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June 4

Electromotive Force and Potential Difference?

I am slightly confused what is the difference between electromotive force and potential difference. From what I currently understand it seems like emf is a theoretical value assuming no internal resistance within a battery while potential difference is the actual, pratical value. Is this correct? 24.125.56.9 (talk) —Preceding comment was added at 00:44, 4 June 2008 (UTC)

You've already looked at Electromotive force#Electromotive force and voltage difference, right? Also note that at potential difference, it has been suggested that this article be merged with voltage. Are you asking about the difference between emf and voltage? The main thing I'm getting out of these articles is that the word "force" in emf is a misnomer. --arkuat (talk) 06:23, 4 June 2008 (UTC)

There is no real difference other than semantic convention. The emf phrase is usually applied to the voltage of a generator and the pd phrase is usually applied to the voltage across a load. However, this can be relative, the load can be a supply to something else so whether a particular item is a load or a source can be a matter of point of view. Arkuat is correct that emf is a misnomer and is therefore discouraged. Voltage is neither force nor pressure (another common analogy). It is potential energy (per unit charge). SpinningSpark 13:12, 4 June 2008 (UTC)

Electromotive force is the voltage (or energy per unit charge) transferred from the power source to the charge carriers (electrons or ions) in a conductor. Potential difference is the voltage transferred from the charge carriers to the load. -steved

mental health

explain the practicle knowledge of the principles, concepts, and methodology in the field of mental health in order. Think of yourself being a mental health couselor. —Preceding unsigned comment added by 76.114.167.213 (talk) 01:11, 4 June 2008 (UTC)

Do your own homework. Think of yourself being a student learning the material instead of a freeloader cheating on-line. DMacks (talk) 01:16, 4 June 2008 (UTC)

That seems like practicle practical advice ;-) --hydnjo talk 01:54, 4 June 2008 (UTC)

Sound cousel counsel too. Clarityfiend (talk) 02:06, 4 June 2008 (UTC)

Mental health - Mental health professional - Social worker - Psychology - Psychiatry. Damn, I really thought it was a question about the meeting of particle physics and psychology. So disappointed. 200.127.59.151 (talk) 15:15, 4 June 2008 (UTC)

ears

Do your ears get bigger as you age? It seems like elderly people have abnormally large ears. —Preceding unsigned comment added by 75.169.24.1 (talk) 02:07, 4 June 2008 (UTC)

This study suggests yes, though it is not an ironclad correlation between ear size and age. --98.217.8.46 (talk) 03:26, 4 June 2008 (UTC)

Yahoo answers[1] is inconclusive but madsci[2] discusses it with a yes in there as well. Sometimes it's only apparent (the flesh-and-hair loss effect) and sometimes it's measurable. Hair apparently falls off the head only to reappear in the nose and ears. Julia Rossi (talk) 03:31, 4 June 2008 (UTC)

See also Do Your Ears Hang Low? Edison (talk) 06:04, 4 June 2008 (UTC)

Can you plug a 115 volt appliance into a 110 volt outlet?

I'm trying to determine if I can plug a 115 volt appliance into a 110 volt outlet. You know, whether or not that would actually work without anything blowing up. I found an answer to a similar question on Wikianswers, but it didn't really help at all. Digger3000 (talk) 02:41, 4 June 2008 (UTC)

In North America, household outlet voltages of 110/115/120V are used interchangeably (see this FAQ). According to that link, appliances are generally designed to operate at 115 +/- 10%, so you should be just fine. Cheers, St3vo (talk) 02:54, 4 June 2008 (UTC)

That's right. They just call them those different numbers and there's no telling what the actual voltage is going to be on any given day. It'll be higher closer to the power plant, too. The power companies don't regulate that very strictly, but they do keep the 60 cycles pretty tight. Our article Mains_electricity#Voltage_levels says "In the United States and Canada, national standards specify that the nominal voltage at the source should be 120 V and allow a range of 114 to 126 V (-5% to +5%)." Also see Mains_electricity#Voltage_regulation. --Milkbreath (talk) 04:04, 4 June 2008 (UTC)

Thomas Edison started out with 100 volts in New York City supplied from the Pearl Street Plant in 1882. He decided to stress the insulation slightly more to achieve the transfer of greater power and the voltage level was raised to 110 volts. A couple of decades later, the nominal supply voltage became 120 volts, again to aupply more power via the same conductors. 120 volts AC is a nominal voltage in North America for many utilities at the transformer terminals. By the time the voltage has dropped through the service conductors and the wiring in the customer's premesis, it may be down to 110 volts at the actual motor terminals, representing the same real life situation. Utility commissions in many U.S. states allow the utility voltage to drop from the nominal 120 volts to 114 volts (a 5 % decrease) for 1 minute. A 115 volt (nominal) motor supplied with 120 volts would generally operate satisfactorily while drawing lower current. As with all Wikipedia Reerence Desk answers, this is provided for information only and may not be relied on as a substitute for professional advice from a licensed professional. No liability whatsoever is assumed. Edison (talk) 06:02, 4 June 2008 (UTC)

Animal behaviour

I want to know some facts about social hierarchy among animals.

• Which animals other than Homo sapiens have social hierarchy?

• I have read the article on Gorilla. The Gorilla#Behavior section of that article does not have much information about their group life. The only information given in the article is:

Silverbacks are the strong, dominant troop leaders. Each typically leads a troop (group size ranges from 5 to 30) and is in the center of the troop's attention, making all the decisions, mediating conflicts, determining the movements of the group, leading the others to feeding sites and taking responsibility for the safety and well-being of the troop.

• • • How the leader of a gorilla group is chosen?
    • If the existing leader of a group of Gorilla dies, then who will be the next leader and what is the selection procedure?
    • If any member of a gorilla group denies the order of the troop leader, then what will be the result?

• Regarding Chimpanzee, is there social hierarchy among chimps? What is the role of violence among chimpanzees? Are they attack one another or conflicts between one group and another, if there is violence then what is the reason behind the violence and what is the usual result of such violence? Otolemur crassicaudatus (talk) 06:39, 4 June 2008 (UTC)

Start from Ethology and then follow the links at the bottom. Dominance hierarchy(pecking order) and Alpha (biology) would probably also be of interest to you. Mountain Gorilla has a bit more on social structure. For Chimpanzee the answer depends on what species Common Chimpanzee is different from Bonobo.76.111.32.200 (talk) 07:00, 4 June 2008 (UTC)

Lots of questions. I'll have a go at the first. Almost all social animals have hierarchies, and that means a lot of mammals including chimps and gorillas. Perhaps the most rigid social hierarchies in mammals are among the Naked mole rats and Damaraland Mole Rats - the only two mammals that are know to display eusociality. Rockpocket 07:05, 4 June 2008 (UTC)

I carefully read the article Mountain Gorilla. The Mountain_Gorilla#Social_structure section answers to one of my question that if the existing group leader dies, then "the family group may be severely disrupted. Unless he leaves behind a male descendant capable of taking over his position, the group will either split up or be taken over in its entirety by an unrelated male. When a new silverback takes control of a family group, he may kill all of the infants of the dead silverback". This section also clearly states A typical group contains: one silverback, who is the group's undisputed leader. Here the fact I still do not understand that what will be fate of a group member if he/she denies any order of the troop leader? Will he/she be expelled from group or anything other? Otolemur crassicaudatus (talk) 07:20, 4 June 2008 (UTC)

Animals don't tend to order one another around. The dominant animal will typically do what he wants do do (which is generally eat, be groomed, and mate). If the other males stay out of his way and do not interfere with him then they will be fine. If they do, then they will likely be attacked until they submit. If they don't submit one of three things will happen: they may be chased away from the social group, they may be killed or the may usurp the dominant animal (who will either submit, be chased away or be killed). Rockpocket 07:29, 4 June 2008 (UTC)

I cut the skin on my knee

Yesterday night, I fell from my bicycle and cut the skin on my knee, for about an inch long, on the tar road. I washed it in Dettol and put on a Band-Aid. I removed the Band-Aid just now.

How come the skin got cut but my pants has no damage?

Why does it look white under the skin on the knee? It looks reddish under the skin on other parts of the body, right?

What is this translucent gel that has formed a thin film on the wound?

--Masatran (talk) 08:33, 4 June 2008 (UTC)

The fabric on your pants is stronger than the skin on your knee? I suspect the 'whiteness' is because your knee doesn't have much by way of muscle between it and the knee-cap, whereas on other parts of the body you do. I think the gel is white-blood cells. Sorry not much use i'm sure someone in the know will correct/answer more accurately in time. 194.221.133.226 (talk) 08:49, 4 June 2008 (UTC)

Sounds more like a scrape than a cut. The fact that your jeans held up is probably due to the fact that there are lots of tiny sharp edged pebbles in the road surface. They work like sandpaper. The sharp edges poked through tiny holes in your jeans and then cut lots of tiny little holes in your skin. The translucent film are white blood cells and a couple of other things your body uses to heal the wound. The white skin can have 2 reasons: Under the bandaid the skin can not "breathe" and is kept moist. The effects are the same as staying in the pool or tub too long. The second is that the blood supply is disrupted, compared to healthy skin, the body is also supplying more white blood cells in proportion to red to the site of the injury. --76.111.32.200 (talk) 09:26, 4 June 2008 (UTC)

(It's amazing how much questions and answers can resemble medical advice without people harrumphing about the Ref Desk rules.)Edison (talk) 21:48, 4 June 2008 (UTC)

Metadiscussion is best confined to the talk page. --Milkbreath (talk) 23:01, 4 June 2008 (UTC)

There is a difference between answering a question about human biology and medical advice - it's a little difficult to tell the difference sometimes, so we err on the side of caution, but I think this case is well within the realms of human biology, not medical advice, since all that's been offered is an explanation for an observation that took place after treatment was complete, no suggests about future treatment have been offered. --Tango (talk) 14:53, 5 June 2008 (UTC)

Huh? If you have an itch and scratch it too much, the skin will be covered with white marks. This is probably due to the surface of the skin being cut, without yet bleeding, swelling, and reddning, and the white cut mark on your knee is likely similar. Hope this helps. Thanks. ~AH1^(TCU) 23:56, 5 June 2008 (UTC)

Parachute for rock climbing

Would it help if rock climbers kept a parachute? Perhaps it would slow them down if they had a fall? --Masatran (talk) 09:03, 4 June 2008 (UTC)

I think that it is not feasible. First the parachute will not have enough room to deploy should the climber. Second, it will be torn by the jagged rocks of the cliff.--Lenticel ^(talk) 09:18, 4 June 2008 (UTC)

See BASE jumping. You would need a significant amount of expertise to pull it off, I imagine, but it could work. --Tango (talk) 12:07, 4 June 2008 (UTC)

Most of the time they use ropes and such tools instead to secure themselves. More reliable than a parachute and works at any height. Regards, CycloneNimrod ^talk?_contribs? 12:49, 4 June 2008 (UTC)

Rock climbing is rarely done on overhanging cliffs. More often, it's done on vertical or near-vertical cliffs, and if you fall on one of those, your parachute won't have room to open -- it'll get tangled and torn by scraping against the cliff. --Carnildo (talk) 21:24, 4 June 2008 (UTC)

Quantum mechanics and wave functions

QM states that prior to observation, nothing can be said about a physical system other than a probability function which seems to be definable to a degree by assumptions about the system's elements. With observation a system's probability wave function will collapse into a precise quantity which is observable by the means of measuring the device applied. – taken from Reality#Quantum physical views of reality.

Does this imply that, prior to the appearance of living beings capable of observing, the entire universe was in a state of quantum superposition? Does this mean that the far side of Pluto, which is not being observed, is in a combination of all the possible states? And finally, if I enclosed myself in a dark steel box, more or less like Schrödinger's cat, would I instantly experiment superposition too? -- Leptictidium (mt) 10:20, 4 June 2008 (UTC)

I don't think there is any real agreement on what "observe" means in that context. Collapsing wave functions doesn't really appear in the theory, it's just tacked on after the fact to explain why we do actually observe fixed outcomes to experiments. Different people have different ideas about how it actually works. Someone else can probably explain what the major interpretations are better than I can. --Tango (talk) 12:10, 4 June 2008 (UTC)

I think the whole universe is in a state of superposition whether it is observed or not! Proper Interval Locality —Preceding unsigned comment added by WROBO (talk • contribs) 12:48, 4 June 2008 (UTC)

Can other animals or even plants not observe? Imagine Reason (talk) 14:49, 4 June 2008 (UTC)

In quantum mechanics, the word "observe" doesn't mean what you think it does. Anything that interacts with a system can observe it: a human, a bacterium, an atom, a photon, anything. --Carnildo (talk) 21:31, 4 June 2008 (UTC)

So why is the superposition of the cat preserved if the bateria in the box, the atoms, and the cat can all observe and collapse the wavefunction? (I have the sneaking suspicion that I may be missing something). Ζρς ι'β' ^¡hábleme! 12:49, 5 June 2008 (UTC)

Hello everyone!

Considering my profile, I might be one of the least qualified persons to comment upon this. But, reading the italicized quoted paragraph gives me an impression that it is to be taken in perspective of Heisenberg's uncertainty principle, which implies that there are certain coupled physical quantities, say position and momentum of a particle that cannot both be determined with absolute certainty (this I'm saying with the risk of talking to real experts). To determine the position (the meaning of observation in the said paragraph) of any particle one will have to "bombard" it with at least one photon. And, the time it takes to return would tell you the position, but the catch is in the process, the photon would have altered the original momentum by an uncertain quantity, so again we become ignorant of the "exact" momentum possessed.

One might think that if a particle is absolutely stationary, then, and if we determine it's position, then we'd be able to determine both (momentum and position accurately), again the above argument would apply, and most importantly, quantum mechanics does not allow for a particle to have zero energy. It has to have at least 1/2h.v² amount of energy (where "h" is the Planck's constant, "v" is actually mu, and stands for certain frequency [loosely put, the frequency at which the particle "oscillates" and does not loose energy in the process]). This energy is known as the "zero point energy". The explanation I gave of the uncertainty principle is kind of crude (qualitative). There are other more complex explanations (like the "particle-in-the-box" example) that also account for certain phenomena like the tunneling effect used in electron microscopes (loosely put, the probability for an electron to exist outside as well as within the walls of a tunnel are both greater than zero!).

One more thing that I'd like to point out is that as quantum mechanics stands today, it is only to account for phenomena occurring at the subatomic scale, not at scales as large as a planet. Even a "small" particle like the a bacterium would be too complex and large to explain. That's why scientists are trying hard to find a unified field theory for a physics that could explain phenomena at subatomic scale as well as really huge bodies like the galaxies in the Universe. It is may be in this context that the Strings theory might come in handy.

Because, of the above mentioned uncertainty, we talk of wave function, which some what corresponds to the concept of trajectory in classical mechanics, which is a cumulative description of a particle's momentum (mass, direction, speed), and of course position at all points in time. Wave function if properly solved can yield the energy possessed by a body (kinetic+potential energy, of which the actual potential energy is again indeterminate), and the probability of a particle existing at a particular position in the coordinate system. So much for the uncertainty principle!

My ideas are greatly based on a book by Peter W. Atkins called "Physical chemistry" that I'd read more than 6 years back, and a program presented on the "Discovery channel" based on a book by Brian Greene called "The elegant Universe" with the same name.

If (the probability of which is very high) my ideas are misdirected, please do let me know. I find these topics very interesting.

Hope my comments would be of some help. Regards.

—KetanPanchal^taLK

Nu (ν) not mu (μ) is frequency. Mu is the notation for micro. I (am not sure but) think a wavefunction is a combination of all possible quantum states of a system. Thus, a wavefunction describes the superposition of all quantum states of a particle. When the particle is observed, the wavefunction "collapses" and becomes a definite state. The probability of collapsing into any of the possible states is described by the wavefunction.Caution: These ideas may, too, be misdirected. This is content from a few months ago obtained from Wikipedia via memory. If any of my statements are misguided, please kindly point them out. Ζρς ι'β' ^¡hábleme! 02:37, 6 June 2008 (UTC)

Perhaps as a physicist in training I can add a little something. Short answer: Your question shows a common flaw in how people receive quantum mechanics. Its all about scale.

The wavefunction is said to contain all the information there is about a quantum particle. The square of the wavefunction is the probability density that tells you the probability that a particle is in any given place. The wave function is determined by the boundary conditions which are defined by its surroundings (see the particle in a box for the easiest to understand example).

When something is 'observed' its wavefunction collapses to a Dirac delta function and it takes on a definite value for that period of time until it begins to time evolve again. The important thing to understand about probability density is that it applies for an ensemble of particles, not one particle by itself. If you have a wavefunction that allows for states 1 and 0, and you measure a particle to be in state 1. It is in state 1 for you to be able to measure that it is in state 1 (its an obvious thing that needs to be said). Its state is known (this is not meant to imply that its momentum/position are simultaneously known, commutator relationships still apply). If you were to take an identical particle and put it in the situation again, you might get 1, you might get 0. The relative probability of getting either of those is based on the probability density of the particle.

All that said, this applies ONLY for quantum particles. It does not apply for cats or as stated above, even bacteria. Or (often) even atoms. These objects are just too large for quantum effects to be observable. Atoms are kind of a gray area in that we CAN make predictions using quantum mechanics, but only if we break the atom down into its components, the electron cloud and the nucleus. But the atom considered as a unit will not typically follow the rules of quantum mechanics.

So yes, one could theoretically say that the far side of Pluto is in a state of quantum uncertainty. But above a certain scale, quantum effects are very difficult to observe and you'll more often find statistical mechanics or thermodynamics or Newton calling the shots. This inability to scale quantum up to an arbitrary scale is, as said above, the goal of a Grand Unified Theory, but we're not there yet. EagleFalconn (talk) 13:52, 6 June 2008 (UTC)

Hi! Thanks, EagleFalconn. I could follow your reply, but only partially so (no doubt, it "Q-U-A-N-T-U-M" physics!). Well, what I particularly didn't understand was the meaning of the term "quantum states". What are the parameters (like wave function, position, energy, spin, momentum or oscillatory frequency are included)? As I had said, I'm very unrelated to the field, but after I'd completed replying, I realized the concept that was being discussed had somehow never come to my attention during (whatever little) exposure I've had of quantum physics, that's why I probably tried to mould the situation in terms of uncertainty. Thanks in advance. Regards. —KetanPanchal^taLK 05:41, 7 June 2008 (UTC)

A quantum state is the case of having a wavefunction. If you change the wave function, you change the state (Disclaimer: Technically, you only change the state if you change the probability density, but its not a distinction that its strictly necessary just yet). From the wave function, everything you mentioned (position, energy, spin etc) is derived. Well, more accurately, given the parameters of the Hamiltonian which are based on the potential energy in the region the wave function is determined, which contains all the information about a particle. It is completely accurate to say that a wave function is defined by its boundary conditions, not the other way around, and the particle in a box that I mentioned earlier is an excellent example of this. EagleFalconn (talk) 13:50, 9 June 2008 (UTC)

Vehicle Fuel Economy declines by 10% for every mile per hour over 60 mph. Is this true?

Common knowledge or media has told me that for every increase in speed by 1 MPH, over the speed of 60MPH, fuel economy declines by 10%. This would result in a fuel economy loss of 50%, from say 15 MPG to 7.5 MPG by driving at 65 MPH. (5mph X 10% for each MPH= 50%. This cannot be true. What is the truth? Steve in canada. —Preceding unsigned comment added by 142.179.218.64 (talk) 13:02, 4 June 2008 (UTC)

Here's a question to answer your question. Say something costs $100. A store charges a 50% markup on the price. Later, when the store is going out of business, they have a 50% off sale. How much does it cost now? shoy 13:49, 4 June 2008 (UTC)

Obviously the 10% rule of thumb as described above can't be literally true, otherwise your fuel tank would instantly empty itself when you hit 70MPH. (I have myself driven over 70MPH and can report that my fuel consumption did not suddenly divide by zero.)

Check out the graph at page 4-23 of this report for a rough idea of how this goes. Obviously it will be somewhat different depending on the vehicle. APL (talk) 14:01, 4 June 2008 (UTC)

Minus 10% and then minus another 10% isn't the same as minusing 20% - pick a starting number and try it. --Tango (talk) 14:24, 4 June 2008 (UTC)

But even taking compounding into account, a 10% drop per 1 mph increase in speed would mean that fuel economy at 70 mph was only 35% of its value at 60 mph - which is clearly not correct. The rate of drop off in fuel economy in the source given by APL above is much smaller than this - only 1% to 2% per mph. Gandalf61 (talk) 14:37, 4 June 2008 (UTC)

It massively depends on the engine and gearbox of the car, too. Different cars are optimised for different speeds, a car with a fairly low-ratio gearbox designed for city driving does lose efficiency quite quickly at high speeds, but a car designed for it generally gets its best mileage at 70-80mph. ~ mazca ^talk 14:27, 4 June 2008 (UTC)

That number surprises me. I thought cars typically saw their most efficient speeds in more like the 30-50 mph range. Where did you read about cars that are most efficient at 70-80? Air resistance becomes way more significant with higher speeds- there's not really any getting around that. Friday (talk) 15:34, 4 June 2008 (UTC)

Yeah. I can see an engine producing peak power in that range, but not peak fuel efficiency for the overall system. — Lomn 18:27, 4 June 2008 (UTC)

The Union of Concerned Scientists guy here says you lose 1% for every mph over 55 (not 10% for every mph over 55) (You have to love the sidebar poll - On a 65mph speed limit road, how slow would you go to save gas? Most common answer - 70!) Rmhermen (talk) 15:46, 4 June 2008 (UTC)

At high speed efficiency is governed mostly by wind resistance, which goes up proportional to the square of the velocity. So, its not linear at al, and depends a lot on the aerodynamic efficiency of the vehicle. Perhaps it is 10% between 60 and 70, but it will be more than that between 70 and 80. We used to (try to) enforce a 55 mph speed limit in the USA just because of the really large fuel savings that would accrue if people stuck to that limit. I really think we need to go back to that, and make speeding tickets a priority revenue source for the states for a few years. --BenBurch (talk) 19:54, 4 June 2008 (UTC)

That was one of the stupidiest laws we ever had. I lived in a hilly area at the time, which results in cars gaining speed going down the hills and losing speed when they went back up. But once they put that absurdly low speed limit in place, we either had to come to a stop at the top of the hills or ride the brakes down the hill to keep it under 55. This wasted fuel, time, and brake pads. Another unintended consequence is that slower cars stay on the roads longer for a given trip, resulting in more cars on the road at any given time, which requires additional lanes to prevent gridlock. StuRat (talk) 04:01, 6 June 2008 (UTC)

Obviously they'd never heard of engine braking if they were riding the brakes down hills. Even an automatic gearbox has a low gear selector override for just such an occasion. Exxolon (talk) 21:07, 8 June 2008 (UTC)

Most Americans have automatics. You can switch to nuetral or a lower gear on long hills, but it's just not practical to constantly switch gears going over a series of short hills. Changing gears that often distracts from driving and you can miss and put it in reverse if you don't watch the gear selector, which means taking your eyes off the road. StuRat (talk) 22:07, 10 June 2008 (UTC)

Why aren't pygmies considered a separate species or sub-species of Homo Sapiens?

