Wikipedia:Reference desk/Science

Wikipedia:Reference desk/headercfg

May 5

Interstellar probes end points.

To date, 4 interstellar probes were lunched. What stars will become end points of those probes? And, how long will it take for each probe to get there? TestPilot 01:06, 5 May 2007 (UTC)

When you say End Points are you asking what's their intended destination? Because as far as I know none of them were planned any further then leaving the solar system. --Kiltman67 02:28, 5 May 2007 (UTC)

StuRat asked a related question on April 29. He provided this, which gives some indication which way they were headed and how fast...after "lunch". Clarityfiend 04:46, 5 May 2007 (UTC)

Chemical rockets, like the ones used to launch those probes, are insufficient for interstellar missions. At their current speeds, it would take them thousands of years to reach even the nearest star at about four light years out. You can count on no serious interstellar missions until someone perfects and builds a solar sail, Bussard ramjet, or something along those lines. Maybe even an Orion if you have a pile of nukes handy. Someguy1221 09:41, 5 May 2007 (UTC)

Not necessarily. All that is required is patience. We can launch a vehicle with enough speed to reach solar escape velocity. So if we are patient we already have the technology. The way to get patient is to live much longer. As I have explained before, I believe we'll figure out how to transfer out intellects into computers within 30 to 40 years. At that point, you can lower the clock rate on your CPU and time will seem to simply fly by. Taking a thousand years to travel to the next star wouldn't be so terrible if it only seemed like a week of your life. SteveBaker 20:12, 5 May 2007 (UTC)

One was destroyed in Star Trek, as for the rest, see Olber's paradox

The current probes are moving so slowly they are likely to be collected by future faster craft and placed in museums before they reach any other solar systems. StuRat 08:08, 6 May 2007 (UTC)

Spider identification

hi i need another idetificaion on a spider as there are many here lol. i got more info then the last time i did this so here it goes. This spider has a clear brown body with a clear abdomin. almost see through and is acording to my aunt about 1 inch big. a bit from this spider isnt exactly deadly but instead it desulves your tissue quite quickly *bout a week for a large noticable area* i really want to read about this spider so a link to a article is much appreciated thanks!! User:Maverick423 If It Looks Good Nuke It 03:42, 5 May 2007 (UTC)

It might be a Brown recluse. The spider bite article lists all venomous spiders that bite humans. -Arch dude 11:14, 5 May 2007 (UTC)

The Brown recluse has a very clear fiddle shape on the back, which wasn't in the description. The wound characteristics do sound like the recluse. When it heals, the wound may be a depressed area like a bullet entry wound. Medical care is essential. Edison 15:09, 5 May 2007 (UTC)

Visible Laser Light

When looking perpendicular to/at a beam of green laser light what am I seeing? Just what is the beam? Would I see it as it passes through a vacuum?

12.175.230.38 04:33, 5 May 2007 (UTC)Greg

This has been asked before; you might find it searching the archives. But, as I recall, the consensus was that you would see laser light scattered by dust particles and other gunk in the air. I'm not sure what you mean by your second question; the beam is light, which differs from ordinary light by being all of the same frequency. No vacuum is perfect, so if the beam was intense enough, you might be able to see it. Clarityfiend 04:56, 5 May 2007 (UTC)

You wouldn't be able to see the beam even in a reasonably high vacuum. Scattering off tiny particles (like air molecules) is fairly inperceivable. I've never personally observed any noticible scattering of a visible-wavelength laser beam (several milliwatts) in a clean room environment (that is, an area where there are very few particles larger than a micron in diameter). Also, the photon created by a stimulated emission has identical phase and propagation direction to the (other) photon that resonantly couples with an excited electron of the same frequency and phase to cause the stimulated emission. Contrast with spontaneous emission (which dominates in sub-threshold semiconductor lasers and is the primary process by which LEDs operate), which releases photons of random phase and propagation direction (and less predictable frequency). Basically, the photons created by this optical amplification process are identical, which is what gives the laser its coherence characteristic. (line width broadening mechanisms in lasers are mostly related to variations in carrier population distribution, which in a nutshell changes the probability for stimulated emission at a given energy) -- mattb 05:42, 5 May 2007 (UTC)

I don't think most of that has anything to do with the question. Someguy1221 09:34, 5 May 2007 (UTC)

mattb, among other things, explained why you wouldn't see the beam in vacuum or in any Cleanroom environment. Also, the Physics portion of the Laser article talks about what and why of lasers. Shinhan 12:52, 5 May 2007 (UTC)

Sorry, my explanation did ramble a bit. The point of it was to explain a bit further about the stimulated emission process since the first response didn't make it clear that lasing implies more than simply monochromatic light emission. I don't think many people realize that stimulated emission does actually create identical photons, not just photons of the same energy. This is an important point. -- mattb 12:38, 8 May 2007 (UTC)

This is one of the comments made about movies - that laser beams would not just show themselves as being solid - in real life you would only see the laser as it hits dust particles or solid objects - so it wouldn't be visible in thin air. Also using fancy goggles to see them would not be very effective at all (apparently). Technologically the lasers in movies would also have to have a laser side that emits the laser beem and a receiving side the detects whether the laser is on or off (and when the burglar steps in front of the laser it does not get received by the receiver and a giant cage will then come crashing down killing the burglar) and apparently that type of technology is a) quite expensive, b) very hard to align the laser and the receive perfectly, and c) ineffective (there are motion sensors that could detect the presence of a burglar).

Apparantly the best way to see the lasers would be to spray a dusty/smoky aerosol.

Rfwoolf 13:48, 5 May 2007 (UTC)

And in fact I believe people working with lasers keep a can of aerosol smoke handy for precisely this purpose. —Steve Summit (talk) 15:06, 5 May 2007 (UTC)

Worth noting is that the path of very powerful visible wavelength lasers can be seen, even in clean dry air (see Rayleigh scattering for an explanation of why). Any laser source you're likely to get your hands on as a private individual won't be intense enough to be seen this way, however. TenOfAllTrades(talk) 14:49, 5 May 2007 (UTC)

Once you have powerful lasers, you can detect the beam by many of its "effects on the air" other than just reflection off solid particles. I used to know when I was near the ArF beam by smelling the ozone created due to ionization of O₂ in the air. Not quite the exact positional observation of "seeing" the beam, but still a good warning sign to make sure everyone was wearing UV protection. DMacks 13:44, 7 May 2007 (UTC)

The beam of a relatively low power "laser pointer" of 20 milliwatts is visible in daylight in a relatively clean dry office environment. Rayleigh scattering/filtering is wavelength dependent, and may alter/enhance the perceived "color", but not as I understand it, manifest it.

So, an apparent visible laser beam is the result of geometric reflections from sub-micron dust? 12.175.230.39 16:33, 5 May 2007 (UTC) Greg

Probably much larger than a micron (on the order of tens to hundreds of microns), but yes, dust is a big culprit. -- mattb 20:28, 8 May 2007 (UTC)

Stinging nettle

Is there any plant that displaces the Stinging nettle that I plant amongst them to drive them out? I know they thrive in wet soil (its under my hegde) and aside from cutting them back all the time, drying out the soil (near impossible) or torching them with napalm, driving them out with another kind of plant was the only thing I could think of. Preferably a kind of plant that I would like to have as a replacement! Or if not, any other good methods to torch the annoying things? Thanks SGGH ^speak! 10:44, 5 May 2007 (UTC)

weedkiller? Tomgreeny 14:54, 5 May 2007 (UTC)

I would also employ some serious week killer - but if you prefer something more organic...If you are patient - then pull them up with as much of the root as you can get - turn the soil over with a spade and cover the area with heavy black plastic (several layers of trash bags weighted down with bricks). This cuts off photosynthesis and will kill anything that germinates. Eventually you'll get rid of all of the seed in the soil and you'll be able to replant with something that can out-perform the nettles. Meanwhile - plant some Rumex obtusifolius ("Dock weed") - which is a natural cure for nettle stings. SteveBaker 15:37, 5 May 2007 (UTC)

Will try, thanks. SGGH ^speak! 16:25, 5 May 2007 (UTC)

You could also try dandelions, which poison the soil and stop anything else growing, but really they are worse than nettles. Or there is some japanese plant around that takes over whole areas, killing every other plant around it. If all else fails, very few plants of any sort grow well on concrete.

The nettle has extensive food reserves in its roots. You can get rid of them by cutting them back repeatedly for many years. Estimates vary between cutting them back 3-4 times a year in 2 years, to 3 times a year for 3 years (source: Royal Horticultural Society, via h2g2). --h2g2bob (talk) 20:11, 5 May 2007 (UTC)

That's why I advise pulling them up (with as much of the root intact as possible) - rather than cutting them down (which leaves you with an extremely vigerous root-stock for a tiny new plant to regrow from). Digging the soil afterwards helps because it exposes more of the seeds to the air and to animals to eat and allows the sun to dry out any remaining roots. But a plant can't survive long without photosynthesis - so covering the ground with black plastic for a while will help to prevent anything that does manage to germinate from growing into a vigerous plant. SteveBaker 04:00, 6 May 2007 (UTC)

With Ground-elder growing in my garden, stinging nettle has a hard time. For the few spots where stinging nettle still grows it can easily be cut down. Though ground elder is considered to be a weed, I can't see why. It's edible, it has no thorns and no woody parts that might hurt. If I was a three year old child, a ground-older field (head height for a child) would be paradise. 84.160.229.189 23:14, 5 May 2007 (UTC)

Nettles only grow (or maybe germinate) with relatively high nutrient levels. Maybe grow some greedy "gross feeder" plants like tomatoes etc. Or reduce nutrient levels, tried but failed to re-find article in "new scientist" on using sugar where fertizer has been spilled; microbial activity then supposedly reduces nutrient levels.Polypipe Wrangler 22:18, 7 May 2007 (UTC)

Mid Atlantic Ridge and transatlantic cables

How come all the communications cables laid across the Atlantic don't melt where they go over the mid-Atlantic ridge with all the tectonic/lava-y activity? No, I'm Spartacus 11:51, 5 May 2007 (UTC)

Why would they? Land / ocean surface over mid-Atlantic ridge is not all hot and molten; quite the opposite, vast majority of it is perfectly solid and quite cold. Take a look at Iceland: mid-Atlantic ridge goes right across it, yet Iceland is not split in half by a lava river ;) . Or did you have something else in mind? Dr_Dima

Now, as far as the tectonic activity goes, yes, earthquakes have broken submarine communications cables several times. Also, (somewhat off-topic), sperm whales are known to have tangled themselves in the cables laid on the ocean surface floor, with lamentable consequences for both the whales and the cables involved. Dr_Dima

Undersea earthquakes do break cables. See 2006 Hengchun earthquake, which seriously disrupted the Asian portion of the Internet. I looked at several cable maps at the time: a lot of different cable routes cross that area because it's on the shortest path for quite a few city pairs. That spot is on a subduction zone, not a ridge. -Arch dude 17:01, 6 May 2007 (UTC)

Individual People with full knowledge of a technology and its foundation technologies

I recently asked a similar question and got some very good answers - thank you all so much - and to a large extent I'm very satisfied with the answers I got and the references to look at.
I just have one more sub-question that wasn't answered that I'd like to posit again...

Question:
Are there individuals out there who have the knowledge of how to rebuild a technology from absolute scratch if they were transported with some labourers back to the pre-civilized world. Very much a hypothetical question, but I'm very curious to know if there are people in this world that have the knowledge to, for example, create electricity if they were transported back to say, 9000BC - keeping in mind that at this time there was very little technology in the world altogether - there would be no wire or furnaces or matches or chemicals or nothing. Just bush/jungle/grassland/swamps/oceans/mountains/forests and pre-civilization.
Or, is such knowledge highly unlikely to exist among single individuals?
You could ask the same question about Rocket Science (which comes after electricity I should hope), or nuclear technology, or aviation, etc

Please keep in mind that in this hypothetical question the individual that was transported back in time with his/her labourers would have no manuals or textbooks to rely on, in fact he/she would have absolutely nothing but his knowledge and the clothes on his/her back. Sure, they could invent paper and write the textbooks then if they wanted to, but as a rule to this question these people are expected to already have the knowledge, not just an understanding of textbooks and manuals.
Rfwoolf 13:41, 5 May 2007 (UTC)

I would say, certainly yes. While a written record, and an established technical infrastructure, are both hugely important, they are not absolute essentials: knowledge, once gained, is very difficult to quench. I would guess that a true expert in any field would have enough knowledge to rebuild that field -- if not from scratch, then from lower-level foundations which other experts could be presumed to be able to rebuild. (For example, a semiconductor designer or fabrication expert might not know enough about metallurgy and machining to smelt the iron and fashion the lathe to construct the vacuum pump necessary for semiconductor manufacture, but skilled metallurgists and machinists would.)

