Wikipedia:Reference desk/Archives/Science/2006 November 27

Hymen of elephants and whales
How thick is hymen of a whale? How thick is elephants hymen? How big is the hole in the hymen?

= November 27 =

Magnets
What is the specific effect - if any that magnets have on recorded items,ie: video tapes, CD's,audiotapes ?
 * Video and audio tapes use magnetic storage, so if the magnet is strong enough it can corrupt the data in them. CD's use a different form of storage (optical), so magnets don't have any effect on them. ☢  Ҡ i∊ ff   ⌇  ↯  00:56, 27 November 2006 (UTC)


 * The effect you are after is called Degaussing, as explained in that article, it is used on purpose to bulk erase magnetic media, but it does often happen by accident. Vespine 02:30, 27 November 2006 (UTC)


 * Note that the fact that cd's are not intended to work through magnetism doesn't mean that magnetism can have no effect on their functionality. Not that I know an effect it could have, but the coating contains metal, I believe, and magnetism could have some effect on that that has some effect that has another effect that may damage the readout of some bits. Or something. DirkvdM 08:00, 27 November 2006 (UTC)


 * The metals used are generally non-magnetic, though, so unless you're moving the magnet or disc fast enough to induce a substantial electric current, a magnet should have no effect on any form of CD or DVD (including -R, +R, -RW, or -RAM). (It might be kind of interesting to see if a disc-destroyer could be built by whirling a disc very rapidly in a very intense magnetic field. Would the disc burn up before centrifugal force shattered it?)


 * Note that certain discs use magneto-optical (Curie point) recording; these might be affected by high-intensity magnetic fields.


 * Atlant 17:43, 27 November 2006 (UTC)

Ion name
Is chlorine as an ion called a chlorine ion or a chloride ion? --The Dark Side 01:55, 27 November 2006 (UTC)


 * An ion of chlorine is a chlorine ion, a chloride ion is an ion of chloride. Chlorine is only a chloride when it is in a compound. Since most chlorides are salts and most salts are ionic compounds a chloride can be also be an ion of chlorine. But an ion of chlorine isn't necessarily an ion of chloride. This may sound like I know what I'm talking about but this is my understanding, I'm not actually a chemist. Vespine 02:23, 27 November 2006 (UTC)


 * A chloride ion is a Cl− ion. This is the only ion of chlorine you're likely to encounter in chemistry, but a chlorine nucleus can have any number of electrons around it, from a bare nucleus (Cl17+) to Cl− or even Cl2− (depending on whether the chloride ion itself has a positive electron affinity). These are all chlorine ions, but none of them are chloride ions except Cl−. —Keenan Pepper 02:50, 27 November 2006 (UTC)


 * Go with Keenan's answer, i think I was on the right track but he sounds spot on:) Vespine 03:32, 27 November 2006 (UTC)


 * Let's put it this way. As only one ion of chlorine, namely Cl- is relevant, it has its own name, namely "chloride". But the more common way of speaking is to call "chlorides" all salts with Cl-. Hence, both answers are correct. This is a general thing in the chemistry of ionic compounds: There all special names for all common anions, and these names are prefixed with the name of the cation (or just the respective element) to form the name of the ionic compound. Another anion involving chlorine is chlorate, see there for further examples. Also notice, that the suffix is significand: "-ide" means that the ion is just a negatively charged element, e.g. chloride, iodide, sulfide, "-ite" and "-ate" is used, when it is a compund anion with oxygen at different oxidation states, e.g. sulfite. sulfate, chlorate. Simon A. 13:42, 27 November 2006 (UTC)
 * Just to repeat what everyone else has said Cl- is chloride and it's and ion.
 * Cl-, Cl+, Cl2+ etc are all chlorine ions but only Cl- is called chloride.

milk and growth
Does milk really make you grow tall (or at least maximize your average height)?--PrestonH 02:14, 27 November 2006 (UTC)
 * Most likely there is an effect, though someone may consider it overadvertised due to calcium issues. Simple Google search shows reliable hints like this. --Brand спойт 03:38, 27 November 2006 (UTC)


 * The Dutch are said to be so tall because they eat a lot of dairy products. Don't know if that is truth or myth, though. DirkvdM 08:02, 27 November 2006 (UTC)


 * Well I drank buckets and buckets of milk as a kid and a young teen, and I grew to be exactly the same height as my short mother. I have extremely strong bones, tho. Which proves exactly... nothing. (Just saying it before someone else does). Anchoress 08:06, 27 November 2006 (UTC)


 * Lots of milk is of course necessary to make bones and teeth. I doubt it makes you taller.--Light current 13:44, 27 November 2006 (UTC)
 * I've never heard that before - got loads of milk and I'm not 'tall' so maybe the answer is no..


 * To explain the irony I read in that remark, milk is just one (possible) factor. If you've 'got the genes' to become tall but don't drink enough milk, you might not achieve your potential greatness. DirkvdM 06:05, 28 November 2006 (UTC)
 * Milk builds stronger bones with calcium, and that may contribute to height by straightening your bones and such. ~ Flameviper 19:20, 30 November 2006 (UTC)

RE2:Electric Intensity
Removed the Q and A repeated from November 23 -- WikiCheng | Talk 05:44, 27 November 2006 (UTC)

2)Question IF the sun would be bought nearer to the eatrh, the earth would have to move faster(more gravitational potential). Threr would no be any need for sudden movement (oscillation) of the sun to cause this force.Since ELECTRIC Field intensity can be modeled the same manner,Then why do we need to Move(oscillate) the Heavily charged sphere????

I'm trying to follow this, but I'm not sure you've got your model correct (or not sure I'm following you). The glow is caused by changing fields. If we had the big charged sphere it could have a constant electric field, like the sun has a constant gravitational field. In this sense though the Earth could be thought of more as a charged particle near the charged sphere (sun). This charged particle would experience an ongoing force caused by the electric field, just as the earth feels a constant gravitational force. --jjron 10:04, 23 November 2006 (UTC)

Well, if you have a tiny negatively-charged sphere attracting a large positive sphere, and orbiting around it, you wouldn't have to oscillate the large sphere if you brought it closer to the small one. But if you want to create gravitational waves, then you have to rapidly wiggle the sun, and it doesn't matter if the Earth is there or not. If you want to create EM radiation, you have to wiggle the electric charges. How does either situation relate to orbits?

3)What Im actually asking is with relation to the glowing tube light under the power line which only glows due to change in electric field intensity but electric field need not change(oscillate) for the electron to get attracted.

Um, yes. The electron will be attracted (or repelled as the case may be) without the field changing. --jjron 12:34, 24 November 2006 (UTC)

4)Well then why do we need oscillating electric field for the tube to glow when we dont need oscillating electric field for the electron to get attracted or repelled??


