Wikipedia:Reference desk/Archives/Science/2007 February 7

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February 7

Rockoon

How powerful would a Rockoon have to be to reach the ISS? Lets say it was launched from 50Km and it was using todays technologies.67.126.140.7 00:08, 7 February 2007 (UTC)

What do you mean "how powerful?" How much payload do you want it to carry to the ISS? Or do you just want to know the required delta-v? --Robert Merkel 07:41, 7 February 2007 (UTC)

Saying I want to carry 12 tons of material to the ISS is the energy required the delta-v?

lightning

Where does lightning come frome? Aidan Age 9

I suggest reading our article on Lightning. Splintercellguy 00:51, 7 February 2007 (UTC)

In a nutshell, lightning is the result of an electric charge buildup in the clouds. When charges are separated (the Earth itself has a charge), there is an electric field between those charged bodies. Once the electric field reaches a certain critical strength, the medium that separates the charged bodies (mostly air) breaks down (ionizes), creating a conductive path on which the charge may flow. This ionization and subsequent rapid current flow is what you see as lightning. -- mattb @ 2007-02-07T03:09Z

Reaction to rice...?

I have this strange reaction to rice: Whenever I cook a bowl of rice and add a can of vegetables or tuna or especially when I eat the cooked rice by itself it gets stuck in my Esophagus or if it makes it down gives me violent and quick sucession hiccups. What is going on? 71.100.10.48 01:53, 7 February 2007 (UTC)

It would be helpful if you could elborate a bit more. Food getting tempoerarily stuck in the esophagus on its way down is a very common occurance (eating too fast, or trying to swallon too big lumps of food). If you've accidentally got sticky rice instead of normal rice, then i wouldn't be surprised at all. Hiccups is also a very common occurance, and generally do occur in quick sucession. Eating too fast also commonly gives people hiccups. I can't really see anything particularly strange in what you have described. --`/aksha 05:36, 7 February 2007 (UTC)

• It could also be the result of something psychological. Do you like rice? If you don't, your dislike of the stuff is probably part of the reason why you're reacting this way. - Mgm|^(talk) 11:24, 7 February 2007 (UTC)

I guess at a sticky rice theory - When I've boiled rice I often 'fry' (it's more like just heating through) in a big pan with a small amount of butter or oil - this really helps separate the grains - you could try that - and see if it still sticks. Hiccups often means you are eating too fast or swallowing too big mouthfuls - I get them all the time.83.100.251.239 12:26, 7 February 2007 (UTC)

Car B has 5 times the mass of car A...

Car B has 5 times the mass of car A and car B has kinetic energy 25 times the kinetic energy of car A. What is the ratio:(speed of car B)/(speed of car A) 02:09, 7 February 2007 (UTC)

I do not think they answer test or homework questions on this board. 71.100.10.48 02:20, 7 February 2007 (UTC)

Kinetic energy is calculated using E=1/2 mv^2m, which is 0.5 multiplied by the mass, multiplied by the square of the velocity. Try to work it out from there. --Bowlhover 03:12, 7 February 2007 (UTC)

A prettier version: $E={\begin{matrix}{\frac {1}{2}}\end{matrix}}mv^{2}$ --antilived^{T | C | G} 11:06, 7 February 2007 (UTC)

why is there no native human population in Antarctica?

Is it because it is simply too cold or infertile for human life, or is it because there were simply no humans there when continental drift occurred? The Mad Echidna 02:50, 7 February 2007 (UTC)

Well a) continental drift is still occurring; but b) the answer is (your) a. Humans had not yet evolved by the time Antarctica was split off. Anchoress 02:58, 7 February 2007 (UTC)

Also, since Antarctica is such a harsh environment, with little flora and fauna, even if there had been humans on it when it separated from the other continents, there is a good chance they would have died out as it drifted further south towards its current location, and its climate and ecosystem became progressively more inhospitable. Maelin (Talk | Contribs) 03:52, 7 February 2007 (UTC)

Your guess is as good as any. The reality is that if there were people in antarctica and the question was "How did people evolve in Antarctica?" there would be just as valid scientific answers as the variables and permutations on life are nearly infinite. --Tbeatty 05:53, 7 February 2007 (UTC)

Antarctica broke apart from South America about 23 mya. Modern humans only evolved around 100,000 years ago, and the split between what would eventually lead to humans and chimpanzees occurred 6 mya. In fact, according to Dawkins' The Ancestor's Tale it was only 25 mya that humans, chimps, gorillas, orang utans, gibbons, and Old World monkeys all shared a common ancestor! − Twas Now ( talk • contribs • e-mail ) 06:57, 7 February 2007 (UTC)

Hawaii is newer than Antarctica and has people. They came by boat. I believe the latest genome studies show a "necking" in species which corresponds to a near die out (i.e. a very concentrated population) in the recent past. I don't think the species has been around long enough to support a theory that continents broke off and isolated people (but this is just a guess). I think it's more likely that constant growth away from the center created trait reinforcements. But rarely was isolation a barrier to establishing human cultures. Plenty of islands and continents are inhabited by migration either over land or by boat. --Tbeatty 06:23, 8 February 2007 (UTC)

You are right, Hawaii was only colonized about 1,500 years ago—something I always find remarkable! However, I made the implicit assumption that, though it has been possible to sail to Antarctica for probably thousands of years, it is highly improbable that, since the evolution of modern humans, one would sail to Antarctica and decide to stay there, along with a group large enough to perpetuate the intrepid colony until modern times. It was improbable that Pacific islanders would sail to Hawaii, but once this event did happen, there was incentive to stay since the Hawaiian islands can support diverse macroscopic wildlife (both plants and animals), as opposed to lichen, rotifers, and penguins. − Twas Now ( talk • contribs • e-mail ) 10:25, 8 February 2007 (UTC)

These are the same reasons why noone should have been living on australia until recently, but they were

electromagnetic pump

What equations govern the force exerted by a magnetohydrodynamic (electromagnetic) pump on the fluid running through it?

The Lorentz force is a good starter. ${\vec {F}}=q({\vec {v}}\times {\vec {B}})$. -- mattb @ 2007-02-07T05:14Z

Basis for claims about the economic cost of poor eyesight (among other things).

