Wikipedia:Reference desk/Archives/Science/2007 August 4

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August 4

Beneficial mutations "objective?"

Hello. Quick question. EvoWiki writes [1] (Response, paragraph 2) that "there is no real "objective" measure of whether a mutation is harmful or not." Is this true? I usually take "objective" to mean existing outside of our perception ("it is that way"), and "subjective" to mean within perception ("it seems that way"). I think the author probably meant something more like "absolute." But just in case: it isn't really true that there's no way to tell whether a given mutation is beneficial other than appealing to whether it "seems that way," is it? Schmitty120 02:42, 4 August 2007 (UTC)

I think that is fair because what is considered "harmful" or "beneficial" is subjective. For example, is a mutation in the β-globin chain of hemoglobin "harmful", or "beneficial" or "neutral"? It depends on various circumstances including:

• How many mutant alleles you have
• Whether you are exposed to malaria
• The genotype of numerous unknown genes that interact with hemoglobin

So, depending on your personal circumstances with regards to the above, you might argue the mutation seems beneficial to you (e.g. you are a heterozygote in Sub-Saharan Africa), or the same mutation may appear harmful (you are a homozygote in the West). At a truly objective level assessing whether a mutation is harmful or beneficial is per se is near impossible. Rockpocket 03:11, 4 August 2007 (UTC)

That's overstating the point. If the result of the mutation A is that the victim is stillborn, it's clear enough that mutation A is harmful. If the only result of mutation B is to cancel the effect of mutation A if they both happen, it's clear enough that mutation B is beneficial. The thing is that the effects of mutations, if there even are any, often are not so clear-cut. Even if a mutation simply increased one's lifespan, that might be harmful if it caused the population to outstrip the food supply. --Anonymous, August 4, 2007, 03:21, rewritten 03:26 (UTC).

I don't know the meaning of the word stillborn, but I know that it being a harmful thing is a subjective evaluation of yours. A.Z. 03:37, 4 August 2007 (UTC)

• It means born dead. Now do you still feel that way? --Anon, August 4, 08:54 (UTC).

There are clearly extremes, for example its difficult to argue that mutation A, a dominant negative allele that results in 100% stillborn fetuses is anything other than harmful for one of those fetuses. However, your example about mutation B is a good case in point. The benefit of this mutation is entirely depending on its interaction with mutation A. The effect of mutation B in the absence of mutation A could be mildly harmful or neutral, therefore the effect of mutation B in isolation is subjective. The point of the original statement (in my interpretation) is that genes, alleles and mutations do not exist in a vacuum. Our interpretation of their effects cannot be judged without considering their environment, and that includes the effect of thousands of other alleles and other exogenous factors. Sometimes the effects of genes overwhelms environmental considerations (like mutation A), other times environmental considerations almost absolutely dictates the effect of a gene (like mutation B). The vast majority operate somewhere in between. Rockpocket 03:49, 4 August 2007 (UTC)

If a mutation aids the propogation of the possesor's genes, then it is beneficial. Likewise if it inhibits or reduces the likelihood of that propogation then it is harmful. Survival of the fittest, that is all. However, in many cases whether a mutation was beneficial or harmful can only be ascertained in hindsight, if ever. Dragons flight 04:13, 4 August 2007 (UTC)

I think it's an entirely measurable property. (ie "Objective" as opposed to "Subjective") Evolution is the final arbiter of what is good and what bad - but it always takes place in the context of some kind of environment. Every gene that the mechanism of evolution 'keeps' must have been beneficial (or at least pretty much harmless) in the context that the animal was living in - and every bad gene that's rejected across the population must be bad only in the context of some new environmental factoor - or else why would it have existed in earlier generations?

Examples are everywhere in nature: Look at frogs - a frog that's born without any eyes is normally at a severe disadvantage - and so all frogs have evolved eyes...except for the ones that live in deep, dark caves. When animals get moved into such a habitat, there is an evolutionary pressure to save energy by not having eyes. So is the gene for eyes in frogs beneficial to the frog or not? The answer is: It depends on whether it lives in a cave or not.

My all-time-favorite example is adult Lactose tolerance in humans, In a 'normal' mamallian species, animals develop an intolerance of lactose as a mechanism to force them to wean off of mothers milk and onto regular food in time for the birth of the next batch of siblings. So the gene for adult lactose intolerance is "A Good Thing" in most species - as it was for mankind as recently as perhaps 4000BC. But with the advent of domestication of sheep, goats and cows, that all changes. Suddenly, there is huge benefit in adults being able to consume milk products without discomfort - and lo and behold - lactose tolerance starts to evolve. So is the gene for lactose intolerance a good gene or not? In the context of an agricultural society - it's clearly bad - in the case of hunter-gatherers, it's obviously good. SteveBaker 06:20, 4 August 2007 (UTC)

That isn't entirely so at the multi-gene level, Steve. Evolutionary mechanisms are much more complex than a simple "keep if beneficial, don't keep if not". For example, a mutation that is deleterious could be "kept" due to its tight linkage with a strongly advantageous locus, an example of linkage disequilibrium. Population bottlenecks and founder effects can lead to reproductively deleterious mutations - that may have always been reproductively deleterious - becoming widespread in isolated populations. Its not that they are beneficial to reproduction in a zero sum game, simply that competition from other alleles has been relaxed. Natural selection does not happen at the single gene level, its assortments of alleles that are selected for, and if your assortment is able to successfully reproduce better than another assortment, it will be more successful. But that does not always mean that every single allele in the successful assortment is more beneficial than its corresponding allele in an unsuccessful one. Rockpocket 07:06, 4 August 2007 (UTC)

Okay, maybe I should back up. My impression was that a "beneficial" mutation, in biological terminology, was one that increased an organism's ability to reproduce. Is this correct, almost correct, or completely wrong? And if it is correct, is measuring how beneficial a mutation is "objective" (as in matter of fact, "the pizza contains 5 grams of salt") or "subjective" (as in matter of taste, "the pizza tastes good")? I understand that whether the mutation is beneficial is relative to the environment, but is it still correct to say "It is objectively true that the mutation was beneficial to that mouse over there?" Thanks. Schmitty120 14:27, 4 August 2007 (UTC)

Maybe it's helpful if we consider the whole paragraph you're quoting? It's a response to the claims by those opposed to evolution that "Most mutations are harmful"

Whether a mutation is harmful or beneficial or neutral in terms of increasing the functionality or survival of an organism is highly contextual: a mutation that can be harmful in one environment (such as a decreased subcutaneous fat layer on a polar animal) could turn out to be helpful if the environment changes (such as if the temperature increases). Aside from mutations which simply destroy embryonic development or cause premature death, there is no real "objective" measure of whether a mutation is harmful or not.