 * Because you want the tube to do something continuously, rather than merely do something once. If you have a static field, you'll polarize the tube, which may cause it to glow for a moment, but then nothing further will happen.  You need to keep moving the electrons around to keep the glow going, and since they can't leave the tube you have to move them back and forth in it with an oscillating field.  --Tardis 17:32, 27 November 2006 (UTC)

q nought
Hi. What does the parameter q0 mean in astronomy? 128.36.56.209 04:35, 27 November 2006 (UTC)


 * The cosmological deceleration parameter.     It's how fast the universe's rate of expansion is accelerating/decelerating.  --Bowlhover 04:57, 27 November 2006 (UTC)
 * Thanks for the speedy answer! 128.36.56.209 06:06, 27 November 2006 (UTC)

Unknown Island
I seem to recall from a documentary I watched ages ago that there was an island which arose in the Atlantic near Iceland in an extremely brief period of time, due to a volcanic eruption. I want to learn more now, but I can't for the life of me remember its name. The documentary said that its shores were full of ashes, but seeds from trees started growing within a couple months. I forget the exact year, but I think it was late 60s to early 70s, but I could be confusing this island with the volcanic eruption which was fought off by the icelanders. Sorry if I am confusing... Crisco 1492 06:05, 27 November 2006 (UTC)


 * I believe it may be Surtsey, which happened in the 1960s. Antandrus  (talk) 06:09, 27 November 2006 (UTC)


 * Terima Kasih, ya this is the one. Thanks for the speedy reply! Crisco 1492 06:18, 27 November 2006 (UTC)


 * Surtsey is indeed the most likely, although IIRC it's still above the surface. This sort of thing happens every now and again - in fact a new island was formed by a volcano off the coast of Tonga only a few weeks ago (see here). Another famous example was the ephemeral island (i.e., it has since sunk) of Ferdinandea off the south coast of Italy that - after it sank - was bombed by the US Navy who thought it was an enemy submarine. Grutness...wha?  06:24, 27 November 2006 (UTC)


 * When did that happen? What war was going on? As for teh volcanic eruption fought back by the townspeople, which was that? Maaf, sorry for being a nag. 202.173.17.250 06:29, 27 November 2006 (UTC)


 * That's expained in the article I linked. Ferdinandea rose and sank in the 1830s, but is still so close to the surface that the US mistook it for a sub during the crisis with Libya in the 1980s. Not sure which one was fought back by townspeople though (sounds like a tricky thing to do, too...) Grutness...wha?  06:33, 27 November 2006 (UTC)

It was Eldfell on the island of Heimaey in 1973; the locals fought (sucessfully) primarily to prevent the blocking of the harbor, Iceland's second most important fishing port. Geologyguy 16:51, 27 November 2006 (UTC)


 * I heard it involved hundreds of firetrucks, and pumping water directly from the ocean. Not a simple task, to be sure.  Makes Hollywood's "Volcano" a bit more comprehensible, n'est pas? Crisco 1492


 * Why the sudden change from Indonesian to French? Has your exchange programme been changed? :) DirkvdM 08:08, 27 November 2006 (UTC)


 * Mais non, mon ami. Je suis né au Canada, et ma famille est Français puis Anglais.  Besides, I need to practice my French so I don't forget it.  Il n'y a pas beacoup de personnes qui peut parler la Francais aux Indonesia.  hehe... aku sedikit bodoh... :P

LOL JK about that last sentence... sekali mungkin... Crisco 1492 01:25, 28 November 2006 (UTC)


 * Is that very possibly Indonglish? :) DirkvdM 06:15, 28 November 2006 (UTC)


 * Excuse my French, but shouldn't that be 'personnes qui peuvent parler'? And isn't Indonesia singular? Or am I now being stupid? DirkvdM 06:15, 28 November 2006 (UTC)


 * "qui" is the pronoun here, and it's third-person singular. So "qui peut" is correct.  (At least, that's what I think...I'm not a French speaker.)  --Bowlhover 17:05, 28 November 2006 (UTC)


 * The plural of a verb is determined by the noun, in this case 'personnes'. English doesn't know stuff like plural in verbs (count your blessings), so it's no surprise you got this wrong (even blessings have their flipsides). DirkvdM 19:55, 28 November 2006 (UTC)


 * Hahaha should we move this conversation to the languages department? :P Sorry about my french, but its a little rusty after 2 months without next to no use.  Most of the time here I'm speaking Indonesian, with some conversations with my host brother or some friends at school in English.  There is only one person here I speak French with, and that was a while ago because French was easier for him than english, but now, since I can express myself in Indonesian rather well, I don't speak French as much.  And Dirk, I do believe you are right about Peuvent, it would seem I forgot that it is the plural form of Ils and Elles.  And yes, blessings do have flip sides... Indonesian has NO conjugations like English and French, indeed, the only thing i have to choose from (at least for now) is whether it is an Me- based, Be- based, or a passive voice verb, which begins with di-.  I think thats probably the only reason I speak Indonesian as well as I do now, took about 2 weeks to get the grammar right, and now its just vocabulary (I hope :P) Crisco_1492

Neanderthals
Were Neanderthals characterized by more hair than humans on their backs, legs, arms and chest? 71.100.6.152 06:27, 27 November 2006 (UTC)
 * I'm pretty sure it has to do with cranial capacity, as well as facial bone structure, not necessarily body hair. However, the hair would be an evolution designed to protect them from the colder weather which they endured. Crisco_1492
 * We have no evidence about the amount of body hair. alteripse 13:36, 27 November 2006 (UTC)


 * Did you realise Neanderthals is nearly an anagram of Netherlands? Is there any connection here?--Light current 13:58, 27 November 2006 (UTC)
 * "Neanderthal" is an exact anagram of "a nether land". --Lambiam Talk  14:06, 27 November 2006 (UTC)


 * Thank you! 8-)--Light current 14:27, 27 November 2006 (UTC)


 * "the anal nerd" ? - Keria 23:04, 27 November 2006 (UTC)


 * See our article Neanderthal, in particular the section Anatomy. It gives a list of physical traits that distinguish Neanderthals from modern humans, but also states: "Nothing is known about the skin color, the hair, or the shape of soft parts such as eyes, ears, and lips of Neanderthals." Any depictions of Neanderthals as particularly hairy, as in this display of the American Museum of Natural History in New York City, are based on speculation. --Lambiam Talk  14:06, 27 November 2006 (UTC)


 * But a speculation that makes sense. Their whole bodies were built to withstand the cold. Then again, that may be because they were hairless. :) DirkvdM 19:57, 28 November 2006 (UTC)

Concentric arrangement of radio antennae
When driving through Germany, I have sometimes seen from the autobahn strange structures of the following shape: Several (maybe around 30 or so) tall masts (some tens of meters tall) are arranged in a circle of maybe 50 meters or so in diameter, with wires around the circumferences at several heights. I'd guess that these horizontal wires are just to keep the structure stable, and the vertical masts look like radio sender antennas to me. They typically stand freely in the open counrtyside and are not very common. I always wondered what they were. A collegues just showed me this Google Earth location (which is near Augsburg, Germany), which seems to be a construction similar to the ones I notices. (He saw it from the train). Do you have any guesses? I do not think it to be a radio broadcast sender. Maybe some directional receiving antenna? Maybe even some installation for signals intelligence from Cold War times? Simon A. 13:31, 27 November 2006 (UTC)
 * If you look up Google Image Search for 'antenna array' you might find some pictures of what you are looking for. They could be for powerful weather radars, etc.  --Zeizmic 14:49, 27 November 2006 (UTC)
 * I have just tried, and when I just wanted to reply to you that all the images I find are square arrangements, I clicked to just one more page of results, and there, I found that they are called "AN/FLR-9" (or colloquially: elephant cage) and indeed used for signal intelligence. It seems that we even already have an artcile on them: FLR-9. :-) Simon A. 15:01, 27 November 2006 (UTC)

At first glance, I thought it might be a type of VHF omnidirectional range station though I don't know for sure.