I heard once on the radio that poor eyesight costs the Australian economy something like $1 bn. a year, or something like that (it may have been in the 100s of millions instead). How do people work out the economic costs of things like that? The Mad Echidna 07:24, 7 February 2007 (UTC)

They buy glasses, and a new industry is born! Are you referring to the cost of eye care or the cost of incidents directly caused by less than optimal visual acuity? --66.195.232.121 15:14, 8 February 2007 (UTC)

Yes, this refers to the economic costs of having poor eyesight. Economists are very talented guessers, who know how to use simple mathematics in order to substantiate their assumptions. − Twas Now ( talk • contribs • e-mail ) 15:21, 8 February 2007 (UTC)

Yes, I was referring to the cost of incidents (or whatever, since I don't know what the economists are talking about) directly or indirectly caused by less than optimal (and presumably correctable) visual acuity. I might not have figured all this out, but the article on the radio news bulletin said as a result of the claim, that there were calls for increased optical testing, so I assume it was related to correctable problems that are currently being ignored. Any further info from anyone here would be most welcome. Regards to all The Mad Echidna 18:10, 10 February 2007 (UTC)

Just pulled out my bird's tail feathers by mistake

I was just trying to catch my budgie to give him his eye drops when I accidentally pulled out most of his tail feathers. He doesn't like being picked up and he flutters/runs all around his cage to get away from my hand. He's very quick. I thought I had him but he managed to slip through my fingers as my grip closed on him, so I only had him by the back end. He pulled away before I could reposition my hand, leaving me holding his long tail feathers.

The tips of the feathers have blood on them and he squeaked in pain when they came out but he's not bleeding from his body. He's just sat there looking unhappy now, giving me evil looks, shaking his backside and preening a lot.

Will his tail grow back eventually? --84.64.216.148 08:47, 7 February 2007 (UTC)

According to the article on feathers, "a bird's feathers are replaced periodically during its life through molting, new feathers are formed through the same follicle from which the old ones were fledged." Do you know the state of the follicle? − Twas Now ( talk • contribs • e-mail ) 09:29, 7 February 2007 (UTC)

No, sorry. I don't want to pick him up again and stress him out today. I wouldn't even know what I was looking for if I did anyway. :( --84.64.216.148 10:46, 7 February 2007 (UTC)

If there was no substantial bleeding, he should be okay. Birds molt at least once a year and new feathers ought to turn up at that time. I actually wonder about the feathers pulling out; it sounds like it happened relatively easily. Maybe it's already molting time where you are?

There's a slight risk that your budgie will become habituated to not having those feathers,and may pick them out when they start to grow again, but I think this is a low risk for tail feathers. On the other hand, I could introduce you to one Sun conure who has become very habituated to having a naked chest :-(.

Atlant 13:20, 7 February 2007 (UTC)

What do birds actually need tail feathers for, they don't seem to have any use, so don't worry about them:]Hidden secret 7 19:36, 7 February 2007 (UTC)

Haha, what? How about for steering themselves, and keeping themselves upright in flight? Please don't buy birds, Hidden secret. − Twas Now ( talk • contribs • e-mail ) 20:09, 7 February 2007 (UTC)

Yeah, the OPs budgie will steer like a brick until the new feathers grow in (which I'm pretty sure they will - I've accidentally broken/pulled the odd feather from my birds over the years when trying to catch them). Just be careful that he doesn't bang himself on something when he's flying until he figures out how to compensate. --Kurt Shaped Box 22:31, 7 February 2007 (UTC)

A bird's tail feathers perform the same purpose as the spoilers, air brakes, elevator, and rudder of an airplane. --Carnildo 22:34, 7 February 2007 (UTC)

So, why is it that different species of bird have different sizes and shapes of tail plumage? Compare a budgie's long, flared tail to the short fan-shaped tail of a gull for instance. --Kurt Shaped Box 22:46, 7 February 2007 (UTC)

A budgie-style long tail would be a real pain-in-the-ass when the gull is sitting on the water.

Atlant 01:15, 8 February 2007 (UTC)

Due to my favourite kind of selection pressure, sexual selection! Peacocks and birds of paradise have beautiful plumage because of selection by females. − Twas Now ( talk • contribs • e-mail ) 10:33, 8 February 2007 (UTC)

Which brings us back to another question of mine - how the hell *do* gulls pair up in the first place, when they seem to live in a state of constant war with every other gull and living thing in the immediate vicinity? The only time gulls seem to interact with other gulls is to fight or chase them away. I've never noticed anything that I could even remotely comprehend as 'courtship behaviour' (unless courtship in gulls involves the cock and hen fighting each other) in these critters. I suddenly start noticing pairs of gulls stood quite close together - and not fighting each other. Then they make a nest and presumably have sex. --Kurt Shaped Box 12:09, 8 February 2007 (UTC)

Meatomy

How do you define the medical term, meatomy?

• Try reading this site. Basically it involves a scalpel and a penis. - Mgm|^(talk) 11:21, 7 February 2007 (UTC)

(Site doesn't seem to work? I'm not sure if I should be pleased about that!)83.100.251.239 14:06, 7 February 2007 (UTC)

See Meatotomy. I could be more used to it, but the pictures are ok. 07:06, 8 February 2007 (UTC)

x-rays

i want information of x-rays

• Try reading our article on x-rays. - Mgm|^(talk) 11:18, 7 February 2007 (UTC)

green electricity

What is the need for using green electricity in place of hydroelectricity? How is it useful? - Manavsi 11:54, 7 February 2007 (UTC)

Well, there isn't enought hydroelectricity in many regions / countries. Also hydroelectricity isn't *that* green in certain areas - it is suggested that if you are flooding large areas of forest without having cleared away the vegetation then the anaerobic breakdown of it will cause enough methane to be released to offset CO2 savings from the dam for a couple of decades. --Neo 12:54, 7 February 2007 (UTC)

I'd suggest that the total CO₂ available in say 10 square kilometres (is that reasonable for a resovoir) is piddling compared to the savings from the hydroelectric generation..Or look at it this way - if you burnt all the stuff in the flooded area to make electricity - how long would that last at the same level of production of power - it's nothing like decades.83.100.251.239 13:11, 7 February 2007 (UTC) Sorry - ignore me I was in unreasonably grumpy mood.!83.100.251.239 14:05, 7 February 2007 (UTC)

