Wikipedia:Reference desk/Archives/Science/2006 November 10

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November 10

make nanorobot

I would like to make nanorobot but i don't know what I should study. Is there a specific field of study for that? Mye89 04:47, 10 November 2006 (UTC)Renaud Miclette Lamarche

What you need to study is nanotechnology. It's an emerging field but more and more institutions are offering it in thier syllabus. What you want under your belt is physics and chemistry, and mathematics won't hurt either. Vespine 05:19, 10 November 2006 (UTC)

Electrical engineering would be a good field of study to prepare for a career in building nanorobots. You might find interesting the Wikipedia articles on Robot , Micropower , Integrated circuits , Microelectronics , and Microelectromechanical systems . Edison 06:07, 10 November 2006 (UTC)

Language

1. .If someone sas that a particular language is harsh or ugly,then that's an expresstion of his or her taste.Exlain why please.
2. .Give three(3)reasons to explain why English is currentlythe language of science.
3. .Started as the variety used in South East English,Standard English is now understood and used worldwide.can you explain what is meant by Standard English?
4. .Why is English used widely in India?

Thank you very much!Please be quick!

Please refer to the top of this page where it says to Do your own homework. We really can't stress that enough. Although, we can point you in the right direction. For instance, the article on the English language might have some answers for you. As well as articles linked off of that. Dismas|^(talk) 07:49, 10 November 2006 (UTC)

This really doesn't seem to be a homework question, just from the question that's being asked. That being said:

1. Maybe the linguistics article has something related to harshness of a language? A quick perusal of related topics brought up descriptive linguistics and phonology as things related to the spoken "quality" of a language, though beauty is of course in the eye of the beholder.

2. Well, one or two centuries ago the primary "scientific" language was French and some German. After that, the English-speaking countries sort of started to dominate scientific discourse, which led to the the adoption of English.

3. See Standard English and Basic English (both of which are linked in the English language article).

4. This is an extension of #2 - English is also one of the primary languages used in international business and diplomacy (another being French), so its presence in India is probably directly related to that. See also lingua franca for a more general discussion.

16:39, 10 November 2006 (UTC)

If it weren't homework, if probably wouldn't say "Give three(3)reasons to explain...". Chickenflicker 03:48, 11 November 2006 (UTC)

Just because I'm paranoid...

Yes, I do suffer from paranoia. No this doesn't mean that someone is not out to get me. I just need someone to put me at rest really as this is nagging at the back of my mind. Would it be possible for someone to 'bug' my home, then monitor me remotely from 100 miles away? I invited someone I know online to stay with me for a couple of days last month and ever since, I have noticed things in our online communications that don't seem 'quite right' - comments suggesting that he knows things that he could only know if he were watching me. Like I say, maybe it's just me being paranoid and seeing things that aren't there. I've read the Covert listening device article and from that, it doesn't *seem* possible (he's had access to two rooms of my house, neither of which contains my computer, so it's not my machine sending out, so it would have to be a small hidden camera or a microphone - he's not had access to my house since to retrieve anything). Anyone able to help, or point me in the right direction to info that can? Thanks. Posting anon because I feel a bit embarassed asking this.

What kind of things are you noticing? What has he been saying? Maybe we could help you think of a more reasonable explanation for his comments. Dismas|^(talk) 07:47, 10 November 2006 (UTC)

One of the things he said was a reference to me being quite ill at the moment. I've never told him that I've been ill. That's what tripped me off (I do have these episodes) - thanks, but finding reasonable explanations doesn't really help me. If I could be sure of the technical side, I'd know what to be looking for. --81.79.36.167 07:53, 10 November 2006 (UTC)

Unless he uses equipment already in your house (such as the telephone) a bug would need to transmit. A larger range would require a bigger bug or some relay station to amplify the signal. Any transmitter requires power and unless it uses some power source already in your house, the batteries will run out after a wile. Note that this answer is not based on any knowledge of actual existing equipment, just common sense. DirkvdM 10:25, 10 November 2006 (UTC)

Call a good detective agency and ask if they have detection equipment to check your appartment. Or you can set up a fake conversation with a friend where you slag off the spy and see if there is any change in his character next time you chat. Keria 10:40, 10 November 2006 (UTC)

Have you tried using a metal detector? Not really claiming to be an expert in this, but common sense sort of tells me that bugging a house electronically will require things of metal. Also, when this friend was staying at your place...how often were you in contact with him/her? As in, were you almost always around him/her? Or did you sort of just leave the person in your home? If you were with him/her the whole time, except when they were sleeping, then you can probably rule out anything elaborate.