Whale anatomy question
Do whales have eyelids, like most land-dwelling species, or just a clear nictitating membrane like fish do? CameoAppearance orate 13:37, 27 November 2006 (UTC)


 * These links:, ,, show that at least the bowhead whales, sperm whales, and baleen whales have eyelids.  --Lambiam Talk  14:28, 27 November 2006 (UTC)

wart hog and boar
I can't find the French word for wart hog in my French-English-French dictionaries nor at the Office de la langue francaise translation site,but I see that the boar or sanglier looks like the wart hog.Have read nature.com, wikipedia and other web info but none mention the wart hog as being a sub species or relation of the wild boar so they seem to be completely separate species in Africa,Europe et al.Can anyone confirm that wart hogs and boars are related or not and how do you say wart hog in French? Cochon verrue-haha?


 * It is phacochère. Warthogs and boars both are species in genera in the family Suidae. They are about as related as ducks and swans, both in the family Anatidae. --Lambiam Talk  14:20, 27 November 2006 (UTC)

Digital binoculars
Are digital binoculars (we don't have an article, but Google shows plenty for sale) merely regular binoculars with an integral digital camera (that's what they look like in the pictures), or is there something more going on, like some digital magnification?--Shantavira 15:50, 27 November 2006 (UTC)
 * Those that Google shows just seem to be binoculars combined with a CCD camera. –m y s i d ☎ 17:02, 27 November 2006 (UTC)


 * Yes, they're just binoculars attached to a digital camera. Of course, it's possible for the digital camera to have digital zoom.  --Bowlhover 17:09, 27 November 2006 (UTC)


 * Which isn't zoom at all. It just crops the image. DirkvdM 06:17, 28 November 2006 (UTC)

Evolutionary reasons for plant-based medicines?
Why is it that many plants have natural medicinal properties in humans? In many cases these properties are so complex that scientists take a long time to discover them, and then take even longer to synthesize their active compounds (if they are able to). For instance, aspirin is synthesized willow bark, the heart medication Digoxin is synthesized foxglove, a potentially huge new anti-inflammatory drug is being synthesized from Grains of paradise, etc.

I can't imagine that these complex interactions are coincidental, so there must be some connection. However, it seems unlikely that these properties were evolved for these specific purposes -- willow bark evolved for vascular tissue and to protect the tree. I don't see how having the odd animal nibble on the bark to aid their inflammations could have led to its properties being selected for.

Could anyone explain how such properties are evolved (no ID please)? Thanks! --George


 * "The entire plant is toxic (including the roots and seeds), although the leaves of the upper stem are particularly potent, with just a nibble being enough to potentially cause death." The mechanic of this toxicity is useful in controlled doses. However, rabits don't control doses. Asprin is actually a plant hormone. I'm not going to comment on the other drug - I suspect it has a similar effect - either directly poisionous due to dose, or a lucky coincidence. JBKramer 16:08, 27 November 2006 (UTC)


 * Well there we go -- it's even harder to imagine a simple evolutionary mechanism if the plant is generally toxic. But you propose it's just coincidence? --George


 * Animal toxins may have mutated from digestive enzymes. I was able to find a number of suggest plant toxin branches - starting from chemicals that simply fought decomposers in small doses growing up, to bad-taste mutates to bad-effects. On willow bark specifically - JBKramer 16:49, 27 November 2006 (UTC)


 * I believe you're looking at it from the wrong angle. There is no specific reason or evolutionary mechanism that would make a plant have beneficial results on other animals. It's the other way around! Creatures on Earth developed their metabolisms based on plants (their primary source of food), so certain beneficial reactions are likely to happen. And then, this sensibility to that substance would be passed on to new generations.
 * For example, imagine creatures who have been eating a certain plant with a certain chemical compound for several generations. If few members of that species were particularly sensible to such chemical in a beneficial way, they would not only survive better, but would pass that beneficial sensibility to next generations, and the beneficial effects of that substance would remain in the species.
 * Now take that into account, along with the fact there are several millions of different species of plants, and that our species have been trying these in several different ways for thousands of years now, you'll see that a lot of these stuff was bound to happen.
 * Also, you gotta remember that a LOT of people died while trying to figure what was good to use and what was not.
 * I hope I could offer any help, and sorry for the bad wording. I'm kinda tired right now. :P ☢  Ҡ i∊ ff   ⌇  ↯  16:20, 27 November 2006 (UTC)


 * Sure, that makes some sense, but it doesn't quite. Take the Willow bark example. Willow is a tree found in the northern hemisphere. Humans didn't reach Europe for quite some time after evolving into humans. Yet Africans are just as affected by aspirin as European humans are. Likewise, Grains of Paradise are found in a relatively small area in Western Africa. It doesn't really make sense that our whole species could have evolved dependancies on these plants found in such localized areas. -- George


 * Your wording is fine. It points out a common misconception:  Too many people are of the opinion that Evolution has an end-goal.  For example, Evolution looked at the shrew and said, I want a Human.  What should I do next?  Evolution does not have an end goal - it isn't even an entity that makes choices.  It is merely the reaction of living beings to the environment.  As the environment changes, living beings adapt to it.  As you pointed out, a plant gaining beneficial chemical reactions will likely increase the lifespan of animals who are aided by the chemical reaction.  The longer an animal lives, the more likely it is to reproduce and pass on the trait. --Kainaw (talk) 16:26, 27 November 2006 (UTC)


 * I wasn't proposing a purpose, I was wondering what the selective value to such a trait would be. For evolution to occur, there must be a selective value for any trait. I think the selective value you propose relies on the evolution of the animal with respect to the plant, but it doesn't seem as if it could really work that way, given the willow bark example in my response above (humans pre-evolving a reason to eat willow bark before ever encountering willow bark?) . Anyway, thanks for the continuing discussion! :) -- George


 * There is such a thing as coincidence. All plants contain chemicals for their own evolutionary reasons, when humans eat them, some turn out to be useful, most I think are bad. With somethings like with diseases humans that respond best to local plants will be favoured, but with Aspirin it is probably coincidence that it has pain killing properties (after all so do cocaine and opium). Plants evolving due to humans needing their products would arrive with cultivation and selective breeding. Not sure how recent those were really done with plants though, especially for medical purposes.137.138.46.155 16:53, 27 November 2006 (UTC)


