Wikipedia:Reference desk/Archives/Science/2006 November 23

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[edit] November 23

[edit] LSD , Heroine and Mescaline

what do the 'trips' of each feel like? (differences and similarities) and specially with LSD and Mescaline since they are supposed to be 'mystical eye openers'...what mystical truths or revelations do people percieve when they take them? or what's the effect on the nervous system? (I guess for this I can just read the articles, but I want a perspective from someone who has taken them).--Cosmic girl 01:59, 23 November 2006 (UTC)

Heroine isn't really a 'trip' as much as a 'drop out', I don't think people use it as a 'mystical eye opener' as you call it. I've never tried it but have seen first hand its effects on a couple of my close friends, which makes me want to try it even less! The other "trips" really do vary a lot from person to person and situation, also it has a lot to do with your environment. I have had several different experiences, they range from mild feelings of euphoria, everything feeling a little 'fuzzy', sounds and music can seem to sound 'crisper', you seem to notice things you never noticed before, even in your favourite songs that you've heard a thousand times. More full on symptoms I've experienced is total disassociation, it's seriously can feel like you are dreaming, like anything is possible, like all of a sudden you can understand the nature of the world, how everything, from the cavemen millions of years ago, to the people who grew the grapes in your wine, to the musicians who wrote the music and the ones who inspired them, to the chemists who created LSD so that you could have this trip, everyone is connected by life and love, it's almost tangible. That was my most full on one;)… It was VERY scary, I actually thought I was going to die, but that's a whole other story… I can not tell you that I regret one second of it, that time was one of the most full on experiences I've ever had. I've written songs about it and plan to one day write it into a story or short film or something. If you do decide to do it, take lots of precautions, do it with your closest friends and do it in a safe place! Do NOT leave and do NOT climb anywhere high enough that you could hurt yourself falling down, I can easily see that in a deep dream state you could easily convince yourself that you can fly! And no I'm not kidding. From the length of that rant you can probaby tell how deeply it affected me, I'd had it at least a dozen times before my full on one and have not done it since. I have not decided never to have it again, but I have not activley pursued it either. Otherwise I consider myself pretty normal. ;) Vespine 02:39, 23 November 2006 (UTC)
Heroin mimics endorphins and thus creates a sense of pleasure that is higher than one you would normally experience. But this is just more of the same pleasure that you know from 'real life'. Psychedelic drugs like LSD and mescaline make you perceive reality in a totally new way. I have tried magic mushrooms several times and the term 'eye-opener' seems appropriate. The big question is to what they open your eyes. I wouldn't call it 'mystical', but then I'm not inclined to use such terminology for anything at all. The most important lesson I learned from the fact that the same brain can see reality in so very different ways is that reality as we see it is not necessarily the same as the Welt and Sich (someone should write that article). Well, of course as a philosopher of the mind I already new that, but it added feeling to my thoughts, so to say. And I agree with Vespine's use of the words 'full on experience' and that although it can be very scary it was definitely worth it. Then again, I haven't had a bad trip. Medical disclaimer: if you ever try psychedelics, make sure you're in the right mood and preferably in the company of good friends (who either also take the drug or have taken it before). About thinking you can fly - isn't that angel dust? Based on my experience I don't think I would ever have done anything weird. The world just looked weird. DirkvdM 09:02, 23 November 2006 (UTC)
LSD usually affects the senses and perception - mostly causing visual auditory disturbance and possibly hallucinations. Things may feel different as well. The best way I can describe it is as lots of feedback,hum and noise in the brain - plus short circuits. It could be described as eye openeing - if you need to break things to find out how they work. The effects are similar to those experienced if you ever have a very bad fever (eg malarial fever/food poisoning). My experience of LSD was that any breakthroughs in thinking/ perception/ understanding of the universe would have to wait until the stuff had worn off.. No experience of mescaline. Psylocybin (from magic mushrooms) is similar to LSD but possibly not as 'strong'. I agree in general with the previous two posters - wierd becoming scary for LSD. A bit too strong for my liking or to recommend that any long lasting positive experience could be had. (From a previous discussion about antipsychotics I'd like to state the same point - if you've taken LSD etc - you've just poisoned yourself).83.100.250.186 15:59, 23 November 2006 (UTC)
About the similarity to a fever, at the 2004 world rainbow gathering someone got attacked by a horde (?) of hornets, which gave him sort of a high. He said it was a great trip, if you could take the pain. I think I'll stick to mushrooms. :) DirkvdM 09:24, 24 November 2006 (UTC)