See also Renaissance man (a.k.a. Polymath).

It's an interesting question (as speculated earlier by Atlant) what the critical mass might be. The fewer people you have, the odds of having the right set of experts drops to zero. A single hyperpolymath might theoretically have enough smarts to rebuild or reinvent everything, but he wouldn't have enough time after searching for food, and he'd be too likely to be eaten by a bear.

(You set the bar too low, I think, when you ask about merely recreating electricity. That'd be easy; I'm sure I could do it. The only hard part would be finding copper ore and rediscovering how to refine it, because that I don't know off the top of my head.) —Steve Summit (talk) 14:54, 5 May 2007 (UTC)

Just send MacGyver. He could easily reconstruct mining, metallurgy, and electronics to build a powerful laser in a one hour episode, with 17 minutes deducted for commercials. Edison 15:15, 5 May 2007 (UTC)

Yeah - I think it's possible for a reasonably well educated person to 'bootstrap' technology from zero - the problem I think is doing it in one man's lifetime. First basic shelter, then stone knapping to make basic tools, then better shelter, then capture animals, redirect local water sources for irrigation - start up farming, then make charcoal, find clay, then build a really HOT clay furnace with animal-skin bellows to pump air into it - then try smelting various local rocks and see what metals you can make. Then establish standard units of time, mass and length - writing technology (charcoal on animal skins? Maybe start paper manufacturing.) - write down every equation you can remember or derive - start a library. Build up metal smelting, leather production, farming and timber production up to an industrial scale. Start work on tools - edged tools, hammers, adzes and such are no problem. Once you have those, your burgeoning civilisation may need defensive weapons - hopefully not. We need looms, spinning wheels, ploughs, carts and draft animals. Building saws, drills and metalworking tools comes next - a lot would depend on what metal ores you can find locally and smelt. About now you'll want to start a guild system so your population can start to specialise their skills and train youngsters. Pass on skills for sand-mold making and extrusion dies and such so you can fashion more sophisticated shapes from your metals. Now you need some magnets - there are natural rocks ('lodestones') - and you need your people to keep a continual lookout for them by dangling rocks from thin strings and see if they orient themselves north/south. With lodestones, you can magnetise the iron you've smelted - you should have the ability to melt copper into thin bars that you can then draw out into fine wires - from magnets and copper wire, you could make a simple electrical generator - which you could power with a water mill or animal power. Now you have electricity - your generator design will serve as a motor too - so now you have handy portable power - power tools become possible. Battery technology - leyden jars - that's doable too. I think I could manage to achieve all of those steps given a willing and loyal workforce and enough local resources. My chemistry is weak - so batteries and maybe some of the details of the smelting process would require some experimentation - but knowing the underlying principles should make experimentation go fairly quickly. But I think it would simply take too much time to do all of this in one lifetime. SteveBaker 15:26, 5 May 2007 (UTC)

Is it just me, or are some of the points in these answers reminiscent of the Golgafrinchans' attempts to colonise Earth? 80.169.64.22 16:29, 5 May 2007 (UTC)

The real difficulty here, as well as time, is that there are unlikely to be any shortcuts. Almost all modern technology requires most older technology to have been discovered/created first.

I strongly disagree. Do we need astrology in order to get to astronomy? Do we need to work for a while under the assumption (which we'll know to be false) that everything is composed of earth/air/fire and water before we can move on to chemistry? Certainly not. We'll know that bacteria are the cause of disease and to wash our hands often long before we regain the use of antibiotics. In fact, we could probably figure out how to isolate and grow penicillin in a beef broth before we even have farming back up and running! No - we emphatically wouldn't need to repeat the order of events from the past. SteveBaker 20:06, 5 May 2007 (UTC)

I think there are plenty of people that could go back in time and create, to a certain degree, objects of technological value today. I'm sure plenty of us could develop or redevelop techniques based on memory of general ideas, and, we are much more intelligent than they were, even the best of any historical society, I don't think would compare to, for instance some of us at the reference desk who actually have a good enough general knowledge and good enough skills at learning and finding new things (of course in our case, mostly the internet and books are used, but the same still applies I believe), that we would most definitely equal or beat them. A good swiss timekeeper might be stretching it. Two more notes: I asked a question in the past here about the possibility of building a piano from scratch. This morning I thought of how the "good swiss timekeeper" was made when I was watching a tv show about making watches. Evolution. It didn't just appear. One person didn't just invent the watch. It took hundreds of years and very tiny steps to eventually get to the mechanical or digital watch you may be wearing right now. Mechanical timekeepers were most needed as chronographers on ships, I believe. Pendulums don't work so well on the high seas. [Mac Δαvιs] ❖ 23:17, 5 May 2007 (UTC)

We have the Scientific_method. Doesn't that give us a big jump over all scientist/inventors up to the Renaissance. —The preceding unsigned comment was added by 136.224.90.29 (talk) 04:07, 7 May 2007 (UTC).

Regarding technology

Q. Why paper make noise on tearing ? —The preceding unsigned comment was added by 221.135.246.75 (talk) 15:30, 5 May 2007 (UTC).

As each of the microscopic strands of wood pulp breaks, the energy that's released will cause it to vibrate. That vibration disturbs the air nearby and the resulting air vibrations spread outwards like ripples on a pond - those a 'sound waves'. SteveBaker 15:39, 5 May 2007 (UTC)

Ferroxyl indicator

Do we not have an article on ferroxyl indicator? 81.132.215.242 15:37, 5 May 2007 (UTC)

I don't think we do - there is mention of it's ingredients and function here, where it says: Potassium ferricyanide is also one of two compounds present in ferroxyl indicator solution (along with phenolphthalein) which turns blue (Prussian blue) in the presence of Fe³⁺ ions, and which can therefore be used to detect rust. It is possible to calculate the number of moles of Fe³⁺ ions by using a colorimeter, because the very intense color of Prussian blue Fe₄[Fe(CN)₆]₃. SteveBaker 15:47, 5 May 2007 (UTC)

Do you know anything about ferroxyl indicator: why not add a page on it? --h2g2bob (talk) 20:00, 5 May 2007 (UTC)

Matter waves of photons?

I couldn't find it anywhere explicitly, but are the wave equations for light the very same thing as the matter waves (de Broglie waves) for a photon? —The preceding unsigned comment was added by 87.67.1.240 (talk) 16:28, 5 May 2007 (UTC).

Photons are light (light is made of photons). The de Broglie hypothesis still holds for photons. See also wave-particle duality. --h2g2bob (talk) 19:56, 5 May 2007 (UTC)

The how many-eth cousin is a chimpanzee

Chimpanzees are my great-great-great-... ...great-Grandfather's great-... ...great-Grandson so that makes us cousins like first cousin and second cousin, so what number would a chimpanzee be, and while we're at it, how about the number of a lobster and an oak tree. I think chimpanzees split 30 million years ago so it seems to be something along the lines of 1.5 millionth cousin(30 million divided by 20 years) but I'm not sure because I doubt that the average age of having a child over the 30 million years of separation humanity and chimpanzees is really 20 years because a chimpanzee has kids when it's younger, I think at an age of 6 or something, and I don't know about the lobster and oak tree. Thanks, Jeffrey.Kleykamp 18:09, 5 May 2007 (UTC)

You should read Richard Dawkins' book "The Ancestors Tale" - which shows all of the branching points for humanity going back in history - with approximate years (and numbers of generations where that information can be figured out). He says that Neanderthals and modern humans split 500,000 years ago. Chimps and humans split 6 million years ago - and he suggests 250,000 generations. Flipping throught the book at random, I'm seeing Gorillas at 7 million years ago (mya), other monkeys split off arouynf 40 mya, Amphibians 340 mya, FIsh 417 mya, but before that - we don't have any kind of reliable dating - our last common ancestor with the lobster was probably around 600mya - but that's uncertain. We don't know when we split with the oak tree - it's gotta be a billion years. SteveBaker 19:58, 5 May 2007 (UTC)

planning a family reunion? 59.180.41.78 20:19, 5 May 2007 (UTC)

W'all- I'll be a monkey's uncle! Edison 06:30, 6 May 2007 (UTC)

I figured out that we are chimpanzees 333,333th cousin 666,667 times removed, all you do is take the years when we separated (6 million) and divide that by the average years per generation (I picked 18) to get the number for the cousin-ship and then take the the years that we separated and divide that by the average years per generation (I picked 6) and subtract the number for the cousin-ship from it to get the times removed, does that seems correct?

The problem is that the "average years per generation" number is horribly variable - it's increased dramatically during the last 50 years. The article Generation says an average of 22 years is generally accepted. Also, there is no symmetry in the generational span between humans and chimps. Because Common Chimpanzees are sexually mature at age about 8 years - their generational span might average out at half that of humans - we would expect twice as many generations of chimps to have passed than generations of humans since our last common ancestor. But at the point of separation of the two species, our generational spans must have been identical - so the variation in generational spans over time is another big unknown. I don't think we can say how many generations have passed us by in any meaningful manner. SteveBaker 14:51, 6 May 2007 (UTC)

Steve, you abject pessimist, whaddayou mean it "can't be done"? The previous poster not only got a mathematically sound answer, he got it to six significant digits. You can't argue with that kind of math! —Steve Summit (talk) 15:14, 6 May 2007 (UTC)

The anon poster wins the "2007 Archbishop Ussher Award" for creative use of mathematics in the eternal quest for the truth. :) JackofOz 03:00, 7 May 2007 (UTC)

I posted the calculation and I can prove it, see [[1]], so send me my prize! ;P Jeffrey.Kleykamp 10:21, 7 May 2007 (UTC)

For your lifelong services to to the cause of excessive precision - your ceremonial golden decimal-point is on it's way to you! Of course being a mathematics award, it is a mathematical point.  :-) SteveBaker 23:52, 7 May 2007 (UTC)

non mendelian inheritance in arabidopsis thaliana

Hi folks. I was hoping you could help me with a question.

From "arabidopsis thaliana"

"Lolle and Pruitt agree that Peng et al.'s did observe cross-pollination but note that some of their own data, such as double reversions of both mutant genes to the regular form...."

I know what Peng's study said, basically they had bad design or something. I guess my question is what the h bomb is double reversion. —The preceding unsigned comment was added by 139.225.242.164 (talk) 18:34, 5 May 2007 (UTC).

Gene reversions occur when a mutant allele reverts to a wildtype allele. If the reversion occurs in a somatic cell, it will usually result in mosaicism. The mechanisms for reversion are numerous and not always fully understood. Examples involve Retrotransposons or unequal sister chromatid exchange. A double reversion would be when two genes revert to wildtype in the same organism. Rockpocket 20:52, 5 May 2007 (UTC)

I appreciate your time and effort. 139.225.242.164 21:04, 5 May 2007 (UTC) cyanide_sunshine

Skin Infection Rates

Where might I find data regarding skin maceration while wearing an orthopedic cast? RDunagan 19:56, 5 May 2007 (UTC)

Taking of Wallpaper

This is a duplicate question. Please provide answers at the question's first appearance on the Miscellaneous Desk.