For example, the Pygmy Hippopotamus is considered a separate species from the Hippopotamus. The Pygmy Blue Whale is considered a separate sub-species of Blue Whale. And there are many other examples. So why aren't human pygmies considered a different species or sub-species of Homo Sapiens? Is it because of political reasons or because of actual scientific reasons? ScienceApe (talk) 13:25, 4 June 2008 (UTC)

See Race (classification of human beings)#Race as subspecies. --Elliskev 15:07, 4 June 2008 (UTC)

Good link. In general the meanings of the terms "race" and "subspecies", while vague, mean something pretty similar. So to answer the original question - yes, you probably could call pygmies a subspecies, just as you could call Caucasians, or Maoris, or Koreans a subspecies. In general, though, I think the term "race" is used because it sounds more neutral. To me "subspecies of human" gives an implication of "subhuman" which is obviously worth avoiding politically. ~ mazca ^talk 16:58, 4 June 2008 (UTC)

You seem to be hung up on the term "pygmy". It is not a scientific term, neither when applied to hippos, whales, or humans. It is a name that just means "smaller". It does not denote whether anything labeled it is a different species or sub-species. Membership in a species is determined by a number of factors—no human groups have ever been found who were not of the same species. There has been a long discussion over whether it makes sense to consider human races forms of subspecies or variations, but in there the apparently static appearances of the races is quite deceptive, they are just probabilistic clusters of traits that on aggregate seem to be biologically real but have no distinct genetic basis (other than being said probabilistic clusters of traits—people from X area have a higher chance of having certain traits than people from Y area that is distant), and much of what we consider to be the differences are very superficial and are colored by social cues. --98.217.8.46 (talk) 15:30, 4 June 2008 (UTC)

Well, 98..., you have just described subspecies quite well (people from X area have a higher chance of having certain traits than people from Y area that is distant) in your attempt to prove the opposite. This is part of the problem of defining subspecies for any organism. Rmhermen (talk) 15:54, 4 June 2008 (UTC)

In my understanding of it, the definition of subspecies is considerably more complicated than that, and it is in those complexities that the whole problem of race as a subspecies falls apart. Human racial traits are clinal, which goes against the categorization of subspecies fairly strongly.--98.217.8.46 (talk) 17:39, 4 June 2008 (UTC)

And how do the African Pygmies not fall into the definition of a subspecies exactly? —Preceding unsigned comment added by ScienceApe (talk • contribs) 18:31, 4 June 2008 (UTC)

As yet another example of why not to get hung up on the name: the African pygmies were only called such as early as the 1860s[3], after the categorization of the Pygmy Hippos (1840s). This loose application of similar names to African peoples is tres' 19th-century, and it's interesting to note that the man who was responsible for giving a full description of the Pygmy Hippos to science was none other than notorious scientific racist Samuel George Morton. While I doubt Morton had anything to do with apply the term "Pygmy" to people, it's worth noting that he did think that human races were distinct species (despite the obvious evidence of ability to interbreed), and used it as a way to justify all sorts of things like Slavery. So just to reiterate: "is it because of political reasons or because of actual scientific reasons?" is not exactly the right question; questions about race and biology have long been both. --98.217.8.46 (talk) 15:40, 4 June 2008 (UTC)

That French word is properly très, in case you're interested; no apostrophe. —Tamfang (talk) 21:04, 4 June 2008 (UTC)

Possibly due to a relatively recent Population bottleneck approx 70,000 years ago (the cause is speculated to be the Toba catastrophe theory ), the human species is very similar genetically, more so than other animals with such a large population. This means on genetic grounds it is unlikely that any subsection of the human species will be genetically different enough to be regarded as a subspecies. Due to anthropomorphic bias we tend to regard differences in humans as more noticeable than differences in other animals. I.e. Most people find it far easier to tell the difference between 2 people than 2 snails. GameKeeper (talk) 19:52, 4 June 2008 (UTC)

Gigantic dogs and tiny dogs vary by a greater ratio in mass than larger and smaller races of humans, but the dogs are certainly of one species. Size and color do not necessarily imply speciation. Edison (talk) 21:44, 4 June 2008 (UTC)

Yes they are the same species, but they are regarded as different breeds, which means a domesticated subspecies. ScienceApe (talk) 23:40, 4 June 2008 (UTC)

Hi. Of course, there are claims that creatures such as Bigfoot and Orang pendek are seperate species of the Homo genus, but this has not yet been proven. Thanks. ~AH1^(TCU) 22:34, 4 June 2008 (UTC)

Hi everyone! Hope am not adding to the confusion. Yes, of course apart from the fact that the "pygmy" in pygmy hippopotamus and pygmy whale are adjectives given to an originally "DIFFERENT" species, whereas "Pygmy" as applied to the human "race" is more like the original noun, another thing to consider is a relatively practical criterion for considering a group of animals as one species—that being they can successfully and naturally reproduce among themselves. So, this criterion would definitely apply to Pygmies as well as other named races. Regards. —KetanPanchal^taLK 17:11, 7 June 2008 (UTC)

Well, if that is so, the atomic family is a species ;-). Seriously, Pygmies are, of course, compatible with other groups of humans, and hence form a common species with them. --Stephan Schulz (talk) 17:28, 7 June 2008 (UTC)

The pygmy blue whale is not a different species. It is a different sub-species, akin to a race. ScienceApe (talk) 19:01, 8 June 2008 (UTC)

Baby seagulls

Can baby seagulls swim soon after hatching, like ducklings can? —Preceding unsigned comment added by 90.242.27.201 (talk) 14:00, 4 June 2008 (UTC)

Ducks generally nest on or very near the water, so it's quite necessary for ducklings to swim very early on. Conversely, seagulls generally nest on cliffs and crags a fair distance from the water and the chicks stay in the nest for longer, so I don't think it's likely that the babies need to swim soon after hatching. My guess would be that they gain swimming capabilities about the time they fledge and fly out of the nest, because they are unlikely to encounter the water much before then. I'm not sure, though. ~ mazca ^talk 14:40, 4 June 2008 (UTC)

If the nest is near water, gull chicks do sometimes swim (well, it's really more like splashing around and paddling a bit) in the days before they fledge, once most of their feathers have grown through. Newly hatched babies seldom leave the safety of snuggling beneath the mother gull (though if they try to scramble out of the nest, she picks them up and puts them back under anyway), though they can run within hours of hatching if the need arises. --Kurt Shaped Box (talk) 20:38, 4 June 2008 (UTC)

Escaping from a falling plane that is going to crash

I was on a plane the other day and I always wondered that if a plane is going to crash, yet I am still high enough in the air to parachute down, would I survive? How would you survive, if it is possible? I know now that there are security restrictions on actually bring a parachute pack with you on the plane nowadays. But, if you could, what would you bring so that you can literally jump out of a jumbo jet and survive? Also what part of the plane would have to jump from to survive? --Vincebosma (talk) 15:10, 4 June 2008 (UTC)

Certainly you could do it with a pressure suit and parachute, because Joseph Kittinger did it from over 100,000 feet. But I don't know what altitude you can safely jump from with a parachute but without a pressure suit. Vesna Vulović survived a fall from 33,000 feet with no suit or parachute, but that's rare. This site says you can jump from near 30,000 feet with just a parachute and an oxygen bottle, but I don't know how reliable it is. --Allen (talk) 15:56, 4 June 2008 (UTC)

With an airliner, there's also a very real question of how you're going to safely bail out. D. B. Cooper exited his craft via a tail hatch, but that's an uncommon feature these days, and present-day exits (forward hatches, over-wing windows) aren't designed to let an occupant jump while avoiding wings and engines. — Lomn 16:33, 4 June 2008 (UTC)

• In fact, the Boeing 727 tail hatch that Cooper used was modified after the hijacking and a number of similar events, to keep the hatch locked in flight so no one could do that again (see Cooper vane). --Anonymous, 20:57 UTC, June 4, 2008.

It is not known for certain whether D.B. Cooper survived or not, but it is believed that he did not. 69.140.152.55 (talk) 22:08, 5 June 2008 (UTC)

Furthermore, if you're high enough (like 35,000 feet or so), and you have only the clothing you normally wear on an airliner plus a parachute, you're probably more at risk of freezing to death (or at least suffering severe frostbite, losing limbs, ears, nose, etc.) if you did get out safely. ~Amatulić (talk) 17:24, 4 June 2008 (UTC)

Finally, there is the issue of getting out of the plane. Passengers are not allowed to open the hatches - even if the plane is crashing. So, you'll have to fight your way through the flight crew as well as all passengers that think you are trying to blow up the plane somehow by opening a hatch in flight. -- kainaw™ 18:32, 4 June 2008 (UTC)

Well, if the plane is already crashing -- that is to say, in a clear dive towards the ground -- I doubt anyone is going to be all that concerned about someone trying to blow up the plane or even paying all that much attention to individual passengers (though it's certainly true that navigating your way to a hatch in the ensuing chaos is likely to be challenging). But the real problem is that you literally cannot open the doors of a modern airliner while in flight, at least not if it's properly intact, because the pressure within the airplane cabin is greater than the air pressure outside. The doors in airliners have to be pulled inwards, towards the cabin, before they can be opened, but because the air inside the cabin is pushing against the door, it can't be done -- it'd take far more strength than any human or even several humans possesses to do it. (According to this Straight Dope article, in order to open an inward-opening hatch on the plane, you'd need to exert the equivalent of a metric ton of pressure on the door to yank it open.) Still, for the sake of argument... if we were to assume that the plane was low enough (but not too low), broke up in flight and you were to get out of through the new hole in the fuselage while wearing a parachute... well, with some luck, sure, you could survive, provided you didn't get hit by a piece of the fuselage or anything and kept your head. Still, I wouldn't like to bet on it. -- Captain Disdain (talk) 20:04, 4 June 2008 (UTC)

Hi. Remember however, that if you parachute into a thunderstorm, you are unlikely to survive. The only person ever to survive this was Lt. Col. William Rankin, who apparently does not have an article yet so I'll try and create one later. Hope this helps. Thanks. ~AH1^(TCU) 22:27, 4 June 2008 (UTC)

You might like reading this amusing and practical guide. --Sean 22:46, 5 June 2008 (UTC)

Electric Motors

Domestic electric fans

1. How it works with a rotor where no electricity is supplied ?
2. What is the function of a capacitor attached to the fan?Practically it boosts the efficiency of the motor.
3. Since a generator is the reverse of a motor, it should be possible to generate current from a domestic AC exhaust fan by keeping it exposed to air flow. In that case the current so generated will be AC or DC? What will be the function of the capacitor of a motor in case the same is used as a generator?
4. It is mentioned that aluminium winding is more efficient than copper. But I have never seen aluminium winding wires being used by professionals. Rather copper wire is seen used by them, Why? —Preceding unsigned comment added by Santoshkumardessai (talk • contribs) 15:31, 4 June 2008 (UTC)

To get you started, you could read things like electric motor, electric generator and aluminum wiring. Friday (talk) 15:37, 4 June 2008 (UTC)

Induction motor will also be appropriate for learning about the type of motor used in most mains-powered fans.

Atlant (talk) 19:37, 4 June 2008 (UTC)

The aluminum wiring article linked to by Friday is concerned with grid and building wiring. Aluminum started to become popular in the 1960s when the then Rhodesia led by Ian Smith was under international sanctions. At the time, Rhodesia was the worlds major source of copper and prices went through the roof, even getting into the same bracket as silver at one time. Not sure if this is the same reason for aluminums use in motor windings though, the OP mentioned improved efficiency. Perhaps there is a weight saving, but it is certainly not a very common thing to do. SpinningSpark 20:12, 4 June 2008 (UTC)

At first blush it would seem like a fan motor should generate electricity when the wind spins it. But from childhood experimenting with one, my impression is that it does not have a functioning field current adequate to produce much output voltage. External excitation might be needed in addition to high speed rotation of the shaft. There is also the fact that when powered it spins far faster than is likely to be achieved when you attempt to make it a generator from normal amounts of air flow. Edison (talk) 21:37, 4 June 2008 (UTC)

We do have an all-too-brief article on Induction generators. And yes, they need an external source of electrical power to begin working, although with the right load impedance they'll keep themselves powered-up after that. Essentially, just as an induction motor converts electrical power to mechanical power as the rotor slips backwards against the rotating field, an induction generator converts mechanical power to electrical power as the rotor slips forwards against the rotating field.

Atlant (talk) 11:24, 5 June 2008 (UTC)

I'm speculating here on motor windings, but since aluminum has much less power density than copper, I'm thinking that the windings would have to be that much bigger, therefore a less-efficient motor would result. The weight saving is only a factor in starting the motor, not in running it, and the cost saving in materials would be offset by the larger motor casing and reduced motor efficiency. Franamax (talk) 22:52, 4 June 2008 (UTC)

This motor manufacturer would appear to agree with you on the efficiency issue. SpinningSpark 01:55, 5 June 2008 (UTC)

Ants smell

Here's a thought I have: if we could shrink to the size of an ant, so that the ant was as big as a dog to us, what would it smell like? I know that ants have pheremones, but I'm not sure if these are something a human would smell. Would the ant smell like dirt, since it lives in the dirt? Would it be really stinky? I also heard somewhere that some ants grow fungus. Jonathan ^talk 17:04, 4 June 2008 (UTC)

I guess a giant ant (OK, a regular ant where we were tiny) would smell like a whole mess of normal ants do to us at our present size. Formic acid seems to pretty much override any other smell. --Milkbreath (talk) 17:18, 4 June 2008 (UTC)

If you retained your human sense of smell, you likely wouldn't ever pick up on the pheromones anyway. ~Amatulić (talk) 17:20, 4 June 2008 (UTC)

Surely the ant would still be releasing the same amount of pheromone and your nose would be the same sensitivity it is now I would have thought (assuming your cells are shrunk with you) so i'm pretty sure it'd be no different. Regards, CycloneNimrod ^talk?_contribs? 18:13, 4 June 2008 (UTC)

So humans can't smell pheromones? That's what I was wondering Jonathan ^talk 16:01, 5 June 2008 (UTC)

Humans can smell some animal pheromones. For example, (±)-2-sec-butyl-4,5-dihydrothiazole and 6-hydroxy-6-methyl-3-heptanone are both mouse pheromones. They also have a distinct smell. However, while we humans have the ability to detect the odors of pheromones via our olfactory epithelium, we do not have the ability to detect the active pheromones themselves (because we don't have a vomeronasal organ). Rockpocket 20:18, 5 June 2008 (UTC)

The fungus growing ants are the Leafcutter ants SpinningSpark 19:56, 4 June 2008 (UTC)

Yeah, I definately agree, they would probably smell about the same that a whole bunch of ants do at normal size :) Do some ants really smell like formic acid? I live with pavement ants and I never notice any formic acid smell. Jonathan ^talk 16:01, 5 June 2008 (UTC)

Make yourself an ant farm. We used to just dig up an anthill, dump it all in an old pickle jar, and wrap it in black construction paper. Let them get situated and take a whiff. --Milkbreath (talk) 16:28, 5 June 2008 (UTC)

According to the formic acid article, "As early as the 15th century, some alchemists and naturalists were aware that ant hills gave off an acidic vapor." D0762 (talk) 16:52, 5 June 2008 (UTC)

Not all ants produce formic acid but plenty do, it does have a very distinct whiff that a human can easily smell by sniffing a suitable nest (without miniaturization!) . I have occasionally detected the smell of a nest before actually seeing it. As to whether a human could detect the ant pheromones, that is a tough one. I am sure certain ones would be detectable but millions of years as a eusocial animal which communicates with pheromones means that ant's pheromones are likely extremely subtle . I would expect these subtleties to avoid even a shrunk person GameKeeper (talk) 22:44, 5 June 2008 (UTC)

I don't see what difference size would make at all. Smell is based on two things: the composition of the air and the receptors an organism has. If you shrink, you aren't changing either of these factors: your nose is the same albeit smaller, and the composition of the air would stay the same. Maybe the difference would be that you were closer to the ground, where ants lay pheromone trails? But I mean, you could just as easily get on your hands and knees and sniff. --Shaggorama (talk) 15:24, 7 June 2008 (UTC)

Lidocaine and a couple of other questions

I work in a hospital and onje day I was in the prep room next to the building exit and there was a 100mg in 5ml vial of lidocaine sitting. How dangerous would that have been had it been taken, what could it to if injected intravenously, rubbed topically etc? There was also a 200mg in 10ml of acetylcysteine. Same question applies.

Also, there is much saline and sterile water lying around which might be confused for drugs in an admissions ward. Before I say anything to ward staff I would like to know the dangers of all these things. 92.0.228.141 (talk) 19:36, 4 June 2008 (UTC)

This is a medical question and so will not be answered here. --BenBurch (talk) 19:50, 4 June 2008 (UTC)

I want ACTUALLY asking for medical advice, I was just asking what the dangers would be of such a matter. There are many people admitted to the ward with overdoses etc and have to pass the often unattended toom to go out to smoke. I just wondered what could happen to the patient and things before I consider reporting it to staff if it isn't really a big deal 92.0.228.141 (talk) 20:00, 4 June 2008 (UTC)

Ben they're not asking for any advice, they're just curious. Well, lidocaine should give you an insight into what the drug actually is and you'll soon find little damage could be caused unless you put it somewhere it wasn't supposed to go e.g. stabbing it into someones eye. Topical application e.g. rubbing, however, wouldn't really do much harm at all.

As for acetylcysteine, again read the article first. It's used for various purposes e.g. reversing paracetamol overdoses, mucolytic therapy and also has kidney-protective uses. Insensible use of the drug therefore must have side effects, no idea what though. It also has to be stated about the possible toxicity of acetylcysteine. Read the article for more info. Regards, CycloneNimrod ^talk?_contribs? 20:23, 4 June 2008 (UTC)

Oh and don't worry about the saline or sterile water, they're not dangerous at all really. Regards, CycloneNimrod ^talk?_contribs? 20:25, 4 June 2008 (UTC)

As for lidocaine/lignocaine the amount needed to overdose (IV route) is very high. At least 9 vials of the type you specify. Topical application is harmless: it numbs you, full stop. Same goes for n-acetylcysteine, the biggest risk is that somebody will spill the drugs and slip on the wet floor. (Not as trivial a concern as it may seem). Fribbler (talk) 20:29, 4 June 2008 (UTC)

thanks for the help guys. COuldn't the lidocaine cause problems if injected? Like how far would it travel in the veins? I don't know a lot about pharmacology I#m afraid. And rubbing a vial on an area would numb it? Heh.. sounds wierd. Thanks though. What does "not dangerous at all really" in regards to the saline and water. I know they are technically harmless but what does THAT mean? 92.0.228.141 (talk) 20:40, 4 June 2008 (UTC)

Lidocaine causes trouble if injected in large quantities, as my external link explains. Water and saline are technically harmless? Translation: Don't drill a hole in your head and pour them in, don't drink 758 litres of them in one sitting, don't pour them into an electrical outlet..... :-) We just like to be careful. Everything is dangerous if misused. Fribbler (talk) 20:47, 4 June 2008 (UTC)

Wow, this has really got my inqusitiveness working. I mean how much of someone's arm/body would go numb from injecting it or rubbing it on? 92.0.228.141 (talk) 21:15, 4 June 2008 (UTC)

If it's injected subcutaneously then only a very small area is affected. Quite obviously a topical dosage will affect only the area it's applied to. As for IV, that's a little more complicated. It's all dependent upon the dosage really. Regards, CycloneNimrod ^talk?_contribs? 22:32, 4 June 2008 (UTC)

Ligno/Lidocaine is usually (but not by any means always) given with adrenaline, a vasoconstrictor that makes certain it won't travel too far to, lets say, affect the heart. Fribbler (talk) 22:49, 4 June 2008 (UTC)

True, the exception being when it's used to treat heart defects, particularly arrhythmias. Regards, CycloneNimrod ^talk?_contribs? 23:24, 4 June 2008 (UTC)

Naturally, as an antiarrhythmic, you want it to get to the heart of the matter :-) Fribbler (talk) 23:27, 4 June 2008 (UTC)

My personal feeling on this is that any unsecured materials are a concern, as they are a possible indication of carelessness on the part of the hospital staff, i.e. tomorrow it could be something more dangerous. If there is anything that could be casually stolen by someone walking by to go for a smoke, it's worth a call to the Director of Nursing, what harm will that do? Of course, they might just close the smoking area ;) Franamax (talk) 22:44, 4 June 2008 (UTC)

I couldn't agree more. Regards, CycloneNimrod ^talk?_contribs? 23:24, 4 June 2008 (UTC)

Thanks guys. I mean, as a member of staff in the prep room I see them lying about, but I don't know how accessible it would be to a patient. I am sure if the Sister on the ward had any knowledge of it it would be a different matter as she is the one who is answerable to the drugs. It's just a bit worrying. I don't know if I could say to the director as I have no idea who she is but it is something I will mention to the sister if I see it happen again. —Preceding unsigned comment added by 92.0.228.141 (talk) 18:28, 5 June 2008 (UTC)

Dust from old books

While scanning books in my denomination's archives, I've noticed that some old notebooks (the oldest of which was first used in 1893, and the newest in 1916) leave some reddish-brown (I'd guess; I'm partially redgreen colorblind) dust on the scanner and on my clothes, which is rather difficult to brush off. The dust is obviously coming off of the binding. Can anyone tell me what it is, and/or how we can handle the books so that as little as possible comes off? Nyttend (talk) 19:58, 4 June 2008 (UTC)

By the way, I don't see any publication information, but the books were used by a group of churches that were mostly located in Kansas, so I'd guess that they were bought in the area. Nyttend (talk) 20:06, 4 June 2008 (UTC)

Are the notebooks bound, wholly or in part, in leather? If so, this is probably the result of red rot. Unfortunately, nothing much can be done about it. Deor (talk) 20:21, 4 June 2008 (UTC)

The bindings seem to be leather. Thanks for the link: it seems to describe it quite well, especially the idea of the powdering and the feltlike consistency. I guess this is the reason I'm employed: we want to have the books digitized so that the records aren't lost. Nyttend (talk) 20:30, 4 June 2008 (UTC)

Just to follow up … Here's a page from the British National Archives on the problem; and here's an article by someone who claims to have a treatment. The treatment doesn't look likely to solve the underlying problem, but it may inhibit the powdering off of the leather when the volumes are handled. Deor (talk) 20:55, 4 June 2008 (UTC)

Why electricity 60Hz in some countries and 50Hz in other?

Why are there different electricity frequencies? Why not fewer? Why not others (a metric 100Hz, etc)? --70.167.58.6 (talk) 20:49, 4 June 2008 (UTC)

It's the usual reason that these things arise. People and companies working in different places made different decisions; by the time it became clear that this was becoming an important business and a single worldwide standard would be desirable, existing practice in different areas was too well entrenched; and the important companies whose choices had become the local standard weren't interested in changing their products to be compatible with someone else's from another country.