 * You're still assuming that humans wouldn't be naturally sensible to the Willow bark until contact with it. This stuff was in our genes, and we just found out about the reaction later. Also, scientists nowdays test thousands of substances until they find one that has a certain reaction they're looking for. With years of such practice, we have figured certain characteristics that seem to be associated to certain reactions, but the process still relies on a bit of luck, so to speak. So again, this stuff is bound to happen. ☢   Ҡ i∊ ff   ⌇  ↯  16:57, 27 November 2006 (UTC)


 * Yeah, that's probably the most logical answer. I guess all of life is using pretty much the same subset of chemicals and compounds anyway, making such coincidences more likely. Thanks for all the replies! --George

All drugs are poisons, it is simply a matter of dosage. Hence, if bugs are eating your bark, salicylic acid (Willow bark) will effectively control the bug population (I hav eno idea what the lethal dose is to a bug, but that would be the rational) similarly digitalis is a heart medication, but it is also a very good way to kill someone. All drugs are a matter of dosage and secondary metabolites are often produced for defense mechanisms. Occasionally it is fortuitous, i.e. plant hormones, but when it gets right down to it, there are really only a limited number of aproximate shapes to enzyme active sites, hormone receptors, etc., and so it isn't all that surprising that a secondary metabolite of a plant inhibits a human protein in the micromolar range.--John


 * It's not really a valid question. Turn it around and ask why certain chemicals in plants aren't medicinal.  The reality is that life on the planet is all related.  Therefore, chemicals that are found in different species will affect living creatures.  There may be an evolutionary why aspirin is in willow bark but it's medicinal value may be pure coincidence. Look at it this way: decomposing human bodies provide nutrients and medicine for plants.  What's the evolutionary reason for that?  I would say none, just coincidence and basic tenet of simply being a living creature.  We are all made of the same stuff.  --Tbeatty 04:20, 1 December 2006 (UTC)

availability of medicated stent
I would like to know weather medicated stent for right renal artery is available for usage or not? if available please mail us place and the company name which produces it.


 * According to this link [] they are manufactured by: Johnson&Johnson, Medtronic and ev3. Since you have been able to ask a question on Wikipedia, I'm hoping it's OK to let you chase down the addresses/customer contact numbers. Mmoneypenny 19:02, 27 November 2006 (UTC)

Parabolic sound collecting dish
Please guide me to make a parabolic sound collecting dish. Which material is good for the dish? How far should the microphone be from the dish? What size is sufficient for the dish?


 * The material should be hard and rigid. Rigid plastics or alumin[i]um is commonly used. The microphone should be located at the focus of the parabola. I've heard that you can actually do a pretty credible job using a child's snow sledding disk (which is probably actually a section of a sphere).


 * Atlant 17:48, 27 November 2006 (UTC)


 * The microphone should be placed on the dish's focal point. The size of the dish depends of the wavelength of sound waves in air that you're trying to capture. Humans can usually hear within a range from 20 Hz to 20 kHz. Since most of the lowest (below 300 Hz) frequencies are pretty irrelevant for speech recognition (assuming that's your purpose), a 60-40 cm dish should be more than enough for most of the hearable spectrum that you could use. The larger the dish the clearer will be the sound. ☢  Ҡ i∊ ff   ⌇  ↯  17:57, 27 November 2006 (UTC)


 * If you can get your hands on a discarded satellite dish, you can use it as shown here. --Lambiam Talk  18:14, 27 November 2006 (UTC)


 * On a similar topic - there are many radar dishes that went from a perfect parabolic dish to a tear-drop shape to decrease interference. Has the same been used in sound collecting dishes? --Kainaw (talk) 18:20, 27 November 2006 (UTC)


 * How does that work? What kind of interference are we talking about? —Bromskloss 19:35, 27 November 2006 (UTC)


 * Dustbin lid. Unfortunately the page has been transmogrified to completely remove picture of the old fashioned dustbin.--Light current 21:45, 27 November 2006 (UTC)

how fast is the earth warming?
Every year, how much hotter does earth become? How much hotter has it become in the past 100 years?


 * Perhaps visiting global warming would help?


 * Dragons flight 18:34, 27 November 2006 (UTC)

How much has sea level rised in the last 100 years?




 * [[Image:Recent Sea Level Rise.png|thumb|300px|Sea level history]]
 * }
 * Got that covered too. See sea level rise.  Dragons flight 18:39, 27 November 2006 (UTC)


 * You will have to define what you mean by "earth". The planet does not have a single temperature.  Therefore, you can pick out temperatures of a single city that hasn't warmed much at all (or even become cooler) and use that as your source of "Earth temperature".  You can pick out a handful of major cities.  You can try to gather all the temperatures you can find.  Do you want estimated ocean surface temperatures?  How about places that we don't bother to check - should they be estimated?  All in all, the concept of an "Earth temperature" is a problem for the Global Warming argument.  Yes, nearly all sane scientists say the Earth is warming.  However, there are those who cherry-pick temperatures to make it look like the Earth will be ball of boiling lava in 10 years.  They make the reasonable argument hard to advance because only the nutjobs get major press.  As for the sea level rising, it hasn't risen much - if any.  Keep in mind that when ice that is in water melts, the water level goes down.  So, as icebergs and ocean ice sheets (notably, the North Pole) melt, the sea level will go down.  When ice on land melts, the sea level will go up.  Combined, there is more ice on land than in the water.  So, at some point, the water level should rise. --Kainaw (talk) 18:34, 27 November 2006 (UTC)
 * (taken partially from MSL)Another thing to keep in mind is that finding the MSL (mean sea level) is much more difficult than temperature, as far as I know. MSL is the mean sea height, with reference to a suitable reference surface. Defining the reference level (http://www.pol.ac.uk/psmsl/puscience/index.html#1), however, involves complex measurement, and accurately determining MSL can prove difficult. Finding the MSL change involves comparing the local height of the mean sea surface with a "level" reference surface or datum, called the geoid. In a state of rest with absence of external forces (totally stagnant water), the mean sea level would be the same at every point on the Earth. The geoid would only deviate from the perfect sphere in this theoretical model with local differences in MSL from local deviations in the Earth's gravitational field. In reality, due to currents, air pressure variations, temperature variations, salinity variations, etc., this does not occur, and prevents certain verifiable long term averages from being calculated. Sea level measurements must account for the 228-month Metonic cycle and the 223-month eclipse cycle on the tides. MSL at the Pacific end of the Panama Canal stands approximately 20 centimeters higher than at the Atlantic end. The location-dependent, persistent separation between MSL and the geoid is referred to as "stationary sea surface topography," which varies globally by somewhere around ±2 meters. Doesn't that mean the error margin is 8 meters? Several terms are used to describe the changing relationships between sea level and dry land. When the term "relative" is used, it connotes change that is not attributed to any specific cause. The term "eustatic" refers to changes in the amount of water in the oceans, usually due to climatic changes. The melting of glaciers at the end of ice ages is an example of eustatic sea level rise. The term "isostatic" refers to changes in the land level, of land masses due to thermal buoyancy or tectonic effects and implies no real change in the amount of water in the oceans, although isostatic changes change the MSL because it is relative to the land. Ice ages cause isostatic changes. Ice on landmasses weigh them down, and push the land down. The subsidence of land due to the withdrawal of groundwater is an isostatic cause of relative sea level rise. X [' Mac Davis '] ( DESK | How's my driving? ) 15:59, 28 November 2006 (UTC)
 * Are you sure about the dropping water level in ice water? It seems to me that the ice is displacing its own weight of water, and once it melts (neglecting density variations in liquid water) it is still displacing that precise amount of water, since it is that weight of water.  Shouldn't it have no effect?  --Tardis 22:51, 27 November 2006 (UTC)