I know this isn't really a scientifc question, but since this surely involves chemicals of some kind, does a chemist( or anyone) have any suggestions on how to remove wallpaper? I've heard of products like DIF, and home made mixtures of fabric softener with hot water, but do they work well? If not, what could I use? Thanks! Beeaz193 21:16, 5 May 2007 (UTC)

On HGTV they always use Downy fabric softener on wallpaper. Try checking the website of Sell This House, or a good search and it can tell you what exactly to do. I think they just brush it on and then wait. [Mac Δαvιs] ❖ 23:10, 5 May 2007 (UTC)

Find a local tool rental shop and rent one of those steam-based wallpaper strippers - they work like magic and don't fill your room with nasty chemicals. It's worth the cost just in saved effort. Check out the final section of our Wallpaper article. SteveBaker 01:08, 6 May 2007 (UTC)

Burning Calories

Since a (kilogram) calorie is the energy needed to increase the temperature of 1 kg of water by 1 °C, shouldn't one be able to burn calories simply by immersing themselves in a pool of cool water for an hour or so, and letting body heat warm the water? The Userboxer^Complain/_ubx 21:27, 5 May 2007 (UTC)

Yes, but it wouldn't be very efficient, because most of what heated the water would be the heat we give off as a matter of course. For comparison, one of the reasons why arctic explorers and mountaineers have such high caloric requirements (8000 calories a day IIRC), is to keep warm. Anchoress 21:44, 5 May 2007 (UTC)

Disagree although its going to take much longer than 1 hr. Since the Artic explorers do indeed need at least 8000 cal per day, if follows that if you are not consuming as many calories than it takes to keep you warm, you will lose weight. I believe some of the artic explorers lost about 14 llb per mo even though they were taking 8kcal per day. —The preceding unsigned comment was added by 88.110.17.225 (talk) 22:20, 5 May 2007 (UTC).

Disagree with the part about losing heat anyway. Cold water strips heat away from your body (and thus makes you burn more calories) much faster than cold air. Infact, 30C water (typical indoor swimming pool) feels colder than 22C air (room temperature or the temp of the air in the pool area) because it strips heat away from your body at a higher rate. And by the way, it sounds like you figure it's an "easy" way to lose the calories... but the fact is you will need more than an hour a day to see a difference and it would probably be more agonizing than doing something physical instead. Or maybe you should try a combination of both (ie do aqua aerobics in a colder pool).  Adam2288  T  C  04:04, 7 May 2007 (UTC)

May 6

Uses of propynol

I live on rain water and had a water tampering and found high levels of sulfer and iron and also propynol at 20-30ppm in a 1lt jar, the water was acidic at 4.1. My question is does sulfrik acid contain propynol or what everyday things in our home would contain it? The police are of no use out here in the country and queensland health could only tell me thier findings, I suspect that sulfrik acid or concrett lime was placed inside the tank but I am having trouble finding full list of poisions in the product list. regards Kenpeds 03:41, 6 May 2007 (UTC)

From here;

"Propargyl alcohol has several major use areas. They include: reactant/chemical intermediate; pharmaceutical intermediate; agricultural chemical intermediate; corrosion inhibitor; solvent stabilizer; and polymer modifier (ACGIH, 1992; Kuney, 1994; Lewis, 1993; STN International, 1995b). Some examples of these uses and some specialty or potential new uses are presented in Table 2. In addition to the above uses, ACGIH (1993) and Lewis (1993) list "soil fumigant" as a use for propargyl alcohol. However, further literature and database searching failed to substantiate this use; and, responding to a request for information, Dr. Bill Burnham of EPA's Office of Pesticide Programs (OPP) reported that he was unable to locate any record of this chemical being used as a fumigant (Burnham, 1995)."

Propargyl alcohol is a synonym for propynol. There's a bit of a list of more synonyms here. Aaadddaaammm 04:57, 6 May 2007 (UTC)

This sounds rather serious, like somebody is trying to kill you. I'd set up cameras and motion detector lights to catch anyone who attempts to poison you again. StuRat 07:54, 6 May 2007 (UTC)

If someone is actually trying to kill you, don't play amateur detective. Seek professional assistance; see my comment below. TenOfAllTrades(talk) 18:21, 6 May 2007 (UTC)

The most immediate concern is to prevent this from happening again, which is why the lights and cameras are needed, this will discourage another poisoning, or at least make you aware when it happens, much like tamper-evident packaging. Also, if you can produce footage of a neighbor dumping something into your water supply, this would also likely justify a search warrant, and/or arrest, by the police. StuRat 05:08, 7 May 2007 (UTC)

I have all the set up camers and lights ect ect now and I know who the person was but proving it is different, I looked up the info you sent but has anyone got the making of what the propynol would have come in? I was thinking sulfurik acid becorse of the smell and fumes being a steem like vaper coming out of the tank. the tank was full 25,000 ltrs which run the whole house and the propynol was 20 to 30 ppm in a 1 ltr sample, so I am trying to work out how much was used and how long was I drinking and washing in it before the chem reaction happend? my 21 month old girl was very sick and my wife who just had surgery was also sick with bleeding internal. I am just concerned for the long time health my little girl. Kenpeds 08:43, 6 May 2007 (UTC)

Is there any possibility this could be acid rain ? That would be the case if you sometimes get rain falling through gases in the air released by industrial areas in major cities. StuRat 17:56, 6 May 2007 (UTC)

No. Acid rain does not contain propynol, and a pH of 4.1 is quite a bit too low for rain in rural Queensland. TenOfAllTrades(talk) 18:21, 6 May 2007 (UTC)

If you believe that you have been poisoned (deliberately or accidentally), your best bet is to see your physician (and your daughter's pediatrician). Be sure to bring a copy of the water testing report and the MSDS: link. Propynol is a common ingredient in corrosion inhibitors; it is widely used in industry. (Is it possible that there was some sort of accidental backflushing of a heating or cooling system liquid loop into your water? Such systems often contain corrosion inhibitors and various other nasty chemicals.)

For your reference, a single bottle containing 500 mL to 750 mL (a pint to a pint and a half) of propynol would be sufficient to produce a concentration of 20 to 30 ppm when uniformly mixed into 25 000 liters of water. It is not going to be an ingredient in sulfuric acid; the two chemicals are incompatible.

If you have reason to suspect that the contamination was deliberate, go to the police. Be prepared with the water testing report, MSDS for propynol, any medical reports on health problems you believe (or your physician believes) are related to possible propynol exposure, and a description of your water system's design. Your physician may also – with your permission – be willing to speak directly to the police. If you feel that the local police are not providing sufficient assistance, the Queensland Police Service website provides contact information for police headquarters as well as instructions for registering complaints.

While the suggestion above to include security lighting is not a bad idea from a general security standpoint, please don't assume that it's your responsibility to play Remington Steele and do all the investigation yourself. Your health is too important to leave to amateur detective work, and I am aghast that someone would suggest you deal with all this on your own. TenOfAllTrades(talk) 18:21, 6 May 2007 (UTC)

But before getting all worked up and starting a legal case, please first consider StuRat's idea about acid rain for one more moment. The few measurements of rain pH in rural tropical Australia have shown an average pH of 4.5, similar to Sydney levels, largely from natural vegetation sources of acidity [2]. A few values as low as 3.5 have been measured. The rain pH is highly seasonally dependent in tropical Australia, with the lowest pH values occurring in November at the beginning of the wet season. Thus a pH of 4.1 isn't extraordinary. Where in Queensland are you located, and when did you collect the water? Are you in the tropical region? Are you near or downwind from any human acidity source, such as the Mt. Isa smelter or some local power plant? As for the Propynol, note its use as a polymer modifier. Do you by any chance use a plastic tank? Or do you pipe the water through plastic tubing? If so, you might consider whether the propynol could have simply leached out of the plastic. Modifiers such as plasticizers are notorious for leaching or outgassing from plastics. The water presumably spends a lot of time sitting around in the tank and tubing. As for health effects of propynol, the US Environmental Protection Agency, based on very limited data, suggests a reference dose (a concentration estimated to yield "negligible" risk of health effects over a lifetime of exposure) of 2 micrograms per kg of body weight. That would correspond to only a few grams daily intake of your tank water. So you may want to fix the problem, if the concentration is reproducible. Before freaking out too much, however, note that the EPA reference value was based on an "uncertainty factor" (a factor they lower the reference value by when they don't have clear toxicity data, in the spirit of "better safe than sorry") of 8000. --mglg_(talk) 19:31, 6 May 2007 (UTC)

Hi all, no the tank is steel and qld health advised me that the leavals they found was to high to be in acid rain, I have found that Hydrochloric acid uses Propynol as a solvent and that might explain my eyes burning and blisters, also the rooten egg smell and viper like a steem coming from the tank??? as far as I can work out we where exposed for probely 3-4 days before I noticed the vipper from the tank. I live outside of Kilcoy 1hr from brisy and no factery or industral sights near us. The water was all 100% rain collected and the tank overfloed the day I found the affects. We are waiting on QLD police complaints to get back to us (public holiday today) as for my lighting and security camers all I can prove with them is what I capture at that time and it might only be simple tresspassing. At less I have gotten more ideas and info in the last 24hrs of this sight then all my questions and surching over the last 6 weeks on others. also everyone in my area are on tank water and no other complints or pollution have been reported. a house 2 doors down had a falling out with this man 3 years ago and the next day he found a white substance in his gutters testing was done on his water and the powder but nill to report as not anougth was found (same police still) and to him it is all just a pain in the ass. again thank you all for your help and ideas and keep them coming as the more info I have the more situations I can discount Kenpeds 21:57, 6 May 2007 (UTC)

Do you live close to a mine? Acid mine water from mines is incredibly acidic (pH values of -3.3 are common); only a few millilitres leaching into your water tank could reduce the pH to 4.5, and it's quite possible that propynol might be used in the mining industry, getting mixed in with the runoff. Laïka 11:44, 7 May 2007 (UTC)

With that acidity, if it is Hydrochloric acid, wont the zinc dissolve as well? Is this persons tank at risk of damage? (should the water be dumped and pay for more water rather that risk tank damage?).Polypipe Wrangler 22:14, 7 May 2007 (UTC)

I have found that Propynol is used in Hydrochloric acid so I must have assumed the wrong acid. The tank water has been dumped (25000ltrs) and the tank is getting replaced. New question is how much acid in that size tank I am taking a guess but would 10 ltrs be a ball park?? Kenpeds 02:30, 8 May 2007 (UTC)

Brainstorming specific examples for biology themes

Hi,

I'm trying to create a list of specific examples for the following themes in biology. I've got a couple of examples, it would be great if you could add to the list. Alex Ng 04:28, 6 May 2007 (UTC)

Energy Transfer Concept that energy flows from the sun into plants and into animals that eat them. Could look at energy currency in the cell (ATP)

Continuity and Change/Evolution

Relationship between Structure to Function

(Polymers) Cellulose: Beta-linking of glucose monomers results in firmness in plants

(Different organs/parts of organs and their functions)

Neuron:	Narrow shape (high SA/V ratio allows for quick change in Na/K ion concentration.
Node of Ranvier	increases speed of impulse transmission
Na/K Pump	maintains resting potential/restores resting potential
Villi:
Smaller microvilli	increases surface area for reabsorption
Single cell epithelial	faciliates reabsorption of nutrients
Alveoli	Massive, branching surface area allows for rapid oxygen uptake, carbon dioxide dumping.
Single cell epithelial	faciliates diffusion of oxygen and carbon dioxide
Moist membrane	faciliates diffusion of gases

PROTEINS. The structure of proteins dictates their function. Their 3D (tertiary) structure is dictated by their primary structure (amino acid sequence) which is dictated by the gene.

You could look at gross anatomy stuff, like um... long legs -> running, egg shell shape -> can't break it, gills -> breath underwarter, structure of the skin keeps stuff out (and in!)...

I would actually phrase it - lungs ->breath above water, since, you know, it's newer ;-) I'm not even gonna make a guess on where insect breathing apparatus fits in, though :-/ Someguy1221 05:26, 6 May 2007 (UTC)

Regulation/Homeostasis:

Blood glucose concentration (insulin lowers blood glucose levels by storing glucose as glycogen, glucagon increases blood glucose levels by doing the opposite) Maintaining proton gradient in mitochondria to keep ATPase making ATP. Glutathione reductase keeps glutathione reduced which keeps the right proteins disulfide-linked.

