Wikipedia:Reference desk/Archives/Science/2010 May 3

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May 3

Plutonium

In the Simpsons, Homer's bag has plutonium in it and the police dynamite it, causing a nuclear explosion. Would this happen in real life? --75.33.219.230 (talk) 00:13, 3 May 2010 (UTC)

It wouldn't cause a nuclear explosion, but it would disperse toxic plutonium into the air. Think dirty bomb, not nuke. A decent real-life analog would be the 1968 Thule Air Base B-52 crash. Messy and expensive to clean up. Few if any immediate deaths; maybe some long-term health problems if plutonium was inhaled. Bad, but not as bad as a full nuclear explosion. (Making plutonium detonate in a full nuclear explosion is not easy—see Fat_Man#Technology for a decent description of why.) --Mr.98 (talk) 00:45, 3 May 2010 (UTC)

To explode a nuclear bomb you need to have enough material in one piece to reach the critical mass for the element. That's more or less it. The trouble is that when you have anywhere near that amount it starts to get really really hot and radioactive. So what you go is make a number of small pieces, and when you need it to explode shove them all together into one piece (like imagine a pizza, pull all the slices apart, then when it's time to explode push them all back together into a circle). Just exploding the plutonium will not make a nuclear explosion - it will just send plutonium everywhere, which will do exactly the opposite, since now you have lots of small pieces instead of one big one. Ariel. (talk) 02:26, 3 May 2010 (UTC)

This is not, in fact, how plutonium bombs work (so far as we know), but is a common misconception. Plutonium weapons use a solid piece of plutonium that is then compressed to a a high density. If you split plutonium into multiple pieces and then tried to combine it, you would have a fizzle, because the combination speed would be slower than the reaction speed. Nuclear weapon design has more detail on implosion physics. It is not the "small pieces" model, though this is often how it is erroneously explained in textbooks or encyclopedias (but not Wikipedia). --Mr.98 (talk) 12:02, 3 May 2010 (UTC)

Ummm, actually that is how Gun-type fission weapon operates. Implosion types mentioned above are more powerful, and are most likely the design used by the developed nuclear powers. Googlemeister (talk) 14:10, 3 May 2010 (UTC)

The article you linked to says plutonium CANNOT be used for gun-type fission weapons. --99.237.234.104 (talk) 20:15, 3 May 2010 (UTC)

From my reading it was because of the Pu240 impurities that were not removed in 1940s technology plutonium enrichment (with results similar to Helium 3 contamination), not that it was an inherent property of plutonium itself. Perhaps even with today's production methods we still can not remove the 240, or it is not cost effective? Googlemeister (talk) 20:55, 3 May 2010 (UTC)

This is getting a bit tangential, but while we're all here... the reason you don't remove the Pu-240 is twofold:

1. It is not cost effective. If you can remove Pu-240, then you can also enrich uranium (both require the same level of technical development). So in that case, you have a product flow that looks like this: uranium metal -> reactor -> processing fission products -> enrichment. If you have the technology for enrichment, you can make it just uranium metal -> enrichment and skip the whole reactor phase. (To your credit, you don't have to enrich as much as you do with the uranium. Though it might be harder from a physics point of view... I don't know if the 1 neutron difference between Pu-239 and Pu-240 would change things a bit, as compared to the three neutrons between U-235 and U-238.) You can reduce the Pu-240 levels by varying the way you have your reactor make plutonium, but not to levels that it will work in a gun-type weapon without fizzling, I don't think.
2. More importantly, plutonium is nasty and messy. It is more volatile and toxic than uranium, especially in a gaseous form. I'd think the last thing you'd want to do with plutonium is to make it into a gas and then spray it inside your enrichment machines. The contamination level would be much higher than with uranium and require a lot more expense and effort.

To my knowledge no nation has tried to use plutonium in a gun-type weapon. When they did want gun-type weapons (say, for artillery shells), they used U-235. For everything else, implosion is a far more efficient use of material.

Separate from this is whether the "pizza" design (which is in fact how the plutonium implosion is sometimes depicted and was even considered as a possibility very early on in the project before implosion was invented) would work. It's basically a spherical gun-type design. I don't think any powers ever made weapons this way, probably because the amount of symmetry necessary is probably quite difficult to pull off. (Implosion is hard, too, but if you get it working correctly, it is almost certainly more efficient than any variation of the gun-type design.) Anyway, it is not how any plutonium bombs have ever worked, as far as anyone knows. True implosion is much more efficient. There are ways to do it that involve imploding spherical shells of plutonium (you can fill the center with DT gas for boosting), but again, this is real-deal implosion and not spherical gun-type. --Mr.98 (talk) 00:02, 4 May 2010 (UTC)

Voice

I was wondering, hypothetically, if is it possible to prevent a boy's voice from breaking at puberty. I saw something on TV that put this question in my mind. Of course, I mean without surgeries, medications, etc. Thank you. 76.230.212.190 (talk) 01:07, 3 May 2010 (UTC)

I think you have ruled out the two methods that would work. Castration works (see Castrato for a description of precisely that) and I would expect hormone treatments (well, some kind of hormone suppressant) to work too. I can't think of any other way to do it. --Tango (talk) 01:31, 3 May 2010 (UTC)

(e/c) You'll need one or the other, unless the boy just happens to naturally keep his boyish voice - rare, but not unheard of. See our article about castrati and Kallmann syndrome for a semi-natural way this sometimes occurs. Matt Deres (talk) 01:34, 3 May 2010 (UTC)

You're missing another possibility: Don't speak for the entire length of puberty. Then your voice wouldn't break "at puberty". Of course, it'll probably break constantly when you start speaking again due to atrophy from disuse, but you didn't ask us to solve that problem. —ShadowRanger ^(talk|stalk) 20:56, 3 May 2010 (UTC)

Joke aside, voices crack for a lot of reasons. Puberty makes it nearly inevitable that it will occur sometimes, but you can do things to reduce the frequency. Tensing up makes cracking more likely, so try to relax. Cold water can temporarily constrict the vocal chords, so don't speak for a few seconds after taking a sip of ice water (or drink lukewarm or room temp water). The longer you speak, the drier your throat will get, increasing cracking, so you should drink, just avoid the really cold stuff. You can find other examples online; these tips are generally useful to public speakers of all ages. —ShadowRanger ^(talk|stalk) 20:56, 3 May 2010 (UTC)

River Geometry

There are rivers with various depth and width of flow.How do these parameters get fixed in the nature.Which laws of nature governs them ?.Are there any mathematical relationships? —Preceding unsigned comment added by Amrahs (talk • contribs) 02:23, 3 May 2010 (UTC)

I would assume the depth is related to how hard the material on the land is - soft earth will wash away and make a deep river, while rock won't (at least at first, the longer the river runs, the deeper it gets). The width of the river is related to the topology (elevations) of the land. Gentle hills will make a wide river, steep ones will make a narrow ones. Next the amount of water in the river depends on whatever is feeding that river. Once you know the amount of water, and the size of the river you get the flow rate. See Meander for information on why rivers make those strange winding shapes, it's quite interesting. Ariel. (talk) 02:29, 3 May 2010 (UTC)

Oddly enough, Wikipedia has an article that covers much of this, in some detail. See River. WHAAOE! --Jayron32 03:47, 3 May 2010 (UTC)

There is some maths or 'laws' associated with the branching of rivers, but I do not recall where to find it. 92.28.253.63 (talk) 11:02, 3 May 2010 (UTC)

Rivers are also somewhat fractal in nature, meaning that the rivers are similar to the rivulets which feed them, which are in turn similar to the creeks which feed them, other than scale. StuRat (talk) 13:20, 3 May 2010 (UTC)

Some of the early fractal work was developed by some colonial English engineer whose name I forget, H.... I think, who collated and studied time series for the periodic flooding of the Nile. Edit: it was Harold Edwin Hurst. 92.28.253.63 (talk) 15:22, 3 May 2010 (UTC)

Most of the properties of a river depend on its sources, the distance it has to travel to get to the sea - and the nature of the terrain in between. The ultimate source of a river is rainfall or snow-melt on high ground someplace. Because the water has run downhill, it tends to gather together to make small streams - and those streams merge to make a river. Because the water can only flow downhill, it will fill in hollows in the land to make ponds and lakes - and generally run down the bottoms of valleys. The nature of erosion means that over geological time, the river will make it's own valleys by wearing away the soil and rock and carrying the resulting sandy stuff down-stream. Rivers also get twisty because if (for example) there is a large, hard rock on one side of the river bed - it'll deflect the water off to the side, towards the other bank. If that bank is softer, it'll get eroded - allowing the river to make a diversion around the rock. That diversion points the flow of the water towards another bit of ground - and that too erodes.