Lower frequencies are more efficient with certain types of motors used on heavy equipment and allow for more efficient power transmission; higher frequencies allow transformers to be built more lightly and reduce flicker in lighting supplies. Frequencies around 50-60 Hz turned out to be a suitable tradeoff point between these issues, but there have been large installations using lower frequencies from 15 to 25 Hz for industrial or railway use, and some of them still exist. (And in some areas these frequences have been in households, too -- Toronto was converted from 25 to 60 Hz power only about 50 years ago). As to higher frequencies, 400 Hz is used (I'm not sure how commonly) in aircraft electrical systems, and 20,000 Hz on the space shuttle.

See utility frequency. --Anonymous, 21:11 UTC, June 4, 2008.

Nuclear weapons underground (forgot to give this a title, sorry)

Well, I'm stumbling through this previously unknown Wikipedia section, and I already asked this somewhere else. Apologies. This appears to be the right place. I am writing a novel, and cannot find anything to help me out. A cache of nuclear weapons, simultaneously detonated a mile undergroung would produce what effect? Keeping in mind the necessary piping, elevators, and whatnot involved in a project that far down, what could I expect on the top, in regards to blast force, nuclear fallout, earthquakes and eruptions...

Thanks!! —Preceding unsigned comment added by 12.201.115.120 (talk) 22:08, 4 June 2008 (UTC)

Underground nuclear testing should give a good start. Bear in mind that it won't be all that dramatic except for (1) the immediate area and (2) the political fallout (other places will detect the explosion via seismometers, even if calling it an "earthquake" is exaggerating). — Lomn 22:19, 4 June 2008 (UTC)

If the site was badly planned, there could be radioactive venting to the surface, which has happened in the past. Other than that, triggering a nuke right at a fault could possibly trigger a major earthquake, there's always the possibility of groundwater contamination, releasing the cap on a high-pressure natural gas reservoir. But hey, aren't you the one with the vivid imagination? ;) Franamax (talk) 22:30, 4 June 2008 (UTC)

Also, when you say an underground cache detonated simultaneously, keep in mind it has to be very, very simultaneous, a difference of milliseconds will result in the first nuke just blowing the other ones into vapour. Getting the right neutron density and critical mass is tricky business to trigger even a single nuclear detonation. Franamax (talk) 22:36, 4 June 2008 (UTC)

I agree that there would be fratricide; the first one to detonate would so disrupt others in the same room or in compartments nearby, that they would not produce a nuclear blast of any appreciable magnitude. Their high explosive components might detonate, but the additional band would be negligible in addition to the nuke. Detonating one nuke in an underground cache would be remarkably like the result of an attempt to detonate many in the cache. Not at all like a room full of conventional bombs. If the explosion vented to the atmosphere, the additional fissionable material would add to the radioactive contamination of the area. Edison (talk) 23:41, 4 June 2008 (UTC)

It is also likely that they would need to go off deliberately, it is very hard to accidentally detonate a nuclear weapon, due to the huge amounts of safeguards in them. It would be impossible to accidentally set off an entire cache. Prodego ^talk 03:20, 5 June 2008 (UTC)

I agree. A nuclear weapon is a surprisingly robust and fragile device in many ways. It is far easier to make one not work than to initiate one by accident. The explosive initiator in a warhead must detonate precisely; an outside explosion would in all likelihood impair the explosion. The first device would destroy the second, and the materials would be vaporized; if open to the atmosphere, it would create a secondary "dirty bomb" effect, but I have no idea how much. As far as earthquakes and the like: there would be a lot dependent on the structure of the earth, but I find it unlikely unless it were directly on a fault line. This plot sounds similar to that of Superman and of Space: 1999, both of which were unrealistic. --—— Gadget850 (Ed) ^talk - 10:40, 5 June 2008 (UTC)

One thing to keep in mind is that most currently fields US nukes are at most in the few hundred kilotons. That isn't all that much from a raw yield point of view (though it is considerably larger than the nukes used against Hiroshima and Nagasaki). How much is this "cache" going to have? What I'm getting at is that even if they did all go off, it would only be a few megatons in yield. I'm not sure but I believe the highest yield underground tests were conducted at Amchitka (around 5 Mt of yield in the Cannikin test). There were discussions about possibly triggering earthquakes, and it may have triggered some very light seismic activity, but nothing major.

For me the entire idea of a "cache of nuclear weapons" being stored in some deep underground vault is not very plausible. To my knowledge nuclear weapons are stored fairly on the surface in locked bunkers. If they were underground, they would not be in seismically active areas—not because of a worry that they'd trigger earthquakes, but because nuclear weapons are expensive and the risk of them being damaged by naturally occurring earthquakes would be too high. --98.217.8.46 (talk) 15:01, 5 June 2008 (UTC)

I agree with other comments that only the first nuke will detonate and destroy the others, unless they are very elaborately and intentionally timed to detonate at the same time, and even then it's questionable since there is so little room for error. Unlike nuclear test sites, the storage room sounds like it was not built to contain a detonation, as you describe elevators and piping going up to the surface. These would act as a chimmney for the rapidly expanding gas and vaporized rock. At a mile below the surface, the cache seems deep enough not to produce a crater, but you have to consider the yield of the bomb(s) and the composition of the earth above it. If it's loose enough dirt and a strong enough bomb, you could see a subsidence crater around it as the surface rock loses support from below; near the center of the crater is the chimney through which some of the ejecta managed to escape. This could go up thousands of feet, but would be much thinner than the mushroom clouds we've seen in pictures, due to the narrower orifice of the escaping gas. I'm not sure if you would see a mushroom shape to the cloud, but I don't see why not. Fletcher (talk) 18:27, 5 June 2008 (UTC)

If the fireball itself is wholly contained underground you should not get a mushroom cloud. The mushroom cloud of most nukes is caused by the rising of the heated fireball. (See mushroom cloud for full description.) If there was a significant disruption of the heated matter/gas rising then you'd get a real strange looking cloud, not a neat mushroom cloud. Look at how unpleasant the cloud can be if the bomb is hindered by something as simple as being enclosed in a ship: [4]. --98.217.8.46 (talk) 21:39, 5 June 2008 (UTC)

Good point. That was a funky looking cloud. Fletcher (talk) 14:00, 6 June 2008 (UTC)

June 5

What is the latest scientific understanding of the relationship between dietary cholesterol & coronary heart disease?

The following is an excerpt from this article: [5]

[T]he maximum intake value for cholesterol of 300 mg ... was initially developed in 1968 by the American Heart Association for patients with high blood cholesterol .... Recent reviews of the scientific literature by U.S. authoritative bodies led such groups to conclude that "the relationship between cholesterol intake and LDL-cholesterol concentrations is direct and progressive, increasing the risk of coronary heart disease" and that cholesterol intake should be kept as low as possible within a nutritionally adequate diet.

To date, other countries viewing the same evidence as the U.S. come to the conclusion that the cholesterol in food is not the main influence on blood cholesterol ...

It seems that health authorities in different countries had access to the same evidence but came to very different conclusions about the significance of (high) dietary cholesterol intake as a CHD risk factor.

Could someone versed in the subject shed some light on what the best empirical evidence is telling us about dietary cholesterol & CHD? —Preceding unsigned comment added by 71.175.22.134 (talk) 02:29, 5 June 2008 (UTC)

CHD and coronary artery disease both require a multitude of factors that contribute to their development - it's difficult to talk about one single element, in this case, cholesterol. Yes, high LDL and low HDL show high risk, but now it's understood that such vascular diseases have oxidative stress and inflammatory components to them. Wisdom89 _{(T / ^C)} 05:33, 5 June 2008 (UTC)

On balance, it can be seen that the cholesterol theory of CAD causation has its limitations. First, the liver--as part of normal metabolism--produces cholesterol, quite apart from dietary sources. Second, cholesterol far from being a "villain," is absolutely essential for hormone production and nerve transmission. Third, the evidence is that lipid deposition only occurs after coronary vessel damage from such factors as hypertension and free radicals. Fourth, the concept of simple deposition of fatty substances upon the vessel wall--from blood flow--is flawed. Such deposits occur on the sub-intimal layer, not the surface immediately facing the lumen of the vessel. Fifth, studies exist demonstrating just as high correlation between dietary factors such as high levels of simple carbohydrates (e.g., sucrose), as with cholesterol and lipids. The wise clinician would counsel his/her patients AGAINST dietary extremes, such as excess intake of cholesterol, fat, and refined sugar, and FOR exercise and supplements which might assist with neutralizing free radicals. He/she would also be particularly alert to the risk of CAD in his/her hypertensive patients. Drnovlamas2 (talk) 14:57, 5 June 2008 (UTC) (Dr. T.C.H.)

yeah, it's pretty complex. not only is cholesterol so necessary we produce it, studies where cholesterol is driven way down below 100 show a rise in death rate, from things like accident, homicide, suicide, etc. It may be just coincidence, but it's persistent enough to make you wonder how sensitive function of the brain, whose cell membranes are stabilized in part by cholesterol, might be to the level. and as a kicker, blood levels of cholesterol might be more sensitive to intake of saturated fat than to intake of cholesterol itself. which ties in to the recent failures of efforts to reduce blood cholesterol by interfering with its takeup from the digestive tract by flooding it with large quantities of plant sterols, which sounds like it would work if straight dietary intake of cholesterol were an important factor. and, of course, now we don't look at total cholesterol as so important any more, we have divided it into LDL, "bad", and HDL, "good"; there might well be further subdivisions we haven't identified yet. and as the guy said, the mechanism isn't just like clogging your kitchen drain with fat, it's an active inflammatory process involving some sort of injury to the arterial wall getting scarred up with cholesterol somehow involved in producing big obtrusive scars, with the assistance of white blood cells and so on. which throws the whole thing into the now hugely important category of immune system disorders which appears to cover everything from diabetes to cancer to arthritis. Gzuckier (talk) 15:17, 5 June 2008 (UTC)

Unknown Equation

What is the name of this equation and what is its significance? What does it mean? $\langle \Omega |{\mathcal {T}}\{{\hat {\phi }}(x_{1})\cdots {\hat {\phi }}(x_{n})\}|\Omega \rangle ={\frac {\int {\mathcal {D}}\phi \phi (x_{1})\cdots \phi (x_{n})e^{i\int d^{4}x\left({1 \over 2}\partial ^{\mu }\phi \partial _{\mu }\phi -{m^{2} \over 2}\phi ^{2}-{\lambda \over 4!}\phi ^{4}\right)}}{\int {\mathcal {D}}\phi e^{i\int d^{4}x\left({1 \over 2}\partial ^{\mu }\phi \partial _{\mu }\phi -{m^{2} \over 2}\phi ^{2}-{\lambda \over 4!}\phi ^{4}\right)}}}$ Ζρς ι'β' ^¡hábleme! 05:15, 5 June 2008 (UTC)

I think it means, "I really wanted to show off when I was writing this equation". Or maybe, "Nah, nah, my brain is bigger than yours!" « Aaron Rotenberg « Talk « 06:23, 5 June 2008 (UTC)

Holy shit, is that an integral inside an exponent inside an integral???? Someguy1221 (talk) 06:44, 5 June 2008 (UTC)

Looks like it. As far as I can see this really looks like a meaningless, complicated equation created for the sake of it - though i'd be fascinated as to what it is if that isn't the case. ~ mazca ^talk 08:18, 5 June 2008 (UTC)

this looks like it is coming from conformal field theory or (quantum) statistical physics. Oded (talk) 09:56, 5 June 2008 (UTC)

Well, shows what I know. :) failed all the quantum theory modules on his chemistry degree ---> ~ mazca ^talk 12:41, 5 June 2008 (UTC)

I don't know where it comes from (though something to do with quantum mechanics seems a safe bet), but this looks more like just a definition: the left-hand side is in Dirac bra-ket notation, and I'd guess the right-hand side to be just the same thing written out in more verbose notation. Also, the denominator on the right-hand side seems to be just a normalization factor. What context did you encounter it in, anyway? —Ilmari Karonen (talk) 10:39, 5 June 2008 (UTC)

Well, I came across this equation in Uncyclopedia. However, I believe it is a legitimate equation because I saw exactly the same equation on some YouTube video (most likely about quantum mechanics or calculus). I saw that video when I hadn't yet edited Wikipedia, but had wanted to post a question about it when I started (I just couldn't recall it verbatum). I am pretty sure it is a quantum mechanics equation due to the context of the first time I encountered it, and the bra-ket notation. Also, φ and ψ are used quite a bit in quantum mechanics (I'm pretty sure), and quantum mechanics is known for its confusing equations, ideas, and such. Ζρς ι'β' ^¡hábleme! 11:42, 5 June 2008 (UTC)

I'm pretty sure this is an equation from quantum field theory. And believe it or not, it is an abbreviated form - the D function in the integrals is a shorter way to write another function. I'm pretty sure the entire equation is the Green's function. PhySusie (talk) 12:17, 5 June 2008 (UTC)

Looked it up. I thought it looked familiar. The notation is similar to that in "Introduction to Quantum Field Theory" by Peskin and Schroeder. This equation is used in perturbation theory for interacting fields. PhySusie (talk) 12:34, 5 June 2008 (UTC)

A difficult quantum field theory equation whose source is personal memory via Youtube via Uncyclopedia turns out to be genuine? I am stunned, I don't know what to say. Criticising someone for not using WP:RS is looking like a very shaky thing to do from now on. SpinningSpark 13:17, 5 June 2008 (UTC)

Well, I saw it on YouTube first a while back and then Uncyclopedia last night (I thought it would be funny to see how they spoofed QM). I figured two exact, independent reproductions of the same very complicated formula could not be coincidental. Wait, was that sarcasm? Ζρς ι'β' ^¡hábleme! 14:18, 5 June 2008 (UTC)

Did it occur to you that maybe the video stole the equation from the uncyclopedia? --Shaggorama (talk) 15:28, 7 June 2008 (UTC)

Bodybuilders

What is it that gives bodybuilders such leathery skin? —Angr 05:36, 5 June 2008 (UTC)

Shave off the body hair and apply tan colour and oil. Graeme Bartlett (talk) 12:04, 5 June 2008 (UTC)

You think that's all? The leathery skin seems so universal, I figured it was something like building all that muscle mass increased blood flow to the skin which in turns hardens and reddens the skin and so on. —Angr 16:06, 5 June 2008 (UTC)

Nah. It's just buckets of fake-tan. For increasing visible "definition". Have a look here and compare the pictures of Jay Cutler. He looks normal in the training pictures, then in the posing/in competition pictures he looks like he's made of mahogany. Fribbler (talk) 16:27, 5 June 2008 (UTC)

When bodybuilders are ready for competition they have very low BMI, which is one of numerous reasons bodybuilders have a distinct look compared to the Strongman_(strength_athlete) or Weightlifter. Bodybuilders don't have some inherent leathery skin, but years ago I had a mate I worked out with called Eddy Ellwood (see him here if you're interested [6]) who was one of the top guys around, when he was really cut I swear you could see the muscle fibres! Low BMI and increased vascularity changes the appearance of the skin to look 'leathery' but, as has been pointed out above, the oil and tan are more major factors. 87.112.89.101 (talk) 02:48, 6 June 2008 (UTC)

You can – across his pecs when he gets more into frontal transformer-type positions. Julia Rossi (talk) 04:11, 6 June 2008 (UTC)

research resources for the history of the discovery of anaerobism in bacteria

I need some quick resources that outline how our current information of anaerobism developed -- currently I only have information on who first discovered glycolysis which IMO would be quite after the realisation that bacteria could develop in anaerobic conditions. Also, was the distinction between prokaryotes and eukaryotes clear before the discovery of glycolysis and the other chemical processes involved in fermentation? Also how did our knowledge of the distinction of facultative and obligate anaerobes (as well as aerotolerant species, microaerophiles, etc.) develop? John Riemann Soong (talk) 07:59, 5 June 2008 (UTC)

This kind of history of science research is very tricky, and usually requires physical access to specialized libraries and archives. en.wikipedia has an article on history of biology, but none yet on history of bacteriology. You might find the article historiography of science helpful in thinking about how to approach your problem, although it has nothing directly relevant in it. What you really need is the email address of a helpful librarian at an appropriate medical or university library at a facility where some of the research you're talking about was actually done, years ago. HTH. --arkuat (talk) 07:36, 9 June 2008 (UTC)

Asteroid

If we find a large asteroid heading for the earth, do we have the technology to make a gravitational tractor to save us? Bastard Soap (talk) 14:46, 5 June 2008 (UTC)

The article gravitational tractor mentions that a couple of guys have called it feasible. But, these guys are not exactly rocket scientists.. oh, wait. Friday (talk) 14:50, 5 June 2008 (UTC)

The largest unstated variable here is the amount of time. If you've got one year, no way. If you've got 25, perhaps. If you've got 50, almost assuredly. Note in particular that a grav tractor is slow-acting. Additionally, the mass of the asteroid is a concern -- the larger the asteroid, the less effective a grav tractor will be (and note also that for a sufficiently small asteroid, a Project Orion-style nuclear propulsion solution may be both faster and more easily accomplished). — Lomn 14:55, 5 June 2008 (UTC)

It would be unlikely for us to spot a planet smasher with 25-50 years notice. The percentage of the sky studied is very small. The financial allotment to such things just isn't enough to accurately forecast impact events. The Comet Shoemaker-Levy 9 was only spotted a few months before it impacted Jupiter. ScienceApe (talk) 18:57, 5 June 2008 (UTC)

That depends on the nature of the asteroid. Per our article on asteroid deflection, attention was recently paid to a potential 2029 encounter (21 years out). While that's been ruled out, orbital deflections raise the possibility of a 2036 encounter (28 years out). Further, (29075) 1950 DA is the solar system body with the highest presently known probability of impacting Earth, in 2880. Comets falling from the Oort Cloud and beyond -- no, we won't likely have 50 years' warning. Asteroids in the inner solar system? Utterly plausible. — Lomn 20:29, 5 June 2008 (UTC)

If it's soon, nuke it. If it's a while, paint one side white. Doable, WilyD 19:02, 5 June 2008 (UTC)

Painting one side white is my favourite solution - it has a certain elegance to it. Blowing things up is all well and good, but giving it a makeover has serious class. I'm not sure it's always an option, though - I believe it depends on the rotation of the body. --Tango (talk) 21:51, 5 June 2008 (UTC)

Shouldn't we also paint the other side black? -SandyJax (talk) 21:50, 5 June 2008 (UTC)

No need, a typical asteroid is pretty dark anyway (3-10% of light reflected), and most of the rest are still fairly dark (10-22%). --Tango (talk) 21:56, 5 June 2008 (UTC)

How does painting one side white help? Do only absorbed photons transfer momentum? Also how would you give it a make over exactly? Bastard Soap (talk) 07:37, 6 June 2008 (UTC)

Reflected photons transfer more momentum that aborbed photons - a perfectly reflective surface experiences twice the radiation pressure of a black body. The theory is the same as the principle of the solar sail; implementation details can be left to the engineers. However, the pressures involved are very smnall - about 10^-5 Pa at 1 AU from the sun according to this article. So, by my reckoning, radiation pressure on an asteroid with linear dimensions of the order of 1 km would generate an acceleration of around 10^-8 ms^-2, which would take years to significantly affect the asteroid's course. Also, the acceleration decreases in inverse proportion to the dimensions of the asteroid (because mass increases as the cube of the linear dimensions, but surface area only increases as the square) so the bigger the asteroid the less effective this method becomes. Gandalf61 (talk) 10:44, 6 June 2008 (UTC)

A large solar sail, robotically managed, could be tethered to an asteroid to provide far greater acceleration than merely painting one side white. If the asteroid is lose or crumbly, put a net around it and tether the sail to the net. An ion engine could be tethered to the asteroid instead, to provide small thrust over a long period. It does not take musc force to cause a miss years in the future. Bag it, move it, watch it sail by. Sayonara. Edison (talk) 13:54, 6 June 2008 (UTC)

I think the issue is in the definition of "significantly affect the asteroid's course". A very small change in course at one point in time can result in a very large chance of course years in the future, especially if the asteroid is going to pass close to another massive body (for example, the asteroid that's going to pass close to Earth in 2029 and then again in 2036 - a very slight change in its course before 2029 could result in a massive change in position by 2036, that's why we can't get a precise estimate of where it will be in 2036 until after the 2029 encounter, the slight errors get vastly magnified). --Tango (talk) 14:20, 6 June 2008 (UTC)

Yarkovsky effect WilyD 14:25, 6 June 2008 (UTC)

... which has shifted the trajectory of asteroid 6489 Golevka by only 15 km over the course of 12 years. I rest my case. Gandalf61 (talk) 15:05, 6 June 2008 (UTC)

Which is why if we don't have much time, we bust out the nukes. See my original comment - but also note that for a half black, half white asteroid, Yarkovsky is supercharged compared to the average colour difference across asteroids. If you have 50 or 100 years, it should work well. WilyD 15:13, 6 June 2008 (UTC)

If you do it far enough in advance, 15km could be plenty. --Tango (talk) 15:38, 6 June 2008 (UTC)

How exactly do you paint one side white? You send some paint bombs or something? Also how is it that reflected photons transfer more energy? And do reflected photons decrease in wavelength afterwards? Bastard Soap (talk) 19:15, 7 June 2008 (UTC)

Celluar Biology

Is it true that some part of the blood is a watery fluid, and floating in it is fluid are round particles. Is blood formed in globules with little color, but looking reddish? Where is the oxygen stored in the red blood cells? Are all the blood cells the same shape in humans, is there a difference between animal blood cells and human blood cells, is it true that human red blood cells have a nucleus? What is a cell nucleus, I don’t understand what they are. What is the structure of the cell’s nucleus? What is the hard, clear part near the front of the eye that looks like a piece of glass or crystal? How many nerves does a muscle have in it . why do the muscle in a cow have a striped look, that look like rings and wrinkles, but why to the fiberd How come when you scrape off a bit of chalk, breaking the chalk particles apart, how come they aren’t white at all, they are clear or transparent, like glass, but when they are together, how can they add up to white. What cells does mold send out to make new mold, How are they formed and releases. Is the water in lakes that have “little green clouds” Are the clouds made from dew, why do they look like “earthy particles” and some green streaks, each streak is about as thick as a human hair, coiling in spirals, like snakes. Here is a description: Many little animals…Some were roundish ….Others, a bit bigger,…(were) oval (egg-shaped). On these last I saw two little legs near the head….Two…fins (were) at the rear end of the body….These animalcules (little animals) had divers (different ) colors. Some …(were) whitish and transparent (clear) …Others (had) green and glittering …scales…The motion of these animalcules in the water was so swift, and so various…that it was wonderful to see. These creatures are a thousand times smaller than the smallest living thing I have seen so far. A tiny, spiderlike mite that lives on cheese. When I compared sizes, I speak of volume, not length. A cheese mite is smaller than the dot at the end of this sentence. A “little animal” was about one tenth as long as a cheese mite. Rain Water This water that has been observed has stayed in a pot for several days Observation: Sometimes stuck out two little horns…. (these) moved after the fashion of a horse’s ears. The part between these little horns was flat, their body else being roundish….it ran somewhat to a point at the hind end…. (At this) end it had a tail, near four times as long as the whole body.. these are the most wretched creatures that I have ever seen. I feels sorry for them because they seem to get their tails caught on things all the time. When this happens: They pulled their body out into an oval. . . . (They) struggle(d), by strongly stretching themselves, to get their tail loose….Their whole body then sprang back towards the end of the tail….Their tails then coiled up serpent-wise….This…stretching out and pulling together of the tail continued. Tiny, hairlike structures went all around the top of each creature bell-shaped body. These hair formed a circle. From single angles, the hairs at the ends of the circle look bunched together. These bunches are what I thought were horns ( I had had not seen the other hairs at all). I now know that these hairs stirred up the water. These animals attach themselves to water plants. I soaked pepper in water for three weeks. I wanted to make it soft. Then the larger pieces —Preceding unsigned comment added by 71.191.42.20 (talk) 15:23, 5 June 2008 (UTC)