Interdependence in Nature

Examples of Relationships in Nature:

Relationship	Example
Neutralism (no affect on both)	A lizard resting on a tree root, neither ones really gives a damn.
Amensalism (one is negatively affected)	Bread mold Penicillium secrete penicillin that kills bacteria
Commensalism (one is positively affected)	Can't recall the general name, but plants that live on the bark of trees. The former gets a place to live, the latter is unaffected so long as the former isn't eating it.
Synnecrosis (both negatively affected)	One animal eating some other, poisonous animal.
Mutualism (both positively affected)	Cellulose digesting bacteria in cows steal food from the cow but help them digest grass.
Predation/Parasitism (one positive, one negative)	ANY PARASITE, but i like tapeworms

Re: Today's Feature Picture

"evidence of large bodies of liquid methane on Titan"

....according to the images taken by the Cassini orbiter.

My questions are:

1. Has methane been scientifically and absolutely identified?
2. What could be the source of such substance in a place like Titan?
3. Whence the carbon atom in methane????????????????
4. Has wave activity been recorded on the surface of the "75 large bodies of liquid" ??
5. What is NASA's "definitive evidence opf lakes fillled with methane" on Titan??

Thank you,

(email removed to prevent spam)

(Note: Question reformated to be easier to read, but words were not altered in any way by Sifaka ^talk)

3) Carbon is common on small bodies throughout the solar system. It also exists on larger bodies (Jupiter, Saturn, Uranus, Neptune, and the Sun), but is rare compared with the huge volumes of hydrogen and helium such bodies retain due to their higher gravitational attraction. StuRat 07:43, 6 May 2007 (UTC)

Our sub-article: Titan (moon)#Liquids on Titan says scientists have "definitive evidence of lakes filled with methane on Saturn's moon Titan" and provides this source. Rockpocket 07:50, 6 May 2007 (UTC)

As for (1), you can confirm what element something is just by looking at it - see emission spectrum / absorption spectrum. --h2g2bob (talk) 08:37, 6 May 2007 (UTC)

Exactly, there were a number of elements that were discovered this way, such as helium whose emission spectra was first identified in the Sun, hence the name. And if I'm not mistaken, this was prior to its discovery on Earth--VectorPotential^Talk 18:00, 6 May 2007 (UTC)

You are not mistaken. That's why the name is wrong: -ium is a metal suffix, but helium is a non-metal. Most elements are metals, I suppose, so it was a reasonable guess. Algebraist 10:32, 7 May 2007 (UTC)

Watts

Hi, I'm trying to work out how many watts a household device is, but dont have any specialist tools. I baselined the current house load by timing the electricity meter outside, then turned on the device and measured again.

The meter wheel measures in kwh (kilowatt-hour) where 266.6 turns = 1kwh

The initial baseline measurement was 43.3 seconds for a single turn.

After the device was turned on, it changed to 25.97 seconds for a single turn.

I'm figuring I should be able to do some math to figure out the wattage, but dont seem to be able to. Please help. E!

Let's see:

43.3 secs for a turn means 3600/43.3 or 83 turns per hour. That's 83/266.6 or 0.312 kw or 312 watts.

26 secs for a turn means 3600/26 or 138 turns per hour. That's 138/266.6 or 0.520 kw or 520 watts.

So, I get 208 watts. Anyone care to check my math ? StuRat 07:36, 6 May 2007 (UTC)

Much appreciated StuRat, the math looks good. I guess I just realised that a watt-hour and a watt are the same thing!! E!

They're not quite the same thing. If you leave a 100 watt light bulb on for an hour, that is 100 watt hours. If you leave the 100 watt light bulb on for a half hour, that is 50 watt hours. StuRat 08:23, 6 May 2007 (UTC)

1 watt-hour is equivalent to 3,600 joules. This is because 1 Watt is 1 joule per second. It already has time built in. Watt x Time = Energy (joules). So Kwh is just a measure of energy used. So, I dont think the math is right. Let's see if I can figure out what I mean.

43.3 secs for a turn means 3600 secs/43.3 secs per turn = 83 turns per hour. That's 83 turns per hour/266.6 turns per KWH or 0.312 kw-hours per hour. Ah, so the hours cancel and you are left with just kilowatts. So, the above math seems to be right. Mrdeath5493 14:07, 6 May 2007 (UTC)

Just to be thorough, this method of measurement seems very susceptible to error, but it looks to be the best you can do for now. Mrdeath5493 14:12, 6 May 2007 (UTC)

If you are going to do those kinds of tests, I'd make sure to unplug your refrigerator, freezer and turn off any electrical heating or air-conditioner (don't forget water heaters) for the duration of the test. Those things are on thermostats and may turn on and off at random during your experiment. Since they are all high wattage devices, that would drastically mess up your readings. But User:StuRats math seems solid to me. SteveBaker 14:20, 6 May 2007 (UTC)

Please look for a kh factor inscribed on the meter. It allows a direct conversion from seconds per revolution to watts. P.S. I doubt that anyone can accurately time revolutions to the hundredth of a second as claimed. Edison 05:21, 7 May 2007 (UTC)

Sure you can - count 100 revolutions - a stopwatch is accurate to a second - divide the answer by 100 - accuracy for one revolution is now 1/100th of a second. All it requires is patience. SteveBaker 23:40, 7 May 2007 (UTC)

I got some complexes in dealing with complex ions

Up to 5 minutes ago I used to believe that precipitates where covalent substances and now I discovered that there're neutral complex ions. I wanted to ask you how can you distinguish between neutral complex ions and covalent substances? Also in atmospheric oxidation eg Fe(OH)2 ---> Fe(OH)3 is it right to say that the oxidation was followed by a ligand substitution?

Oh also anybody know why negative mercury complex ions aren't called hydragates?Bastard Soap 15:20, 6 May 2007 (UTC)

Yup, something precipitates when it's not soluble...can be inorganic or organic and have ionic or covalent character, or be ionic with covalent ligands (or even covalent ions). Dissolve as much table salt as you can in a cup of boiling water, then cool it down, you'll get NaCl crystals. Regarding distinguishing a covalent from a net-neutral ionic, what's the form of the material (do you have some solid precipitate, trying to figure out whether it's ionic, or do you have a structural/chemical formula and trying to figure out what it is, etc)? Regarding naming, dunno. DMacks 19:58, 7 May 2007 (UTC)

My question was about how to figure between covalent dative compounds and simple covalent compoundsBastard Soap 10:50, 8 May 2007 (UTC)

Our dative bond page teaches that there's only a theoretical or academic difference between it an a covalent bond. Could you give some examples of pairs of things you'd like to distinguish? DMacks 13:26, 8 May 2007 (UTC)

So basically there are no experiments that prove dative bonding? Only theoretical inferences?Bastard Soap 13:07, 9 May 2007 (UTC)

According to the article, a dative bond is a covalent bond, the difference in names referring to a (slight) difference in how the bond formed in the first place. Algebraist 14:19, 9 May 2007 (UTC)

Yes, I knew that. What I want to know is if there are some experiments that prove dative bonding is actually taking place.Bastard Soap 18:17, 9 May 2007 (UTC)

Paper hydrolysis??

What happends to the bonds in a piece of paper when it is soaked in water?Bastard Soap 16:13, 6 May 2007 (UTC)

It's the same as the process of dissociation of salts and sugars in water. Water is capable of bonding to the components of the paper, and thus it is no longer so energetically stable for the paper to remain bound to itself. Someguy1221 17:32, 6 May 2007 (UTC)

So it's just partially dissolved? But I would imagine that some water molecules would get in between the structure of the paper as well, correct?Bastard Soap 18:19, 6 May 2007 (UTC)

Yes, and once they're there the paper would rather bind to the water than to itself. The only thing truly seperating this from the dissolution of table sugar is how huge the molecules are, and so you can think of the molecules as long strands bound together, that losen as water pulls them apart. But since they might be wrapped up in some odd fashion, it won't just desintegrate like sugar crystals. Someguy1221 02:10, 7 May 2007 (UTC)

False color satellite imaging

Why do most if not all photos taken by a satellite or any other unmanned vehicle in space are in false color? Why can't they send a true-color camera to take pictures? Examples being pictures of Mars and such. Never understood that. —The preceding unsigned comment was added by 99.244.236.45 (talk) 16:13, 6 May 2007 (UTC).

Many spacecraft do have "true-color" capability. However, they also captyre wavelengths beyond the spectrum visible to humans in hte near-infrared and ultraviolet wavelengths.To allow humans to guage certain realationships a scientist will map the recorded spectrum onto the visible spectrum.For instance: you cannot see the different temperatures of seawater, but hte infrared camera can detect the difference. We then map hotterto red and cooler to blue to show the differences.

The other reason to map colors is for aesthetics: a great many objects in the solar system are visually very boring, subtle shades of gray (for asteroids and the Moon) or brown (for Mars.) By remapping the colors, we can more easily see the subtle distinctions. -Arch dude 16:34, 6 May 2007 (UTC)

Additionally if you are taking pictures through a heavy atmosphere (i.e. Venus) then visual wavelength isn't useful at all. And there are plenty of true color pictures of Mars as well — Google Image search "mars surface" and you'll see a lot of them. --24.147.86.187 17:01, 6 May 2007 (UTC)

For most purposes, you need multispectral images in order to extract the maximum amount of information from the data. They often take photos at a range of different wavelengths - some visual some not. Most of the time the interesting data is available all across the spectrum - and if you are looking outside of the human visual range then you can pull more information out of the images using false color. But on some missions with a particular scientific goal the additional weight and power requirements for a visual spectrum camera may not be justified. Depends on what you are trying to find. SteveBaker 17:47, 6 May 2007 (UTC)

It would be very weird to *not* use imaging outside the human visual spectrum, since that's a totally arbitrary slice of the EM spectrum that happens to have evolved here on Earth where it's useful due to us being diurnal air-dwellers under a UV-blocking atmosphere. There's nothing special or more "natural" about 400 to 700 nm wavelengths. --TotoBaggins 18:32, 6 May 2007 (UTC)

There actually is. Earth's atmosphere is particuarly transparent in the 400-800 nm range. See Optical window for details. Out in space you are of course not bound by such contraints. Dr Zak 18:37, 6 May 2007 (UTC)

Yes, that's what I meant: we didn't evolve to use UV since it's so well blocked, and we didn't evolve to use infrared because we're diurnal, so it's just an accident of fate that the 400-700 nm range is "natural color" to us. --TotoBaggins 20:13, 6 May 2007 (UTC)

Well, not precisely an 'accident'. As omnivores - with a significant diet of fruit, we need color vision in order to be able to see when fruit is ripe - and when it's rotten. Carnivores don't need this ability - which is why (for example) cats and dogs don't have full color vision - it's more efficient not to have things you don't need. Similarly, we don't have UV or IR vision because we don't need it. However, honey bees can see in the ultraviolet and many carnivores (owls for example) can see into the near infra red so there is no particular reason why we couldn't have evolved to see outside of the 400-700nm range if there was a need for that. SteveBaker 05:09, 7 May 2007 (UTC)

Here's a few example links to browse on the topic of satellite hyperspectral, or multi-spectral, remote sensing. NASA's Terra (satellite) has several imaging devices on board. The MODIS sensor scans in 36 wavelength bands in the visible infrared range. The ASTER device scans in 14 different wavelengths in the visible range and infrared. These are not your ordinary RGB digital cameras! Meanwhile NASA's Aqua (satellite) has scanners like the AMSU, which scans 15 to 20 wavelengths, none in the visible light range (all microwave range I think). The QuickBird satellites, used for a lot of the imagery on Google Earth and Google Maps, are less data hungry, scanning in just the blue, green, red, and near-IR ranges. For other planets, there is the Mars Global Surveyor with its TES hyperspectral sensor.