From what I understand what it's saying is that you can't say "this is a harmful mutation". Whether or not a mutation is harmful depends completely on the environment in most circumstances, there is no way you can objectively determine that a mutation is harmful. You can of course objectively analyse whether a mutation is evolutionarily harmful or beneficial in a defined environment. Should the evowiki thing be re-worded? Perhaps, but that's something that should be discussed there not here... Your understanding of whether something is beneficial in evolutionary terms is mostly correct but bear in mind it's the ability of the organism to successfully reproduce. What I mean here is that it's not simply the number of offspring but the number of offspring that the offspring have etc that matters. Nil Einne 15:29, 4 August 2007 (UTC)

Sure - but right there you have your objective measure - how many offspring does the animal with the mutation have compared to the general population of similar animals living in the same environment? Obviously it may be necessary to measure that over several generations - and getting a large enough statistical sample may be tricky - but it's still an objective measure. SteveBaker 17:31, 4 August 2007 (UTC)

Perhaps I wasn't as clear as intended, rockpockets explaination might be better. If not, read on. I wasn't saying you can't objectively determine the effects of a mutation in a defined environment. In the second part, I was simply explaining that determining reproductive success is not a simple matter of 'does this organism reproduce more'. In theory you can objectively measure whether a mutation is beneficial or harmful in a defined environment, but remember it's only that environment (and as rockpocket has explained, it's not simply the physical environment that matters here). But the fact that a mutation is harmful in a defined enviroment doesn't mean you can call it a harmful mutation since it'll likely depend on the environment. If you do, it's not objective in the sense that you're subjectively deciding a mutation is harmful because it's harmful in a certain environment. Therefore, saying "most mutations are harmful" makes no sense. From what I can tell, that's what the evowiki was saying (more or less). Nil Einne 21:40, 4 August 2007 (UTC)

I'd note that it may be overkill to look at the statement "most mutations are harmful" in the context of whole-organism effect or evolutionary fitness. Rather, look at the effect of a random, point mutation on a particular protein. Most functional proteins are the result of a great deal of optimization as the consequence of many generations of selection. At the single-protein level, a point mutation is much more likely to result in harm (loss of important function or gain of toxic function) than in some improvement. You're going to muck up a binding site, or interfere with a fold, or interfere with some sort of signalling, or reduce stability, or (dangerously) increase stability. A molecular or structural biologist, on hearing the statement "most mutations are harmful", will almost certainly shrug and say, "Well, duh." TenOfAllTrades(talk) 22:22, 4 August 2007 (UTC)

Speaking as a geneticist, we do talk about single alleles being beneficial or harmful in the manner you discuss. However, what we mean, albeit often unspoken, is that that allele is beneficial to reproduction in the context of the genotype/enivironment the animal is in. There are, for example, alleles that appear to have adverse effects in BALB/c but not C57BL/6. These are both the same species of mouse, and are kept in identical environmental conditions, the only difference is that there have other alleles that are different (in the same way you have different alleles to me). So, assuming we can objectively determine how that mutation effects their ability to reproduce (that itself is not trivial for the majority of alleles), is that mutation harmful or neutral? It all depends on the context you wish to judge it (in this case, in which assortment of other alleles is co-exists with) and because you can never isolate the single mutation from its genetic environment, you can never have an measure independent of these factors. Therefore deciding when an allele meets the "harmful" or "neutral" criteria (without caveat) is subjective, though the criteria for what makes if "harmful" or "neutral" itself is objective. Rockpocket 18:27, 4 August 2007 (UTC)

All right, thanks for the information. Schmitty120 20:09, 4 August 2007 (UTC)

Thinking about this a little more, today, I guess this could be simplifed by distinguishing between genotype and phenotype. Its very difficult to assign "benefit/harm" effect to a genotype, but not so difficult to attribute to its phenotype. Rockpocket 23:48, 4 August 2007 (UTC)

"Shunning" in gulls? - re-asking as my original question has been archived without answer...

Does anyone know the correct name for the behaviour wherein a sickly or injured gull will be driven from the larger gull flock by force and abandoned to fend for itself/die? From what I've read, albino gulls often get the same treatment? Shunning immediately came to mind but upon reading the article, that term seems to refer only to humans. --Kurt Shaped Box 07:31, 4 August 2007 (UTC)

This is another instance where a dictionary is more appropriate than an encyclopedia. I see not reason not to apply the term to animals and birds. It is a good description of that behaviour. Whether it is the term used in gull behaviouristics I have no idea.--Shantavira|^{feed me} 07:42, 4 August 2007 (UTC)

Thanks a lot. Maybe someone should write a Shunning in animals article? I could start one but it would be completely unreferenced, as I have no idea what to look for in order to research it. I don't think that it's just a gull thing by a long way - but gulls are pretty savage and completely merciless about it (if the individual won't leave, they'll kill it without a second thought) when they do decide to 'shun'. --Kurt Shaped Box 08:02, 4 August 2007 (UTC)

The psychology term seems to be social rejection, but I don't know if there's a standard in biology. Ostracism is another good word though it suggests a complexity not found in animal societies. Shunning is used rarely, as a synonym to avoid repetition, as in this article on chimps. Bendž|Ť 11:10, 4 August 2007 (UTC)

God, can you imagine how fascististic (is that a word?) a gull society would be if they ever evolved as far along as humans? A world where the strong go out and take what they want while the weak are crushed when they are no longer useful. A world where any hint of being slightly different results in persecution and death. Talk about having the whole world painted gray and black. Yes, they'd love gray and black. --84.68.99.28 21:40, 4 August 2007 (UTC)

That doesn't actually sound a whole lot different to the majority of human history. At least gulls don't seem to have the concept of 'racial purity'. :) --Kurt Shaped Box 22:31, 4 August 2007 (UTC)

clouds

what is diff b/w black& white clouds? why dont clouds condense in summer?Prasanth prav 08:11, 4 August 2007 (UTC)

All clouds are white on the side facing the sun. The other side is light if the cloud is thin and a lot of sunlight passes through, or dark if the cloud is thick and dense and much of the sunlight is blocked. See Cloud#Colors.

On the second question I'm not sure exactly what you mean by "condense", but I guess you're thinking about the way things are in places where the climate is dry. If the air is usually dry, then clouds will not often form, and when they do, they will not often produce rain. In other places with different climates, clouds and rain are common in the summer.

--Anonymous, August 4, 2007, 09:17 (UTC).

Just to further on Anon's comments, the colour of a cloud is also somewhat determined by the denseness of the moisture inside it (but he's correct, so far as I've ever read, that the primary determinant is the thickness of the cloud). So, to literally answer your first question, the key difference is that dark clouds are more likely to rain on you in appreciable amounts; fluffy bright white clouds will deliver little or no precipitation. Matt Deres 14:44, 6 August 2007 (UTC)

Dr Donor

What was the name of the doctor who ran a fertility clinic in the US and all the babies turned out to be his?--Shantavira|^{feed me} 13:04, 4 August 2007 (UTC)

Cecil Jacobson. --Joelmills 15:15, 4 August 2007 (UTC)

even though white clouds are there in summer , why dont these clouds form rain?