hey Vespine, that 'everyone and everything is conected in the love of existence' sounds cool....but WHAT was it that you 'found out' ??? I mean...you say that 'even the chemist that made LSD was destined to make it so u could take it' ...I mean... if you felt all that did you get any sense of 'WHY' stuff was like that? I mean ....all that 'love' for what? or just because...? ( I hope I didn't confuse u, but if u get my point, please explain). oh and y did u think u where going to die?!!--Cosmic girl 23:49, 24 November 2006 (UTC)

[edit] can energy be described in million electron volt?

can we describe energy in million electron volt or should it be in mega always

Of course you can write 1000000 eV instead of 1 MeV. The latter is more convenient, though. --Bowlhover 04:47, 23 November 2006 (UTC)

[edit] Is a snapdragon's pollen poisonous?

Today, I decided to eat a petal from a snapdragon flower. (It's really sweet; try some.) My teacher said that the pollen is poisonous. Is it really? --Bowlhover 04:44, 23 November 2006 (UTC)

"It's really sweet; try some." Not if it's poisonous, thanks! My gut reaction is that it wouldn't be, but some unexpected things are. Perhaps you could answer for us, since you tried it - have you had any feelings of nausea, vomitting, aching pains, unexpected death, etc, since eating it? --jjron 10:53, 23 November 2006 (UTC)
Petals do tend to be sweet - the reproductive bits inside are sometimes very sour and can be poisonous. Maybe next you could try licking the pollen off flowers like bees do!
Honestly though don't try eating flowers at random - I'd expect at least half the flowers in and average garden to be at least foul tasting and at worst very bad - eg Deadly nightshade
I ate very little pollen, so there will likely be no noticeable effects even if it is poisonous. I did feel a very mild burning sensation in my stomach right after eating the petal, but that's likely due to the placebo effect. --Bowlhover 03:18, 25 November 2006 (UTC)

[edit] Hydrogen Powered Cars

What is the likelihood that 50,000 or more hydrogen fueled cars will have been sold in the United States by 2020? If this is severely unlikely, I would very much appreciate an explainationas to why. Thank You

This is more prognostication than science. But, if you want reasons why they may NOT be: insufficient development of the technology; lack of suppliers of the vehicles; lack of refuelling stations; too expensive for customers; lack of demand. I could think of more, so could you. On the other hand the US market is pretty big, I'm guessing over 10 million new vehicles a year - 50,000 by 2020 is only about 3,500 a year out of this market, so if it could be profitable you would think the market could support it. --jjron 10:35, 23 November 2006 (UTC)
Also, never forget that Hydrogen is not a "fuel" in the usual sense, any more than electric power is a fuel. There are no large supplies of hydrogen available. The energy in hydrogen is taken from some other source of energy. Hydrogen is analogous to batteries, but hydrogen is an improvement over batteries because there is no need to weigh down the car's fuel tank with oxygen, and because hydrogen might be transferred to a fuel tank much faster than a battery bank can be charged. Yet both hydrogen and electrical energy might still be supplied by an electric power plant (if the hydrogen is created by electrolysing water.) Are there plans to make hydrogen by splitting methane? If so, wouldn't it make more sense to sell cars which carry liquid natural gas or even alcohol in their tanks? --Wjbeaty 13:10, 23 November 2006 (UTC)
Hydrogen can be a fuel, depending on how it is used. It can either be directly combusted in an internal-combustion engine, or it can used in a fuel cell to generate electricity. Either BMW or Mercedes-Benz just announced a limited run of cars that can burn either gasoline or hydrogen. Part of a test, I believe.
The problems with hydrogen are storage and creation. Hydrogen does not store compactly. Large, heavy tanks only hold a few pounds of hydrogen. The cheapest way to make hydrogen is from hydrogen-rich compounds like petroleum distillates and natural gas, which does not make us less dependent on foreign oil and gas and does not alleviate pollution. The cleanest way to make hydrogen is by splitting water atoms with electricity; however, the process is pretty inefficient, and it would actually cause a substantial net energy loss. Coal, for example, can be burned to make steam to drive a turbine to make electricity to zap water to make hydrogen, or it can be devolitized and catalytically converted into gasoline and diesel fuel for automotive use.
It is possible to make hydrogen from renewable sources like wind, tidal, solar, or hydroelectric power, but more pollution would be reduced by pumping that energy into the electrical grid and retiring old polluting coal powerplants than by replacing the modern, clean-burning automobile engine. The exception to this is that areas that have plenty of renewable energy but insufficient power-transmission lines (like the Dakotas) could instead transmit their wind-turbine electricity in the form of hydrogen.
Until a powerful source of renewable, pollution-free power is made, like nuclear fusion, the use of our elecricity sources to make hydrogen will not be the most efficient use of our resources. It is most likely that we will pump renewable-sourced electricity into our electric grid and use off-peak time to recharge our electric cars in our homes. Our electric cars will most likely also have an internal-combustion engine of some size to assist the battery for long trips or remote battery charging, but the fuel for that could be domestically-produced, even from coal or renewable-powered ethanol plants. --Krispos42, 8:16am GMT, November 25, 2006

