noticed this happening anywhere else, I assume it needs certain conditions to happen. If not, please, elaborate how difraction causes this mirrored shadow to appear. In any case I want to know how to replicate this somewhere else ~~Xil (talk) 10:23, 22 August 2010 (UTC)

The region of interest is the overlap of the penumbra or soft gradients at the edges of the shadows. An object produces a penumbra when the light source is larger than a point. The two penumbra of the fist and pipe are due to obscurations of different parts of the distributed light source, which may be uneven. This explains why the umbra grow unevenly as the penumbra merge. I don't expect any diffraction effects where the light is not correlated and the dimensions are many orders of magnitude larger than the light wavelength. Cuddlyable3 (talk) 11:08, 22 August 2010 (UTC)

I notice that happening too. When I put my hand in the sunlight coming through a window, the shadow "stretches" when it nears another shadow. --Chemicalinterest (talk) 11:14, 22 August 2010 (UTC)

Cuddlyable is correct. The poster who led you to umbra was also on the right track - you're seeing the conversion of penumbra to umbra based on a narrowing of the light source as indicated in the figure. Wnt (talk) 12:23, 22 August 2010 (UTC)

I still can't replicate it. I tried nearing my hands to each other under a lamp - the penumbras overlap normaly, no mirroring ~~Xil (talk) 13:13, 22 August 2010 (UTC)

Put one hand closer than the other. You should try (I think) to reach the apex of the lower triangle among the four made between the Sun and the Earth on the umbra diagram. You can't do that if your hands are at the same distance from the light source. Also note a broader source like a window will yield more visible results. Wnt (talk) 15:38, 22 August 2010 (UTC)

Black drop effect. ~AH1^(TCU) 17:46, 22 August 2010 (UTC)

To the left - what normaly happens when shadows overlap. To the right - what happens here ~~Xil (talk) 18:21, 22 August 2010 (UTC)

My hands don't have atmosphere :) besides that appears to be diffrent kind of streaching. I'm not sure it is clearly visible in pictures I took so I'made another ilustration to avoid confusion ~~Xil (talk) 18:21, 22 August 2010 (UTC)

Water

Why is water a pre-requisite for life for every known thing in the world. What's in it that makes it invigorate crops and fuel our body's and how does it work after all its only 2 parts hydrogen and one part oxygen, what so special about that? --Thanks, Hadseys 02:10, 22 August 2010 (UTC)

See water, there is an effects on life section. There are many different reasons why water is important, it is considered a universal solvent, meaning many materials easily dissolve in it and allows compounds to react in ways that are required in metabolism such as anabolism and catabolism. Also, it doesn't fuel our bodies, autotrophic organisms require CO2 and water plus an energy source (usually light in the form of photosyntesis) to produce glucose which is then used for energy and leaves the byproducts water and CO2. Water also has a neutral pH. These are just some of the roles it plays, as to why it has the properties it does is because the arangement of the valance electrons in the atoms that water is composed of and the way those elements bond to one another.--74.67.89.61 (talk) 02:35, 22 August 2010 (UTC)

Water is special because life originated in water, evolved there, and to this day most living things are made up largely of water. It is a matter only of speculation whether extraterrestrial life might have originated in other solvents - while some speak of the advantages of water for life, it is difficult to say how advantageous it really is by the standards of some other life we've never seen. Wnt (talk) 12:30, 22 August 2010 (UTC)

Actually no, water really is special. All the hypothetical types of biochemistry have severe problems that probably make them impossible. Ariel. (talk) 17:16, 22 August 2010 (UTC)

Spider

Can anyone help identify a spider without a picture? It's body is about the size of the index finder distal phalanx. It's body and legs are hairy. It has about 3 black bands on each leg. It seems to be a reddish/brownish color. The back end of the spider has a black circular spot with 2 yellow dots in it. It is not hiding his fangs as they are massive. It seems to be extremely aggressive. The web is massive. It is spinning it starting from the outside then going inside. I currently reside near Pittsburgh next to a wooded area. I'm mostly concerned if it is poisonous but I'm not going to mess with it either way. I'll have someone else take care of it. :) 74.109.217.103 (talk) 02:36, 22 August 2010 (UTC)

After taking a quick look it seems to be a typical Orb-weaver spider. 74.109.217.103 (talk) 02:57, 22 August 2010 (UTC)

Could be a European garden spider? 99.114.94.169 (talk) 03:37, 22 August 2010 (UTC)