 * Yes, I am sure. Ice is less dense than water - which is why it floats.  Most of the ice is below water - very little above it.  When ice melts, it becomes more dense - so it takes up less space.  Taking up less space means that the overall water level goes down.  Try it yourself - it's fun for the whole family!  Put a bunch of ice in a cup of water.  Mark the water level.  Put another cup of water without ice next to it and mark the water level.  When the ice melts, check the difference on each glass.  The one without ice is there to see how much left due to evaporation.  You'll find that the water level is much lower in the ice-water cup after the ice melts. --Kainaw (talk) 23:19, 27 November 2006 (UTC)


 * Are you really really sure? I only ask because when we were doing this in school, I'm sure we learnt that the water level stayed the same. The amount of ice above water was supposed to be equal to the amount more space ice takes up than water. This is, if we are marking the water level, not the top-of-the-ice level. Skittle 23:48, 27 November 2006 (UTC)


 * Detailed example: let's say ice's density is 0.9 g/cm^3.  We throw a 1 g ice cube (that's 10/9 cm^3) into a cup of water.  Water pushes up on it with the same force that gravity pulls down on 10/9 cm^3 of water.  In our case, gravity applies 1 g of force to the ice cube.  When the ice cube sinks so that 0.9 g of it is below the water's surface, the force of gravity (1 g) will equal the water's buoyancy (0.9 g of ice = 1 cm^3, 1 cm^3 of water = 1 g).  At this point the ice cube stops sinking, so 1 cm^3 of water (0.9 g of ice takes up 1 cm^3) is displaced.  When the ice melts, it will turn into 1 g of water, or 1 cm^3 of water.  --Bowlhover 04:32, 28 November 2006 (UTC)


 * So it displaced 0.9g of ice displaced 1 cm^3 of water (0.1 g was above the water line). When the ice melted, 1 cm^3 was replaced as water, therefore the water level remains unchanged.  The density difference is why the ice isn't covered to the top, but it doesn't change the displacement.  --Tbeatty 05:30, 28 November 2006 (UTC)


 * You're missing one crucial element: while you're correct in saying that ice floating in the oceans doesn't (or barely) change sea level when it melts, not all ice on the Earth floats in the ocean. Quite large chunks of it are on land (Antarctica, most notably). When that stuff melts, it's a net increase in global sea levels. &mdash; QuantumEleven 12:36, 28 November 2006 (UTC)


 * Can't argue with that, but I didn't claim global warming will not raise sea levels. I claimed that melting icebergs in the ocean won't raise sea levels.  --Bowlhover 01:24, 29 November 2006 (UTC)

The biggest error in global warming is correction of the heat island effect of cities. Measurements over many years are affected by the growth and size of the city. Global Warming does not mean warming happens everywhere and estimating the overall increase is very difficult if not impossible. Consider that the Albany, New York has been cooling while New York City has been getting warmer. Is this measurement error, correction error, or real differences? The next questions is whether warming will continue and is it related to human activity. There is a real question as to how warming affects water vapor in the atmosphere. Higher temperature means more capacity for water in the atmosphere but may also mean more clouds and therefore more reflections out to space. Tbeatty 05:35, 28 November 2006 (UTC)
 * I don't think we know of the nature of the correlation between water vapour content in the atmosphere and temperature. Of course, generally, warmer planet equals more water vapour and increased albedo, meaning greater planetary reflectivity. Everything always seems to be in the goldilocks zone. :) NASA Link. The UHE is not as big a problem as some people say it is I don't think. All you have to do is rely on proxies and data stations out in the middle of nowhere. Although the whole "temperature is going up in the Northern hemisphere, and is still flatlining in the southern" is kind of freaky. There are more and bigger cities in the Nothern Hemisphere than southern, based on city radiation, however it is usually attributed to there being more land in the Northern Hemisphere. [[Image:Earthlights dmsp 1994–1995.jpg|thumb]]X [' Mac Davis '] ( DESK | How's my driving? ) 16:38, 28 November 2006 (UTC)
 * Clouds reflect Sunlight during the day but work as a blanket at night. That is something one can easily expeience in everyday life. I don't know how the two will balance against each other.
 * About whether the warming is caused by humans, is it a coincidence that scientists predicted it and then it happened? Next, people pointed out that the Earth has been in a global warming phase for thousands of years, so there is at least a natural cause. True, but is it a coincidence that shortly after scientists predicted a warming, it soon started happening really really fast? And I mean really really fast. As far as is known, temperature changes of a few degrees take place over at least thousands of years (which was already considered extremely fast), and that has indeed happened over the last few thousand years. But then it was predicted it would start to happen in hundreds of years and now it looks like it's happening over mere decades. That's about 100 times faster than 'normal'. DirkvdM 06:49, 28 November 2006 (UTC)


 * I agree, but it is also true that during the hot months (i.e. what global Warming predicts will be longer and hotter summers), cloudy days are cooler than sunny days. As for scientists predicting it, keep in mind that they predicted cooling in the 1970's and it did cool.  The reality is that science is a self-fulfilling prophecy.  Scientists that make correct predictions get more coverage.  It is not surprising that scientists that espoused global warming are credited with discovery and the field grows.  1000 monkeys on a 1000 typewriters may recreate Shakespeare at some point but I hardly think that one monkey should be credited with prescience and intelligence.  Let alone, giving credit to me for predicting a monkey might recreate Shakespeare.
 * Do you remember the compelling global cooling scenario? Clear cutting forests created large open areas that reflected vast amounts of sunlight which caused global cooling.  This in turn cause the ice caps to grow which in turn reflected more sunlight and the positive feedback loop was created.   Very compelling and logical.  This coupled with heating oil shortages and relatively cold (though not historically cold) 1960s/1970s (every year was cooler than the next with Blizzards regularly on the news).  Not unlike the global warming positive feedback loop that is being espoused today.   The problem is that warming won't be continual.  The results?  keep the hype but change the name to "Global Climate Change" or "Abrupt Climate Change".  This allows any type of weather to warrant political action.  I personally am very sceptical about the dire consequences.  I think the earth is much more resilient than we give it credit.


