Wikipedia:Reference desk/Archives/Science/2007 May 5

= 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&#39;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 [], 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. Rockpock  e  t  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 UserboxerComplain/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)