These processes are sufficiently complex - and so sensitively dependent on things like precisely where a particular (now completely eroded) rock was half a million years ago - that although we understand all of the processes very well, and can make pretty good mathematical models - we can't predict the precise shape or flow rate of any particular river from first principles.

SteveBaker (talk) 13:24, 3 May 2010 (UTC)

Isnt that all obvious? 92.28.253.63 (talk) 15:20, 3 May 2010 (UTC)

Although most of what Steve says is pretty much correct and very straightforward, I will disagree with him on two counts. I think that we can pretty well figure out what shape a river will have (braided, meandering, etc.) based on a combination of bank cohesion, sediment flux, and aggradation rate. And although what Steve says about being deflected around rock and boulders is probably correct in itself, it is not generalizable in that way. Meandering in itself is actually a self-forced phenomenon by which any irregularity in the channel will cause the flow to become nonuniform and focus high shear stresses in one location and lower ones in the others. This in turn focuses zones of erosion and deposition in a positive feedback that gives the meandering river patterns that we see. (Likewise, this gives the patterns of bars in braided streams.) Awickert (talk) 20:48, 3 May 2010 (UTC)

There's a useful introduction to fluvial geomorphology here [1]. DuncanHill (talk) 13:27, 3 May 2010 (UTC)

(outdent) I actually work as a sedimentologist / fluvial geomorphologist, so I might be able to help!

1. First, the river article is really bad in terms of geomorphology and doesn't mention hydrology much. Fixing it up has been on my mental to-do list for a while, but you know how those things go...
2. River channel morphology is controlled by events that are large enough to move sediment and/or erode the bed or banks. Most flows do not change the channel.
3. There are downstream relationships (empirically-derived) that give the depth, width, and slope of rivers as a function of discharge. See river regime. But this doesn't answer your question.
4. The width of a river channel with noncohesive/nonvegetated banks is given by a critical value of shear stress against the channel banks. If the river is narrow (relative to the difficulty of its flows to carry bed sediments), the shear stresses on the channel walls will be higher than a critical value to move these sediments. Therefore, the banks will erode. But as a channel widens, bank shear stresses decrease. If it overwidens, this will result in deposition on the banks. This is how a channel maintains its width as well as its width:depth ratio. There are a whole ton of theoretically-sound (i.e., not just empirical) equations that describe this, but the end product is what I wrote here.
   • This changes with the application of bank cohesion (e.g., vegetation), but the same principle applies. It is just much harder to erode the banks, so the flows are deeper and narrower.
5. An endmember of bank cohesion would be a bedrock channel, and results in a completely different morphology because bedrock channels are sediment-supply-starved. Here, the channel is able to incise a deep canyon (much deeper than its flow depth) because it erodes its bed, but doesn't have a sufficient sediment supply for much deposition to occur.

Hope this helps, Awickert (talk) 17:34, 3 May 2010 (UTC)

space-time continuum

Do anybody 'feel' the 4-dimensional space-time continuum in everyday life? —Preceding unsigned comment added by Amrahs (talk • contribs) 02:28, 3 May 2010 (UTC)

Space time? Then yes - everyone. 3 dimensions space, 1 of time. Do you mean 4 space dimensions? Then no. Ariel. (talk) 02:32, 3 May 2010 (UTC)

If you're talking about 4 spatial dimensions (plus time), then the question is a slightly tricky one. Obviously nobody directly perceives anything more than 3 spatial dimensions, but if string theory is correct and we actually have over a dozen dimensions - then in a sense, the mere existence of everything around us would be a consequence of all of those dimensions - and because we 'feel' all of those things, we are all feeling the consequences of those additional dimensions. String theory claims that these extra dimensions are "small" so we can't detect them. Think of this as being stuck inside a long, narrow tube - the length of the tube allows use to move freely along it - but it's so narrow that we can't move sideways or up and down. In this situation, we have one 'large' dimension, and two 'small' ones. Of course, in such a situation, we can see the sides of the tube and be aware of their proximity because even though those dimensions are small, they are still larger than our bodies. But the extra dimensions in string theory are very small indeed - much, MUCH smaller than the size of an atom. So small, that we don't even notice that they are there - and so small that we have been unable to devise a means to measure or even detect them. SteveBaker (talk) 13:13, 3 May 2010 (UTC)

Isopropanol, Peroxides can Result in Explosion & Injury?

i was reading the article on here and it says Isopropanol can form Peroxides? i keep my bottle with out the cap on. does that help? how can i test for peroxides? also if it forms them wouldent that make it caustic? i use it on my skin. —Preceding unsigned comment added by Tom12350 (talk • contribs) 03:03, 3 May 2010 (UTC)

See Peroxide, especially the safety section. I am not sure isopropanol itself is much of a problem, but acetone can spontaneously form acetone peroxide and many ethers can form ether peroxides. It generally takes a pretty powerful oxidizer to oxidize an alcohol to a ketone, but from the ketone or ether to a peroxide, something as simple as excess oxygen and a radical initiator, like UV light, could do it. You could also run into serious trouble if you mix ANY organic compound with hydrogen peroxide, and many households have both hydrogen peroxide and several common organic compounds together. Not sure it's a huge problem in your bathroom cabinet, but it may be. --Jayron32 03:45, 3 May 2010 (UTC)

Here's the article, if anyone's interested: Isopropyl alcohol. The sources cited for the peroxide claim include a materials safety data sheet [2] and an incident report [3]. The MSDS claims that it "may react with oxygen in the air to form peroxides", while the incident report claims that "The probable cause of this explosion/injury was peroxide formation associated with Isopropanol, perhaps accelerated by grease metal/solvent reactions". It further elaborates that "Literature review indicates that Isopropanol, with air contact, can develop peroxides, which can explode when concentrated". However, the big thing to note in the incident is that the isopropyl alcohol was concentrated overnight, making a probably insignificant concentration of peroxides into an explosive concentration. Jayron's probably right that it's hard to oxidize isopropyl alcohol to acetone, so the concentration of peroxides built up in most cases will be extremely low. However, the moral of the story is:

1. Keep your isopropyl alcohol in a closed container, and don't open/close it frequently.
2. Don't concentrate any potential peroxides by allowing a large amount of isopropyl alcohol to evaporate.
3. If you are going to concentrate or heat the alcohol, test for peroxides first.

I don't think it's a big deal for households with isopropyl alcohol: if it was, we'd hear a lot more about it. This incident had a lot of factors that made an explosion possible (keeping it uncovered overnight, evaporating it to concentrate peroxides, and heating), none of which should be present at home. Furthermore, when reading the incident report, it appears that even the suppliers and lab workers were unaware of the danger, indicating that it doesn't happen very often, even under these more favorable conditions. Buddy431 (talk) 05:31, 3 May 2010 (UTC)

The peroxides are usually formed in small amounts - typically around the cap - the danger (in addition to the damage caused to a person by the exposion) is that when they explode they will break the bottle and/or ignite the rest of the liquid.