Hmm, is this homework? Ζρς ι'β' ^¡hábleme! 15:33, 5 June 2008 (UTC)

Seems to be a bunch of incoherent babblings. Clarify the specific question you are asking. Jdrewitt (talk) 16:00, 5 June 2008 (UTC)

The text from "here is a description" on seems to be at least partly from Antonie van Leeuwenhoek. I think just the part before that is the actual question(s). Anonymous, try asking fewer questions at a time. --Allen (talk) 16:48, 5 June 2008 (UTC)

I count 19 separate questions, all of which could be answered by looking at blood, blood cells, cell (biology), cell nucleus, eye, muscle, chalk and clouds. D0762 (talk) 16:48, 5 June 2008 (UTC)

Brain

What is the result(or complication,s)of scatterd leigon's through out the light matter's of the brain?--216.37.249.110 (talk) 17:31, 5 June 2008 (UTC)

Scattered legions are typically indicitive of occupation by the Romans. Complications include widespread viticulture, use of Latin and Jupiter worship...... Seriously though, a useful article... here. Fribbler (talk) 18:24, 5 June 2008 (UTC)

No, no, the op did not ask for legions, they asked for leigons which might be like reading the tealeaves in geometric figures. SpinningSpark 19:09, 5 June 2008 (UTC)

Gentlewikipedians, it is considered bitey to poke fun at a questioner. To demonstrate the shred of sense of humor it takes to ridicule mispelling is not as good as demonstrating the intelligence it takes to figure out what it means and answer accordingly. We should also take pride in invariably exhibiting goodwill and a welcoming posture. And don't forget the roads. And the public baths. But really, don't bite. --Milkbreath (talk) 19:20, 5 June 2008 (UTC)

Aw, come on let us have a little fun ;-). Ζρς ι'β' ^¡hábleme! 19:48, 5 June 2008 (UTC)

I'm with Milkbreath on this one. If you want to have fun biting newcomers, do so with the ones that come here and write out their homework questions word for word (question numbers and all!). This is a serious question, it deserves a serious answer, regardless of an easily made spelling mistake. --Tango (talk) 21:26, 5 June 2008 (UTC)

True. Sorry OP! I did provide an answer in my response at least, though. :-) Fribbler (talk) 21:38, 5 June 2008 (UTC)

Sorry too, without Fribblers excuse. SpinningSpark 21:46, 5 June 2008 (UTC)

Wow, Tango, please calm down. I truly did not mean to offend anyone. I was only joking. Sorry, Ζρς ι'β' ^¡hábleme! 23:11, 5 June 2008 (UTC)

And to help the original poster avoid these hazing rituals in the future, the word meant was presumably lesions. Confusing Manifestation(Say hi!) 23:33, 5 June 2008 (UTC)

Isn't it a homework question?  :-} Julia Rossi (talk) 04:21, 6 June 2008 (UTC)

Right i'm going to be useful and provide a decent answer for the OP here. I presume you meant lesions, in which case it depends very much where the lesions are in the brain. There are far too many nerves which stimulate far too many different processes to give you a definitive answer but to see a good example, i'd see multiple sclerosis, probably the best known of all the lesion-related diseases (although it is autoimmune). Regards, CycloneNimrod ^talk?_contribs? 10:57, 6 June 2008 (UTC)

There are too many variables to predict what would happen: location, total volume of brain affected, lesion size, etc. But one very interesting phenomenon whereby the brain is injured by diffusely scattered lesions is called postperfusion syndrome, or "pump head". It has been proposed that cardiopulmonary bypass generates scores of tiny air emboli that travel to the brain and cause cell death, leading to subtle neurocognitive changes. --David Iberri (talk) 00:09, 8 June 2008 (UTC)

Possessions

Hi. I am watching an episode of Most Haunted. It showed a man being "possessed" by two different spirits in succession. I have witnessed with my own eyes what seemed to be a woman being possessed and, apparently, exorcised. Some reliable acquaintances of me have described similar incidents to me. Could there be any truth to such "possessions". If not, what is the scientific explanation? Thanks. ReluctantPhilosopher (talk) 18:28, 5 June 2008 (UTC)

There is no truth to "demonic possession". There are many possible explanations for the phenomena that have led to a belief in demonic possession, among which are ergotism, mental illness (including especially histrionic personality disorder and monomania), and fraud (where a charlatan and his accomplice simulate the event). Hoax for hoax' sake can't be ruled out, either. Mass hysteria, another name for fervent religious belief, can lead people to believe they've witnessed what they have in fact not. --Milkbreath (talk) 18:46, 5 June 2008 (UTC)

Take a look at this link [7].--Eriastrum (talk) 18:51, 5 June 2008 (UTC)

Also see Spirit possession. A lot of people believe in spirit possession... I don't personally, but it is an integral part of some religions, like Haitian Vodou. So to say there is no truth to it is akin to saying there is no God; in other words, it might be a statement beyond the scope of science as the field is generally understood. Also, besides actually believing in spirit possession, there is a third explanation besides mental illness and dishonesty. This third explanation is when one is raised in a culture that believes in routine spirit possession, even healthy people can have experiences that they interpret as spirit possession. --Allen (talk) 19:22, 5 June 2008 (UTC)

Ok, Milkbreath should probably have said "As far as science is concerned, there is no truth to demonic possession", but considering this is the science reference desk, he probably considered that implicit. Your third explanation is what, I think, he meant by mass hysteria. --Tango (talk) 21:22, 5 June 2008 (UTC)

Sorry; I don't think I was clear enough. I actually was assuming that Milkbreath meant "as far as science is concerned." My argument is that, as far as science (as commonly understood) is concerned, science has nothing to say about the truth or falsehood of spirit possession, because belief in possession doesn't necessarily entail any empirical claims. I know it could be argued either that belief in possession does entail empirical claims, and it can also be argued that science does have things to say about non-empirical claims. I just wanted to point out that those aren't the kinds of responses you typically get from scientists about religious claims. --Allen (talk) 22:16, 5 June 2008 (UTC)

(ec) I am not a scientist, so I have nothing to lose by telling the truth—no faculty, no students, no grant granters, no constituency, no book-buying public. There is no such thing as a demon. My mother could tell you that, and she's no scientist, either. She would add that there's no such thing as monsters under the bed. But some of us will not be comforted, I guess. --Milkbreath (talk) 22:40, 5 June 2008 (UTC)

(Remove indent) ...science has nothing to say about the truth or falsehood of spirit possession. I disagree. Science may well say that given all of Milkbreath's alternatives, the chances that possession is true are pretty much negligible. Zain Ebrahim (talk) 22:35, 5 June 2008 (UTC)

Science doesn't give absolute answers, it never has and it never will. The closest you get is whether or not there is significant evidence to support a theory, and in the case of demonic possession, there is no significant evidence to support it, so scientists will generally assume that it doesn't exist (unless they are specifically testing for it, of course). If there is demonic possession but it is in all ways indistinguishable for psychosis, then it isn't a scientific matter, and it is still accurate to say that, as far as science is concerned, there is no such thing (or, that it is just a form of psychosis). That's not saying there is no such thing, just that there is no empirical evidence to suggest that there is. --Tango (talk) 22:59, 5 June 2008 (UTC)

Perhaps another way of putting that is "if there is no way, even in theory, to tell the difference between psychosis and demonic possession, then there is no difference between the two and now we're just talking about which name we should give this phenomenon". For the moment, "psychosis" is the more suitable name so I guess it will stick until psychotic patients' heads start spinning around. --Sean 23:07, 5 June 2008 (UTC)

Don't all these arguments apply to God just as easily as to demons? Milkbreath, you're disclaiming a scientific perspective... but Zain, Tango, Sean, would you all be just as quick to say that, as far as science is concerned, there is no God? You'd have high-profile company, of course, in people like Christopher Hitchens... but I still think you'd be in the minority. --Allen (talk) 01:21, 6 June 2008 (UTC)

I am not making an argument. I am stating the obvious plainly. There is no such thing as a demon. --Milkbreath (talk) 01:36, 6 June 2008 (UTC)

I don`t see why any theory, regardless of whether God or demons are involved, cannot be tested using the scientific method. The principle of science (and of all academic disciplines) is, in brief, that an alleged phenomenon which cannot be proven convincingly is false. Thus, unless evidence that is more than 50% likely to be true is found supporting the existence of demons, one assumes demons are non-existant. The same concept applies to God; since there is no convincing reliable evidence that deities exist, they do not. One cannot simply read a book written thousands of years ago by unknown authors and consider it scientific proof. --Bowlhover (talk) 03:16, 6 June 2008 (UTC)

I'm a Christian and I consider myself a scientist too, but I keep the two very separate. "...that an alleged phenomenon which cannot be proven convincingly is false" is a bit ridiculous by any standpoint because even scientifically it doesn't make sense. In science there is no such thing as proof. Nothing is proven, at all. Nothing is disproven, at all. It just becomes overwhelming likely in either direction. If someone is looking for answers that science can't provide, religion can be the answer. On the other hand, religion clearly can't explain a lot of things and that's where human nature, and science, comes into it. But again this is just my opinion. Regards, CycloneNimrod ^talk?_contribs? 10:54, 6 June 2008 (UTC)

You're right, "proven" is the wrong word, "demonstrated" would be better. Science is about rational, logical explanations for things, and that requires empirical evidence. Religion is about faith, it's a completely different matter. People like religion because of a basic fear of the unknown. Science can't answer every question we want answered (yet, at least), so people look elsewhere for the answers. The answers aren't particularly meaningful, but people don't really care about that, they just want an answer, and anything will do. This is the science reference desk, however, so we're interested in the scientific point of view, and in that point of view there are no demons and no gods, since there is no empirical evidence for them. --Tango (talk) 14:15, 6 June 2008 (UTC)

My intention was to say "that an alleged phenomenon for which there is little convincing evidence..." Religion can indeed provide answers, but those answers are not based on evidence but on the blind belief called faith. --Bowlhover (talk) 02:58, 7 June 2008 (UTC)

All right, thanks fellas, your responses were really illuminating. However I don't think we have to lump the existence of God with probable hoaxes like possessions, that's a different concept which may take many meanings. Thanks again! ReluctantPhilosopher (talk) 09:17, 6 June 2008 (UTC)

Well, philosophically there is not too much difference. One religion's gods may well be another religions demons. Religions have evolved over time, and there is a lot of disagreement about which (if any) is right. On this I'm with Dawkins - why would one believe in one particular religion, but not into any of the other equally well supported (by evidence, not infrastructure, of course) ones? --Stephan Schulz (talk) 13:01, 7 June 2008 (UTC)

What I meant was one can have a religous view in which one believes in a higher spiritual truth or reality or power, but doesn't believe that the so called possessions are due to demons. For instance I consider accounts of possessions as superstitious and false but I still believe in (for very good philosophical reasons) in a higher truth which I endeavour to find out. And this higher truth doesn't have to be a "personal" good necessarily, nor a god of the gaps, but a real experience which solves the mystery of life. ReluctantPhilosopher (talk) 16:29, 7 June 2008 (UTC)

One should believe in one religion and consider all other religions bullshit because one has been grown in a culture that blindly believes in one religion and considers all other religions bullshit. I you think about it religion may be viewed as an organism which evolves and does anything it can to protect it's self. Bastard Soap (talk) 19:27, 7 June 2008 (UTC)

I think we might be getting a little off-topic... --Tango (talk) 20:29, 7 June 2008 (UTC)

Social-dependance on alcohol

People claim that smoking relieves stress but are wrong because the equilibrium that the brain strives to attain actually results in smokers being more stressed when not smoking, such that their averaged-stress level is no better than that of non-smokers. Can the same be said of people that drink to relieve inhibitions? Do the brain compensate and make them more nervous and dependent on alcohol? Why? ----Seans Potato Business 19:53, 5 June 2008 (UTC)

No. If memory serves, alcohol is a depressant and nicotine is a stimulant. Drinking really does relax you, even if you're not an alcoholic. --Tango (talk) 21:12, 5 June 2008 (UTC)

Alcohol addiction can lead to harsh withdrawal symptoms such as tremor, seizures, etc. This would be considered a stimulated state, though stress is probably not the right word. An alcoholic drinks alcohol because they are dependant, and need it to prevent the withdrawal symptoms. Most substance addictions lead to things like desensitization and downregulation of receptors, leading to physiological tolerance, so an increased dose is needed, until a point where the body is reliant on that substance for it to maintain properly. --Mark PEA (talk) 22:14, 5 June 2008 (UTC)

Of course, if you are an alcoholic, you'll be dependant on alcohol in much the same way a nicotine addict is dependant on nicotine and will get similar withdrawal symptoms. However, the question was about the fact that it's wrong to say smoking relaxes you, since it's actually just relieving withdrawal symptoms, and whether the same can be said for alcohol, which it can't. Alcohol relaxes you whether you are addicted to it, or not. --Tango (talk) 22:54, 5 June 2008 (UTC)

Withdrawal symptoms for alcohol can be quite severe, see Delirium tremens. No such thing for nicotine AFAIK. So no, withdrawal symptoms are definitely not similar. --Dr Dima (talk) 23:39, 5 June 2008 (UTC)

True. How about "and will similarly get withdrawal symptoms"? The symptoms themselves may not actually be the same, but the basic idea of withdrawal is a constant. --Tango (talk) 00:11, 6 June 2008 (UTC)

Drinking really does remove inhibitions. Mostly has to do with fear. Fear is an inhibitor. Drinking dulls the senses and the emotional aspects along with it. ScienceApe (talk) 01:24, 6 June 2008 (UTC)

That's kinda semantics though. The end result is ultimately a dampening of one's "inhibitions" through diminutive senses, in this case, fear. Wisdom89 _{(T / ^C)} 02:50, 6 June 2008 (UTC)

Maybe another factor for an alcohol-assissted confidence boost is that you could blame it should something goes wrong. You could say that, "well I made fool of myself on the party because of the alcohol maybe the host should have provided a less intoxicating drink".--Lenticel ^(talk) 03:53, 6 June 2008 (UTC)

Fear isn't a sense, it's an emotion. --Tango (talk) 14:07, 6 June 2008 (UTC)

Alcohol affects the parts of the brain that control judgment. Part of the ability to feel fear comes from the ability to perceive consequences. Alcohol lessens the ability to perceive consequences, and thus reduces fear and inhibitions. Also, as has been mentioned before, alcohol is a nifty excuse in our society (NOT speaking from personal experience!) for having behaved badly or stupidly, as long as you don't do it too often. "You slept with WHOM? Oh, I get it . . . you had a few too many." (Spoken with a condescendingly sympathetic smile.) 66.215.224.253 (talk) 20:05, 7 June 2008 (UTC)Aletheia —Preceding unsigned comment added by 66.215.224.253 (talk) 20:01, 7 June 2008 (UTC)

Inner workings of the package that Edge shaving gel comes in

If I remember correctly, as you use up a can of Edge shaving gel, the can feels like it is empty at the bottom and full at the top. This is different for most other similar packaged comsumer products - the liquid inside a normal can of shaving cream obviously sits at the bottom of the can. So, I have two questions:

• What exactly is going on inside the Edge can? Is there a pressurized balloon that expands pushing out product from the bottom to the top of the can?
• Can you think of any other types of products that are packaged in a similar way?

ike9898 (talk) 21:56, 5 June 2008 (UTC)

An alternative guess: the cream could be in a pressurised balloon (or other kind of container) which shrinks as it's used up, and is attached to the top on the can. --Tango (talk) 21:58, 5 June 2008 (UTC)

I see a few patents for "floating piston" designs. Essentially the bottom appears to be a pressurized compartment (injected via the black rubber valve after the can is gel-filled and sealed), separated by a rubberized disk from a top compartment containing the gel. Gas expands, pushes piston up, forces gel out the top. DMacks (talk) 06:08, 6 June 2008 (UTC)

From my experience working for Gilette which makes a similar shave gel...the 'gel' is actually inside a pouch that is, as the op said, attached to the top of the can. The remainder of the can is filled with a pressurized inert gas that squeezes out the gel when the button is pressed on the top, which establishes a pressure gradient allowing for the squeezing to take place. EagleFalconn (talk) 14:18, 6 June 2008 (UTC)

Can you speculate as to why such an unusual package is needed for this product? ike9898 (talk) 19:27, 6 June 2008 (UTC)

The common alternative for pressurize dispensing would be to have a siphon/dip tube going to the bottom of the container, with the gas "on top pushing down". That arrangement only works if the can is held vertically upright, however, whereas the squeezed-bag design works in any orientation. DMacks (talk) 19:50, 6 June 2008 (UTC)

Thanks, guys. ike9898 (talk) 20:26, 6 June 2008 (UTC)

Open access - self archiving

If someone self-archives their scientific papers, can they get a link on pubmed so people know that it's self-archived? Otherwise people have to cross their fingers and search, usually in vain, just in-case. ----Seans Potato Business 22:01, 5 June 2008 (UTC)

That's something to ask PubMed. If someone self-archives a scientific paper that wasn't published in any journal recognized by PubMed, then of course PubMed wouldn't link to it. On the other hand, if someone archives an article that is published in a recognized journal, if I were PubMed I wouldn't link to it. Links not under PubMed's control can become invalid, and maintaining a database of external links would be a nightmare. ~Amatulić (talk) 18:06, 6 June 2008 (UTC)

June 6

Ballpoint pen ink

I've noticed that the ink from many ballpoint pens-- as well as from cheap disposeable fountain pens-- has a reddish or coppery-brown sheen, regardless of the ink's color. However, this vanishes when the ink dries or sinks into the paper(although it remains visible on non-porous surfaces). What component of the ink causes this metallic appearance? 69.111.189.55 (talk) 02:12, 6 June 2008 (UTC)

Well, until a chemist comes by, I found a patent for the composition of ball point ink: "An oil-based ink composition for a ballpoint pen which comprises a colorant, a resin and a solvent [of an alcohol... blah blah)" doesn't tell us much, but Ink brings up iron oxide. So for my money, oil sheen and/or iron oxide something. Julia Rossi (talk) 09:22, 6 June 2008 (UTC)

Mmmh - might be formation of dye at the surface - ie the dye might be a surfactant - inks probably contain surfactants. Also when ink liquid evaporates some dye might come out of solution - a bit like the skin on a milk pudding or something.. When it dries all the different colours are 'in the same place' so you won't notice the effect. You knew that inks (black) are made from different colour dyes (red/green/blue etc) - not all but most.87.102.86.73 (talk) 20:10, 9 June 2008 (UTC)

Huge Problem

Up until just recently, I've had a huge problem. The temperature in my bedroom was 90 degrees Fahrenheit. (Only a slight exaggeration.) I finally broke down and got a window air conditioner, and while that solved the temperature problem, now I have another huge problem. Every five minutes (only a slight exaggeration), the AC, apparently, draws too much electricity. This causes my lights to dim, among other things. And now it's starting to effect other things. For example, it has caused my computer to turn off and restart right when I'm in the middle of things. Is there anything I can do (that won't get me electrocuted) to resolve this? Digger3000 (talk) 03:35, 6 June 2008 (UTC)

Ask an electrician for help to upgrade your power, or secondly add a small UPS to your computer, so that it can withstand the power sags. Graeme Bartlett (talk) 06:01, 6 June 2008 (UTC)

Household wiring is supposed to deliver a reasonably steady voltage even when a heavy load comes on. Your description makes me worry that some part of your wiring is actually defective and unable to pass the proper amount of current; or alternatively that your wiring is overloaded and the air conditioner should be blowing a fuse or tripping a circuit breaker, but it isn't because the wrong size fuse/breaker is in place. Either of those conditions could be a fire hazard. Obviously I'm not in a position to say if there is a real hazard, but I really think you need to get an electrician in and have this looked at. --Anonymous, 07:36 UTC, 2008-06-06.