John Doe Plant

File:IMG 8934.JPG

This is the plant in question

I took some seeds from the school biology lab last year and planted them at home just to see what I would get. The result is a flourishing collection of about 1 - 2 foot high, thin grey/yellow-stalked plants with dark green tear drop leaves about 1 - 3 inches long found only at the very top of the stalk. Seeds bud along the edges of every leaf, numbering in their dozens. These seeds each have small 1-2mm leaf-like things around them while they are still growing on the edge of the mother leaf, and they fall off if flicked or blown strongly upon, and land at the foot of the mother plant and grow there. What on earth am I growing here? SGGH ^speak! 13:40, 4 August 2007 (UTC)

I don't know, but at the risk of drifting off-topic, all I can say is that it's a good thing this isn't a horror movie, or some other kind of fiction! —Steve Summit (talk) 13:46, 4 August 2007 (UTC)

what do the flowers look like? Nil Einne 14:43, 4 August 2007 (UTC)

It's flowerless... I'll try to take a picture of it. SGGH ^speak! 15:32, 4 August 2007 (UTC)

What you are describing sounds like plantlets, not seeds, forming on the stem of your plant. Hence your observation that it is flowerless. The succulent plant Bryophyllum is well known for reproducing in this fashion. However, your description of the plant as a whole does not seem to fit. Try doing an image search on google with the key term "Bryophyllum" and see if any of them look like your plant.--Eriastrum 17:34, 4 August 2007 (UTC)

I have added an image of it. SGGH ^speak! 21:35, 4 August 2007 (UTC)

Turned out to be Kalanchoe daigremontiana, thanks for your answers though :) SGGH ^speak! 22:22, 4 August 2007 (UTC)

Bryophyllum daigremontianum is a synonym of Kalanchoe daigremontiana. --Eriastrum 23:28, 4 August 2007 (UTC)

It's a little leggy; could use more light. Bendž|Ť 07:22, 5 August 2007 (UTC)

metric tons conversion to litres fuels

How do I convert metric tons of Fuel (petrol and gasoline) into litres ? 12.500 metric tons = ................litres ?

They Petrol article says "The weight-density of petrol is about 737.22 kg/m3". You do the math... (If you can't check out density and tonne and litre) Nil Einne 14:31, 4 August 2007 (UTC)

The result will vary, depending on the type of diesel and its temperature. Diesel fuel oil 20 to 60 at 15ºC has a density of 0.820 to 0.950 kg/L. A good average value is Diesel oil 40 at 15ºC with a density of 0.850 kg/L. 1metric ton = 1000 kg, 1000 kg / 0.850 kg/L = 1176.47 liters SGGH ^speak! 14:33, 4 August 2007 (UTC)

Sunflowers with 2 heads

I am growing some sunflowers at the moment and one of them is developping two heads which look like they´re going to become twin flowers in one plant. Is this normal and what is it called? Also, I have planted seeds (such as orange/lemon pips and a mango) and I am getting two plants sprouting from one seed in some cases, like twins - what is this and can I separate them when transplanting? Many thanks in advance for any information or links! --AlexSuricata 14:42, 4 August 2007 (UTC)

Double-headed sunflowers are not "normal", but on the other hand they are not unusual. Keep in mind, of course, that a sunflower "head" is not really a single flower, but an aggregation of numerous flowers (technically called "florets", I believe). Such flower heads are characteristic of the Sunflower Family (Asteraceae) and are usually called "composite". I have seen double-headed flowers on a number of different types of plants in the Asteraceae, including dahlias and chrysanthemums. I don't know if there is a technical term to describe these double flower heads.--Eriastrum 17:11, 4 August 2007 (UTC)

I know when my dad raises orchids, he buys some sort of plant hormones for orchids and makes a small incision with a razer and places a bit of that hormone. More often than not, that cut will sprout a bud. Maybe something in the soil you're using is promoting this multiple bud growth? --Wirbelwindヴィルヴェルヴィント (talk) 20:47, 4 August 2007 (UTC)

efficiency of transport

Hello. I'm trying to find data concerning energy efficiency of water transport. The only figures I've found so far is for inland US waterways. Fuel_efficiency_in_transportation#US_Freight_transportation see table which gives a similar figure to railroad...

However I was wondering about bulk shipping - containers and bulk solids etc, specifically with comparison to rail (Figures in terms of Watts per tonne per km or equivalent), I don't know enough about fluids to guess at energy losses, so can someone help. My guestimates using the data on Suezmax size ships give a figure of about 10x more efficient than rail (at best). Any feedback would be appreciated.87.102.93.50 15:14, 4 August 2007 (UTC)

The link you gave goes to this website [2] which while discussing people does talk briefly about cargo at the end including this link [3]. I don't know how much you'll find though since I'm guessing bulk shipping vs rail comparisons are not that common. Bulk shipping I would guess predominantly competes with air or has no competitor. However the energy cost of bulk shipping has received attention particularly given the recent hype about 'food miles'. See the article for one report into the overall energy cost of food production. The energy cost of shipping food from New Zealand to Europe was obviously one factor considered in this report and although there would I presume be no info on rail transport in the report, it might be useful for your own research. Indeed from memory the energy cost of shipping products from one country to another is sometimes said to be lower then the energy cost of transporting the products internally via truck Nil Einne 16:49, 4 August 2007 (UTC)

Thanks, the second link you gave was spot on - 5 times better than rail it seems. I was thinking about comparisons between for instance

China to UK via suez channel vs. China to UK via trans siberian railway

or

East USA to West USA via panama vs. East to West USA via rail.

It looks like sea is far better even with a longer route, possibly due to scale rather than anything else, which suprises me a bit because water is quite hard stuff to push through (compare swimming vs walking as not a very good comparison..)87.102.93.50 17:17, 4 August 2007 (UTC)

Well, I do remember reading in Garraty's US history text book that before a highway was finally built across Pensylvania, shipping something by wagon from Philidelphia to Pittsburg was more expensive than sailing it down the east coast, into the Gulf of Mexico, and then hauling it upstream through a series of rivers to finally reach Pittsburg.

Is the earth materially closed?

Since the earth was formed eons ago, have any atoms been lost out to interstellar space from the earth/atmosphere system? Have any been gained? josei 17:29, 4 August 2007 (UTC)

It's not even close to being a closed system. Large numbers of meteoroids hit the planet every day, and yes, gas is also lost to space. --Trovatore 17:45, 4 August 2007 (UTC)

As the mass being exchanged per year is a only small fraction of the total mass of the earth, it is fair to say that the earth is close to being a closed system. Bo Jacoby 17:54, 4 August 2007 (UTC).