An additional precaution is to keep the bottle in a dark place (no light). Sf5xeplus (talk) 10:51, 4 May 2010 (UTC)

Before big bang

What was there before big bang ????????? --Extra999 (Contact ^me + _contribs) 10:50, 3 May 2010 (UTC)

A black hole according to an article "It's black holes all the way down" by Ben Gilliland in the Metro (Associated Metro Limited) of 30 April 2010, pages 22-23. It mentions an URL www.cosmonline.co.uk but I have not been able to find it yet. dit: You could see it here http://e-edition.metro.co.uk/home.html but it requires giving an email address (which is not verified). In the e-edition, its on pages 24-25. 92.28.253.63 (talk) 11:03, 3 May 2010 (UTC)

What was where before the Big Bang? --KägeTorä - (影虎) (TALK) 11:12, 3 May 2010 (UTC)

In fact, there may not even be a "before", as both time and space came into being at the big bang (but that's only one possibility, per A Brief History of Time). --Stephan Schulz (talk) 11:40, 3 May 2010 (UTC)

See also (seriously) Turtles all the way down, which does discuss the issue. --Jayron32 12:13, 3 May 2010 (UTC)

I usually respond with the question: "What was there bewhat the Big Bang?" :-) - DVdm (talk) 12:35, 3 May 2010 (UTC)

There are quite a few possibilities - and we don't know which is true, and (worse still) there are reasons to believe that we may not ever be able to know which is true. Certainly one possibility is that both time and space were created at the instant of the big bang - hence there is no "before" and no "there". Other possibilities are that the universe is cyclic with big bang leading to expansion, then slowing, then collapse and finally a big crunch that would be the source of the next big bang. Another possibility is that the universe is symmetrical in time - with the history of the universe being played out backwards before the big bang. Right now, most of this stuff is speculation. The best answer is "We don't know" - and I'd say that Occam's razor suggests that time and space both started at the big bang - so there simply was no "before". This is hard to get your head around - but there is no guarantee that physics will be readily comprehensible to human minds. SteveBaker (talk) 12:52, 3 May 2010 (UTC)

The other posibility is that the big bang represents a sort of "cosmic censorship" (see cosmic censorship hypothesis) in that, since it represents a singularity, that is everything is in the same place at the same time, there is no means of extrapolating anything earlier than the point of the big bang, meaning that while we may idly speculate as to what (or when) anything (or anytime) existed before the Big Bang, its moot because the nature of the big bang makes it impossible to verify any hypothesis about what may have existed before it. --Jayron32 12:56, 3 May 2010 (UTC)

A big mind-boggling question is why is there any universe(s) rather than just nothing. 92.28.253.63 (talk) 16:37, 3 May 2010 (UTC)

Depends on what you mean by why. If you mean "what processes brought the universe about instead of nothing happening at all" then see anthropic principle. At worse, its a meaningless question because we are here to ask the question in the first place, if the universe did not exist, there would not be an us to question why it did not exist. If you mean "for what purpose was the universe created instead of leaving behind nothingness" then you are starting to veer into territory that religion or philosophy rather than science is equipped to answer. Immediately below this post, SteveBaker will come saying that science is perfectly well equipped to answer questions of grand purpose, and then give no qualifying statement, or propose any experiment or method which would show how science could answer such questions. --Jayron32 18:25, 3 May 2010 (UTC)

That's a little unfair. I've already said that we may not ever be able to know the answer to this. The reaction that you are referring to happens when someone says that it's not science's business to be investigating these matters - or that this is a subject only for philosophy or religion or UFO researchers or some other bogus field. That's something I do take objection to. If there is a way to investigate something, science should absolutely do that - there are no areas that are "off limits". However, there most certainly are situations (and this may well be one of them) where it is not possible - even in principle - to know the answer. But the proof of that applies just as well to philosophers and religious types. Proof of impossibility is still proof. SteveBaker (talk) 21:22, 3 May 2010 (UTC)

Sorry about mischaracterizing your standard arguement. I fully agree that there are no areas of which science should be "off-limits". Still, there is some stuff which science is clearly not equipped to answer. You seem to agree on that as well. However, we disagree that that then means there can be no answer. There can be one, just not one which science can provide. As such, it may be a very personal answer, over which people can respectfully disagree, but it still can be a very real answer which is useful in informing people's lives, and upon which people may act. --Jayron32 21:29, 3 May 2010 (UTC)

Without evidence of any kind, the more normal word for "answer" is "guess". So sure, if we can't figure out what (if anything) caused the big bang - then we are at liberty to guess - but we shouldn't go around suggesting that this guess is of much value. That being the case, you might as well say that the universe was sneezed into existence by the Great Arklesiezure as that it came from a black hole in some older universe - or any other guess you might come up with. The trouble is that with a literal infinity of possible causes - all of which are equally probable - the odds of your guess being correct are essentially zero. SteveBaker (talk) 23:27, 3 May 2010 (UTC)

That's Great Green Arkleseizure, Steve. Mustn't forget the colour. --Psud (talk) 05:20, 6 May 2010 (UTC)

You are still confusing cause with purpose, and confusing the Big Bang with creation. There's no problem in concept with using science to discover the cause of the Big Bang. Again, it may not be possible due to the laws of physics, but the concept is sound. Discovering the cause of the universe doesn't add to my understanding of the purpose of the universe, or of my life. Knowing the details of the process that created me doesn't grant me any insight into the knowing the purpose for which I was created. Furthermore, even if a furtherback cause for the Big Bang were discovered, it wouldn't change the nature of "creation", it pushes the date farther back, if you will, but still doesn't answer the fundemental questions of creation itself. Changing the identity of the creation event doesn't eliminate the questions surrounding creation itself. I understand you don't spend much time pondering things of this nature, things like "purpose", but can you atleast concede that they are valid matters for human discourse and reason, and as such, there are going to be valid discussions regarding them, even if you yourself have no interest in such discussion? --Jayron32 14:39, 4 May 2010 (UTC)

Buddha said that creation was a false concept, that creators don't exist. Why should "nothingness" ever exist without somewhere there being something? 67.243.7.245 (talk) 20:33, 4 May 2010 (UTC)

Human centipede - possible in real life?

Apologies in advance if this question causes you to consider concepts that you'd rather not have considered...

In the movie The Human Centipede, the mad doctor character creates the titular outrage against nature by attaching three people together by their digestive systems (i.e. sewing person B's mouth to person A's anus, then person C's mouth to person B's anus - the idea being that it is then sufficient to feed only person A, with B and C being nourished by poop and second hand poop, respectively). Nasty, huh?

Now, the movie advertises itself as '100% MEDICALLY ACCURATE!' (granted, which may be one of those standard horror movie marketing things intended to further disturb the audience) and the director says that he actually consulted with a top surgeon to design a feasible series of operations by which the human centipede creation could be accomplished.

Question is this (for the medically-qualified here, mainly) - quite simply, would someone *really* be able to do carry this out in real life? If so, how long would the human centipede realistically be able to survive and what sort of medical complications might arise? I'd imagine that there would be a whole host of things that could go very badly wrong, very quickly.

I do hope that my question doesn't fall afoul of the RDs 'no medical advice' rule... :) --Kurt Shaped Box (talk) 12:24, 3 May 2010 (UTC)

Coprophagia ——but this not address the nutritional value to humans, which I suspect is inadequate. Graeme Bartlett (talk) 12:29, 3 May 2010 (UTC)

Just as an aside, I really was expecting that article to contain an user-created image of a man eating faeces. --Kurt Shaped Box (talk) 12:37, 3 May 2010 (UTC)

Apologies if you are a lady coprophagiac for the Male chauvinism exhibited by the above poster. Cuddlyable3 (talk) 20:58, 3 May 2010 (UTC)

As with many "based on a true story" films, there is no requirement for any claims the films make about their own accuracy to be true. Vimescarrot (talk) 12:51, 3 May 2010 (UTC)

The professional in the article you linked to mentions the necessity of an IV drip, essentially making the whole procedure redundant (you're just pointless making faeces go through two more digestive systems to no effect - you may as well attatch a fifty-foot tube to Person A's anus). Obvious complications would be the myriad diseases you can pick up from excrement (cholera is my first thought, there are dozens more) and, without an IV drip, malnutrition. Vimescarrot (talk) 12:58, 3 May 2010 (UTC)