 * Scientists like to look at trends. The Earth MSTA has been going up for about a little bit. Science is all about predicting, but in climatology we're not there yet. When the temperature started going down fractions of a degree the scientific consensus was global cooling. Trends, are all we have in predicting. We're trying to figure out what happened before, and what is happening now. The IPCC's Third Assessment Report (I have it right here!) and it states "Climate models now have some skill in simulating changes in climate since 1850." We just guess what is going to happen, based on trends, based on the time scale, and we're also trying to figure out what happened before. Climate systems are nonlinear and chaotic, then it can be difficult to predict the future. This isn't like a "how fast will the bowling ball be going one meter above the ground if it was dropped from five meters" question. Also note that proxy-deriven data is less reliable than human-taken datas for obvious reasons. About the clouds, usually just the albedo is looked at, and we have gas isotope ratio proxies for those. It has been going up as well. How much, what effect does it have, and how strong is that effect? Debatable. I wish we just knew. That would be easier. X [' Mac Davis '] ( DESK | How's my driving? ) 15:59, 28 November 2006 (UTC)
 * Yeah yeah, global warming is just a big guess, I can't argue with that. But even the most conservative guesses show Earth should warm up after doubling the atmosphere's CO2 level.  It's how much it will warm up that's not for certain.  --Bowlhover 16:52, 28 November 2006 (UTC)


 * The problem is that scientists want to have near absolute certainty but politics can't afford to wait for that sort of thing. If there is a strong indication that things might go horribly wrong then action has to be taken before we can be certain. And by now it's so obvious that no-one can miss it. I don't know about elsewhere, but in the Netherlands the 10 hottest years since 1901 all fall in the last 17 years and unless the temperature tkes a dive over the next few days, this autumn will become the hottest in 300 years. The previous recordbreaker was 2005 (shared with 1731). This year also had the hottest august in 300 years, the hottest july, the hottest september, the second hottest october and probably the second hottest november in 100 years. You could say that that is just this year, but most hottest months since 1901 fal in the last two decades. That is becoming more than a hint. But like I always say, don't trust me. Trust the scientists. If they don't know, then who does? DirkvdM 20:24, 28 November 2006 (UTC)


 * In my opinion, it is comments like the previous one that hurt the global warning message. For every person who says it is hotter than ever where they live there's a person who can say the opposite.  We just had the first snow-game in Seattle last night.  It snowed in Charleston, SC last week - in November!  Global warming isn't about your personal city having the hottest trend in 100 years.  It is about global warming.  One effect of global warming is radical weather patterns - the kind that send snow too far south and heat waves too far north.  Perhaps the "warming" should be dropped from "global warming" so people can get over the concept of "If I look at this here thermo-dilly-bob and it'n says it ain't too hot, then there ain't none that there global warming stuff goings on." (Yes, I grew up around plenty of backwards country folk) --Kainaw (talk) 20:53, 28 November 2006 (UTC)


 * "The problem is that scientists want to have near absolute certainty but politics can't afford to wait for that sort of thing." Umm, Dirk, is it "say-the-opposite-of-what-you-mean day" already?  I thought that's on the 31st!  --Bowlhover 01:24, 29 November 2006 (UTC)


 * Ehm no, science is about finding the truth. Politics is about taking action before reality does it for you. DirkvdM 21:17, 29 November 2006 (UTC)


 * Before spending billions of dollars on reducing global warming, I think you'd want to be nearly certain that the money isn't going to go to waste. In science, if a theory has a 70% chance of being correct, scientists will say "ok, this is probably true, though we'll need to do some more experiments".  --Bowlhover 03:52, 30 November 2006 (UTC)


 * But in politics a 70% risk of climate change should be an incentive not to wait for further research but take instant action because the potential losses are huge. Crops will start to fail. How many and how seriously may not be certain, but there will be losses and those have to be weighed against the cost of intervention (if we ignore the human tragedy for a second). But this intervention does not have to cost money. It can save money. After all, saving on exhaust fumes means saving on oil expenditure. Do the same thing with less fuel and you've got a win-win situation. Traffic is a good example. Use strict laws to make people drive at a steady pace and in unison and that will in itself save fuel. It will also reduce traffic jams and thus irritation, fuel and (working) time (=money) wasted. Win-win-win. A nice side-effect is that it can save hundreds of thousands of lives per year. Often young lives, that money has been poured into but not yet given its full yield. So more money savings. Win-win-win-win. What's stopping us? A sense of 'freedom' in how we drive our cars. But if that freedom gets you stuck in a traffic jam, what is it worth really? DirkvdM 09:31, 30 November 2006 (UTC)


 * Snow in the Seychelles? That is indeed quite extraordinary! :) I bet they danced in the snow. I wonder what kind of dance they did.
 * But seriously (before SCZenz deletes me again), you mention cities. I mentioned a country. I admit that I went into a little too much detail with the months and autumn. But you have to agree that all 10 hottest years since 1901 falling in the last 17 years (and almost all 10 coldest years falling in the first half of the century) is a pretty serious (and convincing) trend. But I agree that radical (and less predictable) weather is a much more serious threat. The effect that may have on agriculture should really scare the shit out of people. Here in the Netherlands there is a lot of stress on rising sea levels (and thus global warming) for obvious reasons (euphemistically called 'getting our feet wet'). But increased rainfall in Central Europe will come our way through Rhine and Meuse and that combined with a high sea level and more fierce storms should also impress the Dutch (North Sea flood of 1953 - I'm surprised I haven't heard any references to that yet). DirkvdM 21:17, 29 November 2006 (UTC)

Endangered species, man made?
Isn't it a bit far fetched to suggest that a natural environmental condition could have been affected so quickly by human actions? A few hunters going after a bunch of birds and geese isn't exactly going to affect a thousand year old cycle of extinction/speciation on the earth, I mean there were extinction events thousands of years before there were ever any human beings around, and now there still are, obviously there haven't been human beings living there the whole time doing it, so why attribute it to human actions? It seems like this was more of an excuse for Clinton to get the federal government involved in the personal affairs of Americans, then a serious study. So the question, in light of current science, does Clinton's theory of 'Endangered species' still hold water?--Gomer pylon 18:22, 27 November 2006 (UTC)


 * You might ask this question of the whales. I think they could enlighten you on the effects mankind can have on some species.


 * Atlant 18:35, 27 November 2006 (UTC)


 * Interesting that you use whales... numbers were generally going up right before action was taken. X [' Mac Davis '] ( DESK | How's my driving? ) 17:02, 28 November 2006 (UTC)


 * Get a few hunters together ... to make fertilizer - Keria 18:54, 27 November 2006 (UTC)


 * ... or ... for hog feed. The IUCN Red List of Threatened Species goes back to 1963, and the International Union for Conservation of Nature and Natural Resources itself was already founded in 1948. The Convention on Biological Diversity was adopted in 1992, before Clinton took office. It has been ratified by 188 countries, not all of which are Clinton puppets. --Lambiam Talk  19:11, 27 November 2006 (UTC)


 * I wasn't aware that Bill Clinton was a population biologist, or that a theory of endangered species was attributed to his work. Good on him, though, if he's been diversifying.