Most scientists (I'm certain there are exceptions) will explain that the Earth's magnetic field makes it as close to a closed system as possible. -- Kainaw^(what?) 18:17, 4 August 2007 (UTC)

Perhaps for things going out, but meteroids that make it to the surface contribute matter that is quite large relative to any atoms that escape out of the field. So I would say it is inputted to, if not outputting quite as much? SGGH ^speak! 22:02, 4 August 2007 (UTC)

Most of the earths material is enclosed to the inside, and exchanges only sporadically by volcanic action. Thus the effect of escaping gases and incoming meteroids is very different when viewed considering the whole mass or the atmosphere and the geological surface. 84.160.204.218 20:13, 5 August 2007 (UTC)

Atmospheric escape, Giant impact hypothesis, catastrophic blow-off, meteorite dust --JWSchmidt 03:01, 6 August 2007 (UTC)

Boiling with less than the recommended minimum level of water...

My mum has bought a kettle based on its aesthetics but the minimum water level is 0.7 litres! She will use it often for only making one cup of tea at a time. The heating element is not a conventional coil-shape but constitutes the bottom of the kettle. Is there something food-safe that we can put into the kettle to displace water and take it up to the 0.7 litre mark? Frankly, I think the government should prohibit the design of devices where aesthetics takes presidence over efficiency... --Seans Potato Business 18:05, 4 August 2007 (UTC)

I have the same kind of kettle, and frankly I don't bother with this 0.7 litre mark. I often boil less than half a litre. And concerning your wish for governmental interference, have you given any serious thought to what type of society that would create?? Lova Falk 18:22, 4 August 2007 (UTC)

The type with practical kettles? You make it sound as though my idea could be the basis of some sort of dystopia...

Anyway, I want to be able to boil with only 0.25 L... --Seans Potato Business 19:03, 4 August 2007 (UTC)

A dystopia "is usually characterized by an oppressive social control, such as an authoritarian or totalitarian government." Yes, that would be an accurate description of a government that prohibits the design of devices where aesthetics takes presidence over efficiency. Your mother's freedom to buy a device that is more beautiful than efficient is a very important freedom indeed. Lova Falk 19:57, 4 August 2007 (UTC)

PS It is the government's ideas about the value of aesthetics that is the problem for me. A government creating minimum requirements for the efficiency of devices is fine with me. Lova Falk 20:05, 4 August 2007 (UTC)

Buy a travel kettle, they are small. Easily available in the UK, dont know if you have them in the US, if that is where you are from. If I was in the UK I could take the big kettle back to the shop and get a refund; in the US would the shop proprietor produce a pump-action sawn-off shotgun from under the counter and request you to leave the shop with your kettle but without a refund? 80.2.211.116 19:10, 4 August 2007 (UTC)

For a single cup of water, the microwave is faster and more efficient. -Arch dude 19:16, 4 August 2007 (UTC)

I'm rather sceptical of that claim, particularly for efficiency. Do you have a source, or some calculations I could look at? Skittle 00:25, 6 August 2007 (UTC)

Mum hasn't kept the packaging nor the receipt and has already been using it a month, so I'm not sure that getting a refund is possible (this is about the UK, yes). I'll look into the microwave idea but will warn other readers that boiling water in the microwave can be dangerous (see Wikipedia article on microwaves). --Seans Potato Business 19:22, 4 August 2007 (UTC)

Yes, and you can't really make a cup of tea in a microwave. A friend of mine boils the "minimum" amount of water, makes her tea, then keeps the remainder in a thermos flask for later. I regard this as a little eccentric, but it is ecological end efficient. I drink tea by the mugful, usually two at a time, so boiling the minimum amount isn't a problem for me. I reheat tea in the microwave if necessary.--Shantavira|^{feed me} 07:32, 5 August 2007 (UTC)

As to what you could put in it that won't be a health problem, won't anything that doesn't give off anything in boiling water do? Such as any material that kettles are made of, ie a piece of metal? The biggest problem seems to me to be putting something in it that won't start bouncing about. Attaching it to the bottom doesn't seem workable, but maybe something that fits snugly? I'd don't know how easily you can do this with the kettle in question. DirkvdM 09:08, 5 August 2007 (UTC)

It also needs to be something with a low specific heat capacity, otherwise it will still be wating energy just to heat a block of something. I thought perhaps a ceramic block or glass paperweight, that wouldn't conduct the heat very well. Will glass cause a problem if it rests on the bottom of the kettle? --Seans Potato Business 16:56, 5 August 2007 (UTC)

The problem with putting something into the kettle is that either:

• It conducts the heat away from the element - in which case it's consuming the energy you're trying to save...it's behaving just like water would have done.
• It doesn't conduct the heat away from the element - in which case that part of the element overheats and melts - or catches fire or something.

Either way, you lose! That's why they tell you to put enough water in it in the first place! You have to have enough water to completely cover the heating element - if you don't then it'll destroy itself. SteveBaker 21:14, 6 August 2007 (UTC)

Piloting a spacecraft

This may be more of a science fiction question than a science question, but here goes: Would it be plausible to control a spacecraft (I'm thinking especially of small fighter craft) with a stick, like they do in movies? In an airplane you can only bank, dive and climb; but in a spacecraft, you could pivot horizontally or vertically, you could roll, or you could move up, down, left or right without changing your direction of flight. How could you control all these movements with Star Wars-style airplane controls? And as a followup, what would be a more plausible set of controls for a small, maneuverable, spaceplane-like fighter craft? (Or is such a craft just hopelessly implausible to begin with?) --Lazar Taxon 19:01, 4 August 2007 (UTC)

One crucial maneuver that is possible for a spacecraft, but not for a fixed-wing aircraft, is rotation about the vertical axis. You could could control this by twisting the stick. This assumes a spacecraft with one main fixed reo nearly fixed main engine, and appropriate additional thrusters for pitch, roll, and yaw: this seems to be the default science fiction convention for a fighter and for most fictional and real spacecraft. The yaw control is very important: since ther is not air, the spacecraft can spin so that it is facing backwards with refpect to is velocity vector, and in fact is must do this to decelerate. -Arch dude 19:13, 4 August 2007 (UTC)

There should be no probs building a joystick that works retrorockets etc on the spaceship’s surface and makes it go anywhere you like, at any speed. Of course you are positing a fighter craft. But what a lot of people still forget is that space, unlike air space is a very very big place. Ordinarily, there is simply no need to go charging about like a blue-arsed fly. Star Wars is responsible for continuing the sci fi idea of space as a crowded arena of comets, and asteroid belts that team with gigantic boulders every three feet or so. In the Flash Gordon episodes of the 1930s (and in just about all of space fiction prior to the first sputniks of the 1950s, people still had the idea of driving a rocket ship like a jet. With the pilot up front, the ship made a lot of noise, it had its rockets on ALL THE TIME (just like a jet) and the pilot sat up the front, looking thru the window as he “drove” his ship. Ships went from planet to planet in a matter of days, and there was none of this stuff about orbiting around the world. Rather like Star Wars and sci fi today.