The key phrase here is "based on" - meaning that they started with a perfectly normal story with nothing unusual or unexpected about it - and blew it out of all proportion. If you imagine a real-life doctor who did a study on the efficiency of the human gut and discovered (not unreasonably) that some percentage of nutrients remained on excretion. A movie "based on" that true story could certainly contain this much nonsense. Sadly, there are no legal requirements for the correctness of movie blurbs! SteveBaker (talk) 13:01, 3 May 2010 (UTC)

I bet there is some implied legal requirement for a movie advertisement to be accurate, as with other ads. If they put out a blurb for a movie claiming it's a kid's movie and it's really a porno, I think they could get in trouble, for instance. The movie Kindergarten Cop seemed close to that line, being advertised and titled as if it were a cute kid's movie, but actually being a violent movie no child should see. StuRat (talk) 13:09, 3 May 2010 (UTC)

(after ec)Thanks for the answers so far, guys. FWIW, I don't believe that it was ever stated that the movie is 'based on a true story' - just that the director asked a surgeon how *he* would go about sewing three people together, ass-to-mouth, if he was an insane doctor... --Kurt Shaped Box (talk) 13:10, 3 May 2010 (UTC)

Since most the nutritional value has been removed after the first run, starvation would be an issue for the 2nd person and even moreso for the third. A more realistic way to have one person medically feed others might be to splice their circulatory systems together, although this would require compatible blood types. If only one person was fed, they would then get hungrier, because much of the nutrition would be used by the other people. In this way, it might be similar to having a tapeworm. The other people, who would be denied food, would still be hungry due to an empty stomach, but might not starve, if enough nutrition was received through the shared blood. The person who does eat might eat 3x the normal food and still not gain weight. Have I just invented a new fad diet ? :-) StuRat (talk) 13:05, 3 May 2010 (UTC)

I haven't seen the movie, but the article on it seems to imply that the nutritional needs of the people are not met and that one of them begins to suffer from blood poisoning as a result of the arrangement. That sounds about right to me. Not only would the nutritional value of feces be very low, it would be full of all sorts of gut flora that is quite toxic to humans, and not nearly enough water to survive on. Person #2 in the conga line would probably get quite sick, which would probably mean that person #3 would get... less than nutritional byproducts as well. I think the centipede would not survive long—numbers 2 and 3 would probably get quite ill, and at the very least would dehydrate themselves. --Mr.98 (talk) 13:23, 3 May 2010 (UTC)

Source: "100% MEDICALLY ACCURATE" at 2:17 (video). The standard for Wikipedia is verifiability not truth. Cuddlyable3 (talk) 20:51, 3 May 2010 (UTC)

I'm a little surprised no one has mentioned E.coli.. I read once somewhere that even if you are starving to death, don't eat human poop. Bad effects will far outweigh any benefit. Vespine (talk) 22:43, 3 May 2010 (UTC)

Well, I did mention gut flora, the larger category of stuff in yer guts of which E. coli is a distinguished member... --Mr.98 (talk) 23:39, 3 May 2010 (UTC)

This film happens to be medically inaccurate. The writer's claim that some un-named Dutch doctor supposedly gave some sort of medical "approval" concerning the "medical accuracy" of the procedure, is obviously nothing more than a crude advertising hoax or false-hood. Otherwise, where is this supposed doctor's name listed in the advertising? There is no known medical instance of anyone ever successfully stitching two people together.

In fact the only account I have been able to unearth of such a gruesome experiment comes from the annals (no pun intended) of the infamous Nazi doctor, one Dr. Josef Mengele. This doctor once attempted to permanently stitch two twins together, only to find that they both promptly contracted gangrene at their suture point, and could not "grow together". In the writer's fantasy of a "human centipede", in addition to the certain gangrene that would have been induced at the suture points, there is the question of asphyxiation. Certainly the middle and tail members of the trio would have reflexively regurgitated at the time of their first forced "meals", and then quickly suffocated in their own vomit. The entire proposition is ludicrous at best, and a new genre of sadistic snuff films at worst. Scott P. (talk) 21:00, 6 September 2010 (UTC)

"Man-made global warming can cause volcanoes"

There was a documentary on C4 last night called "The Volcano that stopped Britain". Near the end they claimed that man-made global warming caused volcanos to erupt by melting the ice on top of them. How do they get away with spreading such nonsense? I like to think I'm pretty liberal but i've lost most of those views since seeing this. Aren't there laws against knowingly spreading lies?--92.251.130.74 (talk) 14:16, 3 May 2010 (UTC)

That's interesting, I was watching a program last night on National Geographic about the same volcano, and it spent a fair amount of time covering the mind boggling amount of ice that the volcano its self melted, though not nearly the amount of an event in I think 1996. Definitely seems like a major flaw in the program if they think man made warming could even approach the heating effects of a volcano. Beach drifter (talk) 14:30, 3 May 2010 (UTC)

Even if hte ice was melted, that wouldn't cause the volcano to spontaneously erupt would it?--92.251.130.74 (talk) 14:42, 3 May 2010 (UTC)

Perhaps it was a phreatomagmatic eruption, i.e. one pertaining to the contact between magma and water (from melted ice?) Regards, --—Cyclonenim | Chat  14:48, 3 May 2010 (UTC)

After reading several articles, it seems there are phreatomagmatic components to the eruption, but they are side effects due to the location, and not the cause. Beach drifter (talk) 14:54, 3 May 2010 (UTC)

I think the idea is that GW could cause ice sheets to melt, which causes post-glacial rebound which in turn could release pressure on volcanoes causing an eruption. I agree that its not really necessarily to scare monger like this with relation to GW - its bad enough as it is - but I guess it makes for exciting TV. 131.111.30.24 (talk) 16:03, 3 May 2010 (UTC)

Almost correct, but nothing to do with post glacial rebound (though both have the same cause). Awickert (talk) 17:40, 3 May 2010 (UTC)

(outdent) Removing ice sheets reduces the vertical confining pressure on a magma chamber, increasing deviatoric stresses and causing an eruption. This is also well-documented in a study in Iceland of lava flow volumes during the last deglaciation. To the original poster of this: if you've changed your views by calling something "nonsense" and "lies" without knowing what you're talking about, I suppose that's your call. Though I admit: modern-day documentaries can over-dramatize to the absurd, and sometimes bungle the facts, making skepticism natural. Awickert (talk) 17:40, 3 May 2010 (UTC)

(edit conflict) It's a real theory that melting glaciers can trigger eruptions due to decompressing active magma chambers. Basically, by removing the pressure of 100 m of ice (for example) you cause more of the superheated rock to melt and more gases to escape and this might cause an eruption to happen hundreds of years earlier than it would have otherwise. It is important to note that this is about triggering volcanoes and not causing them. Melting ice certainly doesn't cause a magma chamber to form. At best it might provoke an existing magma chamber into erupting a little bit early. It's not specific to global warming either, people argue about changes at the end of the last ice age triggering eruptions. Dragons flight (talk) 17:43, 3 May 2010 (UTC)

Even if that were true, the resulting eruption would be less explosive then it would otherwise have been, and therefore cause far less trouble then one that goes Krakatoa. Googlemeister (talk) 19:27, 3 May 2010 (UTC)

How do you know that? Awickert (talk) 19:57, 3 May 2010 (UTC)

Simple thermodynamics. If you have a pot on you stove filled with boiling water and place the lid on (for the purposes of this experiment you can assume this makes the inside of the pot airtight), as the water boils, it forms steam. Steam has a volume far larger then that of water, so without anywhere to go, the pressure increases. If the lid is lightweight, this pressure will force the lid up, and steam will escape and some water may boil out of the pot. Inconvenient perhaps, but not a catastrophe. If you make the lid heavy, or better yet, weld it to the pot, when failure finally occurs, the pressure differential will be far greater, and so will the damage. Googlemeister (talk) 20:42, 3 May 2010 (UTC)

Ah, OK. Thanks for your answer! Unfortunately, volcanoes aren't that simple, largely because there is no constant "burner" and the "lid" is both nonuniform in its material properties and evolving through time. So for example, with a heavier lid, the lava may freeze before it gets to the top, making less of an eruption. Or conversely, to bring in another issue, the eruption may be less damaging without the glacial lid because it won't trigger jokulhaups. (Also, as an aside, Icelandic volcanoes don't have the right composition to go Krakatoa...) So what you say is an interesting idea; when I get a chance I'll see if I can find anything published about it. But I would caution against making authoritative claims about complex systems based on simple models in the meantime (unless you do a little research and find out that you are indeed correct). Best, Awickert (talk) 21:00, 3 May 2010 (UTC)

OK - our OP needs to calm down and do the tiniest scrap of background research.