Otherwise, yes...keep a good record of all communications you have with him (so emails, IM logs). If you find any hard evidence of being spied on, contact the police or some expert first, instead of confronting the person.

Alternatively, exactly where did they stay in your home? It may not be that they're spying on you, but simply that the person snooped around your place during their stay. Do you keep a journal or diary or anything that they could have found? If you live with other people, the perhaps that person talked to them, and just found out some stuff about you which you haven't personally revealed. --`/aksha 11:07, 10 November 2006 (UTC)

The longer you think about ther more ways you will imagine how somebody could spy on you, and the you will have to convince yourself for all this possibilities that they are actually not plausible or practible. Now, I feel the urge to apply to your common sense and ask yourself: why should he spy on you? But I imagine that this is harder than it sounds as you are actually suffering from an illness clouding your common-sense reasoning. I hope you have someone to help you through this, a therapist, doctor or at least some good friends that you still trust. However, one thing needs to be pointed out: You say that fact that he knew you are ill tipped you off. Make yourself aware how much "invisible" information the human voice carries. If a friend of mine whom I know well phones me I might be able to guess whether he is well or ill just from the way how he says "hello", before he even went on talking. There is no spying in this -- our brains analyse these hidden clues automatically and subconciously all the time. Simon A. 11:54, 10 November 2006 (UTC)

He could have a small battery-powered bug that sends a weak signal just outside the home. Then, outside, he could have a powerful rebroadcast station that's either plugged into an outside outlet or has powerful batteries. Another option would use the phone. The bug could be in the phone, and could be programmed to record everything in the room, then call him at 3 AM and upload the recording to his computer. Also, I think it's a bad idea to allow people you meet on the Internet to stay at your home normally. But, if you're the paranoid type, it's especially bad, as it will lead to this type of problem. StuRat 16:51, 10 November 2006 (UTC)

Was you paranoid alredy from before this someone stay with you? Is it possible he is enamored of you?

Hevesli 17:09, 10 November 2006 (UTC)

Yes, he absolutely could. Both via conventional monitoring technology (hardware), and thru software. Check out this recent article. Anchoress 17:17, 10 November 2006 (UTC)

The easiest way to bug you would be to install software on your computer that would allow him to see whatever you type to others. (Did you tell anyone else you were ill?) This method would require no hardware and unless you were very computer savvy could be made very hard to detect. That's how I'd do it, anyway. --24.147.86.187 01:40, 12 November 2006 (UTC)

Supercharger

If we add an low resistance air filter and then an air pump to compress the intake air of an fuel injected engine, will there be a increase in performance??Or do we need to tweak the ECU settings???

See turbocharger--Light current 14:39, 10 November 2006 (UTC)

Or see supercharger. And yes, I would assume you will want to increase fuel flow to match the increased air flow from the blower, if maximum power is your goal. StuRat 16:35, 10 November 2006 (UTC)

Whats the diff. Is there one?--Light current 16:37, 10 November 2006 (UTC)

Yes, a turbocharger is driven by the engine exhaust, which has the disadvantage of not providing much boost at low speeds, only at high speeds, while a blower is driven off the engine using a belt or chain. StuRat 16:41, 10 November 2006 (UTC)

Super answer! Thanks 8-)--Light current 16:46, 10 November 2006 (UTC)

Thanks (I'm not just blowing hot air, here). :-) StuRat 17:26, 10 November 2006 (UTC)

please tell me about te project (TREFFIC PUMP)

hi, i m nishant srivastava frm (bhopal) india.i m i B.teck final yera student of mechanical engg. i m working on a project TRAFFIC PUMP.. this project is basically use for water lifting.the hollow speed breaker of the material of rubber contain NON RETURN VALVE and this brekar are attached with pipe which also contain the NRV ..when the heavy vehical passes over the brekars then water lift in contineous ..so tell me mor abt that thank u