In fact, if you rem 2001 you will get an idea of what it might be like on an interstellar voyage. Like being in a giant oil tanker making imperceptible progress against a background of emptiness, and taking decades to get anywhere. So you might have a joystick, but there would be precious little joy in it. Just aim for Alpha Centauri, push the button, and go downstairs and play computer games for the next 25 years. Why would you have human controlled jets, when in space you could just get guided missiles to do the job. On earth, where the terrain and atmosphere make it much harder, nevertheless, I doubt if human powered military aircraft will see the year 2040. All drones and missiles. Myles325a 06:57, 9 August 2007 (UTC)

So maybe you could have an airplane-style stick, but in addition to tilting it forward and back, left and right, you could also pull it straight up, push it straight down, move its base left and right, and twist it? (I guess it just bugs me that in a lot of science fiction, they treat spacecraft as if they were airplanes, and they seem to have no clue how things really move in space.) --Lazar Taxon 19:26, 4 August 2007 (UTC)

Use buttons on the stick to toggle between different flight control modes?87.102.93.50 20:09, 4 August 2007 (UTC)

I've never flown a real plane, but I've flown many simulators (real ones that are full-size replicas of 727, 747, and 767 aircraft). The yoke is only part of the flight control. There are also rudder pedals on the feet that can be moved right and left as well as tilted up and down. I don't see why a spacecraft would eliminate the pedals. As for flying a spacecraft with a joystick, there have been many video games that use a single joystick for flight. Normally, the joystick rolls or tilts the craft. A separate thrust (forward/back thrust) is used for displacement. -- Kainaw^(what?) 20:20, 4 August 2007 (UTC)

Yep, I totally forgot about pedals... --Lazar Taxon 20:52, 4 August 2007 (UTC)

The Space Shuttle uses two controllers, the rotational hand controller (RHC) and the translational hand controller (THC). The RHC controls pitch, yaw, and roll, like the stick you've alluded to. The THC moves the shuttle forward and aft, up and down, and left and right (all in the orbiter's frame). Between the two, all 6 degrees of freedom are covered. anonymous6494 04:36, 5 August 2007 (UTC)

I work with an unmanned underwater vehicle which can move in all three directions, and rotate in all three directions. We use an ordinary gaming joystick, the Logitech Extreme 3D Pro [4]. The main joystick's forward/back, side-to-side, twist, and throttle actuators give us 4 of the 6 axes we need. We don't usually care about controlling pitch angle and roll angle, but when we do, we can use the additional "hat" controls on the end of the joystick.

I suspect a lot of gaming joysticks have a full 6 axes, because the gamers have thought about these problems in detail and need valid solutions, even if Hollywood hasn't. —Steve Summit (talk) 12:38, 5 August 2007 (UTC)

Try the Orbiter space simulator and see for yourself.

How do you declare a theory?

Every time you read something, it often relates to a theory that has been put forward. I was wondering how you actually put a theory forward? Im a keen follower of physics and have my own ideas on certain issues and (even though there probably rubbish!) i would like to put it forward. Im doubting that Stephen Hawkings will read this but im sure someone out there must know. If someone could help me with this, i would be much appreciated. Thanks a lot. Chris

You can declare a theory yourself in the bathtub if you want; there's no special process. If you want opinion formers in the subject to read about it, you need to write a scientific paper and have it accepted by a widely read peer-reviewed journal. -- Finlay McWalter | Talk 19:21, 4 August 2007 (UTC)

And to ask a further question, how would i write a scientific paper? Is there a specific layout or format that i should use?

Scientific_literature has some guidelines. But realistically I would think you would need to get a PhD and a position at a university (or at least co-author with someone who has) for a paper to be considered by a respectable journal. Tomgreeny 19:44, 4 August 2007 (UTC)

I work in computer/medical research. All of the journals I've worked on papers for have very strict guidelines for who can submit a paper, how they can submit a paper, the format the paper must be, how the paper must be reviewed, how edit requests are handled, and who has publishing rights on the paper after being accepted. All you have to do is contact the journal you are interested in. -- Kainaw^(what?) 19:48, 4 August 2007 (UTC)

One easy option for you is to present your theory (briefly please) on this desk and ask if anyone knows if similar theories exist - in all likelyhood even if you came up with the idea off your own bat numerous others will have had similar ideas.

You could publish your theory on the internet though getting others to read it might be problematic. Alternatively write it up and take it to the nearest relevant university department and ask someone to look at it (request an interview). You can only try. That said in general publishing in a scientific journal (as others above have siad) is a closed shop and you would need not only lots of qualifications, but also references from other academics.

I know of no way that an 'amateur' can get published but there are numerous forums and q/a sites on the internet that you could get some feedback on what you have thought. So be bold and ask.87.102.93.50 20:19, 4 August 2007 (UTC)

Basically you need to ask yourself, why should somebody devote any time to my theory? Why would they think I know anything about the topic? Do I know enough about it to avoid making silly errors?

Let's assume you are in fact informed on the topic and can have something to say about it, but do not have any easy way "in" to the established physics professions (there have been some people who ended up being very influential who were in just such a position, but it is VERY rare, and to most of those who are thought of as being "outsiders," like Einstein, were highly educated in the subject and not nearly as "outside" as popular culture leads us to think they were). What do you do? The first step is to make sure you haven't done something silly and obvious. A good way to do that is to find someone with a little knowledge and run some of your ideas by them. (Even this very Reference Desk is not at all a bad place to do that, as there are a number of people on here with good technical education and understanding.) Assuming you don't hit some major, obvious roadblock, then you need to seek out someone already in the profession who will give you their time. This might not be the easiest thing in the world — you don't want to come off as a crank, and you need to convince someone you are worth their 10 minutes. Just writing to professors is likely to do nothing — Departments of Physics (and individual professors) have bulging "crank files" of people who write in with impossible proposals and baseless theories. I doubt most of them give such things more than a second's consideration. They certainly aren't likely to actually work through it step-by-step and try to figure out whether it has much merit — their economic livelihoods are rooted in their spending their time on their priorities and work, not yours.

But let's say your theory is good. You manage to convince a physics professor at your local university to have a 15 minute meeting with you. You run it by them. Maybe they like it. Then you can use them to try and make connections with other more established members of the profession. With a "sponsor" you can much more easily get something taken seriously and potentially examined by a peer-reviewed journal. (This is, mind you, pretty much how outsider Einstein was able to get his relativity theory taken serious; Max Planck, a very well-respected physicist at the time, was responsible for pointing people to Einstein's work and convincing them it could not simply be ignored.)