I don't see any problem (in principle) with the idea that (a) global warming melts glaciers and other ice deposits...which (b) reduces the pressure on the top of glacier-encrusted volcanoes...and (c) that it is possible that reducing the pressure on the top of the magma chamber of a volcano could trigger an eruption. Imagine a volcano that is just on the edge of having built up enough internal pressure so it's on the verge of exploding...just on the tipping point...then melting the glaciers could be enough to cause an eruption that might not otherwise have happened for another 100 or 1000 years. It might also change a slow oozing magma flow into a full scale explosion - as water from the melting ice could be flashed into steam inside the magma chamber, increasing it's ability to overcome the reduced pressure on top.

So this isn't nonsense (meaning non-sense) because it does actually make some kind of sense. I just don't know whether that's really what happened.

Whether that is specifically what happened in this case would require some considerable study. So I googled it. :-) It turns out that it's not just C4 the BBC who are saying this - this article in the Daily Telegraph newspaper claims the same thing. It turns out that their claim (and therefore, probably, C4's the BBC claim) is based on a study by the Royal Society who are a rather prestigious bunch of scientists.

Hence, I think our OP is WILDLY overreacting. C4 The BBC is most definitely not lying because a lie is a deliberate untruth - and they are only repeating what some extremely reputable scientists are saying. So it's not a lie. Channel 4 The BBC are doing their job - and in this case, they are doing it well...so quit complaining about that!

The guys at the Royal Society may be mistaken (a mistake is a non-deliberate untruth) - but they too are not lying. This is properly published, peer-reviewed work, in "The Philosophical Transactions of the Royal Society". That journal has been the gold standard for scientific reporting for 300 years (Sir Isaac Newton was published there!). So C4 the Beeb didn't say anything that's in any way unreasonable.

Now - if you wish to place your own extensive scientific training your privately obtained data and your own in-depth study into this subject matter against people who were published by the Royal Society - please feel free to do so...but don't expect us to be wildly sympathetic to your cause because the odds are very good that you're guessing! So, IMHO, you should assume that (like most BBC documentaries) this was well researched and based upon solid scientific sources. Certainly, the idea that there might be some law you could invoke is WAY out of the question!

SteveBaker (talk) 19:43, 3 May 2010 (UTC)

I thought it was channel 4 and not the BBC? C4 don't have the best track record on documentaries (The Great Global Warming Swindle springs to mind) so perhaps the OP was correct to be sceptical. 86.7.19.159 (talk) 19:58, 3 May 2010 (UTC)

I'm sorry - you're right. I'll fix my response. SteveBaker (talk) 20:39, 3 May 2010 (UTC)

Using the phrase "I like to think I'm pretty liberal but..." suggests the OP considers the issue a political not a vulcanological one.Cuddlyable3 (talk) 20:09, 3 May 2010 (UTC)

And if this were the rabid right-wing politics reference desk, I'd have answered accordingly...but since this is science - and AFAICT, they nailed the science perfectly - we have to take an appropriately offended stance. SteveBaker (talk) 20:39, 3 May 2010 (UTC)

Dare I suggest, Steve, that a more effective approach would be to explain what the paper suggests would happen, without the command to take it as verbatim truth because it's from the Royal Society. I think you'd be more persuasive if you yourself didn't seem so defensive about it, and if the alternative you offered was more varied than "take it on faith because of who said it". I don't think responding to a polarized view with an even more polarized view generally accomplishes much. Just my two cents. --Mr.98 (talk) 23:34, 3 May 2010 (UTC)

You mistake what I'm saying. The question before us is: Was Channel 4 lying (as our OP so vociferously alleges) when they said that this global warming theory is a true possibility? No!! Clearly they were not lying because (like Wikipedia and other responsible journalists) they relied upon 'reliable sources'. Nobody can seriously doubt that one of the oldest and most respected scientific journal on the planet is a reliable source!

Now, it might be that there is an error in the paper in that journal - nobody claims that their peer-review system is infallible. Or it might be that the journal (for some utterly bizarre reason) faked the entire thing and there is a gigantic secret conspiracy. But what we cannot doubt is what Channel 4 said. They reported results from a reliable source...they absolutely, 100% certainly, did not lie. If the documentary is wrong (which seems really unlikely under the circumstances) then Channel 4 is not to blame. They can't even be accused of making a mistake...they honestly reported a reliable source - and that's the very best we could hope they'd do.

As for the Royal Society - for sure, they occasionally make mistakes - no journal is ever 100% infallible. After all, we had 200 years of everyone reporting that Newton's Laws were right - then Einstein came along and proved them all (very slightly) wrong. But given the choice - and given that you aren't a vulcanologist - should you believe your own guesses about how volcanoes work? Or should you believe a paper published in one of the most respected journals in the world? By all means be skeptical - by all means dig out the paper and read it yourself - but PLEASE don't go off on a major rant about some Channel 4 documentary without at least some sort of evidence beyond "gut-feel".

SteveBaker (talk) 00:45, 4 May 2010 (UTC)

Regarding Aren't there laws against knowingly spreading lies? No - OFCOM decided that it is outside of their remit to punish broadcasters over the accuracy of their programs - see this, only news reports have to be factually accurate. 131.111.30.21 (talk) 12:24, 4 May 2010 (UTC)

Internal and external cell conditions - source?

I need to find a source (preferably in table form but I can always form one from the data) which provides cell conditions for Na+, Ca++, Cl- and K+ ions with respect to their concentrations internally and externally? Anyone know of such a source? Regards, --—Cyclonenim | Chat  15:50, 3 May 2010 (UTC)

Articles Nernst equation or Resting potential may help. Cuddlyable3 (talk) 17:02, 3 May 2010 (UTC)

Membrane potential also would be useful. The lede mentions all 4 ions. See also ion channel and Ion transporter and Plasma membrane Ca2+ ATPase and Na+/K+-ATPase. Cytosol#Ions discusses actual concentrations, and has a handy chart that lists difference between intracellual concentrations and blood concentrations. Extracellular fluid has some figures as well, though not in a handy chart. --Jayron32 18:19, 3 May 2010 (UTC)

Supporting ladder on stairs - sideways

I need to position a ladder on some stairs, sideways so that it leans against the wall at the side of the stairs. The stairs are eight inches deep, but the ladder is about 15 inches wide. Thus one foot of the ladder will dangle unsupported.

What is the best practical way to support the ladder firmly and safely? The stairs are not very wide either, and are covered in carpet. Thanks 92.28.253.63 (talk) 16:31, 3 May 2010 (UTC)

You'll need to find a device which extends the leg of the ladder on the downstairs facing side. Something like this, but I'll let more knowledgeable people give you advice on specific products. Note that this stabilises the ladder to the usual extent like it would on the floor, but particular care should be taken not to wobble the ladder whilst you're on it. Regards, --—Cyclonenim | Chat  16:34, 3 May 2010 (UTC)

Cut out a big block of wood and fix it to the lower stair, although obsiouly in a maner which you can remove it.--92.251.141.43 (talk) 16:40, 3 May 2010 (UTC)

In a professional setting, those needing to carry out work on stairs usually construct a scaffolding platform, as I myself have seen done on several occasions while employed in facilities maintenance: indeed, in the UK it is contrary to Health & Safety Regulations to carry out actual work more than 2 metres above the ground from a simple ladder, which should only be used for access and inspection; also, ladders should always be secured in place at top and bottom (the latter can be done by a workmate rather than mechanically). What an individual chooses to risk doing in a private setting is, of course, up to him/her, but you may wish to balance the worth of your intact neck against the cost of getting the job (whose specific setting, scope and duration we do not know) done by a trained professional.