It doesn't strike me as unreasonably grumpy! The reservoirs in question as well were (I'm recalling more of the article) those in places like the rainforests (so lots of plant matter) and in areas which only feature relatively shallow grades (so a large area of lands flooded). Plus its not CO2, but the global warming effect of the methane released which is at issue - hydropower is pretty much inevitably preferable in terms of CO2. --Neo 14:56, 7 February 2007 (UTC)

Creating dams is not "green". They flood large areas, which further reduce habitat for flora/fauna of that region. It is like building a giant city all at once. Limnodynastes depressus was lost to science for 30 years (thought extinct), because its only known habitat was flooded by a dam. It has since been found elsewhere, but there is very little knowledge of it because nobody knew where it was for a long time. Also, the fact that it could have been completely wiped out because of a single dam doesn't justify it for me. I'm not totally against them, but there needs to be a lot of environmental considerations to take place before it happens. The Australian Greens movement of the present began with the opposition to an hydroelectric dam. --liquidGhoul 14:50, 7 February 2007 (UTC)

It does not necessarily equal burning the submerged trees all at once. An article in a recent Popular Mechanics or Popular Science or some such told of billions of dollars worth of mature timber submerged but still harvestable after many years under water. The waterlogged and barkless timber can be sawn off at the base after a flotation bag is attached, by a robot submersible with a long chain saw. It is collected by a barge and taken to a sawmill. It goes from being a hazard to navigation when the water level is low, to being a resource, with a special "green" tag added to the final product when the lumber or furniture is sold at retail, so it can be sold at a premium. Edison 21:38, 7 February 2007 (UTC)

Ah the cynic in me gets to come out. It's a truism that all substantial sources of energy in an industrialized country are, by definition, not "green." Therefore, Hydroelectric energy was green until it was built. Wind farms were green until they were builty. Nuclear was green until they were built, etc. --Tbeatty 06:07, 8 February 2007 (UTC)

More possible chess moves than particles in the universe

I've heard it said that there are possible moves in a game of Chess than there are particles in the universe. Has anyone else heard this and does anyone know if it is true; it sounds absolutely ridiculous to me but I have no proof.--Ukdan999 12:20, 7 February 2007 (UTC)

From Chess#Mathematics_and_computers: "..the number of legal positions in chess is estimated to be between 10^43 and 10^50, with a game-tree complexity of approximately 10^123.."

So thats half the question answered. The number of possible moves will be much greater than 10^43.83.100.251.239 12:40, 7 February 2007 (UTC)

But surely there are way more particles in the universe. If there are around a 200-400 billion stars in our galaxy and around 100 billion galaxies in the universe, that's many trillions of stars, each with possible planets orbitting them. So how many particles in a typical star. And that's not even counting all of the asteroids and other bits and bobs floating through space. --Ukdan999 12:50, 7 February 2007 (UTC)

I don't know but I'll ask - then the answer will come..

OK assuming most of the mass of the solar system is the sun, and most galaxyies are similar and have suns like are own that gives.. mass of sun = ~2x10³⁰kg x ~300x10⁹ (suns in galaxy) x ~100x10⁹ galaxyies per universe = ~60,000x10⁴⁸ = ~6x10⁵² kg of matter in the universe... Assuming most of that is hydrogen atoms that gives ~6x10⁵⁵ moles of hydrogen = ~6x10⁵⁵ x ~6x10²³ (atoms per mole) = 36x10⁷⁸ atoms... So thats still less than the number of chess games that can be played - but more than the number of positions..83.100.251.239 13:05, 7 February 2007 (UTC)

Now given that for each position in a game of chess there is a maximum of ~150 moves (usually less) the total number of possible moves can be estimated by

moves per position x number of positions

which equals 10⁵⁰ x 150 = 1.5x10⁵²

That's many times less than the number of atoms, in fact 36x10⁷⁸ atoms/1.5x10⁵²positions = 2.7x10²⁷ times less.

ie there are around 2,700,000,000,000,000,000,000,000,000 times more atoms in the universe than there are moves in a chess game (very rough estimate)

You were right.83.100.250.165 14:36, 7 February 2007 (UTC)

According to the article on atoms, there are approximately ~10⁸⁰ in the universe. Please remember to do some research before asking questions. − Twas Now ( talk • contribs • e-mail ) 20:14, 7 February 2007 (UTC)

It's a fair point you make - but sometimes info is difficult to find - I would have never thought of looking in 'atom' for that - though I did look in 'universe' obviously..83.100.250.165 20:18, 7 February 2007 (UTC)

Keep in mind that, when such estimates use the term "universe", they're generally talking about the observable universe; that is, that part of the universe that's close enough to have been influenced by the same event in the past. There may well be infinitely many particles in the whole universe. --Trovatore 20:17, 7 February 2007 (UTC)

I don't believe that current scientific theories support that as a possibility, but I could be wrong, and for that matter the theories could also be wrong.

Anyway, I'd just like to point out that the original question referred to the number of possible moves in a game of chess. This is not a gigantic number. For example, a white rook could start on any of 64 squares and move from each one to any of 14 other squares, where either it won't capture or it will capture one of 5 possible black men, and there are also 2 ways to castle. That's 64x14x6 + 2 = 5,378 possible white rook moves -- actually less because there are some squares where there couldn't be a black pawn to be captured. You could increase the count if you say that rook from a1 to d1 giving check is a different move than rook from a1 to d1, or if you distinguish which rook (according to its original starting point) is moving, or which black pawn is captured, that sort of thing. The total number of possible moves in chess, depending on your definitions, might be something like 100,000 or 1,000,000 or maybe even 10,000,000... but it isn't going to be something gigantic.

The way the gigantic numbers arise is by considering the total number of positions, or even more, the total number of different possible games. Note that these are the numbers quoted above.

--Anonymous, February 8, 2007, 01:18 (UTC).