 * Human-driven extinctions have been around for a long time&mdash;some are the direct result of human hunting/trapping/poisoning/eradication, while others are the result of the effects (deliberate or otherwise) of introduced species carried (again, deliberately or otherwise) by migrating/trading humans.


 * You're going to have to be a bit clearer about what specific question you're asking; consider phrasing your question as a question, rather than as a thinly-disguised conspiracy theory. TenOfAllTrades(talk) 22:09, 27 November 2006 (UTC)


 * Dunno about Clinton, but you said it - extinction has always been going on, due to loads of causes. Humans are just one such cause. But humans are pretty powerful (technology) and numerous (five billion of just one species our size is quite excessive). A new factor is climate change. Species that are more or less specialised will have to move to new areas that have the right temperature (in general towards the poles or uphill), but other condiditions there might not (probably will not) be right for them, in which case they may not be able to survive, depending on how versatile they are and how fast they can evolve to adapt. And some will not be able to move so fast, such as plants, which often move at just a few metres per generation. DirkvdM 07:05, 28 November 2006 (UTC)


 * If humans are unnatural than where did we come from? The Native Americans are largely regarded as very close to nature, and about as easy on nature as you could get before they where whitemanized. Native Americans around Yellowstone didn't like the "old-growth" forest very much at all; the forests may look astonishing and impressive, but they're dead landscapes for game. They set fires, making sure the forests burned down periodically. They made sure there were only islands of old-growth forest in the midst of plains and meadows. The forests that the first Europeans saw were hardly "primeval." They were cultivated—the Native Americans changed them to their liking. Its not surprising there is more old-growth forest today then there was one hundred and fifty years ago. A leading theory says that early Native Americans hunted mammoth and other large animals to extinction, they burned forests and changed the environment to suit their purposes.  Humans have the ability to adapt to all kinds of things, using not only their DNA, but their minds. Plenty of animals change their environment, beavers and termites come to mind. They aren't drastic, or close to the scale you say. Well, a few beavers controlling a river sounds a bit off scale, but it is natural. Beavers have been doing it for so long, that it becomes part of the environment, as if it wasn't before. It's normal, and everybody adapts to your adaptation. Coral? Coral can be called "slow" but it is such a weak organism, and it changes the enivronment so much. The Great Barrier Reef is host to uncountable amounts of other organisms, as well as affecting ocean currents. X [' Mac Davis '] ( DESK | How's my driving? ) 17:02, 28 November 2006 (UTC)


 * I severely doubt the native american population was ever large, widespread or co-ordinated enough to hunt anything to extiction. And humans are unatural now, whatever you get told. If we were natural, if our society was completely razed, we would just put it back up, like an indian would have, if his village was destroyed, he would catch a bison, and make a new teepee or whatever, civilized humans are completely incable of survival without there support system, if new york was razed, half of them would have probably died by the end of the first week. Philc  TECI 19:02, 28 November 2006 (UTC)


 * It doesn't take a very large human population to have a dramatic effect on large animals, as there aren't very many of them, either. As for human's causing extinctions, there is absolute proof of this in many cases, such as the passenger pigeon. StuRat 08:11, 29 November 2006 (UTC)


 * Oh yeh, there are various animals that are extinct because of us, but often they are by large populations, in co-ordinated efforts, eg the romans with the Atlas Bear and North African Elephant. Philc  TECI 19:12, 30 November 2006 (UTC)

Your original argument contains a logic flaw, paraphrased as "since other things cause extinction, there can't possible be more causes, so humans can't be a factor". Just because A causes C, this does NOT mean that B cannot cause C. This illogical argument is popular with anti-environmentalist in all areas:


 * Since methane, carbon dioxide, ozone, etc. are also produced by natural processes, we can produce any level we want and not worry about the consequences.


 * Since global temps vary naturally, we can ignore any signs of global warming.


 * Since radiation also occurs naturally, we don't need to worry about nuclear contamination.

StuRat 08:11, 29 November 2006 (UTC)


 * Right, it's the scale that counts. A species the size of humans doesn't usually go beyond a few million. We've got a thousandfold of that. Also, humans are part of nature. But in nature shit happens too. All the time, actually. We need to defend oursselves against that, not make it worse and say "oh, it's ok, that's nature." That goes for the climate as well extinction. We can use biodiverity to our advantage, such as new crops when old ones fail. It's not just 'that cure against cancer somewhere in a rainforest' that talk about this is often limited to. DirkvdM 09:49, 30 November 2006 (UTC)

Humans do have a direct effect on the extinction rate, and extinction selectivity of species. Briefly put, where humans go, big animals die: escpet the ones we domesticate. Ask the big flightless birds of polynesia...actually they are all dead. Human induced climate change and environmental destruction is also leading to a massive extinction. There have definitely been bigger extinction events, and ones that wiped out almost everything, and the planet survived. But it lost a lot of evolutionary lineages each time. Also, never, in any extinction event, have large animals pulled through. It doesn't look very good for us. Gradual elimination of members of the food chain is like playing Jenga. It doesn't look like the chain is suffering any damage until you pull out the key peice and it all comes tumbling down. The African Savannah is a good example of modern human effects on local extinction. A change in agriculture brouhg in by Europeans in the 19th century led to the halt of the farming of traditional crops and led to the introduction of European crops. This of course caused a large change in the local ecosystem which led to collapse. Hence the fact that parts of Ethiopia, Sudan, and Chad which were once able to sustain reasonably large populations are failing: soil quality is falling, and not enough local plants to replenish it. Greater populations on limited resources are also leading to major environmental pressures. This is going on all ove rthe world.


 * I believe that part of Africa and the Sinai peninsula has been undergoing a continuous desertification since the end of the last ice age, not due to any human activity, but just changing climate patterns. StuRat 05:18, 1 December 2006 (UTC)


 * Note that there is another factor at work - overpopulation. The great famine in the Sahel was in part due to modern medicine keeping people alive, but people not responding to that by getting fewer children. The ecosystem was sufficient to support the former population, but not the new one. Alas we can do little about overpopulation in the short run, even though it is the major cause of the disruptive effect of humans. So in the meantime we need a smaller impact (footprint) per person. Which is not to say that that will plunge us into poverty. We just need to let go of the notion that we have to keep on accumulating more wealth despite the fact that we already have more than we need. DirkvdM 08:07, 1 December 2006 (UTC)


 * And why accumulate wealth of our own when we can just sponge off the taxpayers, right ? StuRat 11:35, 1 December 2006 (UTC)

Big human cube
How heavy would a 100x100x100metres cube be on earth if it had the density of the average human body? - Keria 18:46, 27 November 2006 (UTC) P.s.: not psychopathic homework!