Anonymous is right. You describe a dangerous situation. See "Overcurrent". --Milkbreath (talk) 10:31, 6 June 2008 (UTC)

From my limited knowledge, I believe air conditioners are usually installed by electricians because they draw more current than normal. They circumvent the normal wiring of the house, using stronger cables.59.100.206.238 (talk) 11:15, 6 June 2008 (UTC)

Not window air conditioners. Those are just big appliances with standard plugs. --98.217.8.46 (talk) 19:58, 9 June 2008 (UTC)

I figured you might suggest a UPS. But the thing is, I do have my computer plugged into a UPS. Even so, my computer has completely lost power a few times. Not every time the power sagged, but a few times. And even when the UPS does do its job, it beeps every time the power sagged. And as annoying as that is, it'll probably be even more annoying when my house is burning to the ground. Yeesh, I should probably get that checked out, soon. Do you think it would help at all if there were fewer things plugged in in my room? There's not really much I can unplug, but I could try it. Digger3000 (talk) 11:56, 6 June 2008 (UTC)

Yes, as a temporary measure before getting an electrician to check your wiring I would definitley do whatever I could to reduce the load. -- Q Chris (talk) 13:34, 6 June 2008 (UTC)

A qualified electrician could monitor the voltage at the air conditioner outlet and at the main panel to determine the quality of the incoming voltage and the voltage drop from the panel to the outlet. I do not recommend an amateur trying to measure/correct these possible electrical problems because electricity can kill you. Low voltage at the air conditioner outlet can cause the motor to draw more current to maintain its mechanical output to the airconditioner compressor. The additional current causes the voltage seen by the air conditioner to drop, in a vicious circle until the current is so high that a breaker trips or the air conditioner motor overheats and a thermal protective device in it cause it to trip offline to cool down. Then the cycle repeats. Blowing a fuse or tripping a circuit breaker at the house utility panel may occur. The causes may be multiple, and in combination: 1)A long run of small (#14) wire from the utility panel to the air conditioner outlet. (Helped by having an electrician run a #12 20 amp circuit from the panel to the outlet. Putting in a larger fuse would be idiotic, of course). 2)Use of an extension cord to run the AC (Try plugging it directly into an outlet) 3)The circuit may be loaded down with other loads, such as the computer you mentioned. (Remedy:Get the air conditioner on its own circuit). 4)The air conditioner might be defective, inefficient or too large. Try a different one of the same size if available. Try a high efficiency one with a higher energy efficiency rating, which should draw less current, or try a smaller air conditioner. 5)The service wires from the transformer to the house might be too small, resulting in too-low voltage when the building draws high current. This is a job for an electrician or the utility, depending on where you live. 6) There might be a loose neutral connection between the utility and the house or inside the house wiring. Symptoms might be some light getting brighter when the air conditioner circuit voltage drops. A job for an electrician and the utility. 7)The utility might be supplying low voltage, due to loose connections in the service wires, your transformer being too small, a heavily loaded circuit or to your being near the end of the circuit, or to a lack of capacitor banks, or to intentional voltage reductions (brown outs) or to poor voltage regulation at the substation or along the feeder. If this is diagnosed by actual measurements, complaints to the utility, or to your public officials if the utility won't correct their deficiency,might get corrective action. If you can report to the utility that an electrician has measures illegal low voltage for extended periods (over 1 minute) at the main panel with an accurate RMS volt meter, you could demand that the set a recording voltmeter at the meter, to confirm the finding, and that they then correct it. In many US locations 114 volts (5% below 120) is the minimum legal voltage at the electric meter. This allows the voltage to drop a bit in the house wiring and still be able to operate the air conditioner at the other end of the house. Edison (talk) 13:42, 6 June 2008 (UTC)

Here's your answer. But as a stop gap solution you might just try putting it at a colder setting to make it run longer. It's the compressor start-ups that draw the most current. Or let it cool the room first, then turn it off and cool yourself with a fan for a few hours. Fletcher (talk) 14:12, 6 June 2008 (UTC)

I agree with Edison that an easy short-term solution is to put the AC on a difference circuit. Even if your electricity was working correctly you'd be blowing fuses/tripping circuits with that arrangement as you describe it. You'll either need another circuit installed or need to run an extension cord to a difference one. --98.217.8.46 (talk) 19:58, 9 June 2008 (UTC)

Another Unknown Equation

In the spirit of the question above, what's the meaning of engie's "favourite" equation? --antilived^{T | C | G} 05:22, 6 June 2008 (UTC)

I don't know what it means, but it's not an equation (no equals sign). Algebraist 13:27, 6 June 2008 (UTC)

It is apparently an expression for the amount of light reflected from an object illuminated by several sources. It's used in ray tracing. [8] --Heron (talk) 20:18, 6 June 2008 (UTC)

Holographic projection...

i would like to know if there is a technology confirming to holographic projection such that the projection is not made on any solid or liquid medium as in the case of Musion's 'Eyeliner foil' —Preceding unsigned comment added by 61.17.218.119 (talk) 07:02, 6 June 2008 (UTC)

Yeast and brewing

Does anyone know how to balance this reaction? C12H22O11 = C2H5OH + CO2 All the reactions I can find use glucose. But when making beer, they don't use glucose, they use maltose. I can't work out how to balance it though.

Thanks, Wikiwikijimbob (talk) 12:23, 6 June 2008 (UTC)

Don't discount the possibility that you might need a water molecule on one side or the other - on a brief look it seems to balance similarly to glucose if you add a water molecule on the left hand side. Not sure, though, but it's worth checking. ~ mazca ^talk 13:03, 6 June 2008 (UTC)

I'm going to second and say that you're going to need a water molecule on the reactant side and also may have copied down the formula of the original carbohydrate wrong. Carbohydrates have a C:H:O ratio of 1:2:1. EagleFalconn (talk) 14:26, 6 June 2008 (UTC)

No, that's the correct formula of maltose. Algebraist 14:30, 6 June 2008 (UTC)

The C:H:O ratio of 1:2:1 is only true for monosaccharides, and only in its most narrow meaning (discounting e. g. deoxy sugars). Icek (talk) 18:10, 6 June 2008 (UTC)

Thanks, it's much appreciated. Wikiwikijimbob (talk) 19:27, 9 June 2008 (UTC)

effect of overly large stimulus

Assuming you have a way to bypass the senses, imagine you have a microphone, a mechanical tounge, an artificial nose and a camera attached directly to your brain. What would happen if you received 100000000dB,the full light u a supernova and any other overly large stimulus which would normally devastate your receptive organs? 193.188.46.64 (talk) 12:37, 6 June 2008 (UTC)

Your guess is as good as anyone elses, it is difficult to give definitive answers to such speculative questions. Jdrewitt (talk) 13:08, 6 June 2008 (UTC)

For any realistic artifical sensory apparatus, though, it will be devastated by such a stimulus, just as an unassisted human would be. Algebraist 13:23, 6 June 2008 (UTC)

And even if it wasn't, a proportional signal to your brain would probably involve sufficient current that brain damage would ensue. Not to mention the effects on the rest of your body of being close to a supernova or a 100,000,000db noise! ~ mazca ^talk 13:26, 6 June 2008 (UTC)

I think the question is assuming that the artificial sensory apparatus are robust enough to cope with the stimulus however large and it is purely asking how would the brain interpret the signal (not how the rest of the body will cope). It really depends on how the sensor communicates to the brain which is too speculative since such a technology does not exist. Jdrewitt (talk) 13:35, 6 June 2008 (UTC)

Does the OP realise that the dB scale is logarithmic, and a 10⁸dB noise would have energy immeasurably greater than that of the observable universe? Algebraist 13:47, 6 June 2008 (UTC)

(ec with algebraist)Just to put this in perspective, the entire output of the sun is around 638dBμ. Even the largest galaxies with 10¹² stars still output less than 1000dBμ. I doubt that the amount of power represented by 100,000,000dB could be generated in the entire universe. Exposed to that kind of output, you are going to have bigger worries than what your sensors are made of. Sensors, you, your brain, your planet and your galaxy are all going to be vapourised. SpinningSpark 13:50, 6 June 2008 (UTC)

I think the most serious problem is that it'll cause the gravitational collapse of the entire universe. Algebraist 14:04, 6 June 2008 (UTC)

To be charitable to the OP I think we should assume the energy is just larger than what a person would normally encounter (but not so large as to destroy the universe!), and that the subject's body is protected from it, so he experiences it only through the artificial sensors. Not being a neuroscientist I really can't say what would happen; however, it seems unlikely the brain can distinguish signals at levels that would kill the physical body. I would think there is an upper limit beyond which it makes no difference how strong it is; the brain will interpret it as extreme light, extreme noise, etc. The artificial sensors would have to progressively step-down the signal so as not to damage neurons. A brighter light would have to be stepped down further, resulting in no difference in perception. But i don't know what happens at that upper limit of stimulation -- would it provoke a fight-or-flight response, a panic attack, a seizure? Fletcher (talk) 14:56, 6 June 2008 (UTC)

They would be rather poorly designed sensors if they provided enough current to damage the brain, they would reach their maximum safe output levels and that would be it. You'd see nothing but white and hear probably nothing but a whoosing sound of all the matter traveling past or perhaps a banging noise from the shockwave, if the sensors were calibrated to normal human sight and hearing. If they were calibrated for optimum observation of a supernova, then you would see the supernova, the amount of energy that the sensors receive does not have to correlate to a larger amount of energy put into the brain. Brain-computer interface may be enlightening. -- Mad031683 (talk) 16:39, 6 June 2008 (UTC)

Higher intensity of sensory input causes higher frequency of neuron firing, but no change in the action potential. The frequency is limited by the time needed to restore the resting potential, at least a few milliseconds. Icek (talk) 18:04, 6 June 2008 (UTC)

While I don't think these directly answer the OPs question, they may be interested in visual prosthesis and neural prosthetics as they describe the current state of the art. SpinningSpark 16:58, 6 June 2008 (UTC)

I was indeed assuming that the sensors where robust enough, and I just typed in an insanely huge number to stress that no person could receive such a stimulus naturally. So assuming the electronic interface communicates using normal neurons the largest signal possible will be determined by the inactive time of neurons? I was mostly interested in how would the brain change to accomodate these stimulus. How does the brain change in response to normal stimulus? Bastard Soap (talk) 20:07, 7 June 2008 (UTC)

flowers

which part of the flower is the pollen & the egg cells produced? —Preceding unsigned comment added by 96.10.123.85 (talk) 14:17, 6 June 2008 (UTC)

Have you looked at flower and plant anatomy? Those might be good places to start. Friday (talk) 14:39, 6 June 2008 (UTC)

Hypothetical Suicide only

This question has been removed due to the possibly dangerous outcomes that could amount from any answers given. Not only could the answers be seen as morally fragile, but there may also be legal implications should anyone stumbling upon the page take action with what they've heard. For these reasons I have removed the question, should anyone disagree they can talk to me further on my talk page. My sincere apologies to the OP. Regards, CycloneNimrod ^talk?_contribs? 21:12, 6 June 2008 (UTC)

Diagnosticians

What do diagnosticians actually do and why are they necessary when there are plenty of doctors who are specialised in different fields of medicine? Thanks. Clover345 (talk) 17:48, 6 June 2008 (UTC)

There are consultants for every field indeed. But what if you don't know which consultant to refer a patient to? Many symptoms are vague: Malaise, lethargy, widespread pain.... A diagnostician specialises in signs and symptoms rather than any specific disease or organ system. In many ways general practitioners act as diagnosticians (especially in the UK and Ireland where you cannot see a consultant directly, only by GP referral). Fribbler (talk) 17:59, 6 June 2008 (UTC)

According to the entry on diagnostician, it's simply a generic term for someone who makes diagnoses, and that someone is most likely a doctor. ~Amatulić (talk) 18:02, 6 June 2008 (UTC)

Could an A&E consultant act as a diagnostician and are there diagnosticians other than GPs in the UK? Clover345 (talk) 18:11, 6 June 2008 (UTC)

An A+E doctor (any rank) is a good example of a diagnostician. As far as I know, here in Ireland (which usually means it's the same in the UK) there arn't any "diagnosticians" by title such as there are on House. Fribbler (talk) 18:19, 6 June 2008 (UTC)

Here in the U.S., "diagnostician" is a descriptive term, not a specialty.Scray (talk) 03:41, 7 June 2008 (UTC)

BACILLI MICROORGANISMS

1)HOW DOES IT LIVE?

2)WHERE DOES IT LIVE (ITS ENVIRONMENT)?

3)DOES IT THRIVE BEST ALONE OR WITH OTHER MEMBERS?

4)WHAT ASSISTS IN ITS EXISTANCE?

5)HOW DOES ONE BECOME INFECTED WITH IT?

6)(CHAIN INFECTION) HOW DO MICROORGANISMS CAUSE INFECTION AND HOW TO PREVENT ITS SPREAD?

Genisa (talk) 19:51, 6 June 2008 (UTC)

Mmmm. Tasty, tasty homework. Sorry, we won't answer these for you but we can point you in the direction. Unfortunately, I don't know enough about this topic. Regards, CycloneNimrod ^talk?_contribs? 20:11, 6 June 2008 (UTC)

No, we cannot really answer these for you. Besides, it'll be worth your while to do a little research. Allow me to point you in the direction of a great and very informative website. [9]. Wisdom89 _{(T / ^C)} 20:21, 6 June 2008 (UTC)

Largest molar mass

What known compound has the largest molar mass? 65.31.80.94 (talk) 20:49, 6 June 2008 (UTC)

Periodic table. Wisdom89 _{(T / ^C)} 20:50, 6 June 2008 (UTC)

He asked for a compound. That can't be determined solely from the periodic table, can it? Ζρς ι'β' ^¡hábleme! 21:04, 6 June 2008 (UTC)

Well excluding answers like macroscopic crystals and neutron stars, the answer is probably a protein. The largest one in the human body is Titin at nearly 3 million Dalton. Any advances? SpinningSpark 21:35, 6 June 2008 (UTC)

DNA. Dragons flight (talk) 22:18, 6 June 2008 (UTC)

Backelit or any other cross linked polymere or a piece of graphite a sio2 crystal ..... there are many possible canidates.--21:38, 6 June 2008 (UTC)

I think for the purposes of this challenge that we can exclude polymers, as crystals are also excluded and look for a compound with a well defined formula, and therefore molecular weight. Earlier here we were trying to identify the densest gas. Graeme Bartlett (talk) 22:54, 7 June 2008 (UTC)

Natural occurence of dry ice?

Does solid CO₂ occur naturally anywhere on Earth? At high pressures, for example? Or the at -89.2C (cf. sublimation point of CO₂ -78C), would CO₂ precipitate from the air?

Cheers!

Aaadddaaammm (talk) 22:08, 6 June 2008 (UTC)

I have heard that the small partial pressure of CO₂ means that only a tiny amount of Carbon Dioxide solidifies, even at extremely low temperatures, so any dry ice formed would be invisible. Can't remember where I heard/seen that, though. Fribbler (talk) 01:12, 7 June 2008 (UTC)

Probably not naturally, although there may occasionally be liquid carbon dioxide in Carbonatite volcanic eruptions which start from the mantle. After the sun dies however there should be carbon dioxide frost formed, if the earth survives. Graeme Bartlett (talk) 23:00, 7 June 2008 (UTC)

Even if the Earth survives, the atmosphere will probably be completely blown away, so there won't be any CO₂ to sublime. --Tango (talk) 10:42, 8 June 2008 (UTC)

This chart indicates a vapor pressure of about 0.02 bar = 2 kPa at 154 K. The atmospheric partial pressure is only about 38 Pa. So even at -119°C it wouldn't solidify, for the same reason that water doesn't condense as long as relative humidity is below 100%. Icek (talk) 21:22, 8 June 2008 (UTC)

June 7

Stones in trees in Yellowwood State Forest

Regarding the new Wikipedia article about Yellowwood State Forest, is it possible the stone simply sat down on saplings and waited for them to grow? --77.125.94.96 (talk) 01:17, 7 June 2008 (UTC)

That's impossible. If a large boulder was weighing down a sappling, there is no way it would have been able to not only grow, but be able to support the weight of the rock, especially if it was just starting to grow.--十八 01:43, 7 June 2008 (UTC)

In any case it seems to me that it's just as unlikely that the boulder walked over and sat on a sapling as it is that it climbed a fully grown tree by itself. SpinningSpark 00:59, 8 June 2008 (UTC)

Phobos (moon)

I have a book on Mars with me that says if Phobos survives the Roche limit and does not break up, the moon will blast a crater over 100km across on Mars. How is the crater's diameter calculated given the object's velocity and volume?--十八 01:45, 7 June 2008 (UTC)

Just to let you know, this smells a little bit like a homework question. But answering your question straightforwardly, I would imagine that the crater's diameter is calculated given the object's velocity and mass (not volume) based on the energy that would be delivered to the regolithic substrate, this latter mostly based on theory investigated by experiments conducted by curious physicists tossing projectiles into things that resemble the Martian regolith. --arkuat (talk) 09:21, 7 June 2008 (UTC)

The article Impact crater might help. SpinningSpark 10:12, 7 June 2008 (UTC)

[10] has some information, for Earth at least. --Fangz (talk) 11:20, 7 June 2008 (UTC)

Thanks, I found this site through the site you provided which works fine. Also, to answer Arkuat's speculation, it's not homework per say. I'm writing a research paper and I wanted to calculate which parameters would have to be taken into effect for the crater to be over 100 km in size, as stated in the book (as it just gave the figure, not the calculations, or even the parameters, involved).--十八 00:54, 8 June 2008 (UTC)

Sorry for my speculation, I ought to have edited it out before posting. arkuat (talk) 05:46, 8 June 2008 (UTC)

Hi. This simulator has impacts for other planets, but it's a bit oversimplicified, and uses Marvin Martian as its theme. Thanks. ~AH1^(TCU) 13:57, 7 June 2008 (UTC)

Threshing and winnowing?

In agriculture, what is the relationship between the activities of threshing and winnowing? What I mean is, are they:

• exclusive either-or activities, two different ways of accomplishing the same purpose (that is, if you thresh, you do not need to winnow, or if you winnow, you do not need to thresh) OR
• both required activities that do not accomplish the same purpose (and if this is the case, does threshing have to come before winnowing, or winnowing after threshing, or does the order not matter?)

—Lowellian (reply) 01:49, 7 June 2008 (UTC)

The latter (and the former). Threshing means bashing the grains to get the chaff (seed-coats, bran) off the grain (what later gets ground up into flour). Winnowing means throwing the resulting mixture (separated, but still mixed in a heap) into the wind or water, to make a bunch of chaff floating away on the wind or water, and a heap of grain sinking in the wind or water. I'm guessing the confusion arises from modern-tech agricultural combines that do both jobs with one vehicle. --arkuat (talk) 06:38, 7 June 2008 (UTC)

Hybrid car mileage

Why do hybrid cars get better gas mileage in city than highway tests, when no others do? NeonMerlin 02:20, 7 June 2008 (UTC)

On the highway, a major energy loss is to wind and road friction, losses not addressed by hybrid technology (and hybrid generate most of their electricity during braking, which doesn't happen much on the highway). In the city, energy loss is during braking and idling. Hybrids recovery energy during braking, and shut off the gas engine during idling. Perhaps others have more technical answers, but I think of it in terms of primary energy loss and how it can be recovered.Scray (talk) 03:20, 7 June 2008 (UTC)

Interesting answer. I had always assumed -- without giving the matter much thought, until now -- that it was simply that batteries can't make a car go 60 mph.

So, Scray and I are both interested in others' more technical answers! -- Danh, 70.59.116.253 (talk) 22:54, 7 June 2008 (UTC)

Scray basically is right, there is not much to add. Electric engines are highly efficient, but the energy ultimately has to come from the IC engine. If you need continuous high energy output, your IC engine will run either way. The primary advantage of the electric engine is in energy recovery during braking and idling. And yes, batteries can make a car go any reasonable speed - this just depends on the dimensions of the engine. The first few land speed records were all obtained with electric cars (although the fastest one was only 65 miles per hour). --Stephan Schulz (talk) 23:35, 7 June 2008 (UTC)

I was under the impression that a big part of the gain comes from using a smaller ICE. An ICE large enough to provide sufficient peak acceleration is inefficient when you're not accelerating; with a hybrid vehicle the electric motor provides extra acceleration and you can get away with a smaller ICE, which leads to better efficiency even on the highway. Someone else will have to say whether this makes sense, since I know nothing about cars, but Hybrid electric vehicle#Benefits seems to back it up. -- BenRG (talk) 23:47, 8 June 2008 (UTC)

A possible method for superluminal travel

I thought that if there is a warp in space, the area doesn't change, but the warp is curved. So, if anybody could travel straight forward in a warped area without being pulled to the center of gravity, the distance will be cut and superluminal travel may become possible. Can you please tell me is this method possible? Please reply!!! —Preceding unsigned comment added by Superwj5 (talk • contribs) 08:02, 7 June 2008 (UTC)

• Have you read the article on dark energy and especially the section on negative pressure yet? If not, I'm afraid you'll have to rephrase your question in simpler terms. --arkuat (talk) 09:11, 7 June 2008 (UTC)

• You might find the article Alcubierre drive interesting (but highly controversial) and also most the scientific papers cited in that article have links to online preprints. Another of our articles that you could look at is wormholes. SpinningSpark 10:20, 7 June 2008 (UTC)

• Much as I would like to have FTL travel (preferably in my lifetime), Einstein tells us that any form of superluminal communication will break causality - i.e. you can get next weeks lottery numbers today. Given that choice, I vote for a proper sequence of cause and effect.... --Stephan Schulz (talk) 13:41, 7 June 2008 (UTC)

  As long as you have local causality, things should be ok, and space warping techniques usually don't involve travelling faster than light locally, just faster from the perspective of the rest of the universe. Just losing global causality means what people usually call "time travel", is it really so bad to have a universe which allows for time travel? --Tango (talk) 13:34, 7 June 2008 (UTC)

  Yes! Nature abhors a time paradox... --Stephan Schulz (talk) 13:30, 7 June 2008 (UTC)

  Time travel doesn't necessarily involve paradoxes. --Tango (talk) 16:43, 7 June 2008 (UTC)

What you describe sounds similar to a possible method of time travel I read about (superluminal travel and time travel are very closely related) involving cosmic strings. I believe there were two orbiting each other and as you went round them in a particularly way, you got back to where you started from before you left. I don't remember the details, but it sounds vaguely like your idea. If wouldn't work with regular matter, it needs to be a cosmic string. --Tango (talk) 13:34, 7 June 2008 (UTC)

Many of these methods are summarized at Time travel# Time travel to the past in physics. Clarityfiend (talk) 18:54, 7 June 2008 (UTC)

Reduce voltage drop through a diode

I'm making a solar-powered microcontroller device using 5 0.47V 100mA max solar panels in series, feeding through a 7660 to double the voltage to power my IC (Atmel ATTiny13V) and my RF transmitter. According to the datasheet, I need 2 diodes in series from the 7660's output. That's 1.4V drop already, which is way too high for my purpose. I've switched to Schottky diode but that's still over half a volt lost. What are some ways to further reduce this loss? I've looked at synchronous rectification but have no idea what parts are available for drop in replacements for my diodes; I've also thought of using a transistor with the base and collector connected together, will that work? --antilived^{T | C | G} 08:50, 7 June 2008 (UTC)

Why do you have to use that device in particular? There are heaps of dc-dc converters out there for all kinds of different voltages. You would be better off selecting a device for the voltage you want to deliver, see for instance [11], rather than jump through hoops getting this one to do what you want. The one you have picked seems to be specifically for generating a negative rail from a positive one and can also co-incidentally do voltage doubling. Basically, it is not the best chip for the job. A quick Google search or a look through an electronics component catalogue will get you lots more to choose from. SpinningSpark 11:00, 7 June 2008 (UTC)

Availability is one thing, that device being instantly available is a huge plus. The one that you've linked to is a regulator not a voltage converter and therefore unsuitable for my use. Inverting voltage and doubling voltage are based on pretty much the same principle anyway so it's not unusual to see both functionalities on the same chip. --antilived^{T | C | G} 11:54, 7 June 2008 (UTC)

Actually, I think you will find that that device I pointed you to is a switching device rather than a linear regulator, it is just made to be pin compatible with linear regualtors of the 78xx series. However, your complaint is justified because it is step-down rather than the step-up you need. Sorry, my bad. Try this one [12]. I know inverting and doubling can be done with the same device, but neither of those things is what you really need. Availability - you are in New Zealand right? Try here [13]. SpinningSpark 13:59, 7 June 2008 (UTC)

No that's still not suitable for my use. My input voltage (from the solar cells) is only 2.35V max, and will almost certainly be lower than that during most of the day. I only need 20mA at the most so a device that can supply 2.5A is quite an overkill for me. --antilived^{T | C | G} 23:06, 7 June 2008 (UTC)

United States Of America

Q:When is the national blonde brownie day celebrated in the U.S —Preceding unsigned comment added by 117.194.193.239 (talk) 12:28, 7 June 2008 (UTC)

See here: Wikipedia:Reference desk/Miscellaneous#United States Of America - Copied over there as this is the science desk. Regards, CycloneNimrod ^talk?_contribs? 13:16, 7 June 2008 (UTC)

Cancer stage vs grade

Is there a difference between the terms grade and stage with respect to cancer classification? --Seans Potato Business 17:17, 7 June 2008 (UTC)

The stage refers to the invasive ability of the cancer. The grade refers to how similar the tumor is to the surrounding tissues. See Cancer#Classification. Regards, CycloneNimrod ^talk?_contribs? 17:48, 7 June 2008 (UTC)

I think some clarification might help: Stage is the degree to which the tumor has invaded, not its ability to invade (a very aggressive tumor, with high ability to invade, can be detected at an early stage, i.e. before it has actually done much invading). Grade is determined by comparison to benign (surrounding) tissue, but is actually the dissimilarity relative to normal tissue (high grade means very different from normal).Scray (talk) 20:08, 7 June 2008 (UTC)

Scray is correct. A common saying in pathology helps one keep the two straight: "grade the tumor, stage the patient". --David Iberri (talk) 00:00, 8 June 2008 (UTC)

Stopping earth quakes

We have articles on weather control and asteroid deflection, but are there any proposed methods on stopping earth quakes? Is it possible to do this? ScienceApe (talk) 17:33, 7 June 2008 (UTC)

It's really not feasible since we can't stop plates from colliding with each other. Regards, CycloneNimrod ^talk?_contribs? 17:49, 7 June 2008 (UTC)

We had a discussion of this last year. See Wikipedia:Reference desk/Archives/Science/2007 October 11#Controlling earthquakes by setting them off. Algebraist 18:59, 7 June 2008 (UTC)

Well, there's fiction about it: the novel A földrengések szigete by Fehér Klára. Also in fiction, the Little Prince regularly cleans his volcanos so they don't have violent eruptions. – b_jonas 09:52, 9 June 2008 (UTC)

I know of no proposals for stoppng earthquakes, short of waiting for the core of the planet to cool. However, stopping earthquake damage is straightforward: earthquakes do not kill, buildings do. —Preceding unsigned comment added by 67.131.66.162 (talk) 18:16, 9 June 2008 (UTC)

Indeed, we even have an article on that: earthquake engineering. – b_jonas 19:10, 10 June 2008 (UTC)

Phenylketonuria

I have todo a 15 page essay on Phenylketonuria, and i need alot of research from this site, do you know where i can find 15 PAGES of INFORMATION including, pictures, graphs and websites that my science class can visit

--Katiesorfleet (talk) 17:38, 7 June 2008 (UTC)katiesorfleet

Phenylketonuria is a good start. That's the only article we have on it, otherwise just use Google. Regards, CycloneNimrod ^talk?_contribs? 17:50, 7 June 2008 (UTC)

Specifically, look at the sources at the bottom of Phenylketonuria. Like any other encyclopedia, you should not be using Wikipedia as a research paper source; you should using to get a general overview of the subject. Paragon12321 (talk) 21:17, 7 June 2008 (UTC)

Why is LSD illegal?