"Current scientific theories" do indeed support the possibility of an infinite (and infinitely massive) universe. There's a discussion in the observable universe article; also, you can look in Wikipedia talk:WikiProject Physics (or maybe its archives); I raised the question there some time ago. Search for "inflaton". --Trovatore 01:20, 8 February 2007 (UTC)

Thanks for all the responses! So, to summarise, there are NOT more possible moves in a game of chess than there are particles in the universe. However, there ARE more possible games of chess than particles in the universe. This seems a lot more realistic to me than the original statement. Thanks again. --Ukdan999 01:31, 8 February 2007 (UTC)

No. of particles in the universe

See Wikipedia:Reference_desk/Science#More possible chess moves than particles in the universe Could someone who knows please give us the (estimate of) the total number of particles in the universe. Thank you.83.100.251.239 12:56, 7 February 2007 (UTC)

Google says somewhere between 10⁷² to 10⁸⁷. -- mattb @ 2007-02-07T13:19Z

Thanks83.100.251.239 14:02, 7 February 2007 (UTC)

Observable universe#Matter content give a lower-limit estimate of 10⁸⁰ atoms in the universe. DMacks 14:54, 7 February 2007 (UTC)

Searching for machine meant for washing biodiesel

Where to find or any relevant website to search for high tech machine for washing biodiesel...?

use an internet search engine such as google on [www.google.com google] with a search term of "washing biodiesel" there are more than 2000 hits. Other search engine would have hits too. GB 06:45, 10 February 2007 (UTC)

dynamometers

How long do typical racing car engines run over a race weekend? How many horse power does a typical F1 engine produce during pre-race testing? How many horse power does a typical saloon racing car produce during pre-race testing?

Look in the Formula 1 article - here you will see that current Formula 1 race cars run at 552 kW. The engine also has to last two races, along with qualification. In the Australian Grand Prix the race length is 307.57, so multiply that by 4, and divide by the average speed to get the time the engine will run. If its just the one qualification and race you are after then taht will be double the length. GB 06:58, 10 February 2007 (UTC)

some questions about trees

A few years ago I decided to grow some trees from seeds, a horsechesnut and some oaks. Both of these are supposed to be deciduous, and since it is winter, none of them should have leaves on. But they do. So I have a few questions about leaves:

1 My horsechesnut tree started growing new leaves at the begining of january. Is there any reason why it would do this? 2 And will it have any effect on the health of the tree? 3 Some of the leaves on this tree haven't opened yet, is it normal for some leaf buds to open weeks after the others? 4 My oak trees have had the same leaves on them since they first grew, shouldn't they fall off every year? 5 These leaves are also sharp around the edges, like holly leaves. Is this normal for this sort of tree?

Seriously, what is going on with my trees?

Hidden secret 7 15:42, 7 February 2007 (UTC)

Hello, is anyone there:? Can't anyone help me with this:(HS7 17:44, 8 February 2007 (UTC)

How's the weather out there? − Twas Now ( talk • contribs • e-mail ) 17:48, 8 February 2007 (UTC)

It's snowing a bit:)HS7

Maybe you have live oaks. − Twas Now ( talk • contribs • e-mail ) 18:37, 8 February 2007 (UTC)

1.Could it be that you have had warm winters; not cold enough to cause the leaves to drop off -

2.This can be a problem in some plants as a sudden frost in Feb can kill the leaves harming the plant..

3. Leaf buds not opening - are the trees in pots or in the ground - if they were grown initially in pots and are still in them they might have reach the capacity of the pot - preventing any further leaf developement (root growth not sufficient)

5. Sharp - with points? The oak 'seed' is an acorn right? Just checking. Oak leaves are 'lobed' in my experience - though checking the article oak reveals that some species can have pointed leaves - see Oak#Classification - can you clarify - sorry I can't be much help.87.102.37.185 18:44, 8 February 2007 (UTC)

We do usually have mild winters, which could have something to do with it:) I don't know exactly what type of oak they are, unfortunately:( And the leaves had already fallen off the horsechesnut, and more grew this year:) But I expect you are right about them being an unusual specis of oak:)HS7

Why do we have faces?

As silly as the headline seems, it is my question.

Most larger lifeforms on Earth have readily identifiable faces. Infants can differentiate between the face ends of animals. It's relatively easy to identify the 'face' of a fly, a spider, a bear, a pig, a flounder, a whale, etc.

How is it that life on Earth evolved with the vast majority of the critter having similar facial structures? Why don't some beasts have their mouths in their abdomens, near the stomach? Or their eyes in the palm of their hands, to raise them higher to see farther? Or their noses in their feet to facilitate tracking?

Why are most animals arranged in the two eyes, nose, mouth conformation?75.74.243.218 16:45, 7 February 2007 (UTC)

Without giving an answer why not take a look at Symmetry (biology)#Bilateral_symmetry for a few reasons, and don't forget that not all animals have bilateral symmetry.

Note that the ability to move (with some speed - not crawling like starfish) demands a streamlined - eg linear shape (fish for example) - by extension to this putting the mouth and eyes at the front makes it more likely to catch food.. So that would be a reason to have mouth and eyes and other sensory organs - at the top/front.

Note that very slow animals often don't have bilateral symetry and often have the mouth in the middle - hope that helps.83.100.250.165 17:04, 7 February 2007 (UTC)

A notable exception to your example is squid and their relatives - there's a lot of squid.. they also seem to match your description of "..mouths in their abdomens, near the stomach? Or their eyes in the palm of their hands.." to a certain extent..83.100.250.165 17:40, 7 February 2007 (UTC)

Consider that the mouth is involved in lots more than just "getting food in, headed towards stomach". See also cephalization. DMacks 17:08, 7 February 2007 (UTC)

It would seem useful to be able to see and smell what you are about to eat. A second eye adds a wider field of vision, Stereopsis when the two eyes face front as in humans and other Predators, and a spare when one gets injured.Edison 21:31, 7 February 2007 (UTC)

There is good developmental and anatomic reasons for why the eyes, nose, ears and mouth (for tasting) are in close proximity to the brain. And there is good reasons for why the brain is found at the end of the spinal cord. Its also a good evolutionary strategy to have your sense organs facing the direction your move. Add all these together and you get the basic body plan - including the recognisible face - that is found almost ubiquitously in the chordates (at least, in Craniata) and in many invertebrates too. While its most likely that the facial arrangement is homologous (i.e our last common ancestor has a face like structure), its possible that a similar structure evolved multiple times. When a strategy works, nature tends to favour it (see convergent evolution). Rockpocket 23:35, 7 February 2007 (UTC)

Space

I've moved this question from Wikipedia:Reference_desk/miscellaneous so that you are more likely to get a good response...83.100.250.165 17:10, 7 February 2007 (UTC)

If a seed is germinated on earth, the roots go down while the leaves reach upward toward the sun, I assume this has something to do with gravity, thus allowing the roots to know where down is. So, in space, if one were to germinate a seed, a)would it germinate b)would it do so in an effective manner.