No, no it would not. Electrolysis is not that difficult. My question has still not been sufficiently answered.

Then maybe you need to clarify it. Or if you just want random guesses about the future, ask on an astrology site. Please sign your contributions and show some manners to people that have tried to help. --jjron 22:31, 23 November 2006 (UTC)
You might find Hydrogen Economy an interesting article, specifically the section about Problems in implementation. Vespine 00:17, 24 November 2006 (UTC)
OT but since you wikilinked the first but not the second, you might be interested to know that Hydrogen economy#Problems in implementation will work... Nil Einne 07:17, 25 November 2006 (UTC)

[edit] disinfecting cloths

are asepti-wipe II disinfecting cloths a good product in dentistry

If they are used in a dental facility, they would need to be approved by the FDA and possibly the ADA, both of which would evaluate them fully. While there may be better products on the market, anything approved by the FDA or ADA is safe and effective. Droud 16:00, 24 November 2006 (UTC)
But only for Americans --ColinFine 11:39, 26 November 2006 (UTC)

[edit] Properties of Bone

What is the difference, if any, in elasticity between living bone and dead/aged raw bone? Aged meaning aging from slaughter to domestic purchase. What are the changes that take place in bone upon death, changes that affect tensile strength? I don't want to break any living bones to compare and I'm interested in the why as well as the what. Circulation to the bone ceases, of course, but what changes take place that would affect the mechanical properties? Thanks for any help on a question that's been nagging for some time. Rareberry 07:13, 23 November 2006 (UTC)

Aged in the sense you use is not very aged at all, and pretty well preserved regardless of its age (i.e., otherwise the meat surrounding the bone would be rotten). Therefore I would guess the elasticity of the bone would not be very different at all to a living bone. The more a bone was really aged the more changes would be noticed. You have already mentioned that circulation would cease. As the formerly living cells desiccated and the bone tissue in general dried out it would tend to become more brittle. Gradually chemical changes would take place in the bone matrix which would also alter it, but exactly what and how quickly would depend to a reasonable extent on how it was stored (buried, sat in the sun, frozen, etc), as this would affect what other chemicals it would react with and how quickly the reactions would occur. I'm not sure this really answers your question, but it's a start. --jjron 09:56, 23 November 2006 (UTC)
See bone according to this article bone consists of a mineral calcium hydroxyapatite combined with an organic polymer "bone is essentially brittle, it does have a degree of significant elasticity contributed by its organic components (chiefly collagen)." As the bone ages I would expect it dry out - the collagen would as it dries shrink and dry up to - therefor dry bones would be brittle compared to live bones.. However if the bone is still in the meat (such as a pork chop of leg of lamb) it will still be moist - so should still be elastic. The other effect here would be decay of the collagen - I wouldn't expect this to happen until the meat surrounding it was thoroughly rotten. Perhaps someone with more knowledge on necrosis and atrophy will turn up. (please insert correct terms for decay after death)83.100.250.186 16:14, 23 November 2006 (UTC)

[edit] RE: Electric intensity

In fifth edition of APPLICATIONS OF ELECTRO-MAGNETICS by KRAUS and FLEISCH,(Page 50-60) a man stands under a transmission line and a tube light glows without power.So if Electric field is only a function of charge density,then will the same effect happen if we place a highly charged sphere which also has high electric field intensity???