? ScienceApe (talk) 19:07, 7 June 2008 (UTC)

Well, the risk of a bad trip comes to mind. For other reasons you might want to read about the effects in the LSD article. - Dammit (talk) 19:12, 7 June 2008 (UTC)

According to the DEA, because it has "a high potential for abuse and serve[s] no legitimate medical purpose" [14], Someguy1221 (talk) 19:14, 7 June 2008 (UTC)

So same as alcohol and tobacco right? ScienceApe (talk) 02:53, 8 June 2008 (UTC)

I agree on tobacco (no redeeming qualities) - if it came to market today it would never get approved (so I can only surmise it is vested interests including farm lobbies and addicts that sustain the business). Alcohol in moderation, however, appears to have some benefits like reducing heart disease. Scray (talk) 03:29, 8 June 2008 (UTC)

Meanwhile marijuana, which does have a legitimate medical use and less of a danger from abuse than alcohol, remains illegal. I'd agree it's all a matter of when it was introduced. Those drugs introduced early on were accepted while the latecomers are seen as dangerous: "Those damn kids with all their pot, it makes me so mad, now light my cigar and get me my whiskey !". StuRat (talk) 18:26, 8 June 2008 (UTC)

Marijuana's initial illegality had a lot more to do with keeping wood pulp prices up than it being considered dangerous. Matt Deres (talk) 02:02, 9 June 2008 (UTC)

(ec) Because legislators in whatever jurisdiction it is you're talking about have made it so. In many jurisdictions, this is required by the UN Convention on Psychotropic Substances (full text). The preamble to that treaty states that it was passed to safeguard public health. Presumably they were thinking of flashbacks and Hallucinogen persisting perception disorder. Algebraist 19:18, 7 June 2008 (UTC)

I wouldn't say tobacco has no redeeming qualities, since studies have shown that nicotine is good for the brain. Just that the risks tobacco introduces far outweighs the benefits. --Wirbelwindヴィルヴェルヴィント (talk) 02:56, 9 June 2008 (UTC)

Toothpaste toxicity (fluoride)

There's a warning label on every tube of fluoride toothpaste that states that the poison control center should be contacted in case more toothpaste is swallowed than is used for brushing. This is because fluoride, the active ingredient in most toothpaste designed for adults, is toxic and can cause acute sickness or death if taken in sufficient concentration. Of course, almost nothing is entirely safe (even drinking too much water too quickly can prove fatal), and warning labels are notoriously overcautious. We've all swallowed toothpaste now and then with no ill effects. How much toothpaste would have to be ingested in order to induce fatal fluoride toxicity in an average-sized (say, 170 lb.) adult? —Preceding unsigned comment added by 66.215.224.253 (talk) 19:51, 7 June 2008 (UTC)

Maybe you should read fluoride poisoning. Anyway, there's no warning label on my tube of fluoride toothpaste. --Heron (talk) 20:24, 7 June 2008 (UTC)

Looks as though the probable toxic dose is about 5 mg/kg (many sources). Given your example of a 77 kg (170 lb) adult, that would be about 385 g. Labels of toothpaste I see list fluoride ion content around 0.14% w/v (0.14 g/100 mL, or 1.4 g/L), so 385/1.4 = 275 L (35.75 gallons). That's a lot of toothpaste!Scray (talk) 20:32, 7 June 2008 (UTC)

So we're looking at the thirty to forty gallon range - wow. Thanks, Scray. I guess the warning label is decidedly overcautious after all. According to the toothpaste article, ingesting too much toothpaste can cause minor digestive upsets such as nausea and vomiting, so I suppose someone has ingested enough of it in the past to suffer some discomfort, but it isn't anything serious after all as the packaging would imply (and Huron, most brands do include such a warning label on the box the toothpaste comes in or on the tube itself, as the aforementioned article will confirm). Stupid warning labels. —Preceding unsigned comment added by 66.215.224.253 (talk) 20:57, 7 June 2008 (UTC)

Umm isn't it 385 mg, which is 0.385g? At that level it'd only take 275mL, or roughly 2 tubes of toothpaste to reach the toxic dosage. --antilived^{T | C | G} 23:33, 7 June 2008 (UTC)

Yes, I think you're right. However, our article says the lethal dose is about 70mg/kg, did Scray drop a 0? What are the many sources? Or does toxic dose differ from lethal dose? --Tango (talk) 01:08, 8 June 2008 (UTC)

My deep apologies - and thanks to 66.215.224.253 for catching my gross slip of the prefix (i.e. I jumped from mg to g). I should have said 385 mg (not g) of fluoride, which then equates to about 275 mL of toothpaste, or a little more than 2 "family size" toothpaste tubes as the toxic dose. The lethal dose, about 14 times that (5 vs 70 mg/kg) would be about 30 large tubes of toothpaste. So, spit don't swallow, and don't worry about the fluoride unless someone comes up with convincing evidence that lower doses are toxic.Scray (talk) 01:30, 8 June 2008 (UTC)

This is all, of course, assuming it would be a adult that ate the toothpaste, which seems highly unlikely. If it were a young toddler, the lethal dose would be much more feasible. Paragon12321 (talk) 04:24, 8 June 2008 (UTC)

Wouldn't it be just as unlikely for a toddler to swallow a propotional amount of toothpaste, say 3 large tubes, as for an adult to swallow 30 ? Also, wouldn't they get ill from things other than fluoride (like the artificial sweeteners) at lower quantities of toothpaste ? StuRat (talk) 18:18, 8 June 2008 (UTC)

Well, I checked the label and the box, and they do advise supervising children under 7 to "minimise swallowing". I took that to mean that adults can guzzle as much of the stuff as they want. Looks like I'll have to limit myself to 2 tubes a day in future. --Heron (talk) 17:40, 9 June 2008 (UTC)

There are other dangers to eating toothpaste and excessive fluoride other than death. If you eat toothpaste as a child you will develop dental fluorosis, which, while not at all life-threatening, is pretty lousy, and requires a lot of expensive dental work to correct. (So says someone who has a full upper set of veneers thanks to extreme fluorosis—$500 a tooth, to be replaced every 10 years or so, and an unpleasant procedure). --98.217.8.46 (talk) 01:33, 10 June 2008 (UTC)

applied sciences

Why is it that a physicist can become an engineer buu a biologist cannot become a doctor? —Preceding unsigned comment added by Clover345 (talk • contribs) 20:47, 7 June 2008 (UTC)

Biology is a very different job than medicine. There's a difference between knowing how a cell works and knowing what to do if something is wrong with it. Generally, no one dies if a biologist makes a mistake. Paragon12321 (talk) 21:15, 7 June 2008 (UTC)

There is a difference between theoretical knowledge and practical skills. A physicist knows the theory behind engineering, so can probably design a nice new bridge, say, but they couldn't pick up a welding torch and make it. Likewise, a (human) biologist knows all the theory about how the body works, but they can't just pick up a scalpel and start cutting bits out of it. Knowing the theory is a good start and would certainly help you in a related applied job, but there is more to learn before you can actually start doing it. --Tango (talk) 21:20, 7 June 2008 (UTC)

I agree with Tango, though I bet a lot of physicists would have some learning to do before they could design a bridge. But being trained in biology would still be a giant head start if you wanted to become a doctor. I went to a small college with no official premed program, so most aspiring doctors majored in biology. --Allen (talk) 21:25, 7 June 2008 (UTC)

A physicist would have to get more training in the laws of physics as they apply to the field of engineering or his particular field of engineering before he could be successful as an engineer, or at any rate, if he didn't know enough about the laws of physics as they applied to engineering, he couldn't become an engineer, period. Even if he impressed someone with his credentials, he wouldn't last long at the job. There's nothing to stop a biologist from becoming a doctor, if he goes on to study the principles of biology as they apply to the human body (arguably a greater narrowing than that from physics to engineering, requiring greater specialization; remember, biology is the study of all that is alive, from bacteria to plants to ecosystems, and the correlation between "knowing how it works" and "knowing how to fix it" is much less in biology than in physics). Furthermore, because doctors deal literally with matters of human life and death, it is required in most places that they go to medical school, get a license, etc. Anyone who wants to become a doctor has to meet those requirements, regardless of prior training. A biologist would doubtless have an easier time than someone from an non-life sciences background in some aspects of medical training, but it's still necessary to get training in the field in order to go into the field. Diagnosis, administration of medication, surgery, psychiatry, and bedside manner are aspects of the medical field with little or no parallel in the field of biology as a whole, and many of them are crucial for any doctor to know. In short, medicine is a very demanding specialty that requires much knowledge that biologists simply don't possess - unless they go on to study medicine. 66.215.224.253 (talk) 21:27, 7 June 2008 (UTC)Aletheia—Preceding unsigned comment added by 66.215.224.253 (talk) 21:27, 7 June 2008 (UTC)

Let's also not generalize all physics here. A theoretical physicist is going to have a lot less at hand knowledge than, say, a physicist who specializes in materials science, when it comes to going into engineering. String theory does not tell you much about how to build a bridge; even a fairly generalist physics education does not tell you much about the properties of materials, of specialized techniques, of technologies. --98.217.8.46 (talk) 19:10, 8 June 2008 (UTC)

One difference to consider is that biological organisms are so complex that you really can't predict things very well from first principles. You could have the complete genome of an organism and be utterly unable to predict how many eyes it's going to have or how to treat its diseases. Most human-made -- i.e. engineered -- things are simple enough that you can understand them from the ground up in a way that biologists and doctors might never be able to. --Sean 01:23, 9 June 2008 (UTC)

Synesthesia

Is there a type of Synesthesia involving smells? —Preceding unsigned comment added by 71.32.207.35 (talk) 23:13, 7 June 2008 (UTC)

This article mentions sound-odour synaesthesia. But it says that it's rare. Fribbler (talk) 23:50, 7 June 2008 (UTC)

I think its rarity can be explained in the context of the cross-activation hypothesis for the Neural basis of synesthesia, as the olfactory cortex in humans is relatively well isolated from other sensory cortex areas. --Dr Dima (talk) 06:26, 8 June 2008 (UTC)

June 8

Suppose that we discovered a large-ish asteroid on a collision course with the earth...

How close would it have to get to us before we could accurately calculate where the point of impact would be? --Kurt Shaped Box (talk) 01:46, 8 June 2008 (UTC)

Don't shoot until you can see the whites of their eyes. Hmm.. perhaps the point at which any changes in its speed or direction are found to be due mostly to the Earth's gravitational pull. The acceleration would theoretically have to be constant, or at least known at all times.--Russoc4 (talk) 01:53, 8 June 2008 (UTC)

Modelling orbits is mostly about having a large number of observations over a long time. Think of it this way. If an object is moving at a typical orbital speed of ~20 km/s, then a 1 m/s variation in that speed would lead to a change in the expected location of 150,000 km over 5 years, which would be a very noticable range of variation. If you have a long enough period of observations, you can be very precise about future orbital positions. For example 99942 Apophis, which will make a close approach in 2036, has it's predicted distance to Earth at that time nailed down to 3381 +/- 8 km (1-sigma). Dragons flight (talk) 02:44, 8 June 2008 (UTC)

Hi. 1950 DA, for example, has a roughly 1-in-300 chance of colliding with Earth in the 2800's, and we've calculated that the Earth's Atlantic Ocean faces the asteroid on its near pass/possible collision date. We don't know its exact chances yet, but we have observed its rotation enough to know this. Hope this helps. Thanks. ~AH1^(TCU) 16:49, 8 June 2008 (UTC)

Looking into the past

moved from talk page

If when we look towards the center of the Universe, we are looking billions of years into the past how is it, the Earth traveled to the distance it is now from the center of the Universe before the light from billions of years ago?

Did the matter that made up the Earth and the rest of the planets materialize in place?

Or did we actually travel faster than the speed of light?

Please excuse grammar and spelling.—Preceding unsigned comment added by 97.89.59.10 (talk) 01:29, 8 June 2008 (UTC)

Well we're obviously not anymore if we can see it. Not sure how that happened though. Probably we were quite close to those stars a looong time ago and space has been expanding at nearly the speed of light or something, so the light has been sloooowly catching up to us. So by the time it finally finishes its 1-inch trip by overtaking us, it's already billions of years old. I don't know, sounds wrong? --.froth. (talk) 03:32, 8 June 2008 (UTC)

There is no centre of the universe. When we say the universe is expanding, we don't mean it's all moving out from a centre, it's more like blowing up a balloon. The 2D rubber surface (ignore the fact that it's contained in 3D space, just think about the rubber) doesn't have a centre, each bit is stretching as you blow it up. If you draw some dots on it before you start you'll see those dots get further and further apart, but they never actually move, it's just the rubber inbetween them gets bigger. When all the matter was created shortly after the big bang, it filled the whole universe and has been spreading out as the universe expands ever since. This means bits of matter can be very far apart without having to have actually moved at all. --Tango (talk) 10:35, 8 June 2008 (UTC)

<----> Ok, even if there is not a center of the Universe, Which I’m not sure is true.

In order to look back in time and space to the Big Bang,

Would we have had to travel faster than the light in order to arrive here first in order to see it?

Is it possible the matter that makes us up arrived here before the light that was emitted from the Big Bang arrived.

could that be possible unless we actually traveled faster than that light, right?

I mean according to the rules; matter can not travel faster than light, so the light that was emitted then would have been at this point in time/space way before we arrived at this point in time/space right?

Please help me understand the logic.

Again please excuse grammar and spelling

<------>

See inflation (cosmology). Yes, the universe grew faster than the speed of light for a microscopic fraction of a second during the Big Bang. As a result, we are only now seeing light from matter we were next to previously (though at that time, none of the current matter had yet condensed). It is also worth noting that the cosmic microwave background, i.e. the "light of the big bang" actually was created ~3 minutes after the "bang", so that light comes from after we were seperated. Also see: Timeline of the Big Bang. Dragons flight (talk) 21:10, 8 June 2008 (UTC)

It's not true that the universe expanded faster than light during the inflationary epoch. Depending on how you define "expanding faster than light", either the universe never expands faster than light or it always expands faster than light; there's no definition that singles out the inflationary epoch. -- BenRG (talk) 23:27, 8 June 2008 (UTC)

(ec) The ideas of expansion of space, seeing "old photons" that are only now arriving to us, etc. comes up fairly often on the Science Ref-Desk. Here's a recent discussion focussing on how things can be further away than conventional "object at speed-of-light" would suggest: Wikipedia:Reference desk/Archives/Science/2008 March 26#Faster than light/Big Bang question. Not a direct answer to your question (which I don't fully understand), but something that may clarify some general/related ideas. DMacks (talk) 21:18, 8 June 2008 (UTC)

Actually, the CMB was released about 400,000 years after the big bang. You were close. ;) --Tango (talk) 21:33, 8 June 2008 (UTC)

The photon epoch begins at 3 minutes, the last scattering event (and end of equilibrium) came a few hundred thousand years later, but I think arguing that point is splitting hairs about what you mean by light created by the big bang. Dragons flight (talk) 21:49, 8 June 2008 (UTC)

We can see light from the early universe because the universe is homogeneous. The primordial fireball that emitted the light filled the whole universe, and the light that it emitted also filled the universe, and it still does, there being nowhere else for it to go. Cosmic inflation is the currently favored explanation for the homogeneity, but there's too little evidence at this point to say whether it's correct. -- BenRG (talk) 23:27, 8 June 2008 (UTC)

This is weird, and maybe I'm reading things wrong, but I believe you're all answering a question that wasn't asked and possibly even explaining them wrong...the way I'm reading the OP's question is "Why can we see into the past by looking at light from far away objects?" The answer is: Because the speed of light is finite instead of infinite. An easier example to understand is sound and the echo effect. When you shout at a large cliff, there is a delay between when your voice is projected and when it comes back as an echo. That time delay is due to the finite speed of sound. In fact, if you knew the speed of sound and the distance to that cliff you could calculate how long it took for your voice to get there (or knowing time you could calculate distance). In the same way, because we can determine the distance to the star using astronomical observation techniques, and knowing the speed of light and the fact that it is constant in the universe, we can determine how long ago the star emitted that light. EagleFalconn (talk) 14:13, 9 June 2008 (UTC)

Lunar Module Ascent Stage

A rocket launch on Earth is a jarring event even for a spectator. The sound and the fury of getting even a modest payload to Earth orbit is simply awesome. The scales involved seem overwhelming.

Why is it that a Lunar Module's Ascent Stage taking off for lunar orbit ( youtube link[15]) seems like such a walk in the park? It's not hundreds of feet tall, just 12. It only weighs as much as 5-10 cars. No ground crew required, no days sitting on a launch pad prepping. No drama whatsoever. Shouldn't the theatrics be 1/6th as much as they are on Earth? Sappysap (talk) 02:51, 8 June 2008 (UTC)

Well, it was just a vehicle to get the astronauts up into orbit (a few hundred miles?), not all the way to the Moon, so they didn't need much life support equipment. It also didn't have to overcome our stronger gravity, plus there was no air resistance or weather to worry about. For all these reasons, it didn't have to be as humongous as the Saturn V. Besides, who says there wasn't a lot of prep work anyway? Clarityfiend (talk) 03:25, 8 June 2008 (UTC)

It's not strictly proportional because you also need more fuel to lift the additional fuel, and more fuel to lift that extra fuel, ad infinitum. So, the higher the force of gravity, the larger percentage of the rocket that must be fuel. A chemical fuel rocket would hit some limit where it could never even achieve orbit from a planet with gravity above a certain level. (I wonder what that point would be ?). StuRat (talk) 14:16, 8 June 2008 (UTC)

Let's do some math to illustrate my point. If we say some type of fuel has enough energy so 10 lbs of fuel can lift 100 lbs of cargo into lunar orbit from the Moon, we would then need 60 lbs of fuel to lift that cargo into Earth orbit from the Earth, before we take into account the fuel needed to lift the fuel. Now, the 10 lbs of fuel would require 1 lb of fuel to lift, and that 1 lb would require 0.1 lb of fuel, for a total fuel weight of 11.1111... The 60 lbs of fuel would require 36 lbs to lift and that would require 21.6 lbs, etc., for a total fuel weight of 150 lbs. Note that the ratio between 150 lbs of fuel and 11.1111... lbs is 13.5:1, far more than the 6:1 ratio of gravity. This effect gets even worse when using fuels with less energy to mass.

So, we have the following reasons so far:

1) This "compounding effect" of fuel weight.

2) Only going to orbit versus escape velocity.

3) Air resistance.

4) The much lighter payload. StuRat (talk) 14:34, 8 June 2008 (UTC)

Don't forget the other implications of having no air resistance on the Moon. The lander is not required to have an cylindral, aerodynamic shape, so it doesn't need to be supported prior to launch while on the platform. Tail fins and other stablization systems are also not needed. On Earth, a rocket's exterior must be at least strong enough to withstand the air pressing on it. I'm not sure whether the casing adds significant weight to the craft, but no such strong structure is required on the Moon. --Bowlhover (talk) 15:59, 8 June 2008 (UTC)

Energy to orbit (neglecting air resistance) in terms of the central mass, M, radius of the object, R, and altitude to orbit, h, is approximately proportional to $M{R+h \over Rh}$. The mass of the moon is 7×10²² kg, versus 6×10²⁴ kg for the Earth. The radius of the Earth is 6370 km, versus 1740 km for the moon. And lastly you need ~180 km altitude to clear the Earth's atmosphere, versus only 20 km for the moon (to clear the mountains, though Apollo actually used 100 km).