And as a second question. Menstration cyles in women are, or so i am told, coincide with the moon, (much like ocena tides) hence every 28 days. How would this be affected in a) zero gravity b)when out of the pull of the moon and c) if one were on another planet which had serveral moons or (b) no moons.

Thanks guys Mr Anonymous 81.144.161.223 16:08, 7 February 2007 (UTC)

I doubt it has so much to do with gravity as with the roots seeking soil nutrients and the leaves seeking sunlight. So I imagine that they would do fine in space, see hydroponics? Just a brief mention there. -- Justanother 16:18, 7 February 2007 (UTC)

Question 1. You should look at Root#Root_growth " At germination, roots grow downward due to gravitropism, the growth mechanism of plants that also causes the shoot to grow upward" - so lack of gravity will be an issue... I can't say more..83.100.250.165 17:43, 7 February 2007 (UTC)

Excellent point. Here and here are some links. The first is a proposed experiment and the second an actual, if casual, experiment. In the casual experiment the plants did not grow because capillary action appeared to be stronger than the reach for light. A substrate might be designed that could negate that effect. --Justanother 18:02, 7 February 2007 (UTC)

From a NASA chat session[1]

[ Yuli_Berkovich - 216 - 18:00:47 ]

RE: [ Does gravity affect your plant growth significantly?

Of course, gravity affect all plants significantly. Fortunately we can replace influence of gravity on root and stem orientation by means of another environmental stimulus: light distribution for stems and water distribution for roots.

--Justanother 18:09, 7 February 2007 (UTC)

Regarding the second question, see Menstrual cycle#Etymology_and_the_lunar_month and Menstrual cycle#Menstrual_cycles_in_other_mammals, and be careful to avoid presuming that correlation means causation. DMacks 18:24, 7 February 2007 (UTC)

Related to this, what experiments have been done to test the growth of plants in space? A greenhouse would have abundant sunlight, would help in some small way to convert carbon dioxide back to oxygen, and could furnish tasty sprouts and greens. It would be useful on a Mars mission and probably essential (with artificial light) on interstellar mission, manned stations away from Earth or Space colonization. Biosphere 2 has experimented with this in an Earth-born environment. What experiments have been done on seed germination and hydroponic gardening, in all of the history of the space program? Edison 21:20, 7 February 2007 (UTC)

Well Googling on Yuli Berkovich I came up with this and this. Yuli seems to be "Da Man". --Justanother 22:14, 7 February 2007 (UTC)

I greatly appreciate your help, and the answer the first part of my question, was very interesting, and thanks goes out to all responsible. However, to come back to the second part of my question. I have read the article on Menstrual cycle#Etymology_and_the_lunar_month How ever if one looks at the cite, I do not belive this to be conclusive as A) it was done by men. and B) they class their book with the paranormal!?!? There is nothing abnormal about menstration. : ^ As cited by Adams, Cecil, "What's the link between the moon and menstruation?" (accessed 6 June 2006): Abell, George O.; Barry Singer (1983). Science and the Paranormal: Probing the Existence of the Supernatural.

So concerning interplanetary colonization and space expolration in general, could any one help further with the above question? Thanks guys, and Ladies.

Menstration tends to be out-of-synch unless women live in close proximity. They don't have to be far enough away that they'd see any difference in lunar effects. I think it all comes down to hormones & pheromones. I'm guessing that if one woman took birth control pills, every woman on the spacecraft would eventually have a cycle synched to her placebos.--Joel 09:34, 10 February 2007 (UTC)

What is it that causes different meat to taste a different way?

Hi all, I am wondering why different meat that's unspiced still tastes a different way, ie beef and chicken, pork and fish. I understand that they are in different Classes biologically, but what is it specifically that alters their taste, in scientific terms? Do different proteins taste differently or what? Much help appreciated ! Xhin 18:42, 7 February 2007 (UTC)

I'm not really qualified to give a full answer but this : http://www.madsci.org/posts/archives/Mar2003/1048043552.Gb.r.html may help..

It seems then that the maillard reaction is responsible for causing the formation of certain flavoursome compounds in cooked meat. I'm sure that's not the only factor.83.100.250.165 19:38, 7 February 2007 (UTC)

Umami might be part of the answer. --JWSchmidt 01:48, 8 February 2007 (UTC)

Alps and Mountains

What is the difference between alps and mountains? In Europe there are both alps and mountain ranges; why the dirrence?

The Alps are a specific mountain range:) But alpine areas are places with mountain like climates and vegetation, usually on mountains:)Hidden secret 7 19:33, 7 February 2007 (UTC)

"Alp" does mean "any high, especially snow-capped, mountian" OED, but it is mostly used as such only in poetic or jocular contexts these days. The etymology is "said by Servius to be of Celtic origin, and variously explained as meaning ‘high’ (cf. Gaelic alp a high mountain, Irish ailp) and ‘white’ (cf. L. albus).]" OED. --Shantavira 08:40, 8 February 2007 (UTC)

The description of a mountain range as 'alps' is quite common eg 'altai alps' 'himalayan alps' - I imagine it is necessary for the mountain to have snow on top to truly fit the description..87.102.2.204 10:06, 8 February 2007 (UTC)

well i live in switzerland..and an alp is actually the cleared meadows or pastures on the side of a mountain...its english speakers that have connoted alps with the mountains themselves and so now one can also think of alps as the mountains themselves...yet when i tell a Swiss im headed to the alp...it means im headed to the grassy area where the cows/goats/sheep are likely grazing if its warm season...not the mountain peak...and we call the mountains in the center of europe "the alps" because they have these usually steep natural/unnatural cleared open grassy areas that the ruminants graze on...there are actually two definitions now yet they are tied together...Benjiwolf 15:01, 10 February 2007 (UTC)

Changing Iris Color

What are some of the reasons that an iris will change color? Are their any possible ways to change it, say from dark brown to light brown?