Based on your description, the pumping action of a traffic pump is pretty much the same as that of a muscle pump in the human body. Go to Google Images and search for "muscle pump" or "skeletal muscle pump" to find illustrations of its action. You had a pretty understandable description of a traffic pump. Is there something specific that you don't understand? --68.238.248.188 14:01, 10 November 2006 (UTC)

I can think of one negative: You can either put the rubber hose on top of the road, in which case it will wear out much more quickly, or imbed it in the road, which will cause the road to flex more, and wear out slightly more quickly. Also, being near the surface, the water would be subject to freezing, but I assume you would only use this system in portions of India where the temperature stays above freezing. StuRat 16:32, 10 November 2006 (UTC)

You need something like they used to use for picking up water by railway engines at high speed: a long trough full of water and a scoop on the engine. Whoosh!--Light current 16:35, 10 November 2006 (UTC)

That would slow down the truck (and pull it off the road, if the scoop was on one side only). I believe the goal is to pump water, say for residential use, for "free" (not costing the trucks anything). StuRat 16:39, 10 November 2006 (UTC)

how much electricity is produced

i would like to know about the amount of electricity that is produced when a peizoelectric material is used that is the relation between amount of elec produced and the dimensions of materials required????/

See piezoelectricity--Light current 14:38, 10 November 2006 (UTC)

Separating Mixtures

I have a beaker full of water, salt, and iron. I want to separate them from each other. The salt has dissolved in the water, and I assume the iron will be at the bottom of the beaker, and that it is finely ground up into a powder. I know that I should boil the mixture and separate the water via distillation, but how should I separate the remaining substances? What can I do to separate the salt and iron? Thanks for any help. --ClockFace 15:01, 10 November 2006 (UTC)

If the iron has already separated at the bottom, just pour off the water (keep it for the boiling stage to isolate the salt). You might then want to add distilled water to the iron, stir, wait for it to settle, then pour it off several more times to remove any remaining salt. If the iron particles were too small to settle, then a centrifuge would be needed. StuRat 16:12, 10 November 2006 (UTC)

A magnet or electromagnet would be able to selectively remove iron particles from the solution in the beaker. Then boil off the water and only the salt is left. I expect that is why the problem specified a ferromagnetic material instead of some other material. Edison 16:26, 10 November 2006 (UTC)

Pouring off the salt water is known as decantation. —Keenan Pepper 16:46, 10 November 2006 (UTC)

Why not use a filter paper to remove the iron particles. The remaining brine can be evaporated to get the water and salt separated. 8-)--Light current 16:30, 10 November 2006 (UTC)

I would like to thank you all for your quick responses. Thanks a bunch! =] --ClockFace 18:50, 10 November 2006 (UTC)

To remove all the iron you are gonna have to increase the pH of the water to facilitate precipitation of iron oxide (some will be colloidal, but it will dry out on the filter eventually). Since the iron oxide will not be ferromagnetic, a filter will be more useful than a magnet to separate iron from the salt water (which may or may not be brine, the poster did not indicate the amount or kind of salt). Distillation is probably the easiest way to then resolve the salt water. Tuckerekcut 18:55, 10 November 2006 (UTC)

Does anyone else think this sounds suspiciously like a homework question? Skittle 21:55, 10 November 2006 (UTC)

To me, it sounded like they wanted help doing a chem lab, in which case, giving them a few pointers is OK, so long as they actually do the lab work themselves. StuRat 22:47, 10 November 2006 (UTC)

Rusting iron in water

Why is there iron oxide in the mix. The OP didnt say there was/. And of course we assume the salt is NaCl--Light current 20:25, 10 November 2006 (UTC)

Maybe your chemistry is a bit rusty, but small iron particles in saltwater would rapidly oxidize. StuRat 21:54, 10 November 2006 (UTC)

Not without an oxidiser!--88.110.36.197 03:46, 11 November 2006 (UTC)

There's always dissolved air in water. StuRat 08:34, 11 November 2006 (UTC)