Anyway, there's a few links to browse. One could spend a lifetime learning about this stuff, and some people do! Pfly 04:13, 7 May 2007 (UTC)

Earth's Spin

The previous question started me thinking. If you theoretically attached a giant rocket booster on the earth's crust to counter rotation (imagine that the booster wouldn't just break away with a piece of crust into space) and you blew up the moon to avoid it's annoying tides, the earth would never star spinning again?Bastard Soap 16:26, 6 May 2007 (UTC)

Well, one assumes that stopping the mantle from rotating wouldn't stop the vast liquid iron core from continuing to rotate. So when you turned off the motors, the friction between core and underside of mantle would gradually bring everything back spinning again. But I guess if you left the motors firing - adjusting the thrust to keep the earth from spinning, you'd eventually stop the core from spinning too. At that point, the earth would not start spinning again. SteveBaker 17:42, 6 May 2007 (UTC)

Being hit by a giant meteor might start the Earth spinning very slowly. StuRat 17:47, 6 May 2007 (UTC)

Many satellites are tidally locked to their gravitational big-neighbor the way the Moon is to the Earth. In the absence of spinning, perhaps the Earth would be lock onto the Sun, which would set it spinning at 1 revolution per year. --TotoBaggins 18:41, 6 May 2007 (UTC)

Also, that's going to take a *lot* of rocket fuel to stop the Earth from spinning. Maybe a mass-driver made with a supergun would be more environmentally sound? --TotoBaggins 18:45, 6 May 2007 (UTC)

A supergun uses fuel to propell a bullet which would impose a reaction of the earth, I'm not sure but I think in using rocket fuel you would have less losses of forcesBastard Soap 20:51, 6 May 2007 (UTC)

ahh heres a quick little experiment you can try for this. grab a regular egg spin it and then place your finger on the middle *gently* to stop the egg. release the egg and it will start spinning slowly again! its pretty awsome try it. User:Maverick423 Im in ur science steeling ur gravity 00:55, 7 May 2007 (UTC)

That's because the contents continue to spin, and quickly get the shell to spin again, too. StuRat 02:50, 7 May 2007 (UTC)

Which is the point of the experiment, and why Maverick suggested it... Skittle 19:59, 8 May 2007 (UTC)

Agreed, but it didn't seem so obvious that the original poster and all subsequent readers would necessarily understand without an explanation. StuRat 23:25, 9 May 2007 (UTC)

I don't think fuel is going to cut it (I can't find info on the energy content of rocket fuel, so I'm using petrol). According to my calculations, the earth has a rotational energy of about 2.6*10^29J. That's equivalent to about 7.4*10^21 litres of regular gasoline. So if we dug out all the earth's oceans to about 20km (about twice their current maximum depth), got rid of the water, and filled them with petrol, we would have about enough fuel for the task. If we could use it with 100% efficiency. </silly calculations> I think this plan is going to take UWTB. Algebraist 10:29, 7 May 2007 (UTC)

How about all the nuclear fuel in the world? (it was all just theoretical though mac)Bastard Soap 23:16, 7 May 2007 (UTC)

According to uranium, a kilo of uranium can produce 20TJ if you somehow completely fission it. So we're looking at about 10^17kg of uranium, i.e. 100 trillion tonnes. According to some random webpage, the earth's crust contains about 65 trillion tonnes. I'm too lazy to check up Thorium and suchlike possible fuels, so lets guess that they could make up the difference (my figure for the energy need is an overestimate anyway). So now all we need is a magic wand for extracting all uranium from the crust and putting it in our perfect reactors. Progress! (btw, who or what is mac?) Algebraist 14:17, 9 May 2007 (UTC)

You is mac. Then we can always cover up all the surface of the earth with a solar pannel Bastard Soap 18:49, 9 May 2007 (UTC)

Apnea

Are there any exercises which are specific to increase lung capacity and general respiratory pigment content in the body?Bastard Soap 16:30, 6 May 2007 (UTC)

Exercising at altitude will result in increased haemoglobin concentration in the blood. See Altitude sickness#Altitude acclimatisation for details of physiological adaptions (healthy and otherwise). David Ruben ^Talk 16:53, 6 May 2007 (UTC)

If a person has sleep apnea and is obese, then any exercise which helps them lose weight is likely to help. StuRat 17:45, 6 May 2007 (UTC)

Thanks but I was interested in particular exercises done at normal altitude which would have a particularly pronounced effect on lung capacity and respiratory pigment. I already knew about altitude aclimitasation and had thought about buying a hypoxic air generator but it's way too costly for a poor assed student such as me'self.Bastard Soap 17:55, 6 May 2007 (UTC)

I would guess that holding your breath would increase lung capacity, as would aerobic exercises, like jogging. StuRat 02:47, 7 May 2007 (UT

Blood doping by storing blood and adding it later works. So do certain hormones (EPO) that stimulant blood production. It's normally used to treat cancer or win the Tour de France. --Tbeatty 03:59, 7 May 2007 (UTC)

holding your breath helps alot. then stretch your chest by pushing it out while holding your breath. its what i do and it works for me. youll feel some pain but remember pain is weakness leaving the body =) User:Maverick423 Im in ur science steeling ur gravity 14:42, 7 May 2007 (UTC)

don't get anaemia.

And don't get an enema. (It's unlikely to help your lung capacity). StuRat 03:09, 9 May 2007 (UTC)

At least you will smell fresh inside :p Bastard Soap 12:36, 9 May 2007 (UTC)

42.2

I'm sure that the number 42.2 is important in atomic physics somehow, I just can't think where. Can anyone help me out? 128.243.220.42 19:37, 6 May 2007 (UTC) (User:Ollie)

I suspect 42.2 is just a pretentious version of 42, which is the most important number to the life, the universe, and everything. alteripse 19:55, 6 May 2007 (UTC)

Nah, this is proper physics I'm talking about ;) 128.243.220.42 19:57, 6 May 2007 (UTC)

42 (number), and [3] ? -- Consumed Crustacean (talk) 21:30, 6 May 2007 (UTC)

Could be one of the atomic weights of something? --h2g2bob (talk) 22:46, 6 May 2007 (UTC)

No, none of the above. I've now got home and had chance to look through my books and lecture notes, and I think I am making things up. All I can think is that I was getting mixed up with 54.4, the second ionisation energy of helium. Anyhow, many thanks for your suggestions. →Ollie (talk • contribs) 22:54, 6 May 2007 (UTC)

"Acrylic has an index of refraction of 1.49 for visible light4. Because the refractive index of

air is 1, total internal reflection occurs when the angle of the incident light ray is equal to or greater than 42.2°" (from here? —The preceding unsigned comment was added by Aaadddaaammm (talk • contribs) 02:19, 7 May 2007 (UTC).

Flower Identification

Can this flower be identified? J Are you green? 20:09, 6 May 2007 (UTC)

It looks like Foxglove.199.126.28.71 22:01, 6 May 2007 (UTC)

Sorry, 199.126, it is not foxglove. --mglg_(talk) 00:43, 7 May 2007 (UTC)

The flower does look like a foxglove to my untrained eye, but the stem isn't very foxglove-eque. Aaadddaaammm 02:27, 7 May 2007 (UTC)

Might it be a snapdragon? It's certainly a much better resemblance to the snapdragons we have in Australia, than the picture at that article. I can't say I've seen a snapdragon with this pinky-lilacy colour before - but then, IANAB (I am not a botanist) and IANMOAG (I am not much of a gardener). -- JackofOz 02:53, 7 May 2007 (UTC)\

Could it be a Texas Bluebonnet, or other type of Lupin? Bluebonnets are not always blue, just to nip that argument in the bud, so to speak. Where was the photograph taken? --LarryMac 14:58, 7 May 2007 (UTC)

The photograph was taken in the Mid-eastern US. However, it was in a garden, so I'm not so sure if that is helpful. J Are you green? 20:52, 7 May 2007 (UTC)

I do not think this is a lupin; the leaves grow alongside the flowers. J Are you green? 02:31, 8 May 2007 (UTC)

Dimensions

How come objects exist only in the 3rd dimension, and not anything higher? A response on my talk page or to let me know thus would be greatly apprieciated, thank you.199.126.28.71 21:54, 6 May 2007 (UTC)

Well, for a start, they don't, because there are at least four dimensions to space-time (although under general relativity you can't really say that there are three dimensions of space and one of time, although you can usually treat three of them as "spacelike" and one as "timelike"). Secondly, string theory generally suggests that there are at least six more, but they're curled up tightly so we don't notice them. (To visualise this, imagine you lived on a cylinder of infinite height but finite radius, so your world has two dimensions - along the height dimension and around the circumference. Now shrink the radius to something incredibly small, so it seems as though there is only one dimension left, although there may still be enough indirect evidence for you to discover the second dimension.) So it's not that objects only exist in four dimensions, but that we can only perceive four (and our perception of time is quite different to our perception of space). Recommended reading: Flatland: A Romance of Many Dimensions. Confusing Manifestation 22:54, 6 May 2007 (UTC)

(edit conflict)

That is just an observational fact: the world we see appears to have 3 spatial dimensions. There is no (known) fundamental reason for the number 3. In fact, according to some physical theories there are fundamental reasons for the number of spatial dimensions to be much larger, maybe 10 or 11. These theories sweep the extra dimensions under the rug (make them undetectable) through a trick called compactification. --mglg_(talk) 22:58, 6 May 2007 (UTC)

I thank you for trying to explain, but your explaination is confusing.199.126.28.71 23:55, 6 May 2007 (UTC)

We live in a three dimensional paradigm, nothing more. It doesn't make it real or true, it's just the best way we have found to explain it at the moment. Just like when we thought the world was flat, until someone found enough evidence to support a new model and contradict the current one. Fortunately if you see problems with the current three dimensional model at least you can discuss your ideas without the fear of being burned at the stake. Vespine 00:00, 7 May 2007 (UTC)

See Hypercube. We only perceive 3 dimensions. It is our limitation. There certainly could be 4 or more physical (i.e. not time) dimensions. We just don't perceive them. We lack the spatial imagination. I have see constructs of a "shadow" that a 4 dimensional object creates (it's 3 dimensional). Mathematically it can be described. A 4th physical dimension is orthogonal to the 3 physical dimensions we perceive. I believe string theory currently predicts at least 9 physical dimensions exclusing time. --Tbeatty 04:12, 7 May 2007 (UTC)

So, please explain WHY 'We just don't perceive them.'? Why is it our limitation? Thanks.199.126.28.71 05:53, 7 May 2007 (UTC)

I don't think that's known. We may perceive them in ways that we don't understand yet. For example, mass warps space into a fourth physical dimension. We perceive this as the earth orbiting the sun in a circle. But we are really moving in a straight line in four dimensions. we didn't realize this until the General Theory of relativity was published. The interesting thing is that is impossible (at least for me) to physically imagine 4 dimensions. I always have to move it to two dimensions warped into the third. For example, imagine a 2 dimensional plane wrapped around a sphere (i.e. the surface of the earth). It is easy to visualize moving in a straight line but travelling in a circle. It is really hard to take that to the 3 dimension case and imagine three dimensions warped into a 4th. Where does it warp too? This is where mathematics solves the problem. Mathematics exists where imagination fails. Imagining 4 lines that are all orthogonal to each other is impossible, but describing them mathematically is not. --Tbeatty 06:28, 7 May 2007 (UTC)

Well, were talking about spatial dimensions, not einsteinian dimensions. Could aliens see, per se, in 4 dimensions? If we had bigger brains would we or even, could we see in 4 dimensions?142.244.52.207 17:53, 8 May 2007 (UTC)

If you are interested in this stuff, you should try to get your hands on The Elegant Universe, which is a really interesting documentary on string theory and what not, and from what I recall, they did talk about the number of dimensions in the universe. - Akamad 12:07, 7 May 2007 (UTC)

Imagine you are a "point" - then you only have length and you can only move down a straight line. This line is your world. Then next imagine you are a set of points, or a line. Then you have length and breadth and you can only move around on a flat surface. Your world is flat :) Then imagine you are a box with length, breadth and height. Now your world is not flat anymore. You can jump and dive etc. YOU are this box. Your world is thus. Now imagine if you are a "superbox"' with an extra fourth dimension. To reach another superbox, you don't have to travel along a surface to reach another superbox. Your world has connection points between all superboxes that makes travel faster (or instantaneous depending on who you argue with) - so in the old world a box was a collection of planes, now a superbox is a collection of boxes. If this had to translate to our world, we would travel to other points of the world with ease. Sandman30s 13:54, 7 May 2007 (UTC)

Oh! I love answering this question - it's one of my favorites!