Whilst you wait for a proper answer I can suggest that you look at Iris (anatomy)#Color, and maybe Eye color - it seems that melanin (as found in hair) is responsible for all the brown colour in eyes - and that it's levels can increase with age.. Also disease may cause an iris colour change..83.100.250.165 20:42, 7 February 2007 (UTC)

Someone (probably a sceptic) has removed my answer:( But I searched on the internet and apparently medical treatment with iodine can also affect iris colour:)Hidden secret 7 20:48, 7 February 2007 (UTC)

Something that should not have been removed is that you can get contact lenses with different colors.

Some treatments for glaucoma, such as prostaglandin analogs, are known to change eye colour in maybe 10% of patients. Its thought that prostaglandin acts on eye colour by mimicing a natural hormone that mediates melanin production. People have reported that when they are ill or under stress that their eye color becomes darker or lighter. A modified version of the pigmentary hormones are also produced during stress (and when you stress fish and frogs, they change colour for this very reason, see chromatophore). Rockpocket 23:13, 7 February 2007 (UTC)

Just as an aside, I had a friend, Jaffa, whos eye colour would change with his moods, i cant now remember the corrolation but it was for example Brown when happy, green when sad, blue when arroused ect.

Are you sure it wasn't green for worried, black for angry, pink for embarrased...

As I said I dont remember the Emotional colour correlation.

A certain Dr. Mengele once tried to change some children's eye color by injecting them with methylene blue, but it failed to do anything but injure them. [2]

On a less horrifying note...the iris has folds in it, so that not all of it shows, most of the time. I imagine one's apparent eye color might change a lot as pupils dilate and constrict, especially given the variations from the center to the edge in hazel eyes like mine. That might partly explain the emotional effects described above.--Joel 09:20, 10 February 2007 (UTC)

Spinal cord syndrome by french doctor?

I am looking for a french doctor that had a syndrome named after him. The main symptoms were when you bend your head down you get numbing and pain radiating down your arms and legs. I am unsure how to spell his name and need the correct spelling and are also looking for specifics on this syndrome.

Probably not "Maladie de Charcot, after the French doctor Jean-Martin Charcot" ??83.100.250.165 20:21, 7 February 2007 (UTC)

I suspect we're talking about L’Hermitte’s sign, named after Jacques Jean Lhermitte (or Jacques Jean L'Hermite) - Nunh-huh 03:47, 8 February 2007 (UTC)

Lewis dot structure for XO32- (X = F,Cl,Br,I)

For the hypothetical compound XO32-, what would the most reasonable lewis structure be? I can think of two possibilities:

1) Two X-O single bonds, one X=O double bond. The singly bonded oxygens carry a negative charge, and the halogen carries a lone pair and an unpaired electron and is uncharged.

2) Two X=O double bonds, one X-O single bond. The singly bonded oxygen carries an unpaired electron and is neutral, the halogen carries three double bonds and a charge of -2.

Option two requires 16 valence electrons on the halogen and is unreasonable for fluorine. It does place the charge on the most electronegative atom for Cl,Br,I.

I ask this because I have been asked to draw the molecular shape of this compound. Am I correct in thinking both options give T-shaped geometry (making the point moot)? Thanks for comments 132.194.13.115 20:49, 7 February 2007 (UTC)

OK before I start you wrote XO32 - did you mean XO₃ or X₂O₃ ???83.100.250.165 20:58, 7 February 2007 (UTC)

Right did you mean XO₃^2-..83.100.250.165 21:02, 7 February 2007 (UTC)

If so the theoretical ion is a radical anion, see radical (chemistry) - in terms of a lewis structure it has an unpaired electron - there are an odd number of electrons.

I get

Three X-O single bonds, each O is singly charged, the X is positively charged and carrys an unpaired electron - it has also expanded it's octet to 9 electrons.. (supposedly impossible for F)

Each X is bonded to three O's and has 3 electrons remaining - This should give a 'distorted tetrahedral' structure - the O-X-O angle will be the same between all combinations of O. Alternatively the molecule could be a trigonal bipyramid with O's expected around the middle - giving an O-X-O bond angle of 120degrees.

(see Trigonal bipyramid molecular geometry83.100.250.165 21:24, 7 February 2007 (UTC)

Personally I'd look at the effect of adding one electron to the stable structure ClO₃^- - though I'd be thinking in terms of molecular orbitals - which may not be much use to you? - I'd expect the extra charge to be delocalised ie the structure would consist of resonant hybrids (see resonance (chemistry) - and I find it difficult to accurately predict a structure.83.100.250.165 22:22, 7 February 2007 (UTC)

Beta particle capture surface...?

Would the surface shown above provide better capture of Beta particles than a flat surface and how high a voltage differential would there be between the two plates in a vacumn? (This is not a test or homework question BTW.) -- Barringa 21:40, 7 February 2007 (UTC)

im not an expert on this, but I think there is really no limit (apart from leakage or vacuum breakdown) to the voltage difference that could be created.--DarkFuture 22:17, 7 February 2007 (UTC)

Nikola Tesla's
"Lightning-Protector"
U.S. patent 1,266,175; An early type of dissipater-arrester, which purported to prevent and safely dissipate lightning strikes

Charge accumulates on sharp points (i.e. areas with small radius of curvature). See lightning rod. Nimur 19:33, 8 February 2007 (UTC)

There is a hard limit. Look up how much energy is in the β rays from the isotope in question, and divide by the electric charge to get the voltage necessary to stop them completely. At 0 volts, the particles will travel radially away from the emitters, but for intermediate voltages, their paths will bend somewhat, reducing the amount of current produced. But DarkFuture is right, in that most β rays are energetic enough that field electron emission would probably set in before electric fields started deflecting them noticeably. If you have a reliable minimum radius and gap, and assume perfect vacuum (usually not the best assumption), you can take some proportion of the decay rate and set that equal to the current in the Fowler-Nordheim equation, then back-calculate the voltage. For kicks, you may want to use the current input and an estimate of capacitance to get an idea of how long it will take to charge up: I'm guessing quite a while.--Joel 09:02, 10 February 2007 (UTC)

Moon east

From Wikipedia:Reference_desk/Science#Reversed West and East on the Moon?.