As an alternative to both a straight ladder and to constructable scaffolding (i.e. tubes, clamps and boards), you might be able to buy, or more economically hire, a small mobile scaffold tower with the two sides adaptable to different base heights supporting a horizontal working platform, which are designed for this sort of work: I suggest you make enquiries at a local equipment hire firm, if you can find one. 87.81.230.195 (talk) 19:18, 3 May 2010 (UTC)

Buy a ladder like this one. Then you put the ladder sideways like this. You can get different sizes for that ladder, and there are other brands, which might be less expensive. Ariel. (talk) 21:03, 3 May 2010 (UTC)

No liability whatsoever is assumed by providing this information, but I have seen painters wishing to work on the wall high above a short run of stairs place a ladder against the wall at the bottom of the stairs, then run a scaffold or plank from the ladder to a step at the same level. See "How to use a scaffold on stairways."An old 1906 solution in Popular Mechanics is seen here and some modern solutions are shown http://books.google.com/books?id=RTC8yFaw7ioC&pg=PA32&dq=ladder+stairs&lr=&as_brr=3&cd=6#v=onepage&q=ladder%20stairs&f=false here]. Some modern ladders are made with the two sides independently adjustable as Ariel pointed out. Edison (talk) 21:38, 4 May 2010 (UTC)

Moment of Inertia

My textbook says that moments of inertia about principal axes are constant to the first order for small angular displacements. Is there any way to prove this? Thanks. 173.179.59.66 (talk) 16:53, 3 May 2010 (UTC)

Wikipedia's relevant articles are Moment of inertia and List of moments of inertia. A consequence of the definition of the Sine of an angle x (in radians)

${\begin{aligned}\sin x&=x-{\frac {x^{3}}{3!}}+{\frac {x^{5}}{5!}}-{\frac {x^{7}}{7!}}+\cdots \\[8pt]\end{aligned}}$

is that for small x

${\begin{aligned}\sin x&=x\end{aligned}}$ approximately. Cuddlyable3 (talk) 19:59, 3 May 2010 (UTC)

Great, thanks. 173.179.59.66 (talk) 23:59, 3 May 2010 (UTC)

(edit conflict) Cuddlyable3 is deriving the Small-angle approximation, an often used approximation in physics, and quite accurate for small angles: i.e. an error of less than 0.15% for angles smaller than 5 degrees, about 0.5% for angles smaller than 10 degrees, and still only about 5% for angles up to 30 degrees (yeah, you have to convert to radians when working with it...) Buddy431 (talk) 00:07, 4 May 2010 (UTC)

Don't worry, I understood. Actually, I was aware of the small angle approximation. I just realized that I was using addition when I should have been multiplying. —Preceding unsigned comment added by 173.179.59.66 (talk) 02:29, 4 May 2010 (UTC)

Alcohol for stage fright

Is alcohol an effective treatment for stage fright? Are there any other non-prescription drugs that are as good as or better? Thanks 92.28.253.63 (talk) 17:19, 3 May 2010 (UTC)

Wikipedia cannot offer medical advice. Alcohol is not a prescribed treatment for any known medical or psychological condition. If you are having trouble, please seek advice from a qualified professional, such as a psychologist, who works in this field. The internet, and random strangers that hang out there, is not the proper place to ask such questions. --Jayron32 18:13, 3 May 2010 (UTC)

How is stage fright a condition needing medical advice? I intensely dislike preforming in front of people, but it doesn't require a "qualified professional" to treat. Ks0stm ^(T•C•G) 18:29, 3 May 2010 (UTC)

Stage fright isn't a medical condition - but as soon as someone starts to ask us to suggest drugs to treat it - it becomes a request for medical advice...and our only answer is "If this concerns you - go see a doctor." In this case, it's possible that a doctor might prescribe something. SteveBaker (talk) 19:08, 3 May 2010 (UTC)

I'm not suffering from stage fright, and I do not like alcohol. I was asking in general terms, not medical advice. 92.28.253.63 (talk) 18:23, 3 May 2010 (UTC)

In that case, I reiterate that Alcohol is not prescribed for any known medical or psychological condition. Some people self-medicate using alcohol, usually to less-than-desirable results (alcohol-related violence, cirrhosis, drunk driving, addiction.) Anxiolytic are the class of drugs prescribed for anxiety problems, which stage fright certainly qualifies. None are actually availible over-the-counter, unless you count "herbal" remedies, or "off-the-label" remedies. --Jayron32 18:29, 3 May 2010 (UTC)

That is not strictly true. Ethanol is occasionally prescribed for poisoning by ethylene glycol or methanol. The latter two substances are very toxic, but not terribly toxic in themselves — rather, the damage is done by their metabolites. Ethanol competes for the enzyme that oxidizes or dehydrogenates them, giving the kidneys a chance to eliminate the substances before the toxic metabolites can be formed. --Trovatore (talk) 23:21, 3 May 2010 (UTC)

What you are describing is a result of abuse or over-consumption of alcohol. You can get nasty results if you overdose on pretty much any other chemical, from cough syrup (toxic psychosis), vegetable oil (Cardiac Arrest) or even water (Water intoxication). Googlemeister (talk) 19:23, 3 May 2010 (UTC)

I'm sorry, people have never abused alcohol before. Statistically speaking, there is not a significant number of people to have every overconsumed alcohol to even mention. I apologize for misleading people to thinking that there are ever negative consequences from using alcohol to excess. (as an aside, I am not a teatotaller. I regularly consume responsible amounts of alcohol.) --Jayron32 19:42, 3 May 2010 (UTC)

I'm not going to say anything about its effectiveness, but alcohol is very frequently used for such things. See Dutch courage. --Tango (talk) 19:24, 3 May 2010 (UTC)

So you are going on stage and feel nervous? Then Break a leg !. Cuddlyable3 (talk) 19:36, 3 May 2010 (UTC)

A well-known symptom of alcohol intoxication is the loss of social inhibitions, so it's reasonable to assume that stage fright would be reduced. However, whether the lack of stage fright would outweigh the decreased mental capacity caused by alcohol and make the show better overall, I can't say. --99.237.234.104 (talk) 20:08, 3 May 2010 (UTC)

However, we should not be advising people to treat an anxiety disorder by drinking. Such irresonsible medical advice is exactly what the medical disclaimer is about. Yes, people do drink because they have anxiety. However, to recommend that as a reasonable course of action, to actually state "Yes, it would be a good idea to drink alcohol to combat stage fright" is a fantasticly irresponsible thing to do. If anyone is seeking genuine advice on how to handle stange fright or any other anxiety disorder, see someone who knows how to treat anxiety disorders. Period. --Jayron32 20:28, 3 May 2010 (UTC)

I hardly think it's proper to call stage-fright an "anxiety disorder". This medicalisation of normal feelings is a pernicious trend in late 20th and early 21st century western society. I'd ask an actor or an acting coach for advice about stage fright. DuncanHill (talk) 21:04, 3 May 2010 (UTC)

I didn't advise anybody to do anything. My answer was a scientifically valid statement of well-known facts. --99.237.234.104 (talk) 21:12, 3 May 2010 (UTC)

I agree. "Anxiety disorder" means being anxious about things a normal person wouldn't be anxious about. Almost everyone is anxious about appearing on stage in front of hundreds of people. --Tango (talk) 22:37, 3 May 2010 (UTC)

Before trying this, be sure to watch The big bang theory episode The Pants Alternative (the link has a small spoiler, don't click on it). Ariel. (talk) 21:18, 3 May 2010 (UTC)

If you've gone a way down the path to becoming an actor then you have contemplated the awesome responsibility of addressing an audience from a stage. That you continued along this path probably indicates that you've worked "stage fright" into the equation of what you bargained for. It is unlikely that the fear of going onstage only cropped up at the last minute. You can take heart from your own decision, made time and time again in preparation for your role as stage actor, that this is something that you calculate you can do. Bus stop (talk) 21:31, 3 May 2010 (UTC)