Equating terms, you can see that for a given orbiter mass in order to get to orbit the moon you need only 1% as much energy as you do to orbit the Earth, mostly due to the Moon's greatly reduced mass. Since energy is basically proportional to fuel, you can do with far less fuel on the moon than on the Earth. And that's before considering air resistance, booster weight, and everything else one needs at Earth that you don't need at the moon. Dragons flight (talk) 17:17, 8 June 2008 (UTC)

That doesn't seem right; you should get 0, not infinite, energy as $h\rightarrow 0$. Just comparing the gravitational potential energy at R and $R+h$ gives me ${\frac {Mh}{R(R+h)}}$, giving 1.8% as much for the Moon/20km as for the Earth; is that what you meant? --Tardis (talk) 17:10, 9 June 2008 (UTC)

help please

hello great brains!!! i am trying to prove reflection of electromagnetic waves from metallic surfaces using basic principle of physics.does any one knows that is the proof going to be unique or it has been already done.actually i am trying to provide a firm reason for reflection of electromagnetic waves,in opposition to hypothetical proof provided by hugens.kindly help me that to which university would entertain such proofs.such that it gets recognized.

Reveal.mystery (talk) 2nd year Mechancal Engineering student India. —Preceding unsigned comment added by Reveal.mystery (talk • contribs) 03:34, 8 June 2008 (UTC)

I'm sorry but I don't understand the question. What are the "basic principles of physics" you're starting from? Maxwell's equations? Quantum electrodynamics? String theory? In at least the first two cases it's already been done. Why do you want to do this? —Keenan Pepper 04:00, 8 June 2008 (UTC)

I think what Reveal.mystery really asks is, "why does Huygens–Fresnel principle hold for the electromagnetic waves, and what fundamental principles of modern physics does it follow from?". Well, as Keenan said, if Maxwell equations are basic enough then, yes, it follows from them almost trivially. Simply assume the incident perturbation in electromagnetic field to be a harmonic plane wave (see equation in article if unsure what it is), and solve either numerically or analytically, whichever you like best. Play with shapes of obstacles and their dielectric constant to get the feeling for how the waves interact with surfaces and edges; this is not always easy analytically, so I would recommend using MATLAB. Now, on the other hand, if you are asking where Maxwell equations are coming from, then things really become much more complicated. First and foremost, there is a chicken and egg relation between special relativity and classical electromagnetism. And I really suggest you look no further than that at least until you are well familiar with the latter two. Hope this helps. --Dr Dima (talk) 06:09, 8 June 2008 (UTC)

I have moved the following new question here as it appears to be a continuation of this question. SpinningSpark 12:47, 8 June 2008 (UTC)

many many thanks to active wikipedists for their support. let me explain what actually i tried for: considering the wave nature of em waves i considered the interaction of the magnetic component of the wave with the metallic surface.now further on by applying lenzs law i propose the generation of an opposite directioned current in the plate.the interaction of the orginal and the field generated by lenzs law finally proves my point.

please helpme so that i may further more proceed in this area.basically i require it to be recognized by some university professor or any journal.since the subject dosent pertains to my branch ,such recognition would help me in my resume for my gre(M tech) interview.

Reveal.mystery (talk) 2nd year,Mechanical Engineering student (email removed per Ref Desk guidelines) india —Preceding unsigned comment added by Reveal.mystery (talk • contribs) 12:38, 8 June 2008 (UTC)

See Heinrich Hertz. He did the experiment you describe in 1886 and showed that electromagnetic waves can be reflected. You could experiment with it using a small dipole transmitting antenna, receiving antenna, and a transmitter and receiver, with a means of measuring signal strength, perhaps by measuring the AVC voltage in the receiver. I have read of physics demonstrations using the RF output (often US channel 3) from a video cassette recorder, with a small dipole antenna, and the same channel input on a TV receiver connected to a similar antenna. See [16] , [17] , [18]. Edison (talk) 19:28, 9 June 2008 (UTC)

I had to this as homework early last decade. To solve the Maxwell's equation you have to put on a few extra constraints, such as no electric field parallel to the surface of the plate. Electric charge can only travel on the surface of the plate. Lens's Law is already included in the Maxwell's equations. Graeme Bartlett (talk) 21:34, 9 June 2008 (UTC)

Cancer screening

Does cancer screening refer only to the search for extant disease, and not individuals at risk from disease but that don't actually have it or can the term be used to encompass both? From my brief search it seems that the term is used to cover the search for existing disease only (even if in the early stages) so the ability to predict development of disease may not be inferred from the term. ----Seans Potato Business 11:26, 8 June 2008 (UTC)

You screen only for actual conditions, not for predispositions. If, for example, one tests a population for a gene that predisposes to cancer (say BRCA1), you're screening for the gene, not for cancer. - Nunh-huh 11:52, 8 June 2008 (UTC)

I think you're being too strict about the usage of "screening". In the US, pregnant women are routinely given prenatal screening for certain conditions of the fetus (such as Down's syndrome and spina bifidia). The screening detects elevated risks associated with certain conditions but does not give definitive diagnoses. In fact, the article on triple screen says:

The test is for screening, not for diagnosis,[4] and does not have nearly the same predictive power of amniocentesis or chorionic villus sampling.

--71.162.233.218 (talk) 13:46, 8 June 2008 (UTC)

Not too strict at all, they are screening for conditions that actually exist - but with imperfect tests. Nearly all screening tests need followup tests for diagnosis, because by their very nature, screening tests will have false positives. - Nunh-huh 03:01, 9 June 2008 (UTC)

Weather forecast

I'm not happy with current forecasts. I'd also like:

1) The predicted time of the highs and lows, and better yet a graph of predicted temps throughout the day.

2) A humidity forecast in a form similar to that listed above.

3) A wind speed forecast similar to that listed above.

Does anybody know where I can get such data ? StuRat (talk) 12:36, 8 June 2008 (UTC)

It might help if you said where you are (ie which country). And also what you are currently looking at. SpinningSpark 13:28, 8 June 2008 (UTC)

I'm in the US (Detroit) and use an Internet site for ad-free weather: [[19]]. I also can get forecasts for the temps every 3 hours or so from digital TV station 4-2, but only for the current day. StuRat (talk) 13:49, 8 June 2008 (UTC)

Have you looked at the NOAA site for your area[20] ? I didn't check if it meets all your spec but its a lot more than what you have already. Here's the link to their front page in case I got your local area wrong [21]. SpinningSpark 14:34, 8 June 2008 (UTC)

That works. I found their "tabular forecast" is what I want: [22]. Thanks ! StuRat (talk) 14:45, 8 June 2008 (UTC)

Hi. I live in Canada, and I can find a way to get all three. Here, The Weather Network[23] gives us hourly forecasts. As for hourly humidity and wind forecasts, The Weather Network gives us that every quarter part of the day, but I can also get it at Cleardarksky, although the measurements are vague. Hope this helps. Thanks. ~AH1^(TCU) 16:53, 8 June 2008 (UTC)

Thanks for the answers so far. Does anyone know of a weather forecast given as a graph ? StuRat (talk) 12:48, 9 June 2008 (UTC)

You've already tried the hourly weather graph tab[24] on the NOAA site right? What is missing there that you need? SpinningSpark 19:37, 9 June 2008 (UTC)

No, I hadn't found the graphs, only the tables. That looks good, except that it's for Detroit, Illinois instead of Detroit, Michigan, and I'm not sure how to change the city. StuRat (talk) 03:15, 10 June 2008 (UTC)

Ok, I figured out how to change the city, but, geez, that site's a real bi*** to navigate, isn't it ? I expected to be able to just pick on "Detroit IL" and type in "Detroit MI", but it's never that simple, is it ? StuRat (talk) 03:49, 10 June 2008 (UTC)

Wing layout

Why do most planes have only two wings?

Why layouts with double or three wings on each aren't more common?

And what about having a set of short wings stapled - not broader as the plane - over each other until the plane gets enough drag to fly? GoingOnTracks (talk) 12:53, 8 June 2008 (UTC)

See Biplane#Advantages and drawbacks to biplane designs. Xn4 13:31, 8 June 2008 (UTC)

We don't seem to have anything explaining the unpopularity of tandem wing designs, though. Algebraist 13:32, 8 June 2008 (UTC)

The unpopularity of tandem wing might be explained by its increased stability, which surprisingly, is not always desirable. Certainly for fighter aircraft, maneuverability is king and stability and maneuverability are mutually exclusive. Also, if sufficient stability can be achieved by other means (high mounted wings, dihedral etc) why go to the expense of additional wings. Also some large commercial aircraft (eg Boeing 747) achieve distributed CL (the reason for tandem wings increased stability) by means of the lifting body effect. SpinningSpark 14:05, 8 June 2008 (UTC)

Just one more point, the designer of the aircraft (Rutan Quickie) in the picture in the tandem wing article says he designed it that way so that it resembled the Stars Wars X wing starfighter. Probably not a lot of call for that outside of the kit plane market. SpinningSpark 14:17, 8 June 2008 (UTC)

One big factor seems to be the speed of aircraft. More wings means more lift but also more drag, both of which also increase with speed. Early planes went quite slowly, so needed all the lift they could get, and drag wasn't much of an issue. Current planes are much faster, so getting sufficient lift is possible from fewer wings, while keeping drag low is also more of an issue. StuRat (talk) 14:09, 8 June 2008 (UTC)

Excessive numbers of wings were included in some very early plane designs like the Phillips Multiplane [25] but triplanes are gone now, biplanes rares. Some canards seem like second sets of wings (Beechcraft Starship). Rmhermen (talk) 18:12, 8 June 2008 (UTC)

StuRat has it right - it's to do with drag (and mass). A single main lifting wing is usually the most efficient design to achieve a given lift with minimal weight and drag. In addition, the calculations required to design a multi-wing plane are much more complex, since there is a lot of interaction going on between the various wings (see the canard article for some of the trade-offs of using canards), so it's easier to optimise a one-wing design. — QuantumEleven 15:29, 10 June 2008 (UTC)

How do astronauts commit suicide?

Do they have some sort of suicide pill? Or are they expected to "sink" with the "ship"? —Preceding unsigned comment added by 88.6.118.85 (talk) 17:30, 8 June 2008 (UTC)

We are not a crystal ball - no astronaut has committed suicide in space yet. In fact, only three people have died while in space, the crew of Soyuz 11 due to a malfunctioning vent. (See also space accidents and incidents) While on Earth they have access to any suicide technique the rest of us do. Rmhermen (talk) 17:57, 8 June 2008 (UTC)

I think the original poster was asking about a situation where astronauts were stranded with no hope of rescue—would they be provided with means to commit suicide in lieu of 'waiting it out'? Obviously it hasn't happened yet, but it doesn't mean that no one has planned for it.

To reply to the question, as far as I can discern there is no record of NASA astronauts carrying suicide pills, nor is it likely that Soviet astronauts carried them. (Links to Q&A with shuttle crew, reference to Jim Lovell's book on the Apollo 13 mission.) Several astronauts and commentators note that there's no need to carry suicide pills on a space mission—venting the air from the capsule will do the job quite nicely, and loss of consciousness will occur in about fifteen seconds. TenOfAllTrades(talk) 18:09, 8 June 2008 (UTC)

The first person to perform a spacewalk, Leonov aboard Voskhod 2, secretly carried a suicide pill in case he had been unable to enter the spacecraft and had to be cut loose. --Bowlhover (talk) 18:50, 8 June 2008 (UTC)

Nonsense! How would he take the pill, considering he had a bloody big helmet on?--ChokinBako (talk) 11:30, 10 June 2008 (UTC)

But is venting the air painless? How quickly can it be done? I doubt there's a "vent the air" button on the control panel. Wouldn't that be equivalent to a self destruct button? What if your buddies don't want to die with you? I think the original poster may have gotten the idea of a suicide pill from the movie Contact based on the novel by Carl Sagan. In it, Jodie Foster's character is given a suicide pill before she goes into the machine to take her to make contact with aliens. She is told that the pill has been given out to astronauts ever since the space program began, but it was never made public. She was told that the pill can be useful if she's stuck somewhere with no way to get back home, or trapped. Faced with the possibility of a slow painful death, the pill would put her out of her misery quickly and painlessly. She was also told that the pill is for all the reasons that they "could not think of". ScienceApe (talk) 18:53, 8 June 2008 (UTC)

That's fiction of course (rather a long drawn out one as I recall). I'd be more interested to know just how Leonov intended to administer his pill during the speacewalk given that's he'd be wearing his spacesuit.--Shantavira|^{feed me} 19:15, 8 June 2008 (UTC)

Nope, not drawn out at all. It was a very good movie. ScienceApe (talk) 02:45, 9 June 2008 (UTC)

Couldn't you just like take off your space helmet outside and suffocate?-- —Preceding unsigned comment added by Crystal eyes17 (talk • contribs) 20:59, 8 June 2008 (UTC)

I don't know about the Russian space program, but NASA spacesuits are designed in a way that the wearer can't possibly reach all the latches necessary to remove the helmet, and the assistance of a second astronaut is simply required to get out of it. Dragons flight (talk) 21:04, 8 June 2008 (UTC)

And even if you could get it off, the pressure would kill you before you suffocate since your blood (and all other fluids) would literally boil in the zero pressure of space.--十八 08:27, 9 June 2008 (UTC)

Well boil yes, but not "completely and instantly boil away" and not "astronaut swells up and explodes like in the cartoons":) Actually, the injury/death mechanisms don't seem related to the fluid-boiling issue at all See Vacuum#Effects on humans and animals for more info. DMacks (talk) 08:39, 9 June 2008 (UTC)

There's zero pressure outside your body, but inside, where the fluids are, there is still pressure supplied by your body. Assuming you don't try and hold your breath, which could result in your lungs exploding, death is usually by suffocation and if very quick (about 15 seconds to lose conciousness) - the vacuum almost "sucks" the oxygen out of your blood. --Tango (talk) 14:54, 9 June 2008 (UTC)

I'm pretty sure I heard of one instance where NASA astronauts were accidently subjected to a vacuum during training. I believe they passed out within 15 seconds before realizing anything was amiss, and without lasting injury. Someone may correct me if I'm wrong. Paul Davidson (talk) 13:50, 10 June 2008 (UTC)

I think they knew something was amiss. If memory serves, they reported their last memory before losing conciousness was of the saliva on their tongue boiling. Otherwise, you're right, they repressurised the room pretty quickly and the subject regained conciousness once the pressure got back up to a reasonable level, with no ill effects. I'm sure the incident is described on Wikipedia somewhere, I'll try and find it. --Tango (talk) 13:58, 10 June 2008 (UTC)

Found it: Human adaptation to space#Unprotected effects. Once again, we find that Wikipedia has an article on everything! --Tango (talk) 14:03, 10 June 2008 (UTC)

Garbage into oil?

Was there an attempt to turn garbage or sewage into oil? ScienceApe (talk) 18:42, 8 June 2008 (UTC)

Discover magazine says yes. The company responsible is Changing World Technologies. Clarityfiend (talk) 19:42, 8 June 2008 (UTC)

Why isn't this done on a much larger scale? We have enormous landfills that can be turned into oil. ScienceApe (talk) 02:47, 9 June 2008 (UTC)

When I expanded the CWT article, I found that their particular method costs $80 to produce a barrel of diesel, so until recently, it wasn't very profitable. Besides, the stuff in landfills would almost certainly have to have metals and other inorganic material removed, further raising costs. Clarityfiend (talk) 02:52, 9 June 2008 (UTC)

See List_of_solid_waste_treatment_technologies#Advanced_waste_treatment_technologies methods include pyrolysis Gasification#Waste_disposal Thermal depolymerization amongst others - food waste is popular, as is garbage. Sewage is a possibility but more likely to be treated by Sewage_treatment#Anaerobic_digestion (as it is very wet) making 'biogas' which can be made into oil. If you are still interested try Waste management and follow the links...87.102.86.73 (talk) 17:23, 9 June 2008 (UTC)

The worst case of food allergies and religious food laws

What are the worst known cases of food allergies combined with restrictive religious food laws? E.g., you are not allowed to eat certain foods, but you are allergic to most of the foods that you are allowed to eat. Furthermore, most of the non-allergic and legal foods are not available in the place that you live. -- Toytoy (talk) 19:03, 8 June 2008 (UTC)

Religious food laws rarely limit the diet that much. For example, kosher and halal (which are similar in scope) limit barely a fraction of the pantheon of foods we could eat. I can't imagine a situation where one would need to circumvent these laws in order to avoid eating foods to which we are allergic. Fribbler (talk) 23:00, 8 June 2008 (UTC)

There was a somewhat related case mentioned in the radio recently. Certain christian priests complained that they have to administer masses in towns far away from their home so it would be best if they could drive, but they also have to drink wine for celebratory purposes on the mass, which of course excludes driving. – b_jonas 09:36, 9 June 2008 (UTC)

It's possible to be allergic to alcohol. Both that and gluten intolerance can make Holy Communion difficult. I read (but have lost the link) that members of the congregation may take only one, but Catholic priests must take both the bread and wine. 81.174.226.229 (talk) 11:00, 9 June 2008 (UTC)

http://www.catholicceliacs.org/Bishops.html ? —Keenan Pepper 12:05, 10 June 2008 (UTC)

To be technical, there's no such thing as an alcohol allergy, in large part because the ethanol molecule is way too small to be recognized by the immune system. One can however, have an alcohol sensitivity, which something else entirely. I can't find a specific reference to this on Wikipedia, but Mayo Clinic does a pretty good job. – ClockworkSoul 14:33, 10 June 2008 (UTC)

Let me add on to my statement a bit: there seem be be a number of reliable sources that suggest alcohol allergies do exist but are very uncommon. I'm more than a little skeptical, but I should at least acknowledge them. – ClockworkSoul 14:39, 10 June 2008 (UTC)

If you haven't come across it already, you may be interested in this [26] which mentions several case studies Nil Einne (talk) 18:38, 10 June 2008 (UTC)

Actually wikipedia covers Alcohol flush reaction and Alcohol tolerance resonably okay, which appears to be what the Mayo Clinic link is referring to. I'm not sure about alcohol allergies however. BTW, people with the alcohol flush reaction are unlikely to be trouble by receiving communion since the amount consumed is so low, it's unlikely to cause any problems. Nil Einne (talk) 18:35, 10 June 2008 (UTC)

Rubber

Does all rubber contain latex? —Preceding unsigned comment added by 76.125.70.46 (talk) 20:01, 8 June 2008 (UTC)

In the area of rubber, latex does not indicate the contents of the rubber. It indicates that the rubber has not been vulcanized. -- kainaw™ 20:38, 8 June 2008 (UTC)

Latex is a pretty slippery term; its meaning depends quite a bit on context. Our article includes a fuller description of the different meanings. People who have a latex allergy are sensitive to natural rubber; they're likely not bothered by latex paint (which contains acrylic polymers). Generally – but not always – so-called 'latex rubber' is not vulcanized.

Synthetic rubber can be manufactured using a variety of compounds, many of which bear little resemblance to the ingredients of natural latex. Finally, the pedants will point out that 'latex' describes an aqueous emulsion; 'rubber' is what you get after the latex dries. Confused yet? TenOfAllTrades(talk) 15:54, 9 June 2008 (UTC)

Strange hypnagogic sensations

Sometimes when I'm just falling asleep, I experience a strange sensation -- it feels like my body is being distorted, changing in size or becoming stretched and compressed. It's not painful, but sort of dizzying and disorienting. This often accompanies the usual sensation of floating or falling, and sometimes sleep paralysis occurs at the same time. Is this a documented phenomenon, and what could its psychological or physiological basis be? 69.111.189.55 (talk) 21:45, 8 June 2008 (UTC)

Well, from your subject heading I guess you know about Hypnagogia... the article doesn't describe your experience exactly, but it seems in keeping with the broad set of weird things that happen in that state. Other than that, I don't know. --Allen (talk) 01:24, 9 June 2008 (UTC)

Wow. I used to feel that way often when I was a child and teen. I had forgotten all about that until I read this. At the time it was a bit disconcerting and I didn't know if it was something physiological or if it was all in my mind. My memories of the experience really don't sound anything like what is described in the hypnagogia article. It was more like my sense of scale was all weird; like my body was flattening, or if I closed my eyes I could see/feel in the blackness a perfect line, and I could let myself fall partly into it in a sense. At others it was like my fingers were huge, and it was a wonder I could move them. It is a very hard thing to describe. I don't think I could have then, and obviously I'm not doing a very good job of it now.

I think such sensations usually did happen when I was going to sleep, but I can't tell you if that was the only time or not (it's possible it also happened at other times when I was at rest and had a chance to calmly observe my sensations--e.g. meditation). Maybe it has something to do with the growing process; I haven't felt that way in my adult years. Then again, my sleeping habits have changed significantly since then too.

Anyway, sorry for the non-answer. It was great to hear someone else express the same kind of sensations that puzzled me, and I hope my rambling might in some way help you too, even if it isn't anything close to an "answer". (Keep in mind I'm not giving advise; if this is something you are at all concerned about, consult a medical professional.) --Prestidigitator (talk) 04:37, 9 June 2008 (UTC)

The "huge fingers" sensation happens to me, too; I also lose track of what position my arms are in. Indeed, it's kind of a relief to know that I'm not the only person who has these weird half-dream experiences. 69.111.189.55 (talk) 02:23, 10 June 2008 (UTC)

I used to get it when I was a teenager too. That is when I started to get sleep paralysis, too. My hands would feel enormous but not heavy in any way, just really big. The sleep paralysis was a seperate thing, though, and I experienced it more and more as I got into and went through my 20s. Take a look at the article Kanashibari. --ChokinBako (talk) 11:26, 10 June 2008 (UTC)

June 9

Prevnar vaccine

Is prevnar equally effective in India?Does it make sense to give prevnar to an infant in india, as the cost here is quite something. —Preceding unsigned comment added by 203.112.84.138 (talk) 09:35, 9 June 2008 (UTC)

The concern here is whether Prevnar, a pneumococcal conjugate vaccine available since 2000 in the U.S., and recently (2006) introduced in India, (see here) is effective, since it was developed to protect against the seven serotypes of pneumococcus that are most prevalent in the U.S.

Prevnar protects against serotypes 4, 6, 9, 14, 18, 19, 23, which cause 80-90% of disease in young children in the U.S. In Europe, which has a significantly lower incidence of invasive pneumococcal disease than the U.S., these 7 serovars account for only about 70-80% of that disease. In India, the most common serotypes in children under 5 years were 6, 1, 19, 14, 4, 5, 45, 12, and 7, in that order. [27] So Prevnar would protect against 4 of the 5 most common Indian serotypes, but would not protect against 1 and 5, which are more common in developing countries, and together make up 29% of Indian isolates. Clearly, if the vaccine had been formulated primarily for Indian use, it would have included these serovars rather than 18 and 23; and equally clearly, the vaccine protects against serovars that cause significant amounts of disease in India. An article in Indian Pediatrics notes that 25% of all child deaths in India are from pneumonia, and estimates that 30-40% of these are from pneumococcal pneumonia, meaning that between 123,000 and 164,000 children under the age of 5 die each year in India of pneumococcal pneumonia. Vaccines with either ten or thirteen serotypes, including 1 and 5, are likely to be available in 2010. India meets the WHO’s criteria for countries where pneumococcal vaccination should be a priority for introduction. The risks and benefits in any particular case must be decided in consultation between physician and patient. Since the concern here seems to be financial risk: The cost in 2006 was Rs 3750 per dose plus taxes, and was not covered under the extended programme for immunisation in India. If it chose to, the Indian government could obtain the vaccine at a cost of between 15 and 30 cents (U.S.) per dose. [28]. The editorial cited asks the Indian Academy of Pediatrics to urge the government to develop a process and timeline for introducing pneumococcal vaccination.