If you suddenly bring a large quantity of charge near one end of a fluorescent tube, it will briefly light but then go dark. The continuous powering of the light arises because in the vicinity of an electric current there is a changing magnetic field, which gives rise to a changing electric field, which is capable of re-lighting the tube each time it changes direction, as if it were an AC source, albeit one that doesn't need to be attached to the tube's ends particularly. The fact that the tube can glow forever indicates that there is power present; in this case, it's the power of the electromagnetic radiation that comprises the changing fields. Normally almost all of the power is reabsorbed by the transmission line later in the same cycle, but the tube saps some of it merely by being present. --Tardis 18:27, 20 November 2006 (UTC)
A fluorescent tube would certainly glow if near a sphere energized with high voltage alternating current. Likewise cubes, and any other shapes. There is a severe danger of injury or death when working around high voltage electricity, so experimentation is strongly discouraged. Edison 21:22, 20 November 2006 (UTC)
To light a fluorescent tube, you need an energy flow which requires both a potential difference and a charge transfer (a voltage and a current.) Where is the current? This was answered by JC Maxwell when analyzing the current path through capacitors. Maxwell postulated the existence of displacement current composed of a changing pattern of magnetic fields with no actual flow of charge. For example, the wires leading to a capacitor during charge or discharge becomes surrounded by a magnetic field, but the insulating dielectric supports exactly the same magnetic field, as if charges were flowing through the dielectric. This magnetic field pattern is created by the changing electric field between the capacitor plates. In your fluorescent tube example above, the tube is lit because there is an unnoticed capacitor connecting the tube to the power line. The capacitor's value may be very small, but because the e-field and potential-difference is large, the current through that capacitor and through that tube becomes significant. Capacitance is roughly analogous to conductance, so you can imagine that a small capacitance is like a large resistor, and if connected to high voltage can conduct a significant current. But a small capacitance "conducts" a small displacement current. --Wjbeaty 12:58, 23 November 2006 (UTC)
Hmmm Would you care to define displacement current Bill?--Light current 02:35, 24 November 2006 (UTC)
I don't understand your question. Are you saying that there's something wrong with the definition on WP which you linked to? It looks perfectly fine to me. Don't forget that if you place capacitors in series with a resistor in an AC circuit, the resistor still gets hot... which means that there must be an energy flow across the circuit and towards the resistor, and current in the dielectric of those capacitors. (Imagine an AC circuit built from PZT ferroelectric. It still works, yet the current is entirely "displacement current.") --Wjbeaty 22:48, 25 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?
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)
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??

[edit] Lymphocytes

My 88 year old mother tested "low" for lymphocytes 25/23 (26/46 was listed as normal range) What could this indicate? Jcanet 16:32, 23 November 2006 (UTC)Jcanet

I'm not quite sure what you mean by "25/23" (if it's a lymphocyte% there should be only one value). The usual normal range for lymphocyte percentage (in a differential count) is about 15% to 40%; the usual range for an absolute lymphocyte count is 1000- 3500. If (as it seems from your question) her lymphocyte% is about 25%, it's in the normal range; if the lab is using a fairly narrow normal range of 26-46%, having a lymphocyte value of 25% is unlikely to have any significance whatsoever. A low lymphocyte count becomes significant only when it is really, really, really low. - 16:44, 23 November 2006 (UTC)

Any lab value listed as "abnormal" can be significant or non-significant depending on the clinical circumstances (age and health of patient, medical conditions, drugs, reproducibility, previous values, suspected disease, and many other things). Remember most lab normal ranges are derived from 5th and 95th percentiles for young healthy adults, leaving 1 in 10 young healthy adults above or below the range with no disease. Levels just above or just below the edges of the normal ranges are often of no significance. I assume she pays someone to make this decision and take responsibility for it based on far more information than we have. What has that person told her? Medical opinions here are often worth what they cost you. alteripse 01:13, 24 November 2006 (UTC)

BTW I had a full blood workup a little while ago, and I found this website kind of useful. Don't know if it'll be of any use to you. Anchoress 01:23, 24 November 2006 (UTC)

[edit] Height

In Gattaca, the main character slices his calves open and inserts disks in his bones to increase his height. If one is in his years of growth, is there any more natural and pleasant way to encourage vertical growth? This is a much for curiosity as actual practice. —The preceding unsigned comment was added by 71.252.11.5 (talk • contribs).