First - be totally clear about this - we don't see in three dimensions - for all purposes of this discussion, we may consider each of our retinas to be a 2 dimensional projection screen covered with teeny-tiny point light sensors. No different in principle from a TV camera. Each eye sees only a 2D image - our brains have learned from experience how to guess the 3D nature of the world from two 2D images which are oriented in slightly different directions and positioned a couple of centimeters apart. It's REALLY easy to fool this primitive mechanism (think of any of dozens of 3D optical illusions that fool us). So - we are already 'understanding' a world that has one more dimension than we can see!

So if the world was four dimensional (that is to say 'four spatial dimensions' - calling time a dimension is just wrong in this context), it wouldn't look any different than the 3D world - which in turn looks exactly the same as a 2D world. Our eyes are separated in 3D space - which helps with our limited 3D perception - if the world was 4D and our eyes were separated in that fourth dimension also - then perhaps we would notice that things were moving and had size in that 4th dimension too - but it wouldn't look much different from 3D.

What would a 4D world look like? Well, we already know - you can draw a 4D object using a computer and project it onto a 2D screen that matches EXACTLY how a 4D world would project onto your 2D retinas. If you draw even a 3D object on a computer - you have to make some decisions as to how to drop that extra dimension to get the image onto a 2D screen. We use the rules of perspective (or maybe we use orthographic representations) and tricks like 'depth cuing' (fog!) to indicate the third dimension in a way that completely fools our brains. We can easily model objects inside the computer in 4D,5D,6D or even 100 dimensions - the computer doesn't care much. But in the end, everything has to drop down into 2D to get it shoved through the limited capability of our eyes - and whatever decisions you make about how you drop those extra dimensions to get from 3D, 4D or 5D to 2D completely determines how 3D, 4D or 5D "looks".

If the world was 4D, and if we had a third eye that was separated from the other two in that 4th dimension - then our brains could probably evolve tricks to deal with it - just as we've managed to learn how to get some kind of 3D information from a pair of 2D eyeballs. But the more dimensions you lack information about, the more difficult the world would be to sort out - so with increasing dimensions, the world would get progressively more difficult to perceive - optical illusions would get more and more commonplace until we'd be unable to see anything unambiguously.

So - why doesn't the world have more dimensions? Maybe it does...but they'd have to be "small". What the heck is a "small dimension"?

String theory (which demands large numbers of dimensions that we clearly can't detect) suggests that the missing dimensions are very, very small. Imagine a world where one of our normal dimensions was curved around on itself. In a way, it is - the surface of the earth can be imagined as a 2D surface that's curved in the 3rd dimension. If you head off to the east and keep going - you eventually come back from the west to your starting point. If space were curved that way too - then a laser beam fired off to the East would shine back at you from the West. If you took a powerful telescope and pointed it off to the East - you'd be able to see the back of your own head. OK - so let's grab that 4th dimension and make it smaller. suppose the 4th dimension is like that - but the radius of the 4th dimension was (say) 10 meters instead of the radius of the earth. Looking off in the 4th dimension would reveal vast numbers of identical copies of everything - repeating every 10 meters forever. If the radius of the 4th dimension was just a bit bigger than your body - then looking off into the 4th dimension would reveal a very cramped world in that direction.

But string theory suggests that the 4th through 16th dimensions (or is it 15 or 26? Well, however many it is this week) are so tiny that they are VASTLY smaller than an atom - much, much smaller than an electron. So if you could see into the extra dimensions - all you'd see would be infinite numbers of copies of the 'normal' world - repeated at a spacing much much smaller than the smallest thing that science can detect. This is really tough to imagine - but not impossible. I think it would look exactly like the world actually looks - these extra dimensions simply wouldn't be noticable because looking in "that direction" would look no different.

Cool or what? SteveBaker 23:07, 7 May 2007 (UTC)

Consfusing... maybe? Well, would better discribe it??129.128.67.22 19:37, 8 May 2007 (UTC)

hudrochloric acid

if hydrochloric acid is added to a ph level of 6.5-7.0 water what would be the outcome?

propynol is used as a solvent for hydrochloric acid and my guess would be that the acid would quickly brack down in water leaving traces of propynol?? would it also rise the iron and sulfer leavels of the water?? regards Kenpeds 22:58, 6 May 2007 (UTC)

Umm .. hydrochloric acid is a solution of hydrogen chloride in water. If you add it to water you get a different concentration of hydrochloric acid. That's all.

You could get propynol if you started out with some. There's nothing about water and HCL which is going to synthesise it. --ColinFine 23:26, 6 May 2007 (UTC)

We do not do homework, but look at the article on pH, What do you think will happen to the pH? -Arch dude 09:23, 7 May 2007 (UTC)

Its not home work but if you care to look in yesterdays Propynol you could see why I was asking, I have lab results back but the police can not give me the answers.... Kenpeds 10:57, 7 May 2007 (UTC)

The concentration of the HCl and volume of water it is added to are important; very dilute hydrochloric, like that found in the stomach, would have a pH of 1.5-2, while fuming hydrochloric acid can have a pH of -1. Assuming completely neutral water (and using the values given in the previous question), adding 1 litre of conc. HCl (-1 pH) (about 1 bottlesworth) to 25,000 litres would give you a pH of 3.39; that's pretty strong, but not as strong as the hydrochloric acid in your stomach. Laïka 11:37, 7 May 2007 (UTC)

I apologize for the "homework" assumption. I saw a mis-spelled title, followed by an unsigned one-sentence question, followed by what I thought was an answering paragraph signed by you that appeared to be the sort of ellipitical response we usually give to homework questions. And now to work: if the miscreant added enough HCl to make the propynol noticable, then I suspect the pH was in fact altered at least for a period of time. A change in pH will in fact alter the overall chemistry of a holding tank by quite a bit, and this can in turn change the sulfur and iron chemistry. My house has a swimming pool,and I use a copper/silver system instead of chlorine to disinfect it. Occasionally, my maintaninence company will hire a new employee who does not know the difference. The newbie adds chlorine, and all hell breaks loose. The experts then come out and wrestle with the chemistry to get it back in balance. The basic problem: the chlorine causes the metals to form chlorides, which precipitate. Even when no chlorine is added, you can still get fairly major changes in the solubility of metal salts when the pH changes. If your miscreant added HCl, we should expect to see such changes. I suspect that this could explain the sulfer, also. -Arch dude 00:57, 8 May 2007 (UTC)

May 7

Balloons

What happens to a balloon when its lost into the sky? How about when a huge mass of balloons is released like this? --Russoc4 01:07, 7 May 2007 (UTC)

They rise until they pop and fall back down Coolotter88 01:20, 7 May 2007 (UTC)

How far do they go? --Russoc4 01:29, 7 May 2007 (UTC)

I had one go from Kingston upon Hull (northern UK) to the Loire Valley (mid-France). →Ollie (talk • contribs) 01:40, 7 May 2007 (UTC)

How did you track the balloon? bibliomaniac15 02:17, 7 May 2007 (UTC)

We released a lot of balloons, each with a tag on. If anyone found the balloon and tag, they could fill in where they found it. Our address was also on the tag, so the finder could post it back to us. It was done as a school fund-raiser - people could "buy" a balloon, and the ones that got furthest in the "race" won a prize.

We got plenty back from southern England, and a few made it across the channel. Obviously it's not a very good scientific method for testing how far a balloon can travel - it relies on the balloon travelling to somewhere that it will be found, the tag intact, and the finder being able to understand / being bothered to send the tag back. →Ollie (talk • contribs) 04:03, 7 May 2007 (UTC)

Why do they pop? Do they reach an equilibrium altitude? Aaadddaaammm 02:22, 7 May 2007 (UTC)

They pop because as they go higher and higher, the atmospheric pressure gets lower, so the pressure inside it becomes relatively higher, making it swell bigger and bigger till it pops.  Adam2288  T  C  03:58, 7 May 2007 (UTC)

And any chance that something like what happened with the ducks here could happen with the balloons? Aaadddaaammm 02:26, 7 May 2007 (UTC)

Isn't ballon release generally condemned now because marine critters eat the stuff and choke? --Zeizmic 11:55, 7 May 2007 (UTC)

Yes. In some jurisdictions (for example, New Hampshire), mass releases are being made illegal.

Atlant 14:27, 7 May 2007 (UTC)

anatomy and physiology

a young girl complains that she fatigues easily and seems mentally sluggish. There is swelling in the anterior neck. What condition is suspected and what are some possible causes and their treatments?216.170.153.148 02:16, 7 May 2007 (UTC)

If I'm not mistaken, this is homework. Please search for a possible answer using Wikipedia, other sites, a book, or some other material to derive your answer. bibliomaniac15 02:18, 7 May 2007 (UTC)

And here's a major hint, though not quite the exact answer. If you have trouble with the homework after looking there, get back to us. - Nunh-huh 02:55, 7 May 2007 (UTC)

And if it's not a homework question, please see a doctor. We can't give medical advice. Aaadddaaammm 02:19, 7 May 2007 (UTC)

Well, she is a girl....only puzzle is the neck thing. Other than head trauma which wasn't mentioned Encephalitis, Meningitis followed by Reyes Syndrome would be my top three choices for the unexplained neck pain. And if it's not homework, see a doctor. --Tbeatty 03:53, 7 May 2007 (UTC)

Unfortunately, Tbeatty has re-added his suggestions for the cause of "neck pain", which is not a symptom listed by the questioner. All three suggestions are, of course, therefore completely wrong. And he's re-added his sexist slur that "girls" are "mentally sluggish" - sorry about that. It's inappropriate for the reference desk, but he wants it here. A lot. If you want an informed answer, and the one which your teacher wants, see the link I provided. - Nunh-huh 04:50, 7 May 2007 (UTC)

Oh lighten up. My answer was funner. But fatigue, mental sluggishness, pediatric and swelling of the neck sounds a lot like Encephalitis or Meningitus. While you wait for TSH tests, I'm prescribing anti-biotics as prophylactic measure. --Tbeatty 04:58, 7 May 2007 (UTC)

I don't know why you insist on giving wrong answers, but apparently you do. Because they're "funner", apparently. Neither encephalitis nor meningitis (note spelling) cause anterior neck swelling. - Nunh-huh 05:03, 7 May 2007 (UTC)

Because you already mentioned hypothyroidism? I expanded it to general complaints about the neck. Sorry that it offended you so much. as for the spelling, sorry if I type too fast. Since I had spelled it correctly previously, I don't know why you can't chalk it up tp a typo. 'i' and 'u' are next to each other. thanks for playing. --Tbeatty 05:16, 7 May 2007 (UTC)

Since there already was a correct answer, three extra wrong answers weren't really needed, expecially in answer to a question never asked regarding "general complaints about the neck". The reference desk isn't a place to publish your free associations. - Nunh-huh 05:21, 7 May 2007 (UTC)

Sure it is. I gave three links inside Wikipedia that are concerned with the three main sympotms provided (mental sluggishness, pediatric, fatigue, neck swelling/pain). I generally don't like to do other peoples homework but if I can point them to articles that expand their knowledge on related subjects, I do it. This is the Reference Desk, not the Answer Desk. Sorry if I pissed in your Wheaties, it was not my intent. Done with this thread. thanks. --Tbeatty 05:28, 7 May 2007 (UTC)

Once again: the questioner would be well-advised not to take "answers" from someone who (even now) fails to distinguish between pain and swelling. The reference desk's function is to lead people to the right answers, not lead them astray. - Nunh-huh 05:32, 7 May 2007 (UTC)

Hey! None of that, play nice!Aaadddaaammm 06:03, 7 May 2007 (UTC)

iPod's capacity for headphone impedance

Is my first-generation iPod Nano capable of pushing AKG K240 headphones (impedance 55 ohms per channel)? If not, how much would it cost to get some kind of preamp unit? NeonMerlin 03:01, 7 May 2007 (UTC)

It has been my experience with (non-iPod) mp3 players that using large headphones drains the battery faster. I can't think of a good reason why, since they should be the same impedance as earbuds, but I've never bothered to investigate it quantitatively. Nimur 08:38, 7 May 2007 (UTC)

I'm not sure what the iPod specification allows (>=32 ohms?), but I do know that some old Koss Pro-4AA headphones of mine (which I believe to be 8 ohms) would not work at all on my 3G iPod.