You might like to try this site Spiderzrule. Incidentally, I would suggest your little spider friend is being more defensive than aggressive - unless it came out of the woods chasing you to start with! Richard Avery (talk) 07:21, 22 August 2010 (UTC)

According to our article on spider bite, virtually all spiders are venomous (venom is an injected toxin; poison refers to other delivery methods, so spiders are venomous, not poisonous), with only three genera not being able to inject venom. That being said, most spiders are not venomous enough to do you serious damage and would much rather not have any dealing at all with monsters thousands of times their size (i.e. you). Matt Deres (talk) 13:37, 22 August 2010 (UTC)

Dissolved oxygen

Why warm water has less dissolved oxygen?117.193.106.26 (talk) 06:00, 22 August 2010 (UTC)

Basically this is Le Chatelier's principle and results from the fact that dissolving oxygen in water is exothermic. This website has a good and fairly non-technical explanation: [26]. I actually had to look up the answer to this question, which is scary considering that I studied a chemistry module at university only 2 years ago... time to dig out my old textbooks for a refresher! Equisetum (talk | email | contributions) 09:16, 22 August 2010 (UTC)

Warm water (or soda) contains less carbon dioxide too. You can see when you pop a can of warm soda, it fizzes much more. --Chemicalinterest (talk) 11:11, 22 August 2010 (UTC)

The dissolution of gas into fluid tends to be an unstable mixture. Gas particles tend to be light and subject to large changes in energy with typical collisions. Warm water contains more high energy liquid particles which are better capable of bumping gas particles out of the liquid and back into the air. 24.177.120.57 (talk) 14:05, 22 August 2010 (UTC)

Hydroxyl interaction between air and water may be affected by temperature. ~AH1^(TCU) 17:43, 22 August 2010 (UTC)

Titan's atmosphere

Titan has a pretty dense nitrogenous atmosphere (http://en.wikipedia.org/wiki/Titan_(moon)#Atmosphere). How has it been able to have such a gravitational field, being not heavy or large?Zachilles (talk) 08:01, 22 August 2010 (UTC)

Titan has a much weaker gravitational pull than Earth, indeed. However, it is also much further away from the Sun, so it is much colder. If you take a look at the Barometric formula (Equation 2 to be exact), the height at which the density (and pressure) of the atmosphere drops by a given factor -- say, by a factor of 1/2 -- is proportional to the ratio of gravitational pull to atmospheric temperature. This is one of the factors contributing to the atmosphere of Titan being so dense. There are probably others: maybe magnetic field of Saturn offers some protection from the Solar wind, maybe Solar wind is just too weak at those distances, and so on. Besides, Earth's atmosphere could have been much denser if it wasn't lost once already to the impact that split off the Moon, if you believe that hypothesis. --Dr Dima (talk) 09:26, 22 August 2010 (UTC)

How directly is the object's mass and distance from the sun related to its atmosphere? Venus has 85% of the volume of the Earth, 81% of the mass and 90% of the surface gravity, and is 70% of Earth's distance from the Sun. Yet the surface is twice Earth's absolute temperature, and the atmospheric pressure is 93 times Earth's. (Yes, I know Venus's atmosphere is mainly CO₂, which accounts for the temperature). CS Miller (talk) 19:09, 22 August 2010 (UTC)

Computer science

1. how computer works? how hardware, software, firmware, driver software, cmos bios setup, operating system, inter chip level program etc... are inter linked and works? explain with clear text, flow chart, diagram, animation, example and video-audio?

2. i want to make some own embedded system project. How can i integrate (hardware, software, firmware, driver software, cmos bios setup, operating system, inter chip level program etc...) these things?

3.How software controls and operates hardware with examples? —Preceding unsigned comment added by Pachaimalai (talk • contribs) 11:24, 22 August 2010

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. 90.193.232.65 (talk) 12:44, 22 August 2010 (UTC)

You have to be more specific...which type of computer...which hardware...which embedded system.Smallman12q (talk) 13:14, 22 August 2010 (UTC)

Well, the question is so broad, I'm not even sure it's homework. But in any case, the best place to start is in the articles: computer; hardware, software, and so on. We have articles on all of these topic with clear explanations, charts, diagrams, and so on. After you read the articles, come back with any questions you have, or if anything is still unclear. Nimur (talk) 16:17, 22 August 2010 (UTC)

Also take a look at computer engineering, integrated circuit and CMOS. ~AH1^(TCU) 17:39, 22 August 2010 (UTC)