For discussion of the "piss artist" in acting see [4]. There is a danger that an actor may feel he is doing his best work, when his fellow actors and the audience see someone whose timing is off, who muffs lines and stumbles around. Even one instance of showing up tipsy for a public performance can stick for a lifetime, as happened to Andrew Johnson at his vice presidential inauguration. Edison (talk) 21:29, 4 May 2010 (UTC)

construction, coal

During excavation for a new house, a seam of coal was uncovered. will the coal hold up to a foundation placed on top or is it too soft and will require pilings drilled through the seam and filled with rebar and concrete? It will be a large house and the foundation for the fireplace will be close or on the seam. thanks for any help on this. —Preceding unsigned comment added by Lhirsche (talk • contribs) 18:43, 3 May 2010 (UTC)

Really? You want to ask people on the internet about how to safely build your house? The answer almost certainly depends on the size, extent, and type of deposit. You need to talk to a structural engineer, geologist, or someone similar who can inspect the site and give you a professional evaluation. Dragons flight (talk) 18:52, 3 May 2010 (UTC)

There are lots of different foundation approaches for modern houses. No matter the type of soil or subsurface conditions, you'll need a proper foundation design. So even if there had been no coal there - you'd still be crazy not to have someone design you a proper foundation that's appropriate to the conditions. Specifically, I'd expect coal to be a pretty good rock to build onto - but if an expert says otherwise then there are other options beside the 'pier and beam' approach you are describing. My house is build on some of the soggiest clay imaginable with the bedrock 30' below the house...we have a floating 'waffle slab' that floats on the soil...and that's despite it having foot-thick concrete walls! But you have to consult an expert - the consequences of a foundation/slab failure can be utterly catastrophic. SteveBaker (talk) 19:05, 3 May 2010 (UTC)

There is more then one type of coal, from bituminous to anthracite. They would not have the same structural properties, so expert help is strongly recommended. Googlemeister (talk) 19:14, 3 May 2010 (UTC)

How convenient to have a coal mine under the fire place. What could possibly go wrong? Edison (talk) 19:48, 3 May 2010 (UTC)

Do you live in Centralia, Pennsylvania? Googlemeister (talk) 20:25, 3 May 2010 (UTC)

Just in case you are simply looking for a second opinion, and not actually relying on random people on the internet to build your house, coal is pretty strong and you should be able to build on it. I'd worry about gases being released from the coal though. Methane, and Radon specifically. Radon especially is pretty bad, be sure to handle it properly, either active venting, or some sort of construction technique to make sure it doesn't enter the basement. Also, you may have legal issues. In many parts of the country, you don't own mineral rights under your land, so that coal may not be yours, and I have no idea what that would mean to your house. If it is yours see if it's worth mining that coal (well, selling it to a mining company) instead of building on it. Ariel. (talk) 23:29, 3 May 2010 (UTC)

I doubt if mining the quantity of coal that would be found on a typical house lot would be cost effective. StuRat (talk) 00:21, 4 May 2010 (UTC)

My understanding is that coal mining often starts by finding a seam on the surface, then following it underground. The bulk of the coal is underground, and not limited to the size of a house lot. Ariel. (talk) 00:35, 4 May 2010 (UTC)

Sure, but what's the advantage to you if they pull up coal from your neighbor's yard? APL (talk) 03:13, 4 May 2010 (UTC)

I don't think it's necessarily a non-profit endeavor to extract coal from a neighbor's yard -- there was an answer on this topic posted some time ago, but it's certainly profitable to extract coal even if you have to pay others for the coal you get from under their property. DRosenbach ^{(Talk | Contribs)} 16:48, 4 May 2010 (UTC)

I don't know if you can build a house on it (see a licensed architectural engineer), but I do know you can build a house from it: Coal House (Williamson, West Virginia). -- 174.21.225.115 (talk) 15:30, 4 May 2010 (UTC)

Wouldn't it be a fire hazard? 146.74.230.104 (talk) 00:24, 5 May 2010 (UTC)

No more then a wood house I should think. Googlemeister (talk) 13:29, 5 May 2010 (UTC)

Less actually. Coal is really hard to ignite. I took a blowtorch to a piece of coal once (I don't know what type, but it was very hard and shiny), and it sparked but would not ignite. Ariel. (talk)

Must've been anthracite, it's very hard, black and shiny and notoriously hard to ignite. Bituminous coal is also black and hard, but not shiny, and it ignites a lot easier, burning with a smoky yellow flame. 67.170.215.166 (talk) 00:38, 6 May 2010 (UTC)

how much is $280,000 per year (inflation-adjusted) for 40 years worth today?

How much is $280,000 per year, but adjusted for inflation, ie this value goes up from year to year to account for inflation, and to be paid out for 40 years, worth today? Thank you. 84.153.250.110 (talk) 19:30, 3 May 2010 (UTC)

Do you mean, how much would being paid $280,000 per year, adjusted for Cost of living annualy, be worth if the first $280,000 payment was made 40 years ago? Or do you mean that you are going to be paid #280,000 this year, and want to know what the COLA payments will do to the money over the next 40 years? I am unclear on what you are asking. --Jayron32 19:35, 3 May 2010 (UTC)

Numerous websites will calculate the inflation adjusted values of money, a simple Google search will find them for you. This one shows that $280,000 in 1969 was equivalent to $1,620,160 in 2009. TastyCakes (talk) 19:38, 3 May 2010 (UTC)

Future inflation cannot be predicted. 40 x $280 000 = $11 200 000. Cuddlyable3 (talk) 19:41, 3 May 2010 (UTC)

Well it can be predicted, it just can't be predicted correctly ;) TastyCakes (talk) 19:45, 3 May 2010 (UTC)

Of course, even if you had a true figure, most people time discount; that is, they'd take 90% of something this year than 100% of it next year (rightly or wrongly). So it might be "worth" more or less today than it is in the future, depending on how you look at it.- Jarry1250 ^{[Humorous? Discuss.]} 19:56, 3 May 2010 (UTC)

If it's adjusted for inflation - then isn't the answer just $280,000 x 40 ? SteveBaker (talk) 20:11, 3 May 2010 (UTC)

If the question was asked correctly, then I agree, that's exactly what it is. Vimescarrot (talk) 20:28, 3 May 2010 (UTC)

The question above (which is different from the one below) asks for today's value of a stream of payments of $280K (adjusted for expected inflation) paid annually for 40 years. Even though inflation is adjusted for, you also have to adjust for the time-value of money. So the answer will be lower than $280K x 40, unless the discount rate is equal to (or less than) the expected inflation rate - but there would be no sense in using a discount rate like that. Zain Ebrahim (talk) 11:49, 4 May 2010 (UTC)

Um, I'm the original questioner and your answers don't make sense to me. Let's simplify and say that you will be paid nothing until 40 years from now, at which point you will be paid the then-equivalent of $1,620,160 in today's dollars. How much would you pay for that to happen? Obviously it has to be far LESS than a million, since why would you tie your money up for 40 years for nothin'? What I want to know is exactly how much less. I think it has to do with the prime rate. This isn't homework.... 84.153.250.110 (talk) 20:54, 3 May 2010 (UTC)

That's actually impossible to answer. Inflation is a very tricky thing, people have a very hard time agreeing on what historical inflation has been, that is how to calculate inflation based on what we know has happened to values over the past 40 years. To predict with any certainty what will happen in the next 40 years is literally an impossibility. Inflation has little to do with the Prime rate. The Prime rate is part of monetary policy which is the means by which central banks hope to control inflation. Inflation itself is measured in very different ways; see producer price index and consumer price index for a couple. If anyone definitively knew how to predict inflation reliably, they'd be fantasticly rich. --Jayron32 21:21, 3 May 2010 (UTC)