- Nunh-huh 20:18, 9 June 2008 (UTC)

Hmm, the question is posed as asking whether administering a vaccine is advisable. Isn't that medical advice? With all due respect to the responder, shouldn't this post simply be removed? Franamax (talk) 06:35, 10 June 2008 (UTC)

A request for information is not a request for advice, even if one can imagine that that information may ultimately be used in making a medical decision. No advice has been asked for or offered. The main distinctions between the referenced section in our Prevnar article is that the answer here is a bit more detailed, accurate, up-to-date, world-centric, and referenced than it is there. It's hardly censorable. A medical advice request would have been: "Should I give my baby Prevnar?". That wasn't asked. What was asked is "Is Prevnar effective at preventing disease in Indian babies?" - Nunh-huh 07:16, 10 June 2008 (UTC)

Tooth restoration

before one restores a tooth permanently with amalgam can one temporize with IRM till gingiva improves and better moisture control is achieved for tooth to be restored are there any guidelines for it.

Thanks tanya —Preceding unsigned comment added by Mtanya (talk • contribs) 14:16, 9 June 2008 (UTC)

Is this a homework question? If so, could I have your name so that I never visit a dentist who asks random Internet dweebs to do their homework for them? Thanks. --Sean 14:52, 9 June 2008 (UTC)

Harsh - everyone starts with no knowledge and acquires it through training/education. That they ask for information (perhaps due to laziness at homework, or out of genuine need of help) isn't an indicator of their future abilities in the dental field. Oh and re the Q - I have no idea at all, sorry. ny156uk (talk) 17:23, 9 June 2008 (UTC)

You may want to check out the wikipedia articles: Dental restoration, Temporary restoration or Dental restorative materials, specifically Indirect Restorative materials (which is what I presume you mean by IRM). Checking out the citations in these articles will surely point you in the right direction. Jdrewitt (talk) 20:48, 9 June 2008 (UTC)

In this day of eliminating mercury in the mouth, someone is still using amalgam?—Preceding unsigned comment added by Julia Rossi (talk • contribs) 07:35, June 10, 2008

Psychological concept of your perception of others

I vaguely remember a psychological/philosophical concept from the anime Neon Genesis Evangelion, which was along the lines of your perception of other people - their personality, appearance, your understanding of their motives and such, essentially the version of that person which you hold in your mind, which stems from your memories and previous encounters with this person - could be considered, philosophically speaking, as valid a description of them as that person's actual existing self. Does this concept have its roots in any psychological theory? Thanks. --Sum0 (talk) 20:05, 9 June 2008 (UTC)

That sounds like philosophy, not psychology. I don't see any psychological about that. --Tango (talk) 21:38, 9 June 2008 (UTC)

It's not quite what you say but "projection" could come into it if it means your perceptions are actually subjective. Closer to it is the empathy phenomenon. Julia Rossi (talk) 07:31, 10 June 2008 (UTC)

Enzymes that remove pet urine odor

I understand that certain "enzymes" can break down pet urine in carpets. Something about the enzymes consuming the bacteria. Supposedly the urine smell occurs as bacteria consume the urine. Enzymes are said to kill and or neutralize this activity and reduce or eliminate odor. My question is what exactly are the names of these enzymes ? _____ase I want to know so I can be sure the product I purchase will actually do the job. Thank You, 70.118.255.25 (talk) 23:33, 9 June 2008 (UTC)

I don't think your theory is correct. There are very few bacteria in urine, as it is both sterile initially and somewhat antiseptic. The smell is simply ammonia. Any chemical which reacts with ammonia to break it down into odorless components would work to control the odor. Since ammonia isn't a protein, it doesn't require an enzyme to break it down. 67.38.24.177 (talk) 03:08, 10 June 2008 (UTC)

I don't have a specific answer for the OP, but I want to address a couple of misconceptions in the answer above. First, there's normally very little ammonia in urine; instead, nitrogen is excreted as urea. Thus, fresh urine has very little odor. Certain bacteria produce urease, which will "split" urea and can produce ammonia as a by-product. I suppose it is possible to inhibit the ureases. Second, as this suggests, enzymes act on many molecules other than proteins.Scray (talk) 03:29, 10 June 2008 (UTC)

OP is right as least inasmuch as there is a product that digests or absorbs or renders inaccessible the nitrogen in cat-pee that bacteria feed on. They had to spray a bunch of it when I moved in a year ago - and she was such a nice girl who never even owned a cat, too. I'll try to ask one of the maintenance people next couple of days, but by all accounts, such a theory and product does exist. Franamax (talk) 06:13, 10 June 2008 (UTC)

Googling "pet urine odor" shows lots of (lame) home-remedies and several commercial products using enzymes. We can't recommend a single product, and you will really never get any single name of some particular enzyme that is the "right" one. They are all commercial products, you need to read the descriptions and customer reviews on various websites and figure it out. Reading through the links, there are two or three that I would try. If I can find out the particular product used for my case, I'll post it here. Franamax (talk) 06:30, 10 June 2008 (UTC)

June 10

Feisty baby gull...

Has anyone else here ever seen a gull chick deliberately starting a fight with an adult bird - and winning? Today, I had the opportunity to observe a colony of nesting Black-headed gulls at close quarters in their natural habitat. I noticed that most of the gull pairs had built their nests on small salt marsh 'islands', meaning that space was at a premium. The gulls (being typical gulls) were of course bickering, squabbling and pecking each other constantly over minor territorial encroachments and airspace above the nest. What surprised me, however was to see one of the older chicks joining in.

This particular bird was about 2/3 adult size with partially-grown wing feathers, so he/she was probably about three weeks old, or so. Yes, this youngster was starting fights with any adult gull which came too close to his mother's nest. Not only was he starting fights, more astoundingly he was winning them too! While I was watching, he must've seen off about 15 intruders with his chest-puffed, charging pecks. He certainly wasn't staying on his side of the line either - more than once, he chased an adult gull all the way across the island and into the water with his heel-snapping, causing absolute pandemonium amongst the uninvolved sitting hens. I just can't understand why the adult birds were prepared to take that from a chick...

Oh yes, in answer to the question someone asked the other day - it seems that baby gulls of this species *can* and do swim. I saw birds that were no more than a couple of days old trying to swim away from their nests (much to the annoyance of the parent gulls, who would corral them back, scolding loudly). They seemed to be fully waterproofed too. --Kurt Shaped Box (talk) 01:59, 10 June 2008 (UTC)

That sounds like behavior typically associated with species that have ascribed social status. That is, the offspring of the "alpha pair" may have the right to push around others, even adults. Do gulls exhibit such a complex social pattern as this ? 67.38.24.177 (talk) 03:04, 10 June 2008 (UTC)

I don't think so but I can't say for certain. I'm not as familiar with this species as I am with some of the others. --Kurt Shaped Box (talk) 14:39, 10 June 2008 (UTC)

gravitational redshift

The Pound-Rebka experiment showed that gamma rays lost energy/frequency as they fell through the building, due to gravitational redshift. Only by moving the emitter downward relative to the receiver could the gamma rays be given enough (doppler) frequency to be absorbed. This diagram and relativity-common-sense would seem to support that "time" runs slower for things (like photons) undergoing acceleration.

But the gravitational redshift article (and general relativity) says that light originating from a stronger gravitational field will have longer wavelength when received by an observer in a weaker gravitational field. Redshift for deceleration now! Which is it? The former makes more sense to me.. like a pendulum, the left-right motion of the wave in the horizontal direction stays the same, but the wavefront moves faster due to acceleration from gravity. So a stationary observer sees "more wave" go by for each cycle.. a redshift. So which is it for falling light? Redshift or blueshift? .froth. (talk) 05:27, 10 June 2008 (UTC)

Blueshift. If you move deeper in a gravity well, then you gain energy. Since photons can't actually move faster, the way this is manifest is by their blueshifting to higher energy state. Dragons flight (talk) 05:36, 10 June 2008 (UTC)

Fans and heating/cooling

Two questions:

1. If I put my hand in front of a fan, I can feel lots of air getting blown out. But if I put my hand behind the fan, I can barely feel any air getting sucked into the fan. So where does the air getting blown out the front of the fan come from? It feels like there's way more air coming out then getting sucked in.
2. It's summertime, and for the moment, I'm in a house without an air conditioner. At night, when the temperature drops, the second floor rooms stay way hotter than the first floor rooms and way hotter (by 5 to 10 degrees Fahrenheit) than the outside environment. Presumably, what is happening is that all the hot air from the first floor is rising up to the second floor and then getting stuck in the second floor rooms without being able to go out. I've tried opening all the windows on the second floor, but the temperature seems to still refuses to drop by much up there, probably because there is close to no wind these past few days. I was thinking that I could improve air circulation by sticking fans in the windows. My question is, if I did so, which way should I stick the fans? Would it be more effective in cooling the rooms to have the fans blowing cooler air from outside into the hot rooms, or to have the fans blowing the hot air inside the rooms out the window?

—Lowellian (reply) 07:09, 10 June 2008 (UTC)

Fan pushes air which is in front of its blades. It does not suck from behind. Window fan, or as I call it Exhaust fan may solve your problem. manya (talk) 07:33, 10 June 2008 (UTC)

I'm sorry, manya, but your explanation isn't correct. Fans generally take air from one side of the blade disk and push it out the other side of the blade disk. With regard to the original question, if the fan were mounted in a duct, so that all of the air was constrained to travel within the duct, I think you'd find that air flow would feel the same on either the inlet or outlet sides of the fan. But room fans aren't mounted within a duct so the airflow isn't so constrained. I think the cause of the effect is two-fold: air flows into the fan blades from a variety of directions and a rather large "subtended angle". Because of the large subtended angle, the inflowing air can move at a pretty low velocity and yet move into the blades a large volume of air. On the outlet side, though, the moving air stream is probably more focused, so the same volume of air needs to now move at a higher velocity. A second-order effect is that the outlet air stream probably tends to drag surrounding air along with it, decreasing the stream's velocity but further increasing its volume (in the same fashion as a jet pump moves more water). This would probably be a lot easier to explain if the Reference Desk were equipped with a wind tunnel so you could see, via the smoke streams, the various flows of air. ;-)

With regard to exhaust fans, see whole-house fan.

Atlant (talk) 12:06, 10 June 2008 (UTC)

The best way to clear out the air in a room is to have one window fan blowing air out, and another one across the room blowing it in. I speak from broken-air-conditioner-in-102-degree-weather experience. --Sean 12:56, 10 June 2008 (UTC)

I'm with Atlant with his explanation. To explain it slightly differently, the air being blown out of the fan is focused to travel in a specific direction by the shape of the blades, therefore the moving air takes up a given volume (lets call it x for fun). On the 'input' side of the fan, there is no such restriction on where the air comes from. As the blades push the air directly in front of them out of the way into the volume x above, there is a (momentary, instantaneous, imaginary, useful for this exercise) vacuum that is created because there is no air present. To keep the air pressure in the volume constant, the atmosphere rushes in 'uniformly' and 'from all directions'. Because its coming in from all directions, it occupies a greater volume and (as Atlant said) the flow rate is lower because theres a greater volume flowing.

To address your second concern, Sean is correct. Having all fans blowing outward would be the least useful solution because (assuming theres no other source of air) all of the air would have to travel through the rest of the (substantially warmer) house before it could reach the second floor, which would minimize cooling capacity. If all the fans face in, you'll get lots of cool air in but the warm air in the house will still be present increasing the amount of air that needs to be cooled. But having an equal number pushing in and pulling out will bring an influx of cool air (what the first method lacks) and also remove warm air (what the second method lacks). If done correctly, it will also reduce the amount of electricity needed compared to the other two. EagleFalconn (talk) 13:28, 10 June 2008 (UTC)

You don't even need the fans - just opening one window at the front of the house and one at the back (and the internal doors inbetween) will create a significant flow of air through the house. The fans will increase the effect, especially if there is no natural wind, but they aren't essential for the basic principle. --Tango (talk) 15:25, 10 June 2008 (UTC)

Physics -- Force, Mass and Acceleration

I've been asked this question by somebody who found it in a book (which didn't bother to provide the answer): We know that F=ma. If we consider a constant acceleration, and then plot a graph of the force required to give/achieve that acceleration against different masses taken, the graph assumes the form of a curve. Why is it so, knowing that the relation between force and mass is linear? 117.194.226.154 (talk) 08:11, 10 June 2008 (UTC)

I'd be interested in seeing a sample of that graph, or at least the specific axes used (and anything else non-obvious, like not being simple/unconstrained linear motion, etc). As described, F vs m for some constant a should indeed be linear as you say. DMacks (talk) 08:17, 10 June 2008 (UTC)

I think the only reason it would curve is if a is being factored into the graph, and is only held constant at intervals, but not during the entire length of the graph, or else if a was always the same value it would be linear as stated.--十八 10:06, 10 June 2008 (UTC)

Yeah, it should be a straight line, unless we're missing a key detail. Of course, a line is a type of curve by the strict mathematical definition, so perhaps that's what it means... a rather strange way to say it, though. --Tango (talk) 12:48, 10 June 2008 (UTC)

Yeah, assuming a vacuum with no other forces acting on the mass, it should definitely be a straight line. Certainly in many realistic situations you would get a curve, though, due to things like air resistance or friction on the surface it's travelling on - is that perhaps what the book was referring to? ~ mazca ^talk 12:53, 10 June 2008 (UTC)

Gyroscope

why angulr momentum is in direction of rotting axis?Shouldnt it be in direction of spin? —Preceding unsigned comment added by 220.240.81.247 (talk) 12:40, 10 June 2008 (UTC)

The direction of spin is different on different parts of the spinning body, and at different times. Consider the hour hand on a clock, for example. At 12, the hand is moving to the right, at 3 it's moving down, at 6 it's going to the right left at 9 it's going up. The direction of the axis is the only direction which is constant (that's basically what "axis" means), so it's the only one you can usefully use in the definition of angular momentum. --Tango (talk) 12:51, 10 June 2008 (UTC)

At 6 it's going to the left. Am I allowed to just change your comment to fix minor mistakes like that? — DanielLC 14:22, 10 June 2008 (UTC)

Thanks! I've fixed it. I wouldn't mind you just correcting it, but others might - it's easiest just to reply like you did. --Tango (talk) 15:21, 10 June 2008 (UTC)

Neptune

A diamond on Earth retains a certain shape and hardness(?). What would happen to a diamond if it was placed on the planet Neptune? Will it become harder or change in any way? --Vincebosma (talk) 15:45, 10 June 2008 (UTC)

Also, what would happen if a human spaceship attempted to land on Neptune? --Vincebosma (talk) 15:45, 10 June 2008 (UTC)

This sounds like it might be a homework question, so I won't give you a complete answer. I think the first thing you need to consider is what you actually mean by "placed on" and "land on" - Neptune is a gas giant, there is no land, at least not without going deep down into the thick atmosphere. The things you'll need to consider when determining what will happen to things on Neptune are pressure and gravity. Our article on Neptune will give you some data that should help with that. --Tango (talk) 15:52, 10 June 2008 (UTC)

I guess I'm flattered you thought this was a homework question, but I am a 35 year old man with no homework. Just a curious question. So considering Neptune has no land, the question about diamonds and human spaceships won't matter. I was trying to determine what would happen to things like diamonds and human spaceships on planets (with land) that are at least 20x larger than Earth pressure-wise and gravitational-wise. --Vincebosma (talk) 15:57, 10 June 2008 (UTC)

Planets that large are almost certain to be gas giants. They will have a solid core, but it's a long way down. There will be very high temperatures and pressures, which diamonds can probably survive intact, but spacecraft wouldn't. You might find Galileo (spacecraft) interesting - it sent a probe into the atmosphere of Jupiter, which was destroyed by the harsh conditions (after sending back lots of useful data) - the article gives some details. It is possible to have spacecraft in the upper atmosphere, though, see Floating city (science fiction) for (a little) more information. --Tango (talk) 16:32, 10 June 2008 (UTC)

What you need is a phase diagram for carbon. We don't seem to have one on Wikipedia, but Google should find you several. If you know the local temperature and pressure, you can determine whether your diamond will be stable. I note that diamond is a pretty stable allotrope of carbon at high pressures and moderately high temperatures (thousands of degrees). There has been speculation in the past that the core of Jupiter may be (mostly) a large diamond, formed by the heat and high pressure. There's also suggestion that Jupiter will have layers of other rather exotic materials as well, including metallic hydrogen. TenOfAllTrades(talk) 17:19, 10 June 2008 (UTC)

According to our Neptune article, the core is several thousands of degrees hot, so a diamond could burn (if oxygen was present) or melt (but the high pressure might prevent this). StuRat (talk) 20:15, 10 June 2008 (UTC)

Physics

Are there any scalar quantities which are formed by a product of 2 vector quantities? Can anybody give some examples of such. —Preceding unsigned comment added by 124.43.211.252 (talk) 16:19, 10 June 2008 (UTC)

Yes. See Mechanical work#Force and displacement for one example. --Tango (talk) 16:34, 10 June 2008 (UTC)

(edit conflict) Yes, there are several. It's unlikely that anyone here will answer your homework question for you, however. I'll give you a hint—force is a vector quantity. I suggest you examine the basic physics formulae that you've been taught and look for scalar and vector terms. TenOfAllTrades(talk) 16:38, 10 June 2008 (UTC)

Intelligence enhancing drugs

Have there been any drugs that show a positive correlation between intelligence and their use? ScienceApe (talk) 16:41, 10 June 2008 (UTC)

Have you looked at Nootropic? Friday (talk) 16:42, 10 June 2008 (UTC)

Looking-glass protein

Assume we found an alternate form of life identical to something we know is edible(say, an apple), except that the structure of its proteins and other molecules was opposite in chirality to that of life as we know it. If we ate such "looking-glass" food, would it be poisonous, or just pass through the body inertly? Would it even be possible for mirror-imaged proteins and molecules to form complex life similar to ourselves and what we eat? —Preceding unsigned comment added by 207.233.86.164 (talk) 17:30, 10 June 2008 (UTC)

There is no real bias within chemistry and chemical reactions for specific chiralities. That is to say that enantiomers have the same chemical properties. If we were to come across an apple that had the opposite chirality (for example, all the sugars in it were the enantiomer of dextrose) its effects would be difficult to say arbitrarily. There are certain molecules that the body would simply allow to pass right through as its different chirality would make it neigh impossible for any proteins to sucessfully catalyze the digestion. On the other hand, there are also molecules for which the change in chirality would make them horribly horribly poisonous. See thalidomide. There is no reason for biology to be biased towards R molecules, and to my knowledge research is being done to determine why that bias arose. If I recall correctly, the current theory has something to do with the strong force, which seems a little off kilter to me but I'm not really qualified to judge. (EagleFalconn) 17:46, 10 June 2008 (UTC)

The main theory I know of is that the chirality of organic molecules is purely by chance - it just happens that the first life forms to be successful were of that chirality and every life form since has therefore also been. It's an interesting issue, and has many consequences for the fundamental ideas of evolution. To the best of my knowledge, there is no reason why life couldn't form with everything the exact mirror image of what we observe. Interaction between life forms of each type (for example, us eating a mirror-apple) would be unpredictable, as you say, but interactions between molecules of one type should be indistinguishable from interactions between molecules of the other type. --Tango (talk) 17:53, 10 June 2008 (UTC)

Right, my point in the above comment was to say that there is a theory that states that R may have been favorable due to a strong force interaction, which is to say that it wasn't entirely chance but there was something driving it (perhaps competitive reaction kinetics). Interestingly, it isn't necessarily true that just because an interaction works R,R that it will work S,S. As I say above, enantiomers have the same chemical properties, however diastereomers do NOT. So just because we know what an R sugar coupling with an R protein will do, we don't know if it'll do the same thing with the S sugar and the S protein. EagleFalconn (talk) 19:38, 10 June 2008 (UTC)

That sounds off...unless there's a third chiral thing involved (external entity or noticeably affected by low-level like asymmetric Force), enantiomers are completely structurally identical and perfect 3D mirror images, so why wouldn't one think R-substrate + R-enzyme would be identical and bind identically (except perfectly enantiomerically) to S-substrate + S-enzyme? If they don't, then enantiomers aren't really "perfect mirror images". DMacks (talk) 19:48, 10 June 2008 (UTC)

I agree. Except for the possibility of very small effects with the strong or weak nuclear forces, the laws of physics are invariant with respect to taking mirror images, so the S versions of things should interact with each other in the same way the R versions do. --Tango (talk) 20:08, 10 June 2008 (UTC)

Regarding specifically proteins and amino acids, and the effect of eating an apples with opposite chirality proteins: I'm pretty sure that the D-isomers of amino acids have greatly reduced bioavailability. This comes up because some chemical treatments that foodstuff might be subjected to, such as strong alkali, tend to racemize amino acids. ike9898 (talk) 19:52, 10 June 2008 (UTC)

Increased Gravitational Pull on Earth

What exactly will happen if the gravitational pull on Earth increased ever so slightly? Such as, will I weigh heavier, will certain animal or plant species suffer and die off, etc. --Vincebosma (talk) 19:43, 10 June 2008 (UTC)

That depends on what you mean by "ever so slightly". The Earth's gravity already varies by very small amounts depending on where you are (by about 0.5% or so), and that clearly doesn't have any major effects. It needs to be taken into account for some satellites, I believe, so changing the strength of gravity by less than a percent would probably mess up GPS, but that's about it. Everything would weigh more, but not enough to cause any significant effects. If you increase gravity enough, though, things would start to be unable to support their own weight and would collapse. How much you would need to increase it by depends on what you want to collapse, I don't have any example figures for you, though. I expect it would increase air pressure, although it may in fact decrease it above a certain altitude (the scale height would decrease). I'm not sure what effects that might have, but it could well affect the climate. It would cause the moon to move closer, shortening the length of a lunar month and increasing tidal forces. There are probably all kinds of other effects I haven't thought of, as well. How significant each of them will be depends on how much you increase gravity. --Tango (talk) 20:05, 10 June 2008 (UTC)

How about as a reference, instead of weighing 200 lbs, due to the increase, I weigh 250 lbs.....--Vincebosma (talk) 20:09, 10 June 2008 (UTC)

Jumping from big heights

I have recently seen the Bourne Ultimatum (great film by the way) and was a bit confused by the ending. Bourne supposedly jumps from a ten, I think, storey building into a river and survives. This doesn't strike me as terribly realistic and I'm sure I wouldn't be quite as successful if I tried it. Is this Hollywood bending the laws of reality for its own needs again or is there some military training that can prepare you for jumps like that? Is it actually be possible? Thanks. 92.0.243.212 (talk) 20:16, 10 June 2008 (UTC)