Atlant 14:29, 7 May 2007 (UTC)

iPod earphones are 32 ohms, see [4]. I can't think of any problems besides you draining the battery faster, as Nimur mentioned. J Are you green? 21:00, 7 May 2007 (UTC)

Hmmm... For some reason, I found myself in the Australian Apple site through my Google search... its the same in the UK and US, by the way - [5] and [6]. J Are you green? 21:07, 7 May 2007 (UTC)

If the headphones are higher impedance, they will draw less energy, not more. As Atlant's anecdote points out, sufficiently low impedance headphones can draw too much current from the output amplifier, typically causing an internal circuit protection to kick in and you to hear no output. If the OP is correct about his earphones' impedance rating, there shouldn't be a problem (though the impedance matching may not be optimal). Incidentally, it isn't very difficult to buy or even build a pre-amplifier for this purpose. -- mattb 02:26, 8 May 2007 (UTC)

Mental Illness-

I am a retired Lutheran pastor and lately as I visit elderly persons more and more I am finding folks whose homes are absolute messes. Here are well educated persons who have not cleaned their homes for years. The rooms are total messes. They bring things into the house and never ever carry anything away. I was in a home last week where there was just a path from the front door to what should have been a living room. That room was filled with junk, pure junk. For example there were two garbage cans in the room full of discards. There were boxes of stuff with old clothing piled on top. The piles were taller than me. There were boxs all over what should have been a table in the kitchen. The kitchen counters were covered with junk (out of date phone books, and old newspapers). It would be totally impossible for anyone to prepare a meal in that kitchen. I wanted to see the upstairs but was told that the junk up there is worse than what I saw on the main floor. The downstairs bathroom has not been cleaned for years. How can people live like that? More and more am I seeing this. People know this is not normal and do all they can to keep folks from visiting but they will not change. Is this some sore of mental illness which may or may not be associated with aging? Thanks for your attention to this matter. Robert S. Collins <email removed to prevent you being spammed>

Hello, Robert. It's quite a problem, I'm sure. Have a read of our article on the Collyer brothers to get an idea of just how far such messiness and hoarding can go. It might be an indication of mental illness such as OCD, but I'm not qualified to say, and we're not able to give out such diagnoses here. JackofOz 05:22, 7 May 2007 (UTC)

There's a lot of recent publicity on the problem of "collectors", partly as a result of the various plays on Edith and Edie Beale (Grey Gardens (musical), and another more fictionalized play whose name I can't remember). You might be interested in reading A Book of Reasons, by John Vernon, which is a sort of meditation written when the author's brother died and he found the house in chaotic disrepair, decrepit and full of trash. - Nunh-huh 05:29, 7 May 2007 (UTC)

I believe the condition is called compulsive hoarding. It is not an official psychiatric category (not in the DSM) but it describes what you speak of perfectly. --24.147.86.187 13:29, 7 May 2007 (UTC)

I would surmise that the will to clean is strongly linked with the will to live. Vranak

That is a very bold statement which makes alot of assumptions. -- Diletante 15:54, 7 May 2007 (UTC)

Surmise[7]: To infer (something) without sufficiently conclusive evidence. Like I said, I surmise.Vranak

I reckon this happens more often when people have been really poor in the past. Of course, having such a problem doesn't stop them from being otherwise virtuous.Polypipe Wrangler 22:25, 7 May 2007 (UTC)

I would differentiate between two cases. One is where only potentially useful items are kept, like broken TVs which could, in theory, be repaired. This seems like a simple case of the person's priorities being misplaced, seeing the potential fixed TV as more valuable than the space it takes up. A more serious problem is where things of no value whatsoever, like the classic bottles of urine in Howard Hughes' case, are retained. That, to me, is, indeed, a sign of mental illness. StuRat 02:51, 8 May 2007 (UTC)

universe

Is there day and night on other planets? —The preceding unsigned comment was added by 196.44.157.164 (talk) 08:20, 7 May 2007 (UTC).

Yes. The best illustration I can find seems to be at Season. Day and night is caused by an astronomical object moving (rotating) so that different parts of it are facing the sun (or whatever other source of light is illuminating it, such as a distant star). Nimur 08:41, 7 May 2007 (UTC)

But some planets (such as Mercury, IIRC) have their rotation phase locked to their revolution so that some points on the surface is always light or dark; there is no "day" on such planets. And even if I'm wrong about Mercury, consider Earth's moon relative to Earth; there's no Earthrise or Earthset as viewed from the moon.

Atlant 14:31, 7 May 2007 (UTC)

When one of two bodies always faces the other it's called a Tidal Lock. Jeffrey.Kleykamp 14:46, 7 May 2007 (UTC)

Mercury, as our article says, is actually locked in a 2:3 spin-orbit resonance, which means it rotates three times in every two orbits. But this is indeed a somewhat unusual condition, with simple 1:1 tidal locking being more common. (We don't appear to have an article on spin-orbit resonance, but the relevant section in the Mercury article explains the issue. Incidentally, another remarkable article I stumbled upon while looking for this is Extraterrestrial skies, which describes how the situation would look to an observer on the surface of Mercury.) —Ilmari Karonen (talk) 15:02, 7 May 2007 (UTC)

Yes, there's no Earthrise or Earthset as viewed from the moon, but there still is day and night. To not have day and night, the planet would have to be tidally locked to the Sun, and there are no planets like that in our solar system (although until about 40 years ago it was thought that Mercury was). --Anon, May 7, 22:47 (UTC).

Also note that on the distant dwarf planets Pluto and especially Eris, there isn't much difference between day and night, since, at that distance, the Sun just appears to be a bit brighter than the other stars. StuRat 00:58, 8 May 2007 (UTC)

Fuel Cell

We know that a fuel cell extracts energy from fuel(methanol example). What about if we supply energy to the cell, will the reverse take place( fuel form water & CO2)?210.212.194.209

With Hydrogen based fuel cells it is possible to diver the current into water hydrolysis to get Hydrogen and Oxygen, not sure about methanol though. --antilived^{T | C | G} 09:54, 7 May 2007 (UTC)

In theory, it would probably be possible to make methanol from water and CO₂ in some manner, it just might not be very simple or efficient. The difficulty is that it's not enough to just reduce the carbon and the hydrogen; one would also have to make them assemble into molecules in just the right way. I'm not personally aware of any system that would do so for methanol, but we do have devices that can convert water and CO₂ into sugar (which is an even more complex molecule) — they're called plants. —Ilmari Karonen (talk) 14:50, 7 May 2007 (UTC)

There is a Hydrogen based fuel cell mounted on a little car which anybody can buyfrom Kosmos and this works both ways. If this reaction would work the industry would use it. The formation of methanol from H2 and CO2 in an easy way is an unsolved quest!--Stone 15:55, 7 May 2007 (UTC)

Late 1960s rechargeable batteries

The Cal-Tech calculator (1967) of Texas Instruments, U.S. Patent No. 3,819,921, was the world's first battery-powered "pocket-sized" calculator.[8] It used 11 rechargeable batteries in groups of 3 larger ones (for the circuits) and 8 small ones (for the embedded thermal printer). The specifications of the '921 patent declared that these batteries are 1.5 V each. The Cal-Tech calculator used four bipolar ICs.

For the '921 patent, please visit http://www.google.com/patents and enter 3,819,921. Battery descriptions are on page 27.

In 1970, Canon shipped a "Pocketronic" calculator mainly under the TI design under TI's license. It used MOSFET ICs and was powered by 13 rechargeable Ni-Cd batteries in groups of 4 and 8.[9]

How could anyone in the 1960s get a 1.5 V rechargeable battery? -- Toytoy 12:48, 7 May 2007 (UTC)

The early calculators with rechargeable batteries that I saw just used Nicads (nominally 1.2 volts). Not sure what they could have gotten a steady 1.5 volts per cell from that was rechargeable in the 1960's and suitable for a pocket calculator. Edison 14:35, 7 May 2007 (UTC)

Relation with days

ok so as alot of us notice mondays are a drag. i want to know though is there a scientific name for this? in other words is there a relation between the day we are in and the way our brain react to it? a good example is of course monday. its so slow on monday but is that because our brain percives it as slow?User:Maverick423 Im in ur science steeling ur gravity 17:29, 7 May 2007 (UTC)

I would note two causes. First, if you sleep in on Saturday and Sunday, your body will want to sleep in on Monday. So, getting up "early" will cause you to be tired all day. Second, if you expect a day to be slow, you will notice it as slow. If you expect a day to be fast, you will notice it as fast. You just simply ignore anything that is contrary to your expectation. There are more causes that may be noted. For example, our hospital has more administrative meetings on Monday than any other day - so less work is done. Also, there's a 24-hr process for surgeries. Since they only start on Sunday in emergency situations, Monday only has emergency surgeries. --Kainaw ^(talk) 20:00, 7 May 2007 (UTC)

Probably not 100% what you were asking, but we do have an article on Working time that covers some of these effects such as Mondayitis, Hump day and TGIF (leaving two standard working days on which we apparently function normally; go figure). Confusing Manifestation 22:47, 7 May 2007 (UTC)

Our good humoured friends at Uncyclopaedia have coined their own scietific name for it: Mondayism Rockpocket 02:33, 8 May 2007 (UTC)

We more-edumacated denizens of Wikipedia prefer Mondayitis. DMacks 02:56, 8 May 2007 (UTC)

Chipboard density

Anyone know chipboard density in llb/ sq ft or kg/sq m? —The preceding unsigned comment was added by 88.109.223.242 (talk) 17:32, 7 May 2007 (UTC).

There are some typical densities on the Medium-density fibreboard page. DMacks 17:36, 7 May 2007 (UTC)

Sun spots and tree ring growth

I learned a long time ago that when you sawed through a tree trunk, you saw the tree rings; each ring represents one year if growth. The rings grow at different rates on an approximately 11 year cycle. When there are lots of sup spots, there is a lot of growth, and vice versa. What is the precise physics which links the number of sun spots to the tree grwoing more rapidly. —The preceding unsigned comment was added by 74.101.136.33 (talk) 17:42, 7 May 2007 (UTC).

sunspots affect the temperature of the sun, and therefore the climate of the earth.

Oh boy, no. Sunspots correlate to the intensity of light reaching the earth and this was discovered by E. W. Maunder. This is a parallel effect of the same cause, sunspots are not the causation. I'm not sure about your question, but the field you're looking for is dendrochronology. I'll try and get the answer for you soon :) [Mac Δαvιs] ❖ 19:51, 7 May 2007 (UTC)

The sunspot variations that Maunder discovered, which do seem to correlate to solar output and therefore climate, are not the 11-year cycle, but are much slower. --Anonymous, May 7, 22:49 (UTC).

I've never heard that tree rings vary every 11 years. They do vary, however, with rainfall, growing season length, climate, etc., but I don't believe any of these follow an 11 year cycle. StuRat 00:44, 8 May 2007 (UTC)

sauna use / length of time inquiry

it would be appecreciated if you mention the length of time a person should be advised to stay inside the sauna, leave the sauna, coming back to the sauna... how many times and repetitions are advised... perhaps that coule be under the subcategory of health benefits or intructions

thx

Do you mean "what's the max time at temp X to avoid overheating the body ?". StuRat 00:38, 8 May 2007 (UTC)

starch question

I need to know what plants use starch for, how they make it, stuff like that. And I need to know how I can test something for the presence of starch. A quantitative test would be very useful.

Don't just refer me to the starch article, it is just about the uses of starch in food. —The preceding unsigned comment was added by 172.201.18.115 (talk) 17:58, 7 May 2007 (UTC).

Er, the first sentence of the starch article says "it is used by plants as a way to store excess glucose." Later in the article is a section explaining several tests (though I think they're mainly qualitative). DMacks 18:17, 7 May 2007 (UTC)

Yes, but apart from that. I already know it is a form of glucose and a store, but I need details and more information, enough to write a few paragraphs about it.