I think the iron does not have time to oxidise in salt water without access to free O2. I thought the ions in water were OH- and H+ and therefore no source of free oxygen except for the dissolved air. But I could be wrong. 8-? OK lets assume the water had been boiled to remove dissolved oxygen 8-)--Light current 18:32, 11 November 2006 (UTC)

If you boil the water in air, you still end up with some dissolved oxygen in the water. You would need to boil it in some other gas, such as nitrogen, to remove all the dissolved oxygen. StuRat 20:51, 11 November 2006 (UTC)

OK You win I give up 8-)--Light current 21:11, 11 November 2006 (UTC)

See [1] on rusting. Its very interusting 8-)

Cancer

How does cancer kill? It can't be just because there's an extra lump in the body. Or can it?... Jack Daw 15:13, 10 November 2006 (UTC)

In some cases, yes, because the lump puts pressure on some vital organ, like the heart or lungs or a blood vessel, but that's rather rare (and easily remedied with surgery). More commonly, the cancer cells destroy some system (like the immune system, allowing other diseases to run rampant, or the lungs, depriving the body of oxygen). StuRat 16:07, 10 November 2006 (UTC)

How does it destroy the immune system or lungs? Jack Daw 16:51, 10 November 2006 (UTC)

Generally it kills in three ways: displacement, compression, or metabolism. Some cancers, leukemia comes to mind, can become so widespread throughout the body that they actually replace the cell type they are derived from. In some kinds of leukemia, the cancerous bone marrow replaces all of the normal marrow in the bones, leaving no healthy cells left to produce blood cells. Other times a tumor can grow large enough that is pushes other sensitive organs out of the way or occludes important blood vessels. This usually happens with faster growing cancers, and is most prominent withing the head, where there is limited space to begin with. For the most part, though, cancer kills through "overeating". Cancer cells metabolize and grow vey quickly. Much like teenagers, they eat everything in sight and don't actually do much work other than growing. This leaves other cells in the area hungry, and eventually leads to their death. You might note that these things are not mutually exclusive, and also that benign tumors are capable of the compression and overmetabolism too. Tuckerekcut 16:36, 10 November 2006 (UTC)

How can it displace other cells? Won't the healthy cells keep dividing into more, functioning cells as usual, even if there are cancerous cells dividing as well? As for compression, do cancer cells grow too fast to constantly surgically remove them? That is, is the recovery period for brain surgery for cancer removal longer or shorter than the period at which cancer cells (if they re-emerge) might become dangerously large again? As for metabolism, couldn't that problem be solved by giving the patient an extremely hyperglycemic diet, perhaps through TPN? Jack Daw 16:51, 10 November 2006 (UTC)

Great questions. Displacement is usually secondary to the the metabolic outperformance. Often vascularization of the new growth is more extensive (though less organized) than the normal tissues, which allows the cancer cells to grow faster, and which shunts much of the nutrition to the tumor. As a result, the normal cells die off faster and grow slower, and become outnumbered. In fact tumor cells, even the ones that grow exceedingly fast, can be removed if they are detected, and cerainly don't grow faster than a scalpel. This is why benign tumors are so named. However, if the margins of the tumor are very complicated or if they metastisize, either by "blending" into nearby tissue or by travelling through the circulatory or lymph systems, they can be more difficult to remove surgically. Radiation therapy can help kill cancer cells selectively in a situation such as blending where the tumor is in a known area with blurry borders, and chemotherapy can help destroy cancer cells which have metastasized. Unfortunately a hypernutritive diet won't help much because the nutrition deficit is more of a local problem than a body-wide one. Tuckerekcut 18:46, 10 November 2006 (UTC)

Awesome info, and you picked up on my hyperglycemic->hypernutritive mistake, great. Well, thanks! :D 130.243.242.176 22:13, 10 November 2006 (UTC) <- me Jack Daw 22:14, 10 November 2006 (UTC)

These answers have also hit on one of the primary reasons why chemotherapy is effective. The chemical poison kills all cells but becuase the cancer cells abosrb more poison in a shorter time, they receive a lethal does sooner. The idea is that they will die before the non-cancer cells. --Tbeatty 05:13, 11 November 2006 (UTC)

I'd like to second that. Great answers, guys. I have a PhD in biomedicine and still learned something from this exchange. Rockpocket 03:20, 12 November 2006 (UTC)

We'll be sure to call you "Dr Rockpocket" from now on.  :) JackofOz 23:17, 12 November 2006 (UTC)

Why so big?