Eat well and excercise. B00P 21:20, 23 November 2006 (UTC)
Another case of life imitating art, we don't yet have an article but the procedure is known as Limb-extension surgery. I don't believe it is available in many western countries, but I have heard of people travelling to China and Russia to have it performed. Apparently a pretty risky and painful procedure. Vespine 22:04, 23 November 2006 (UTC)
methinks the life part came first. see also distraction osteogenesis.
The use of somatotropin, as well as delaying puberty by givning gonadotropin-releasing hormone agonists is advocated by some, but is controversial. As far as I know, limb-extension surgery is available in Norway after puberty for people of extremely short stature. The sister of an aquaintance had it performed, and I don't believe she went abroad for the operation. It was a time-consuming and painful procedure, necessitating external fixation while callus formed. --Norwegian Blue talk 00:14, 24 November 2006 (UTC)
That procedure may be unavailable in most Western countries for cosmetic purposes, but it is used theraputically to correct significant differences in limb length. Anchoress 00:17, 24 November 2006 (UTC)

Any way you guys know of, other than eat well and exercise, to grow without any special medicines, hormones, etc or surgery stuff? I'm just looking for day to day stuff I can do. Is there somewhere else you'd suggest I pose the question?

I'm afraid you're out of luck, then. Without hormones or surgery, a fully grown adult isn't going to lengthen their limbs by any noticable amount. 202.10.86.63 02:49, 24 November 2006 (UTC)
What about a few weeks on the rack? 8-)--Light current 04:13, 24 November 2006 (UTC)

"Day to day stuff" to make you grow? How about daily injection of growth hormone? Not very painful, probably pretty safe, and only about $100,000 per inch. Being an inch taller is worth more than your college tuition, isn't it? You can find some pediatric endocrinologists in NYC, NJ, Miami, Phoenix, or the west coast who are pretty free with the prescriptions. alteripse 04:20, 24 November 2006 (UTC)

Well thanks for all the encouragement, alterprise. Mostly just curious, because I saw an ad for a book about encouraging growth (but not only is $100,000 too expensive; $20 is as well.) And who said I was a "fully grown adult"? At any rate, somewhat-depressing point taken. Thanks,

I know a (Dutch) guy with dwarfism who had limb extension surgery. They break (cut?) the bone and put a metal contraption around it to keep the pieces of bone at a certain distance. The body will then fill the gap. Despite this being extremely painful he had it done several times (at differnt places, I assume). He didn't mention haveing to go abroad for this, so it's probably done in the Netherlands. DirkvdM 09:34, 24 November 2006 (UTC)

[edit] Ballon Mothership

If a Walrus HULA airship was built could it:

  • lift 500 tons worth of rocket to about 30 to 50 Km and release it?
  • if the 500 tons made it to 30 or 50 km and anywhere between, could this craft have enough power to reach the ISS using Rutans SpaceShip Ones Hybrid Rockets?
  • If the hybrid rockets do work how much of that 500 tons would it take up?

Thanks for any answers to this question and when I am refering to tons they are short tons.68.120.231.12 21:59, 23 November 2006 (UTC)

The WALRUS HULA project is based on good science, and is possible within the realm of current technology. It would be capable of lifting SpaceShipOne vehicles, but replacing the White Knight launch vehicle with a blimp would require changes in how SpaceShipOne is launched, since it's doubtful a blimp can reach the speeds White Knight does. Droud 16:12, 24 November 2006 (UTC)

[edit] How to remove stain from corroded "copper" coin?

I've just bought a house that had been empty for several months. In the bathroom I found that there was a large unpleasent-looking large brown stain at the bottom of the 'U' of the ceramic toilet. It wasnt what I at first thought it was. I scrubbed away at it and a coin was dislodged. It was a heavily corroded British 2p coin, dated 2000. The Royal Mint

http://www.royalmint.com/RoyalMint/web/site/Corporate/Corp_british_coinage/CoinDesign/2pCoin.asp

says these coins are copper over a steel core. So the stain could be rust with some copper too.

Could anyone suggest how to get rid of this stain please? I've tried scrubbing it, but this has no noticible effect. The 'rust' or whatever it is seems bonded to the ceramic. Is there anything such as for example caustic soda that I could pour down there to get rid of the stain? The stain is underwater. It may have been subjected to bleach or other toilet cleaning-chemicals in the past. —The preceding unsigned comment was added by 62.253.52.10 (talk • contribs).