To try to answer one part at a time:

1. how computer works? how hardware, software, firmware, driver software, cmos bios setup, operating system, inter chip level program etc... are inter linked and works? -- This is a vast subject, the things you've listed might take a full degree program in Computer Science to adequately explain. The starting point is our computer article. Start reading there, then follow the links as necessary to broaden the topic from there.
2. i want to make some own embedded system project. -- OK - but if you truly don't have the basics (which seems apparent from Question (1) then you're a long way from being able to do this. If you actually know more than your question (1) implies, then I would recommend you get an Arduino embedded computer and start to learn to program it and build hardware for it. You can pick up an Arduino computer for around $26 and there are VAST amounts of internet resources you can find to help you with hardware and software that you might wish to create to work with it.
3. How software controls and operates hardware with examples? -- Generally, there are 'special' memory locations inside the computer hardware which are either connected to drive external hardware - or to monitor it. On something like an Arduino computer, you can (for example) flash the LED on the board by writing either a '1' or a '0' to a particular location that the LED circuitry connects to. Similarly, if you were to connect a switch to one of the specialised pins of the Arduino circuit board, you'd be able to have your software read from some other special memory location and the value that you'd get back might be a '1' if the switch is closed and a '0' if it is not. On a more complex computer such as the one you'd find in a laptop or a cellphone, the mechanism is basically the same, but the "operating system" software (like "Windows Vista" or "Android") will take care of the details of how that works and allow the application software to talk in higher level terms such as files on disk rather than individual commands to the disk drive motors, etc.

SteveBaker (talk) 18:21, 22 August 2010 (UTC)

For 1. There are a number of universities that offer joint computer programming and electronic engineering courses. I'd highly recommend them if you are interested in designing your own computer from the CPU (or even logic gates) upwards. CS Miller (talk) 19:19, 22 August 2010 (UTC)

For the details of 3. see memory-mapped I/O, direct memory access and interrupt for some specifics. CS Miller (talk) 19:12, 22 August 2010 (UTC)

Instructions for Filtering Water in Urdu Language?

Can the above be found anywhere? Preferably with drawings or photos? It's for PK flood relief workers to pass out to IDPs. Am reading Twit posts about babies being given dirty water to drink. The disease risk is obvious, and basic instructions will help prevent the more serious maladies. Any and all help is appreciated. —Preceding unsigned comment added by Juju31 (talk • contribs) 11:29, 22 August 2010 (UTC)

I wonder whether WP:RD/L might be a better place for this Nil Einne (talk) 12:14, 22 August 2010 (UTC)

We can file a translation request for water filtration. As you can see from پانی, even the basic articles have poor coverage in Urdu; by comparison to other languages, we don't have many Urdu-speaking Wikipedians. I wonder if the World Health Organization might be a better resource in this case - they have a lot of information in many different languages. Here's their Pakistan Office website and their Basic Development Needs program (which includes water quality and sanitation). You might telephone their office to see if they already have a water-quality brochure that you can help distribute. Nimur (talk) 16:29, 22 August 2010 (UTC)

Indeed one advantage there is it would hopefully be better adapted for the local situation. For example, in Bangladesh a common recommendation is cloth filter of an old sari. This probably isn't such good advice in Pakistan as they aren't so common there (Sari#In Pakistan). Nil Einne (talk) 16:57, 22 August 2010 (UTC)

For Every Human

1. WHAT IS THE OBJECTIVE OF OUR LIFE( FOR HUMANS AS WELL AS A LIVING BEING)? 2. WHAT ARE THE PRINCIPLES OF LIFE? 3. HOW TO LIVE IN LIFE? —Preceding unsigned comment added by Pachaimalai (talk • contribs) 11:33, 22 August 2010 (UTC)

See meaning of life. I don't think anyone here (or anywhere) can answer your question. 90.193.232.65 (talk) 12:41, 22 August 2010 (UTC)

This is a matter of perspective. For analyzing life, see Life course theory. As for objective...Nihilism#Existential_nihilism argues that life is without objective meaning, purpose, or intrinsic value.Smallman12q (talk) 13:12, 22 August 2010 (UTC)

Put another way, probably everyone on here has a different opinion on this, but there is no way at all to distinguish with any reliability a good opinion from a bad one. Certainly no way to scientifically do it. It isn't a science desk question. --Mr.98 (talk) 14:23, 22 August 2010 (UTC)