What direction is east on the moon - according to astronomers, spacemen, scientists etc.

83.100.250.165 21:52, 7 February 2007 (UTC)

Or if east/west is not used - what system is used to define points on the moon?83.100.250.165 22:08, 7 February 2007 (UTC)

Per JPL, the moon has its own system of latitude and longitude with the lunar prime meridian at the center of the near side. Presumably, the center is averaged to account for lunar libration.

Of course, there's no telling what spacemen might use for a coordinate system. — Lomn 22:53, 7 February 2007 (UTC)

OK there are multiple ways.. Thanks - not knowing was really starting to irritate.87.102.2.204 09:59, 8 February 2007 (UTC)

Paleozoic marine animal name

I am trying to remember a name of a Paleozoic marine animal. I'm pretty sure its name starts with "dunkleo-", but I cannot find the remainder of the name, and I do not know how one would go about doing Wikipedia- or Google-searches for partial words. The creature is very distinct-looking for its very strange layer of teeth which appear to be all one jagged structure, like a continuation of the jaw bone. 206.176.113.70 22:05, 7 February 2007 (UTC)

Dunkleosteus - I searched for "paleozoic marine" on google by the way.83.100.250.165 22:10, 7 February 2007 (UTC)

Orbital characteristics

In the planet infobox, (as used here and in other planet articles), under orbital characteristics, four of the parameters are for aphelion, perihelion, semi-major axis, and semi-minor axis. How/why is the first pair different from the second?

--Awesome 23:52, 7 February 2007 (UTC)

The two pairs give two ways of describing the shape of the orbital ellipse. The aphelion and perihelion points are at opposite ends of the major axis, so the aphelion distance (A) and perihelion distance (P) are related to the semimajor axis (a) by 2a = A + P. The minor axis is perpendicular to the major axis and runs through the center of the ellipse (halfway between the Sun and the other focus). The semiminor axis (b) is not a very useful number for astronomical purposes, but it's related to the other quantities by (thinks a moment) a² = b² + ((A-P)/2)². --Anonymous, February 8, 2007, 01:29 (UTC).

I always find these kinds of descriptions useful but complex, so you might want to look at some of the images of an ellipse as a visual aid to the above answer. Put simply, the semi-major/minor axes are measured from the centre of the ellipse, while the perihelion and aphelion are measured from one of the two focal points (in particular, the one where the star is). It wouldn't be entirely unfair to say that the former two mathematically describe the ellipse, and the latter two physically describe the orbit. Spiral Wave 01:56, 13 February 2007 (UTC)

Species and Speciation

I thought that the thing separating species was that interbreeding between two different species was either impossible, or would not result in fertile offspring. So how does a new species evolve considering that it could not be the progeny of the species it evolved from? Is my definition of species incorrect? Is it not an absolute? Have I missed something? Is this a problem for the theory of evolution?—The preceding unsigned comment was added by 129.15.131.247 (talk • contribs).

Speciation occurs gradually, and often when a population of organisms is separated into subgroups by a natural phenomenon (e.g. a landslide, or continental drift, or just gradual migration). The subgroups of the population each evolves independently, responding to the pressures of their environment. Over time, they could adapt in different ways, until eventually the genes of one group are no longer compatible with the genes of the other. Maelin (Talk | Contribs) 04:16, 8 February 2007 (UTC)

First of all, there are several definitions of species. You are referring to the "Biological / reproductive" concept. New species would evolve when separate populations of the same species become separated and evolve in different ways. For example, suppose there is a species of fish in a lake, and that lake dries up, leaving only puddles with fish in them. Over time, the different puddles may evolve different types of fish. When the water levels rise again, and the fish are all together again, there will potentially be more species. − Twas Now ( talk • contribs • e-mail ) 04:17, 8 February 2007 (UTC)

No, no, I understand the patric speciation and how a group of one species can be split apart for whatever reason and therefore be subjected to different environments, each requiring different adaptations, but within each of those split groups, how would the population change into a new species? Eventually, wouldn't a member of the old species have to give birth to a member of the soon to be new species? What does that member of the new species mate with to increase the population of the new species? Would 2 mutants with similar adaptations and opposite sex have to be born around the same time so that they can increase their numbers? Is there some absolute cut-off point for the possibility of reproduction, or is it instead increasingly improbable that viable offspring will be created from a mating of two different species based on the number of genetic differences, meaning that a human and monkey could in fact create fertile offspring, only that it is a gross statistical improbability?—The preceding unsigned comment was added by 129.15.131.247 (talk • contribs).

Just because organism A is "close enough" to organism B to breed and organism B is "close enough" to organism C to breed doesn't mean that A and C can breed. It's not that one generation is one species and suddenly the next generation is a different one. DMacks 05:05, 8 February 2007 (UTC)

This is where the concept of species is sort of blurry. This excerpt from Richard Dawkins' The Ancestor's Tale (one of my favourites) is what you are asking, I think, but in a different way:

If species A evolves into species B, […] there must come a point when a child belongs to the new species B but his parents still belong to the old species A. Members of different species cannot, by definition, interbreed with one another, yet surely a child would not be so different from its parents as to be incapable of interbreeding with their kind. (pp.255)

− Twas Now ( talk • contribs • e-mail ) 05:06, 8 February 2007 (UTC)

If you want Dawkins' subsequent explanations on this, let me know. Oh, and please remember to sign with ~~~~ after you ask questions. − Twas Now ( talk • contribs • e-mail ) 05:59, 8 February 2007 (UTC)

@DMacks: Yes, I understand that not EVERY generation (and certainly not consecutive ones) will be a new species, but the problem I'm having is understanding how there will be (seemingly) new species offspring from old species parents, and how these new species, being, by definition, unable to mate with the old species, will be able to expand their population.