Don't try, it destroys the numismatic value of the coin. Corroded coins get higher market values than cleaned coins. Titoxd(?!?) 23:31, 23 November 2006 (UTC)
But to be honest - a 2000-issue 2p coin is going to be worth face value only. There are far too many of them to have a higher market value. Richard B 23:46, 23 November 2006 (UTC)
i think he means cleaning the stain from the toilet "it seems bonded to the ceramic". you could try pouring a whole lot of vinegar down there and letting it sit overnight. but that acid might not be strong enough with the excess water around. Xcomradex 23:50, 23 November 2006 (UTC)
how about a 2 litre bottle of diet coke!
No no!. All you need is a small amount of HP brown sauce!. Pour enough over the face to form a slight curved sufrace and leave for 24 hrs. Wash off with water. Repeat for other side. then you will have a bright shiny looking coin!--Light current 02:01, 24 November 2006 (UTC)
Guys, he's after cleaning the toilet, not the coin. I'd second starting out with putting a large bottle or two of pickling vinegar from your local supermarket down the bowl and leaving it overnight before scrubbing again. If that doesn't work, contact a janitorial supplies company (check the Yellow Pages or equivalent) and either ask their advice, or just purchase some high-concentration formic acid solution from them. In my experience that stuff will clean almost anything off of ceramic toilet bowls. Just make sure the area is well-ventilated before using it (the fumes are seriously nasty in an enclosed area.) GeeJo (t)⁄(c) • 08:40, 24 November 2006 (UTC)
Oxalic acid will remove rust stains (from iron). It is found in Bar Keeper's Friend, but also in the green parts of rhubarb leaves; just make "rhubarb leaf" tea: works like a charm. Note that it is a poison; do not drink this tea! I have no experience in treating copper stains, which should be greenish, but the term chelation comes to mind.  --LambiamTalk 09:58, 24 November 2006 (UTC)
Cleaning the toilet is simple. Chlorine Bleach--Light current 12:16, 24 November 2006 (UTC)

[edit] If photosynthesis stops, how long have we got?

Imagine all photosynthesis stops all around the world. How long will it be before humans and other animals run out of oxygen and suffocate? Are there any animals that would survive in these conditions? —The preceding unsigned comment was added by 81.104.12.24 (talk • contribs).

Interesting question. We can at least get a rough estimate. This web page, citing an Isaac Asimov article, says that the total mass of animal cells on Earth is 2 trillion (2e12) tons. That would correspond to the mass of say 25 trillion (2.5e13) people. Now this page says that a human consumes on average 260 kg of oxygen per year; the site looks like it might be a bit loopy, but that number is probably good. So if all the animal life in the world consisted of people and had the same total mass, the total oxygen requirement would be 6.5e15 kg/year. That will do as an approximation of the actual total requirement -- obviously some species will need more oxygen per unit mass and others less, but I'd guess we'd be within an order of magnitude. (Additional oxygen is consumed by things like forest fires, but I'm guessing that this isn't significant compared to use by animals.)
Okay, how much oxygen is there? According to this page and others, the total mass of the atmosphere is 5.18e18 kg, which is 23% oxygen by weight (the better-known figure of 21% is by volume or by number of molecules): so the total amount of atmospheric oxygen is just under 1.2e18 kg. Simple arithmetic suggests that this is a 185-year supply, except that our numbers are way too inaccurate to be that precise; better to just say it would be several decades and maybe centuries' worth.
Except that that's wrong, too, because we need a certain minimum percentage of oxygen in the air to live. And in addition, without photosynthesis to absorb it, the air would accumulate carbon dioxide, which is toxic in such conditions. My guess is that we might get by for a decade, maybe several decades, but not more.
Except that humans are a technological species, and while we might not be able to terraform Earth by rebuilding the atmosphere, we would certainly be able to find a way to make supplies of breathable air for ourselves. The human species, as well as its parasites and the other animals that live with us, would be pretty nearly as likely to survive as it is right now, although very likely in smaller numbers: life might be confined to domed areas or something like that. It's the animals outside those human-created areas that would probably die off in decades.
--Anonymous, 00:45 UTC, November—The preceding unsigned comment was added by 24.207.176.159.90 (talk • contribs).
I saw something on TV that said if PS stops, we only have a couple of weeks!--Light current 01:38, 24 November 2006 (UTC)
We have a lot less time than that. If PS stops, it means the sun went out. Very bad day. --Tbeatty 04:18, 24 November 2006 (UTC)
Not necessarily: It could mean we have just had a massive volcano eruption filling the sky with debris. see Nuclear winter etc 8-)--Light current 04:26, 24 November 2006 (UTC)
A volcano eruption massive enough that it completely stops PS on the planet would kill all of us very quickly. Within hours I suspect. --Tbeatty 07:34, 24 November 2006 (UTC)
Don't stop and think that photosynthesis is the only place we get oxygen and carbon dioxide from. That's the elementary school defintion that is not quite right. More here[1] X [Mac Davis] (DESK|How's my driving?) 04:47, 24 November 2006 (UTC)