If there was an ideal objective of life for every human, that would be both idealism and a specific ideology. It could just as well be different for everyone. The biological purpose is reproduction, the philosophical approach may be to seek purpose, and the humanistic ideal is humanism and so on. ~AH1^(TCU) 17:37, 22 August 2010 (UTC)

From a scientific perspective - we (and all other living things) have evolved to pass on our genes to the next generation. Humans (and many other species) also take care of and guide their offspring until they too can pass their genes on. We do this because evolution favors lifeforms that can do that and rapidly eliminates those who cannot or do not pass on their genes. SteveBaker (talk) 18:06, 22 August 2010 (UTC)

However, human population growth has gotten so out of control that people in poorer countries who once had many children are now having few children. Can purpose evolve? ~AH1^(TCU) 18:18, 22 August 2010 (UTC)

Passing genes does not mean "reproduce indiscriminately." It means, "make sure your genes survive into the next generation," which might be more ideally done if, say, you only have one child that you invest a lot of resources in, or, say, if you kill off all of your competitors. Evolution is rather "blind" about the means. This is one of the reasons it is not seen as particularly useful in looking for a meaningful sense of "purpose". It just makes clockwork machines of us all. It is not a very satisfying sense of "purpose". --Mr.98 (talk) 22:24, 22 August 2010 (UTC)

Laser Cutting of Metal Sheets

Sometimes after Laser cutting of M.S. Plates, they show the tendency of lifting up by almsot 50 mm - 300 mm. What will be the reason behind this behaviour of M.S. Plates? Which of any mechanical or chemical parameter playing the major role in this performence of Plates? —Preceding unsigned comment added by 220.225.75.226 (talk) 12:05, 22 August 2010 (UTC)

Are you sure you don't mean 300 micrometers? Lifting a steel plate by 300 millimeters is a heck of a lot. I suspect the cause is thermal expansion from the cutting laser. Nimur (talk) 16:39, 22 August 2010 (UTC)

Yes, but there were no substantial faults in the textbooks WE used!

Textbooks in scientific subjects allways have been, and presumably forever will have to be, rewritten time and time again (because the scientific knowledge and understanding grows as time goes by).

Still, a surprising lot of people, more or less consciously, seems to cling to a strange belief, which one occasionally may hear expressed by the claim: Yes, but there were no substantial faults in the textbooks WE used!
What I am refering to is the situation where the person seems to fully understand that science has progressed over the years, but seem to think that the textbook that himself or herself used is the full, complete and final truth about the subject, and that IT will stand unchanged forever.

I need some approved (published) research reports, proving that this kind of false belief really do exist.
Do you know of any? If so: Could you please help me with some references to it?

P.S.
I am familiar with the concept of the Bias blind spot, so that is not what I am looking for here.
--Seren-dipper (talk) 17:01, 22 August 2010 (UTC)

Not sure about research reports, but many textbooks in the United States promote Intelligent design, or label evolution or global warming as a "controversial" theory. ~AH1^(TCU) 17:33, 22 August 2010 (UTC)

That is surely interesting but not quite what I am after.
Moved clarification up into my original question
--Seren-dipper (talk) 18:12, 22 August 2010 (UTC)
--Seren-dipper (talk) 17:53, 22 August 2010 (UTC)

That seems like a strange position to take. Most people I've met have the opposite experience of discovering that the stuff they were taught from textbooks was wrong. SteveBaker (talk) 18:00, 22 August 2010 (UTC)

I fully agree that it is strange! But still I have met quite a few people who seem to think this way :-)
--Seren-dipper (talk) 18:12, 22 August 2010 (UTC)

Also take a look at lie-to-children. ~AH1^(TCU) 18:04, 22 August 2010 (UTC)

Also have a look at ignorance, confirmation bias, and the scientific method which describes how theories are corrected/changed as new evidence/interpretations are made.Smallman12q (talk) 20:01, 22 August 2010 (UTC)

People often cling to the high value of things that existed when they were young. See nostalgia. I haven't seen that apply to textbooks very much, personally. --Mr.98 (talk) 20:06, 22 August 2010 (UTC)

I'm with the others. I know lots of adults who cling to "what they were taught in school" about certain things, but that's in the face of any and every type of evidence (more recent advances in the field, corrected/amended editions of textbooks, more nuanced/specific/mature analysis, etc.). Is it even possible to distinguish textbook "mistake" from "newer knowlege" and "more advanced textbook"? DMacks (talk) 20:38, 22 August 2010 (UTC)