If you just write up something and put it on the internet, you'll be joining thousands of others who are soundly ignored. In my experience you will also begin isolating yourself from any clear thinking you may have once had, and will become unable to be properly self-critical of your work. My suggestion: start small, see if it makes sense to anyone other than you, see if you have made simple errors, etc., before you try to enact a "paradigm shift". The odds are you have made a mistake somewhere, or do not understand the subject sufficiently to contribute to it in any real way. That's just the "odds" — maybe you are that one-in-a-million shot. But you should be extremely dubious about that possibility, at least as dubious (if not more) than others will be of it (there are plenty of morons in the world who will sign on to anything if they think it is "revolutionary") — at this point, self-criticism is the only thing which is going to help you progress your understanding, and if you lose that then you're just another crackpot, right or wrong. --24.147.86.187 20:31, 4 August 2007 (UTC)

The acid test for a theory is "does it make testable and falsifiable predictions" (ideally predictions about things that matter to someone). So you might have a theory that the universe is shaped like a sausage, and a complex argument that says why. But so what? Some other guy will have as compelling an argument that the universe is shaped like a saddle, or an onion, or a lunchbox. If your sausage theory can predict something testable about the speed of recession of distant galaxies and some astronomer later can measure that and verify your prediction is correct, then you've advanced human knowledge some distance. This is the problem a lot of string theory has - it has some great theories, with very elegant mathematical underpinnings, but so far it makes very few testable predictions (and so its opponents decry it as not really being physics at all, but more a branch of recreational mathematics). Science isn't so utilitarian as to demand every theory be useful, but it does have to make testable predictions. -- Finlay McWalter | Talk 20:51, 4 August 2007 (UTC)

Publication in a peer-reviewed journal would be a very good step towards getting your theory well known amongst other people in the field. However, before you even attempt that, I would strongly recommend finding someone with some kind of scientific background who would be prepared to discuss your theory with you because in all likelyhood that will either immediately find a bunch of problems with it - or if it's truly solid and novel, it will get likely get this person excited enough to support your efforts. If you know someone like that = then go for it! If not, you could certainly discuss it with people from right here on the science desk - most of whom would (I'm pretty sure) be willing to help out. SteveBaker 05:21, 5 August 2007 (UTC)

Chris, you say you are a keen follower of physics, but you're unfamiliar with peer-reviewed scientific articles? Every discipline can use fresh insight, but ask yourself this: how valuable a contribution can you make if you're not even familiar with what's going on in the field? Since you mention Dr Hawking, I'm going to guess that your theories lie in the realm of cosmology. The best way to get to know that field is to spend a decade or so on your doctorate and go from there. The first baby step would be to read peer-reviewed journals (as opposed to stuff like SciAm and Discover, good as they are), like The Astronomical Journal and The Astrophysical Journal. If that stuff is completely over your head, you probably don't have anything insightful to add... yet. Here's the abstract from a recent ApJ article: We study the luminosity functions of high-redshift galaxies in detailed hydrodynamic simulations of cosmic reionization, which are designed to reproduce the evolution of the Lyα forest between z~5 and ~6. We find that the luminosity functions and total stellar mass densities are in agreement with observations when plausible assumptions about reddening at z~6 are made. Our simulations support the conclusion that stars alone reionized the universe. Matt Deres 20:04, 5 August 2007 (UTC)

Planting acorns and fruit stones

I am in the UK and I have a few english oak acorns I would like to plant in my garden. This is mostly for fun, I realise a more efficient way of growing a tree would be buying a sapling. I also have a few plum stones - I think these might be called "pits" in the US, I'm not sure. In a few weeks my very favourite plum variety, Victoria plums, will probably be on sale and so I will have these stones also. Could anyone tell me the best way to plant them please - I will put them in a small pot indoors initially. Things I'd like to know include best time of year for planting, any pre-treatment, depth of putting acorn or stone. There seems nothing about this on the internet. Thanks. 80.0.112.131 19:26, 4 August 2007 (UTC)

According to this, plums are hybrids usually grown by grafting (like apples) onto hardy rootstock, thus the fruit you will get from the trees grown from stones won't be the same as the fruit the stone came from. There is a recommendation there for planting. And here is a site that discusses growing acorns. FYI I used the searched "growing plums" and "growing acorns" for Google searches. There were many hits for each. Flyguy649 ^talk _contribs 19:37, 4 August 2007 (UTC)

Science project - heat to electrical energy transduction...

When I was younger and learning about osmosis for the first time, I came up with an idea that I thought would convert heat energy in a liquid into potential energy that might be harnessed by a waterwheel. I did actually buy some dialysis tubing but my prototype fell apart and made a sticky mess in my room and I never bothered again after that (though I have been meaning to). Anyway, I thought I'd post the idea here so that the world could benefit from my patent-less climate-saving idea or (more likely), I could be told why it might not be viable.

The idea is that a system consists of a length of vertically-oriented impermeable tubing, containing a high concentration sugar (or other suitable solute) solution and to which both ends are attached (via a water-tight seal) a separate length of selectively-permeable membrane. The lower end of the impermeable tube is surrounded by clean water causing a net movement of water molecules through the selectively-permeable tubing at the bottom and up the tube. The water then passes out of the tube via the selectively-permeable membrane at the top, thus allowing the tube to retain its solute concentration. The gravitational potential energy of the water passing from the top of the impermeable tube is then harnessed (e.g. by a water-wheel and electric generator, probably requiring many tubing/membrane systems as described above).

Diagram: [5] --Seans Potato Business 20:12, 4 August 2007 (UTC)

I can't explain it better than Dehydration, Osmosis and the 2nd Law of Thermodynamics. See the last section, "Why it won't work". His system is not exactly the same as yours, but I think the same principles apply. --Heron 21:00, 4 August 2007 (UTC)

Need help finding health issues

I've presented my quandry on my talk page, under User talk:Healthwise#Health issues. If you know anything about the topics I'm exploring, please point out where on Wikipedia or the Web I can find information on them. Thank you. Healthwise 20:13, 4 August 2007 (UTC)

Physics

To Anyone, Please provide the working steps of the solution to the following problem:

Europa, one of the satellites of Jupiter has an orbit diameter of 1.3 x 10^9m and a period of 3.55 days. The radius of jupiter is 7.14 x 10^7m. What is the mass of Jupiter, its average density and the acceleration of gravity at its surface?