Speciation does not seem to occur absent an outside pressure (change in food sources or predation, environmental barriers to population mixing). In time, separate populations within a species will adapt to individual niches (perhaps plants located on windward vs leeward mountainsides or insects feeding on a specific local weed). Given enough time, these populations may diverge enough to meet our human-defined criteria for different species. -- Scientizzle 06:54, 8 February 2007 (UTC)

@Twas Now: Yes, that is a more eloquent way of putting my question. Now, what is the answer? ~~~~—The preceding unsigned comment was added by 129.15.131.247 (talk • contribs).

(when signing, don't include the nowiki tags...) -- Scientizzle 06:58, 8 February 2007 (UTC)

The answer is that "speciation" is a human construct, and mother nature has done quite well without confining herself to human rules for several millenia. -- Scientizzle 06:58, 8 February 2007 (UTC)

Perhaps she has done so for even longer than several thousand years! Whammy! Blammy wowie zowie! − Twas Now ( talk • contribs • e-mail ) 07:07, 8 February 2007 (UTC)

Quite right, but even young-earthers can agree on "several millenia" :) -- Scientizzle 07:15, 8 February 2007 (UTC)

Yes, I believe it was October 23, 4004 BCE? − Twas Now ( talk • contribs • e-mail ) 08:11, 8 February 2007 (UTC)

This diagram provides an excellent visualization of four different modes of speciation. − Twas Now ( talk • contribs • e-mail ) 22:02, 11 February 2007 (UTC)

Dawkins explains, that we should "allow for the possibility that an individual might lie half way between two species, or a tenth of the way from species A to species B" (pp.256). He goes on:

Are there sharp discontinuities between species, or do they merge into each other like first-class and second-class exam performances [referring to bell curve grading]? If we look at surviving animals, the answer is normally yes, there are sharp discontinuities. […] People and chimpanzees are certainly linked via a continuous chain of intermediates and a shared ancestor, but the intermediates are extinct: what remains is a discontinuous distribution. The same is true of people and monkeys, and of people and kangaroos, except that the extinct intermediates lived longer ago. Because the intermediates are nearly always extinct, we can usually get away with assuming that there is a sharp discontinuity between every species and every other. […] When we are talking about all the animals that have ever lived, not just those that are living now, evolution tells us there are lines of gradual continuity linking every species to every other […] in lines of smooth unbroken continuity. (pp.258-9)

In other words, an essentialist view of species is a mistaken view. But a fresher concept of "species" is not what you want to know—so let me take you through some hypothetical steps that would cause two lines of the same species to diverge into distinct species. However, remember to keep in mind this "continuous" view of species.

1. The two populations are separated somehow (often, but not necessarily, geographically separated). For example, one population (A) lives where conditions are moist and fertile, and the other population (B) lives where the climate is dry and barren.
2. Selective pressures on the two populations are different. For instance, members of population A may have selective pressure to evolve water-absorbent skin, while members of population B will have selective pressure to evolve water-retentive skin.
3. Other factors, such as sexual selection are likely to have an effect.
4. After sufficient time, the two species have changed genetically (from their initial species) to such a degree that they can no longer interbreed.

You may want to look up cladogenesis (splitting of one species into two) and anagenesis (change of one species from its ancestral to modern form). I hope this helps—and it should! − Twas Now ( talk • contribs • e-mail ) 08:03, 8 February 2007 (UTC)

Distinct species are unlikely to interbreed, not unable to interbreed. Very often the barrier between two sister species starts of behavioural rather than genetic - ie, they could interbreed, they just don't because they don't recognise each other's breeding display or breed at slightly different times. The Apple maggot is considered a case of incipient speciation - the flies that lay their eggs on apple flowers are still considered the same species as their cousins who lay their eggs on hawthorn, having developed a taste for apples in only the last few hundred years since Europeans introduced apples to North America. Because apples and hawthorn flower at different times, populations which specialise on one or the other need to emerge at different times and be attracted to different scents. Since they emerge at different times, they tend to breed at different times, so mixing is unlikely, but possible (there is no genetic reason that they can't). If you have one parent of one variety and one parent of the other, you might be lucky and inherit the right set of genes that makes you emerge at the right time and go searching for the right flower, or you might get the wrong combination of genes (and be looking for hawthorn flowers despite the fact that you emerged when apples were in flower). If you have the right pair, you merge seamlessly into that population (introgression). If you have the wrong pair, you're dead. So there is selection that favours keeping the two populations separate. In the future there might be more changes that gradually become established in one population or the other, resulting in populations that we might call different species. Guettarda 17:42, 9 February 2007 (UTC)

Vocal Octet

Greetings... I searched the wikipedia pages for the vocal octet. What I got was not what I wanted... Isn't the english vocal octet something "do re mi fa so...." I do not remember the whole octet but on the pages here this octet is not talked of. Could someone complete it for me?

The Do Re Mi page is a good starting point. DMacks 05:47, 8 February 2007 (UTC)

You are referring to solfege:

Do Ré Mi Fa Sol La Si

Do Ré Mi Fa So La Ti

− Twas Now ( talk • contribs • e-mail ) 05:57, 8 February 2007 (UTC)

Or perhaps you have confused 'octet' with 'octave', which in the vocal tradition is sometimes divided into 8 notes and sung with the syllables you mentioned. --bmk

Well, an octet is any group of eight things, so technically "Do Ré Mi Fa Sol La Si Do" is an octet. It is an octet of the eight Ionian mode intervals of an octave. This discussion might belong at the humanities desk. − Twas Now ( talk • contribs • e-mail ) 07:18, 8 February 2007 (UTC)

I think a "vocal octet" would be a group of eight singers. Duet = two singers, quartet = four singers, sextet = 6 singers, so octet should be eight singers. On the other hand, "vocal" can mean "outspoken." A group of eight articulate single-issue citizens forcefully expressing their opinion at a town meeting would be a "vocal octet." -Arch dude 01:14, 9 February 2007 (UTC)

Thanks for the response... 203.187.238.139 05:06, 9 February 2007 (UTC)