No, he said it was the then-equivalent of $1,620,160 in today's dollars, which means 84.153 has removed inflation from the equation. In this revised question, 84.153 is asking what would be a good price for a fixed rate bond which matures 40 years from today for the then-equivalent of $1,620,160 in today's dollars, issues no coupon payments, and is not callable. I am going to venture an answer, based on the current price of 30-year TIPS bonds that sold about a month ago for 2.125%. If we use this as the answer, then your answer will be somewhere under US$720,000 (because you're selling a 40 year instrument instead of 30). The main critical assumption I am making here is that your bond would be backed by the US government and not some company; else a higher interest rate would be demanded. Comet Tuttle (talk) 21:29, 3 May 2010 (UTC)

mm if I'm reading this right, is this now a net present value/time value of money question? If it is, the net present value will depend on what discount factor you use, and that's really up to you. You could use the historical average of a big bond rate like Comet Tuttle says above, or you could use the average stock market growth over the last 50 years, or the average inflation rate or any number you think represents how much more money in your pocket right now is worth than money maybe in your pocket next year. TastyCakes (talk) 21:42, 3 May 2010 (UTC)

Yes, it sounds like a time value of money question. The challenge with these questions is working out an appropriate discount rate. --Tango (talk) 22:41, 3 May 2010 (UTC)

Yes — and 84.153 also didn't specify whether this bond can be sold to another party. If not, and you're already 70 years old and in poverty, there may not be any appropriate discount rate, because you may not want to tie up even $1 in a scheme that will not pay off during your lifetime. Comet Tuttle (talk) 00:02, 4 May 2010 (UTC)

This restated question becomes a question of what interest rate you can earn versus how inflation grows. If you can get an interest rate that consistently out-paces inflation, then take the money now - and invest it. If inflation out-paces interest rates - then let someone else pay the price and take the money in the future. Which of those things wins is utterly unknowable. It depends on how interest rates change - how the stock-market grows (or shrinks) - how much risk you're prepared to take. That last thing is the real problem. Historically, the stock market grows about 5% per year and the inflation rate isn't that high for long. So the stock market ought to be a no-brainer...except for risk. As a lot of people have recently discovered, there is not such thing as a safe stock. Who knows what happens to the major markets of the world over the next 10 years - let alone the next 40! Uncertainly increases exponentially with time. So, we can't reliably answer your question. Risk is the big issue here. If you want to take the money and invest it now - and you expect a 99% chance of beating inflation - then you're forced to take such low-risk choices that you can't make any money. If you only want a 50/50 chance of beating inflation - then you can probably find a set of stocks that will give you a 50/50 chance of winning big-time over inflation. So if you are risk-averse, take the money in 40 years and let whoever is paying it to you take all of the risk. Of course if the person/organization/government who is supposed to do that fails over the next 40 years then you may be completely screwed - so there is no such thing as a 0% risk. SteveBaker (talk) 00:14, 4 May 2010 (UTC)

Here are some thoughts for determining a discount rate. Assuming you give the money to an insurance company, you can use the following sum:

Required return = real risk-free rate + credit-risk premium + liquidity-risk premium

• Risk free rate: You can use Comet Tuttle's suggestion above for the first part: 2.125% (these are ususally quoted as nominal rates).
• Credit premium: Look at the long term (e.g. 10-year) credit spread on highly rated insurance companies. Insurance companies don't typically issue very long term debt so you can also look at banks that might have issued 30 or 40 year bonds.
• Liquidity might not be an issue for you if you don't intend to sell this. There are many many ways to try and estimate this - if you're interested, you can try google.
• You don't need to add anything for inflation if you assume that whatever you get in 40 years will compensate you for whatever inflation did over that period.
• There may be other special circumstances that you would need to allow for.

Then just add them up and discount at that rate. Alternatively, insurance companies sell this kind of product all the time - just call your local insurance broker and ask him how much this would cost. Zain Ebrahim (talk) 12:27, 4 May 2010 (UTC)

Nothing

In the bits of space between the molecules, atoms, ions, &c., do forces still apply? What exists in the space between them in which gravity, magnetism and so on exist to allow the potential forces to exist. I suppose what I am asking is what nothing is, or what 0 actually means. If you could suck all the matter completely out of a given area does it still exist because there is no matter in it to describe it? -russ (talk) 19:54, 3 May 2010 (UTC)

Gravity, magnetism and other such forces are not transmitted by real physical particles that require a "something to exist between here and there" to work. DMacks (talk) 19:59, 3 May 2010 (UTC)

It was once thought that a medium called the luminiferous aether was required to transmit the electromagnetic force, but this idea was incorrect. The gravitational and electromagnetic forces propagate just fine through a vacuum. -- Coneslayer (talk) 20:00, 3 May 2010 (UTC)

There is almost nothing between the stars and planets - but the force of gravity still operates perfectly well. Gravity can be shown to operate between galaxies too - and the space between them has so little 'stuff' in it that we're down to one atom per cubic meter or so! So clearly forces can operate through a vacuum. On a smaller scale, the strong and weak nuclear forces operate at the scale of individual atoms - and (as you say) the atoms are separated by a nice, hard vacuum. The earth's magnetic field is responsible for deflecting charged particles from the sun - and that too operates out beyond our atmosphere - so you can tell that magnetic forces also propagate just fine through "nothing". SteveBaker (talk) 20:18, 3 May 2010 (UTC)

For people that have a problem with forces propagating through nothing, there's field theory. Fields are by no means necessary to explain or understand force propagation through empty space (see Action at a distance), but they do provide a helpful framework for understanding how things like "light waves" propagate through empty space (i.e. Q: "what" is vibrating in a light wave? A: the electromagnetic field). Insofar as concepts like "energy" are "real" so are fields. --Jayron32 20:25, 3 May 2010 (UTC)

But doesn't that mean that a vacuum must exist, which according to Wikipedia is 'only a philosophical concept and never is observed in practice'? -russ (talk) 20:12, 3 May 2010 (UTC)

Well, I don't have much time for philosophers - they cause more confusion than they do clarity. The question here is whether you should have a name for nothingness. A 'vacuum' is defined as the absence of matter - does that make it a useless concept? Not at all, it's an exceedingly handy word - and for beings who live in a world surrounded by air, the concept of a 'vacuum' is sufficiently different from normal existence that it makes sense to have a word for it. Beside, we use 'black' to mean an absence of light - and 'silence' to mean an absence of sound - are those also "only philosophical concepts"? SteveBaker (talk) 20:22, 3 May 2010 (UTC)

(also reply to pierhead above, EC with him below) Vacuum is an asymptotic condition, not a philosophical concept. Science is filled with concepts which are physically impossible to achieve, and yet are very real, such as absolute zero, big bang, speed of light, etc. etc. Being impossible to achieve is not the same as saying its only a "philosophical concept". Things like ontology and eschatology and epistemology are philosophical concepts. A vacuum is a very real, if physically unobtainable, condition. --Jayron32 20:37, 3 May 2010 (UTC)

Classically, you can have real, hard vacuum. Out there between the galaxies there is only about one atom per cubic meter of space. If the atom happens to be in the top-left corner of that cubic meter - then you have almost an entire cubic meter of perfect vacuum. However, from a quantum-theoretical viewpoint, there are two problems with that. One is that fundamental particles don't have exact positions - they are probability clouds - so even if the atom is nominally considered to be in the top-left corner - there is a vanishingly small probability that you'd detect it over a meter away in the bottom-right corner. In a sense, the atom is everywhere at once - so no place in the universe is truly empty. Beyond that, you have the issue of virtual particles where a particle and an anti-particle will pop up out of nowhere - then vanish again just as fast - and this makes it tricky to define precisely what we mean by "empty". Also, there would be a lot of photons and neutrinos out there too...so if you count those, then there is quite a lot of 'stuff' contained in that cubic meter. SteveBaker (talk) 23:04, 3 May 2010 (UTC)

Does not the absence of sound and light constitute an entity in which they are void? The void must surely still exist as those properties which propogate them still exist and are absorbed by their terminal entities? Is there, therefore no (realistic) nothing or zero? -russ (talk) or am i just being needlessly foolish? —Preceding undated comment added 20:34, 3 May 2010 (UTC).

I think you're confusing the existence of stuff with the existence of a concept to describe the situation. "Vacuum" is a concept that exists, even though nothing exists in a vacuum. That's not contradictory. We can label any concept we want. But more importantly, this is a philosophical issue that doesn't have much to do with understanding the science. Rckrone (talk) 21:39, 3 May 2010 (UTC)