[Ans: 1.89x10^27 kg; 1.2x10^3 kg/m^3; 2.7 m/s^2]

Thank You

• Man, this has got to be one of the most lame "please do my homework for me" requests I've ever seen. "I've got the answers copied down from somewhere, but I need to know how to fake that I actually did the math myself." Please, for yourself, and for us, just give it a shot on your own before seeking out shortcuts. Cheating is an ugly habit to get into, and you should treat yourself a little better than that. --24.147.86.187 21:45, 4 August 2007 (UTC)

I think that's a bit too harsh - I assume this is a high school student studying for exams with a list of previous questions and answers. They've tried to solve this one, but don't know where to start, so they ask for some help. I have no idea how to do it, but maybe someone a little more helpful will come along. Aaadddaaammm 22:50, 4 August 2007 (UTC)

The main thing needed is Kepler's third law (the rest is, as we say in mathematics, trivial). Algebraist 22:58, 4 August 2007 (UTC)

I don't know about that. It's been a while since I've been a student but to me, in most cases you would generally have some idea where to start. You might as it turns out be completely wrong, but I would expect most students should at least be able to describe in some detail how they think you should solve the problem or at least what they think you need to know to begin (if they think you don't have enough). If you really have absolutely no idea about how to solve something at all, in most cases I would respectfully suggest you have far, far greater problems then not being able to solve this specific problem and probably should go back to the basics i.e. study the stuff you need to know before you come back to solving problems Nil Einne 06:38, 5 August 2007 (UTC)

OK, let's give a few possibly helpful hints. First, how many problems are there here? Then must you solve the problems in a particuilar order? (That is, do you need the answer from one problem to solve tne next problem?) Which of the three given facts is needed to solve the first problem? -Arch dude 23:44, 4 August 2007 (UTC)

He needs the formulae for 'G' (not earths G, obviously, so I guess that would mean he needs 'g') and he needs the formulae for acceleration. He needs to allow for Jupiters radius when working out the orbital distance. Basically he wants that big M little M balanced-over-the-equals-sign equation that I can't remember off the top of my head at the moment anyway, but I think that covers "helpful hints" SGGH ^speak! 00:03, 5 August 2007 (UTC)

Keplers third, yes thats it. SGGH ^speak! 00:04, 5 August 2007 (UTC)

And to calculate the acceleration due to gravity on Jupiter's surface, try this; this is where the radius really becomes crucial. I hope you know how to calculate density, though. --Bowlhover 06:44, 5 August 2007 (UTC)

You could also, of course, do it using circular motion and Newton's law of universal gravitation. I'd find that easier myself, particularly given an orbit diameter rather than a semi-major axis. How the problem is tackled should depend on what you've learnt. Skittle 00:04, 6 August 2007 (UTC)

Gravity Question

I am not quite sure how to word this question, so bear with me. The globe is an accurate representation of the Earth (I assume). If Person A is standing on one portion of the Earth (let's just say, the North Pole) ... and Person B is standing on one portion of the Earth (let's just say, the South Pole) ... are Person A and Person B standing upside down relative to each other? I am picturing it this way. Say, you have a globe. Place one Barbie Doll as if to "stand" on the North Pole ... place one Barbie Doll as if to "stand" on the South Pole. Won't the Barbie Doll standing on the South Pole essentially be upside down (at least relative to the North Pole Barbie Doll)? And, if so, why doesn't that South Pole Barbie Doll "fall" (i.e., fall off of the Earth into space)? I know the answer "gravity holds us down" -- but if some one can please elaborate. And, by extension (for example), is a skyscraper constructed on the North Pole upside down relative to a skyscraper constructed on the South Pole? Help me understand this. Thanks. (Joseph A. Spadaro 21:38, 4 August 2007 (UTC))

Gravity is a force that attracts all atoms in the universe together (rather weakly). Why that should be the case is way above my pay grade :) So whereever you are on the Earth, it's attracting you and you're attracting it. You're also attracted by the Moon, the Sun, even distant galaxies - but they're so far away that their effect is mostly negligible. All those gravitational forces are vectors, and "down" is the sum (the "resultant vector", if memory serves) of all those vectors. That "down" gravity vector points (almost) to the Earth's centre of mass (it varies slightly - if you go stand near a large mountain its gravity will pull the "down" vector off to one side a bit). So wherever you are on earth, "down" means "toward the centre of the earth". If the Earth was made of some super-dense material such that it had the same mass but was only a few miles in diameter the force of gravity you'd feel would be the same as now, but you'd be able to walk around the earth in a day. -- Finlay McWalter | Talk 21:52, 4 August 2007 (UTC)

Relative to each other yes they are upside down, so to say that if you removed the person from the top and placed him on the bottom without altering his orientation relative to some 3rd party verticle ruler sitting next to the earth, then yes he would be upside down. However gravity is an attraction between large objects. Everything has gravity of a sort (see gravitons for a theory of gravity particles), the only objects large enough to produce the effects of gravity on a detectable scale are astro-bodies like planets, stars etc. Gravity always pulls to the centre of the mass, so wherever you stand on its circumference, gravity is always pulling you "down".

A more interesting theory is, what if you drilled a hole through the centre of the planet and dropped a coin down it, in theory it would yo-yo from one end of the earth to the other as kenetic energy and gravitational energy increase and decrease relative to each other. SGGH ^speak! 21:58, 4 August 2007 (UTC)

It's not true that only large bodies produce gravitational forces at a "detectable scale" - Henry Cavendish accurately measured the gravitational force created by a 350 pound ball in the 18th Century. -- Finlay McWalter | Talk 22:17, 4 August 2007 (UTC)

My bad, I was referring to detectable by a human being and his or her body. SGGH ^speak! 23:58, 4 August 2007 (UTC)

As I'm reading Finlay's example of super-dense Earth, it's entirely incorrect. Gravitational force is a function of mass and distance (distance squared, in fact). If you keep the Earth the same mass but crunch it's diameter way down, gravity goes through the roof. That's what makes black holes. If, however, you replaced the Earth with an Earth-mass black hole, the moon's orbit would stay constant. — Lomn 23:42, 5 August 2007 (UTC)

Here's something more for you to ponder along with the above answers: what if you turned the globe upside down? Why is the North Pole "up" and the South Pole "down"? Why not the other way around? (There is no real reason for it. Everything can be easily flipped into a different coordinate system, there is no reason to prefer one orientation as "up" over the other. "Up" could even be somewhere on the equator, if you considered the rotation of the Earth around the Sun to be a vertical, rather than horizontal, plane. The decision is totally arbitrary.) --24.147.86.187 22:16, 4 August 2007 (UTC)

Here's how I'd explain it. Yes, the globe is an accurate model of the earth. But if you're sitting in your room, holding a globe in your hands, the concept of "down" for that globe is not "down towards the floor of my room". The proper concept of "down" is (just as in real life) "towards the center of the globe".