 * 109 kg roughly, representing the equivalent of about 12 million people. Dragons flight 18:51, 27 November 2006 (UTC)


 * Figure that humans have just about the same average density as water&mdash;we float, but just barely. You can work from there; you should hit something like Dragons flight's answer. TenOfAllTrades(talk) 19:11, 27 November 2006 (UTC)


 * Depends on if your human meat cube has air filled lungs and how much fat, they're both considerably less dense then water. Human meat cube, I like the idea of that! Can I be involved?? ;) Vespine 23:22, 27 November 2006 (UTC)


 * Whydont'cha find the desnity of ballistic gelatin, then do a density-volume-mass problem? X [' Mac Davis '] ( DESK | How's my driving? ) 17:06, 28 November 2006 (UTC)

Wii
Does the Wii have a premium package or is it just one deal? Also what all comes with the Wii upon purchacing it? --Ælfwine 20:55, 27 November 2006 (UTC)
 * Wii, controller, nunchuck controller, disc (wii sports), power supply, sensor bar, video leads and a stand see http://wii.nintendo.com/whatiswii_index.jsp. .No premium package as yet.87.102.20.219 21:20, 27 November 2006 (UTC)
 * Note: this is the science questions page not computing...

Fossils
I have had a good look at pictures of the fossils found in the Burgess Shale and the interpretations made of them by science illustrators. I find them fascinating. Could you point to other paleontological and archeological discoveries showing fossils different from the Burgess Shale? Any link to illustrations of unusual fossil animals would be very much appreciated. Thank you - Keria 22:55, 27 November 2006 (UTC)
 * There are several dozen images on Wikipedia commons that are of fossils. --MONGO 06:02, 28 November 2006 (UTC)

Once you have used up Wikipedia, it's time to move to Google! Rather than fossils, I would concentrate on the beginings of life, life in the Pre-Cambrian, Cambrian and Paleozoic. There are a lot of resources, and full 3-D illustrations. --Zeizmic 12:58, 28 November 2006 (UTC)

Negative buoyancy
Myth or fact?--Light current 23:13, 27 November 2006 (UTC)

Related to humans 8-)--Light current 00:33, 28 November 2006 (UTC)

Some people say they cant swim as they have negative buoyancy!--Light current 02:34, 28 November 2006 (UTC)


 * ? How could it be a myth? Doesn't it just mean the thing is denser than the fluid it is in, and so sinks? Skittle 23:44, 27 November 2006 (UTC)


 * Fact. If you breathe out all the air in your lungs, and then jump into a swimming pool, you'll sink.  --Bowlhover 01:27, 28 November 2006 (UTC)


 * OK. Why?--Light current 01:31, 28 November 2006 (UTC)


 * Because with your lungs empty the average density of your body is higher than the density of the water. See also buoyancy. -- SCZenz 02:31, 28 November 2006 (UTC)


 * Human fat is less dense than water, while muscle is more dense, so lean, muscular people are more likely to sink. StuRat 07:50, 29 November 2006 (UTC)


 * If I breathe out as much air as possible, I still float in the pool.  Skinny friends of mine sink.  (Yes, I need to lose weight.)  Skinny friends swim just fine.   But if we were stuck out in the ocean without any flotation devices, they might tire and die first.  --Wjbeaty 04:55, 30 November 2006 (UTC)

Remote-controlled phone--will these parts work?
As a follow up to an earlier question, I have a speaker phone that I'd like to be able to control remotely. I'd like to hook an RF receiver up to the points on the PCB (inside the phone) where the buttons touch. I have two buttons I'd like to make use of:


 * The on/off button
 * The 6 button

The buttons work like the keys on most keyboards--when a key is pressed, a little dot on the bottom of the membrane under the keys hits the exposed paths on the PCB, completing the circuit, and the phone registers a button press.

So after hunting around for a few parts, I came across these two items: An RF receiver  and the accompanying transmitter. My question is: With the receiver, would it be a simple matter of connecting the two relays on the receiver board to the two pairs of points on the phone's PCB (and then supplying power)? The description for the receiver mentions it has two relays, so would this mean that, when it receives a signal from the transmitter, the relay would then complete the circuit and mimic a button press on the phone? The relay article seems to indicate it does (and each relay can operate in pulse mode, where a pulse would mimic a press-release of a button), but I thought I'd ask here just in case.

Thanks.. --Silvaran 23:18, 27 November 2006 (UTC)


 * Seems you have found the ideal hardware for the job 8-). It is IMO a simple matter of connecting the Normally Open contacts of the relays on the receiver board to the two pairs of points on the phone's PCB. Whether pulsed operation is long enough to open the front door, you will have to try out.(or do you dial 6 to do this-- I cant remember) Also, you need some power for the reciever. You may need to use a battery for this to avoid messing with the phone. In fact I would recommend that you do as this will give you complete isolation of your kit from the phone companies, and therefore increased safety!--Light current 00:42, 28 November 2006 (UTC)


 * The product page recommends a 9 volt adapter, so I may try to go with a 9V battery if I can. Though as this is a custom job, there's no clean battery compartment in which to set the battery, so we'll see (on the other hand, the receiver board has its own DC 9V in).  I hit '6' to get in, and it seems that the relay will stay open for 0.5s, which should be plenty.  Once all hooked up, it should be button#1 (pickup), (talk), button#2 (dial 6), button#1 (hangup). Thanks.  --Silvaran 02:39, 28 November 2006 (UTC)


 * Pleas let me know when you get it working or if you have any problems. 8-)--Light current 02:44, 28 November 2006 (UTC)

Solar flare
A friend in Australia says he heard a news item on the radio about a massive solar flare (in the past couple of days) that disrupted electronic transmissions on earth. I can't find anything about this after searching news.com.au, google, and Wikipedia. Does anybody know what he might have been referring to? --199.3.116.5 23:25, 27 November 2006 (UTC)


 * Go to http://www.spaceweather.com, and check the November 21 archive. (To check the archives, look at the top right corner of the page.)  The sunsport which caused the solar flare, sunspot 926, is now visible.  --Bowlhover 00:26, 28 November 2006 (UTC)


 * Thanks. But, if it disrupted electronic transmissions in a significant way, as my friend claimed, why can't I find anything about it from mainstream news sources? --199.3.116.5 00:55, 28 November 2006 (UTC)
 * I think they missed the 'news flash' due to a flare-up on the Sun! Sorry,,,couldn`t resist. Dave 172.129.2.55 03:22, 28 November 2006 (UTC)


 * I think the problem here is disrupted in a significant way is very subjective. To a scientist, significant may mean it measured significantly on some instruments that read radio interference. To a layperson, significant may mean their Foxtel didn’t work for a day, I'm guessing it was more like the first type of significant. Vespine 03:46, 28 November 2006 (UTC)


 * Agreed. If you can't find any mention of the solar flare in the main news sources, it probably wasn't a big deal.  --Bowlhover 04:02, 28 November 2006 (UTC)


 * If our article on sudden ionospheric disturbance is right, then these solar flares mainly disrupt shortwave communication. It seems to me that microwave satellite links are not effected very much, and as most communication goes vie them nowerdays rather than on shortwave, space weather is maybe not so much an issue any more. Simon A. 14:26, 28 November 2006 (UTC)