Note that a more immediate problem would be the lack of food, since almost all the energy in our food comes directly or indirectly from photosynthesis. So, once all our crops died, and all animals that eat plants die, and all animals that eat those animals die, etc., we would run out of food. The lack of fruits and vegetables and grains would be apparent in grocery stores within days or weeks, with the lack of meat being a problem in a few months. StuRat 08:03, 24 November 2006 (UTC)

Yeah : about 2 weeks as I originally said! 8-)--Light current 12:03, 24 November 2006 (UTC)

One thing not answered as far as I can see: "Are there any animals that would survive in these conditions?". Now perhaps what we would regard as true animals would not survive, but plenty of life would. Mainly bacteria to be sure, but not only - refer to Anaerobic organism for more. I would suspect some animals, such as those that live in the deep ocean, may survive, but that would depend on some other factors such as what they are feeding on. --jjron 12:29, 24 November 2006 (UTC)

The ecosystems around hydrothermal vents are independent of solar-supported ecosystems and support some quite large organisms, including anything up to fish, crabs and octopuses. EdC 23:21, 24 November 2006 (UTC)

[edit] helium

Thursday, November 23, 2006 I was offended by the filth I read. It is my guess that the vulgarity was placed there by a prankster to see whether or not you were paying attention. I will NOT repeat what I read, but I will tell you where to find it: http://en.wikipedia.org/wiki/Helium Look at the last line of the paragraph just above: “Solid and liquid phases”

The next time I recommend these pages to my students I expect the pages to be squeaky-clean. Jason — —The preceding unsigned comment was added by Inventioneer (talk • contribs).

You write as if you think you are addressing someone in charge of something. That's not how Wikipedia works. If you see a problem, the simplest thing to do is fix it yourself. (Usually you can just select from the page history an old version without the problem, then edit and save that -- this reverts all changes made since that version. Put "revert vandalism" in your edit summary.) The page history for helium shows several instances of vandalism in the last little while, and when I lookde at it a few minutes ago, all have been repaired already. Please see Wikipedia:Vandalism.
If you require all the pages to be certifiably squeaky-clean before you recommend them to your students, then you should not do so. Most vandalism on Wikipedia is repaired quickly, but you can't count on it not being seen.
--Anonymous contributor, 00:55 UTC, November 24, 2006.—The preceding unsigned comment was added by 24.207.176.159.90 (talk • contribs).
So, Jason, did you discover the objectionable content before or after you recommended the pages to your students? I wouldn't be a bit surprised if they're the ones who made the changes in question! (Are you and they in Canada, in Manitoba?) -- Anon (a different one) 02:36, 24 November 2006 (UTC)
Only a protected blank page would be squeaky-clean :-) -- WikiCheng | Talk 07:20, 24 November 2006 (UTC)
Yeah, as Anon says the address resolves to Marathon, ISP Bell Canada, Superior Greenstone School. If you really are a teacher, you can figure out who was working there at the time of the edits, 2006-11-23T16:45:01, but my own opinion is that it is really no big deal. Kiddies will be kiddies. Seejyb 11:44, 24 November 2006 (UTC)
That's rather clever of them. Get their own answers from the Wikipedia, the edit the article to mess up any other students who come along later. If I were a teacher, I'd give them extra credit for that. Fortunately, I'm not planning on becoming a teacher. Yes, anyway, this is a user-edited encyclopedia, you can't expect it to be "squeaky-clean". If you're going to recommend reference material to anyone younger than University age, send them to a read-only medium. I'd trust an undergrad to critically evaluate information sources, but not someone who's still at school. Sockatume 03:42, 27 November 2006 (UTC)
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