Interspecies crying

Hi. It is known that animals of one species, other than humans, often befriend a member of another species (do we have an article on that?). Often, a predatory animal befriends its prey, either domesticated or wild. There have also been reports of domestic animals crying. This often occurs as the animal realises it's about to be killed. My question is, and I thought of this one this morning, are there any documented cases of an animal (other than humans) crying over a member of another species? Thanks. ~AH1^(TCU) 17:23, 22 August 2010 (UTC)

Emotion in animals has some interesting links...but I think that some of the things you are stating as truth here are far from solidly known facts. Anyway - Koko the gorilla is known to have expressed sadness when her pet cat died - I'm not sure whether she actually shed tears though. Our article on the cat (All Ball) says that Koko made a sound akin to human crying - but there is no mention of actual tears. SteveBaker (talk) 17:57, 22 August 2010 (UTC)

Have a look at crying and this ask yahoo link, this link on crocodile tears. Are you asking if animals shed tears at the loss of another animal, or simply the display sadness/other emotions at the loss/separation.Smallman12q (talk) 20:06, 22 August 2010 (UTC)

Mostly the first one, I'm asking whether any animals shed tears during a display of sadness at the loss of another animal of a different species. ~AH1^(TCU) 20:37, 22 August 2010 (UTC)

Contact lenses

How can I tell if someone is wearing contact lenses, preferably without staring them in the eye for extended periods. Asking them in this context would be too personal and impolite, but I'm curious. 76.228.196.92 (talk) 20:10, 22 August 2010 (UTC)

You probably cannot. Contact lenses are pretty discreet and unnoticeable, even if you were to stare the person straight in the eyes for extended periods. Why not just ask them? It's not a particularly impolite question. And, with this individual, you must at least have a suspicion that they wear contacts. (64.252.34.115 (talk) 22:46, 22 August 2010 (UTC))

Thistle varieties that spread by root

What varieties of thistle (particularly those known in the Pacific Northwest) are spread by rhizomes or root pieces? I know that Canada Thistle is but that fortunately does not appear to be the more prevalent of the multiple thistle types we are now seeing in our pastures and fields. I simply don't have the time to go down the whole list of thistle varieties and check through multiple references for each to see. Help would be much appreciated. —Preceding unsigned comment added by Crwind (talk • contribs) 20:59, 22 August 2010 (UTC)

what kind of spiders?

spider 1

spider 2

What kind of spiders are these? They seem to be known here as banana spiders, but they don't seem to match. Bubba73 ^{(You talkin' to me?)}, 21:05, 22 August 2010 (UTC)

The images are not showing up for me. Click on the box and then Full Resolution. Bubba73 ^{(You talkin' to me?)}, 21:12, 22 August 2010 (UTC)

The first one appears to be a female Argiope aurantia. Deor (talk) 21:44, 22 August 2010 (UTC)

What's in between the dunes?

So, looking at the featured image of the day for August 22, between the sand dunes there's a large quantity of flat-looking gray/white/blue stuff. It looks to me like the surface of a frozen-over lake, or possibly a sky reflection. I don't think either of those makes sense, so what is it? Are there a lot of salt flats in that area, maybe? The NASA page the image came from doesn't give an explanation. --Anonymous, 21:52 UTC, August 22, 2010.

best guess is that this is a mirage - a reflection of the sky in trace amounts of water vapor boiling out of the sands and gathering in the troughs between dunes. notice how the effect gradually gets stronger towards the lower right (pretty much what you'd expect to see in a reflection with changing angles of incidences of sunlight). --Ludwigs2 22:07, 22 August 2010 (UTC)

The second picture in the Rub' al Khali article appears to show the same feature and is referred to as a "pale gravel plain", which would be a deflation surface covered with rock clasts too big to transport by wind, see Aeolian processes. Mikenorton (talk) 22:10, 22 August 2010 (UTC)

According to the description on Wikipedia: "The image, acquired by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) aboard NASA's Terra satellite, shows dunes as brown with gray regions being the underlying gravel plains." ~AH1^(TCU) 22:38, 22 August 2010 (UTC)

Unknown special character

Saw this double-arrow, inequality-like character here (p. 69 and forth), but can't figure out how to render in wiki (digged through Wikipedia:Math#Arrows, Wikipedia:Math#Logic and Template:Unicode chart Arrows, but found nothing like that). Copying from pdf doesn't help either. Twilightchill t 22:33, 22 August 2010 (UTC)