A mixture of starch and iodine will turn black. It happens to be mentioned in Starch#Tests. Someguy1221 18:21, 7 May 2007 (UTC)

If you're writing "a few paragraphs about it", you'll certainly want to use more sources than just Wikipedia. Googling for starch test quantitative gave me several useful-looking hits about that part of your assignment. We have no idea what academic level we're talking about here, so it's going to be hard to suggest places you can go to learn about "details and more information" beyond "stores glucose" (note, it is not really a "form of glucose" on an appropriate level...what kinds of details and types of information do you need? DMacks 18:29, 7 May 2007 (UTC)

ozone

Can we see the ozone by the telescope? if the asnswer is yes/no how?

Well, According to this wikipedia article, the Ozone_layer was discovered by Charles_Fabry and Henri Buisson, who seem to have been physicists that specialized in optics.

This article Claims In 1879-81, W. N. Hartley and A. Cornu measured the ultraviolet radiation reaching the surface of the earth and found a sharp cutoff, which they correctly attributed to ozone. These pioneering measurements also showed that the bulk of the ozone must be in the upper atmosphere rather than near ground level. The ozone layer had been discovered.

This definately gives credit to Cornu and Hartly discovering Ozone in the atmosphere using Spectroscopy. Charles Fabry is not mentioned.

So the answer would be Yes, you could detect the ozone in the atmosphere with a telescope if you had the proper spectroscopic equipment available. -Czmtzc 18:56, 7 May 2007 (UTC)

That's not what they asked. They asked if it is possible to see the ozone layer, which I presume means only in the visible spectrum. According to Ozone, the gas Ozone is pale blue to the human eye. I'd assume this makes for a more definitive yes. Good luck spotting that blue from the blue of plain ol' sky though. i kan reed 20:38, 7 May 2007 (UTC)

Perhaps a good portion of the blue we see when we look at the sky is from ozone. StuRat 00:34, 8 May 2007 (UTC)

See Diffuse sky radiation for some current thinking about why the sky is blue. The sky I usually see isn't really the same shade as I see coming out of a lab ozone generator. DMacks 00:37, 8 May 2007 (UTC)

Magmatic convection currents

Can any one direct me to a good article which explains how these currents work?Bastard Soap 18:24, 7 May 2007 (UTC)

Plate tectonics? User:Maverick423 Im in ur science steeling ur gravity 20:25, 7 May 2007 (UTC)

ah here we go i read through it a bit to get you this article as well Mantle convection Maverick423 is Im in ur science steeling ur gravities 21:20, 7 May 2007 (UTC)

Mental IIIness

What mental illnesses are related to homosexuality? —The preceding unsigned comment was added by 71.175.118.76 (talk) 21:21, 7 May 2007 (UTC).

None that I am aware of. Vranak

I dont belive there are any mental illnesses related to it, its more of a choice of prefrence. however there are lots of STDs related to intercourse betwen them. Maverick423 Says Im in ur science steeling ur gravities 21:26, 7 May 2007 (UTC)

I'm not sure that sexual orientation could fairly be described as a 'choice of preference' (or just a choice). A preference though, sure. Vranak

Until 1973, the American Psychiatric Association classified homosexuality as a mental illness in itself. Today, homosexuals suffer a higher incidence of mental problems such as depression and suicide (ref: [10]). --TotoBaggins 22:38, 7 May 2007 (UTC)

Whoa! Hold the horses. You are quoting a study from a website called "the national association for research and therapy of homosexuality"!! I've never heard anything more ridiculous. Until the mid 1800 slavery was legal, and today most ethnic minority groups suffer MUCH greater incidents of problems such as substance abuse, incarceration, depression and suicide. Are you going to claim these are racial problems? Don't be a fool, these things aren't related to any specific minority group, they are a commonality amongst all minority groups, because as minority groups they fulfil a specific demographic which isn't mainstream and are marginalised as a result. Vespine 00:28, 8 May 2007 (UTC)

To be fair to TotoBaggins, he didn't claim homosexuality causes a higher incidence of mental problems, simply that they suffer from them. Whether that is cause or effect was not clarified, therefore is is somewhat unfair to label him foolish. Rockpocket 02:00, 8 May 2007 (UTC)

Points of contact

If two surfaces are pushed together, how small will their final separation typically be? Obviously it will be non-zero, since we're not talking about perfectly smooth surfaces, but on what distance scales are we talking? Will it be nanometres, picometres? What is the limiting favour that prevents them from getting closer? I have a hard time believing it's due to the atoms' outer electrons bumping off each other...though I can't think what else it could be. Thanks, Icthyos 22:04, 7 May 2007 (UTC)

Your question cannot be answered because once you go down to the scale of atoms, you will realize that atoms do not have a hard surface. As such, you can never say where one atom begins and another atom ends. Without a beginning point and an end point, how can your measure the distance between them? Ohanian 22:17, 7 May 2007 (UTC)

I believe that it is indeed the like-charges repelling each other that prevents two objects from passing through each other. You might be interested in solid, cold welding and Casimir effect. --TotoBaggins 22:51, 7 May 2007 (UTC)

I think I just have a hard time scaling up from a rigid pattern of atoms to a macroscopic solid - if there's no "hard" surface, is it purely the electrostatic repulsion that stops them from pushing together any further? When I push my hands together, say, am I creating tiny pockets of vacuum by pressing certain regions together so far that all of the air is excluded? Or is the minimum separation greater than the size of the atoms found in air? Icthyos 22:58, 7 May 2007 (UTC)

The atoms in your hands are not "hitting" each other, they are repulsing each other very strongly. Yet, it is electrostatic force, just a teenie weenie scale. M.manary 23:33, 7 May 2007 (UTC)

The repulsive force between atoms (assuming there's no static electric charge or magnetic fields at work, and assuming they're not going to bond) will become noticable on the order of the size of the atoms themselves, which is typically in the range of a tenth of a nanometer. As far as defining where one atom begins and one ends, the volume of an atom is often defined as the region that contains 90% of the electron probability (see electron cloud), although this is completely arbitrary. You can also talk about how far apart the nuclei are. Also, keep in mind that in many cases, only a tiny fraction (less than one percent) of the atoms on the surfaces in contact are actually at this minimal seperation from one another. Someguy1221 23:34, 7 May 2007 (UTC)

Atomic force microscopy is a nice application of atom—atom repulsion repulsion and the limits of the idea of "contact" on that scale. DMacks 00:05, 8 May 2007 (UTC)

Consensus on human evolution?

Is there so-called "scientific consensus" that humans evolved from apes? I'm unsure if this has been definitively proven or if there is some lingering doubt among scientists. This question came about after reading Scientific opinion on climate change. Thank you all. Pizzachicken 23:59, 7 May 2007 (UTC)

Consensus I've heard is that modern humans and modern apes all evolved from some previous (and no longer existing) common ancestor, not humans "from" apes as your question suggests. DMacks 00:03, 8 May 2007 (UTC)

The only scientific debate that has really occured for the last 100 years is precisely how humans and apes evolved from a common ancestor, how different species formed and branched off, etc. There is no evidence that humans evolved from anything other than a primate, or that humans have always existed as they do now. Someguy1221 00:07, 8 May 2007 (UTC)

Thank you for the clarification. Shows you how much I know about this subject. Pizzachicken 00:42, 8 May 2007 (UTC)

All living apes (including naked apes) are descended from other apes, so "evolved from apes" isn't exactly wrong, though taken literally it's almost trivial ("life-forms evolved from life-forms"). —Tamfang 00:51, 8 May 2007 (UTC)

Technically, according to the ape article, humans are apes. The common ancestor between us and the other great apes would probably also be tossed into the Hominidae family, if I've got my taxonomy right. -- Consumed Crustacean (talk) 00:10, 8 May 2007 (UTC)

• The evolution's article talk page has an FAQ where the cite some study that only 99.84% of scientists believe in evolution, although my understanding is that the scientists that don't believe it are most computer scientists, engineers and mathematicians. The adage is nothing in biology makes sense except in light of evolution - and that's true. Furthermore, no "humans didn't evolve from apes proposal exists that doesn't contravene a dozen other well established scientific consensus (~99.85% agreement) WilyD 00:32, 8 May 2007 (UTC)

I don't understand what "99.84% of scientists believe in evolution" refers to. What part of evolution do they believe in? I'm not sure if you're expanding on my question. My original question only referred to human evolution. Pizzachicken 00:42, 8 May 2007 (UTC)

These numbers usually come from small samples taken from large lists like people listed in American Men and Women of Science or the membership of the AAAS, and they include biologists, physicists, mathematicians, maybe computer scienctists and the like.--droptone 04:05, 8 May 2007 (UTC)

If you believe in evolution - there is no reason to assume that humans are somehow 'outside of the system'. A scientist doesn't "believe in" things in the way that you'd think of a religious belief. I'd prefer the phrase "are convinced by the evidence for". So I would imagine the number convinced about evolution but unconvinced by the evidence to including human evolution would be close to zero. We have a vastly better chain of evidence for apes-to-humans than we have for (say) a common ancestor for plants and animals - or the messy first step of getting from inorganic chemistry to self-replicating life. If you can stretch your mind to believe that the incredible diversity of life came from a single common ancestor that came about by sheer flook and then was the mother (and father) of all life - then it's hard to deny that chimps and humans - with their near-identical DNA - are anything other than close relatives. I've spent all my life in the sciences and I've yet to meet a scientist who believed in evolution but who felt that humans were an exception. So whilst I'm sure they exist, they aren't going to put a big dent in that 99.84% number. If you had doubt - realistic serious doubt based on facts and experimental evidence - then it would have to be for that very first step - abiogenesis is a serious test of one's belief in statistics! SteveBaker 01:28, 8 May 2007 (UTC)

It's not impossible to believe that humans are somehow "outside the system". Some very famous evolutionists have advocated such a view! but it is pretty rare now-a-days. --24.147.86.187 01:44, 8 May 2007 (UTC)

I call 'foul'. We're talking living scientists - Wallace died 100 years ago - he didn't have access to DNA evidence and the fossil record was nowhere near as well researched as it is today. SteveBaker 02:17, 8 May 2007 (UTC)

There is basically no doubt that the phylogenetic tree puts humans and apes in the same branch. Anyone inclined towards an evolutionary point of view (almost all scientists) would then easily see an evolutionary narrative in this fact. Now exactly how it happened is not at all clear. There is essentially no debate amongst those who subscribe to evolutionary theory that humans evolved from/as/whatever apes somehow. --24.147.86.187 01:49, 8 May 2007 (UTC)

I just wanted to butt in and remark on your usage of the phrase "definitively proven". Proofs, strictly speaking, do not exist outside of logic and mathematics. Science isn't in the business of proving things. While this is an accepted usage of the word "proof", it is largely useless when speaking about the scientific enterprise. Science is in the business of confirming hypotheses. So rather than wonder if scientists have "definitively proven" the modern theory of evolution, a more apt question is how well confirmed it is. And to answer that question, the main Wikipedia entry on Evolution should provide enough information. I don't mean to sound like an asshole philosopher but when people speak in terms of proof in science they are at risk of not understanding what science aims to do (How can they prove that some vitamin or mineral reduces risk of cancer one day then disprove it another?).--droptone 03:55, 8 May 2007 (UTC)

I think the answers miss the fundamental question which isn't whether or not humans and modern apes have a common ancestor. That is pretty much established through multiple disciplines of science. The question is what has separated humans from animals and how did this "enlightenment" happen? Humans are unquestionably unique in the world. Even asking the question of how we evolved shows this uniqueness. How that uniqueness came about is crux of the problem and there is not consensus either scientifically or religiously. This is similar to your global warming analogy in that the scientific debate is not whether global warming exists but rather its cause (man-made or natural?), extent (how much warmer, if any will it get?) and consequences (will warming make the earth better or worse for its inhabitants?). Those questions get lost in the din of arguing existence rather than the real scientific questions that exist. --Tbeatty 04:16, 8 May 2007 (UTC)

Err, I thought the question was whether or not humans evolved from apes. Not the process by which they did. Your question is interesting in its own right, but that doesn't mean that the answers were missing something. -- Consumed Crustacean (talk) 05:20, 8 May 2007 (UTC)

The only lingering doubt is whether creationists will give up their nonsense.--Kirby♥time 05:21, 8 May 2007 (UTC)