A man standing at the North Pole is "right side up" because his feet are towards the center of the earth and his head is away from it. And even more to the point: his head and feet are along a line which passes through the center of the earth. A man standing at the South Pole is also right side up, because his feet are towards the center and his head away from the center of the earth also. A building at the North Pole is right side up because its roof is pointed away from the center of the earth and its foundations are pointed towards the center of the earth. A building at the South Pole is right side up because ditto.

The fact that, to an observer out in space, it looks like one of these men (buildings) is "upside down" with respect to the other is really immaterial. Both men, both buildings, feel like they're right side up, and none of them fall over or fall off, because, yes, gravity is pulling each of them straight down towards the center of the earth. —Steve Summit (talk) 23:00, 4 August 2007 (UTC)

I know we aren't meant to debate here, but do astronomers have an arbitary universe-wide "up" by which to orient themselves? SGGH ^speak! 00:00, 5 August 2007 (UTC)

Galactic coordinate system. -- Finlay McWalter | Talk 00:03, 5 August 2007 (UTC)

Bullseye, thanks. I hope you saw my point above too (mid text) I don't want to appear too daft :D SGGH ^speak! 00:05, 5 August 2007 (UTC)

To further the point that up and down is all relative, here's a completely valid map of the earth. - Akamad 00:05, 5 August 2007 (UTC)

I personally like that map because it makes Australia seem like a very important country! - Akamad 00:08, 5 August 2007 (UTC)

A very easy way to prove the point is that in Australia where I live, and any country below the equator, we see all the constellations upside down as they are drawn by Europeans and North Americans, and the moon too is the other way around but harder to tell if you are not familiar with the moon's feaures. Vespine 23:04, 5 August 2007 (UTC)

Yes, but then you also have to hang from monkey bars whenever you go outside, to avoid falling off into space! :-) --Reuben 17:18, 6 August 2007 (UTC)

I think some people have already said it, about the definition of down being towards the centre of the earth, I thought perhapes links to Spherical coordinate system and comparing it to Cartesian coordinate system might be interesting. Basically as the Earth is a spherical system, it has spherical symmetry. Although all coordinate systems are simply labels for the same reality, it is often easier to calculate and think in a coordinate system with symmetries. In this case both people are pointing outwards along the radial direction, i.e. both are pointing up. A rotation rather than a translation would be the appropriate way to compare the two. Cyta 08:04, 6 August 2007 (UTC)

The moon is an interesting demonstration of this - but you don't have to recognise the shapes of the craters or anything to spot it. I grew up in the UK (reasonably far to the North of the planet) but spent a couple of years as a teenager in Nairobi, Kenya (which is right on the equator). The shape of the crescent moon in Kenya looked profoundly "wrong" to me. In the UK, it looks like a letter 'C' - and it always puzzled me to hear stories from ancient civilisations who believed that the crescent moon was a boat in which the gods (or whoever) sailed across the sky. It always puzzled me because "my" moon looked nothing like a boat! In Nairobi, the crescent moon is "tilted sideways" (from my perspective) and does indeed have the 'U' shape of a boat. If you can get your mind around it, and wedge into your brain the fact that the moon hasn't changed - you can get a really deep and rather odd sensation that you are lying on your side while you are standing upright! Where I live now (Texas), the moon is halfway between those two extremes...and even after 12 years here, it still looks "wrong" to me! SteveBaker 19:44, 6 August 2007 (UTC)

That's interesting, Steve. I never would have considered that point. Makes sense, though. (Joseph A. Spadaro 22:19, 6 August 2007 (UTC))

Thanks to all for the information and enlightenment. Much appreciated. (Joseph A. Spadaro 22:19, 6 August 2007 (UTC))

Latest consumer battery technology?

What's the most advanced battery technology available to consumer? I say it's Lithium Polymer. My friend says Oxyride. --24.249.108.133 22:51, 4 August 2007 (UTC)

Well surely it depends on what you want the battery to do. There will be one technology that has the most number of charge-cycles, another delivering power fastests, or for longest, another that is i don't know most stable or most reliable or smallest, or whatever else. Of the two you mention the wikipedia articles suggest that Oxyride is non-rechargeable whereas lithium polymer can be rechargeable. So to me rechargeable would be the better technology, just because i loathe going to stores to buy more batteries. ny156uk 23:31, 4 August 2007 (UTC)

Look at NI-MH : There is a really good article on how they used these in Electric Cars. LI-ION is higher energy density, and is lighter too! BUT they are finicky, expensive, can explode we are told, and Degrade over time ( you lose mileage). The NI-MH is here now (but not in USA seemingly ) for EV's. NI-MH requires only watching the temp while charging and the charge rate, it lasts forever* and allegedly can't be 'broken' according to one Ford VP. It is avail in the USA for low power applications like cell phones, and cam corders, etc. EVWORLD FEATURE: NiMH Batteries: Obsolete Technology or Suppressed EV Solution Nicads are finicky too requiring frequent watering (for high amp flooded types you would use in a EV). Lead acid is a poor performer and wears out rather quickly compared to the others. FYI: THE NICKEL IRON (NI-Fe) batteries in Jay Lenos early 1900's Electric Car still work! P.S. We obtained one Ni-MH from a cordless phone. We ran it down to zero volts, yes literally zero volts and kept it at zero volts for one day. Then we charged it back up. It lasted only a short time, BUT then we charged it up again (knowing some batteries have a lazy something or other), and amazingly it ran for a long time after second charging/ go figure. (yes we do research) TripleBatteryLife 13:29, 5 August 2007 (UTC)

What is with TripleBatteryLife and this supposed lack of NiMH batteries in the USA?!? This is complete nonsense! In the first quarter of 2007 alone 180,000 Toyota Prius's were sold in the USA - each one has a battery pack containing a 168-cell nickel metal hydride (NiMH) battery supplied by Panasonic EV. The batteries most certainly do wear out/die/whatever because in the early years of the Prius, the battery pack had to be replaced about every 70,000 miles. Because this is an expensive thing to replace (and yes, it inevitably happened outside warranty), the Prius was getting bad press because of it. The replacement cost of the battery pack was blowing away the savings you got on gasoline prices. Modern Prius's have (IIRC) a 90,000 mile battery warranty - and when the car goes in for routine service, the dealerships test the battery pack and replace individual cells that have 'gone bad' since your last visit - so it is unlikely that the entire battery pack would ever need replacing anyway. But yes, NiMH's are sold in vehicles in the USA in VAST quantities! SteveBaker 19:29, 6 August 2007 (UTC)

Give us a link to website page or good phone number to order NIMH batteries at 12Volts @ 100 amphours. Otherwise what you say is what you accuse (nonsense). (name calling is not within the wikipedia rules . please quit being a violator). thanks. (yeah get with the good spirit of science instead of being emotional). Fyi: Panasonic is a FOREIGN Company. As is Toyota, and Honda.TripleBatteryLife 17:59, 8 August 2007 (UTC)