Why has been the dinosors so big? Is it a thing what can be explained from evolution?

Hevesli 17:01, 10 November 2006 (UTC)

There are certain advantages to size, like being able to defend yourself from a smaller predator or, if you are the predator, being able to kill your prey. This would naturally lead to an infinite race to be the largest, unless there were also some advantages to being small, which there are. Food requirements are reduced, the ability to hide is better, etc. However, to explain why land animals used to be much larger than they are now, one of these advantages or disadvantages must have changed from the time of the dinosaurs until now. Note that sea animals, namely whales, are the largest they have ever been right now, so this change apparently does not apply to the sea. One change I'm aware of is that oxygen levels in the air used to be higher, as demonstrated by air bubbles stuck in amber from the time of the dinosaurs. Our current lower oxygen levels would limit the size of animals, as present dinosaur-sized animals would need to move quite slowly or have greatly increased lung capacities relative to the sizes of their bodies. The oxygen level in water is related to that in the air, although sea mammals don't use the oxygen in the water, but rather breathe air. Also note that different calculations come into place, as sea mammals have reduced energy requirements. This is due to more efficient locomotion and thermal control mechanisms. StuRat 17:20, 10 November 2006 (UTC)

Also note that not all dinosaurs were very big. Skittle 21:51, 10 November 2006 (UTC)

How long did it take for dinosaurs to grow so big? The rise of the dinosaurs started 20 million years after the Permian-Triassic extinction event and they had 160 million years to evolve. The Cretaceous-Tertiary extinction event that wiped them out occurred 'only' 65 million years ago. So maybe 'we' just need more time. But also, mammals require much more energy, and thus much more food, per weight because they are warm blooded and need to keep their temperature up all the time. So a viable population will require a much larger area. So given the same habitat size, reptiles can afford to grow larger. Another thing is how large the habitat can be. If a species specialises more, it will have a smaller habitat and can therefore not grow as large. Maybe mammals have a stronger tendency to specialise. Note that I know little about the subject and am just doing some educated guessing. :) DirkvdM 08:21, 11 November 2006 (UTC)

Well, according to this documentary I saw, dinosaurs were warm blooded. Anchoress 08:33, 11 November 2006 (UTC)

Thank you. Maybe if I feed to mouse oxygen he will grow big after multi generation and can fight cat :-) Hevesli

How are refusals to participate handled on surveys ?

The surveys I see typically have a 3% margin of error. However, I can't believe that over 97% of the people they ask to participate agree, especially if not compensated. I'm guessing they just assume that the participants are representative of the population, while I most definitely would not. That is, if 10% refused, I would add that to the margin of error to get a 13% margin (12.7%, technically). For example, in the recent US elections, most of those who refused to participate in surveys may well have been conservatives disgusted with the Bush administration and the numerous financial and sexual scandals of Republican Congressmen. Thus, their non-participation would bias the survey. Also note that surveys where participants self-select (say a web site with a link to take a survey) have a much higher rate of non-participation, which is unknown, as the number of people who read the ad and decide whether to participate is unknown. How are these issues handled by statisticians ? StuRat 17:07, 10 November 2006 (UTC)

The question is a good one, and I know the answer only to the seond part. Survey where the participants self-select, such as in your example of the web site, are either totally useless or only an extremely rough indicator. Professionals don't take them seriously as far a I am aware. (Actually: As I am a scientist working for a university I occasionally get request to form out web surveys from within the university. These are, however, usually parts of master theses, typically by students of economy or social sciences, and I always have the feeling that the results will be enough to earn a degree but not to publish a paper. Or, worse, the survey originates from some internal project office within central adminstration and tries to assess some work-place related issues in order to burn some money for pretended actionism.) For properly random-sampled survey, I imagine that the bias problem is the reason why the precentage of refusals are always given. Maybe you are supposed to form your own opinion how this contributes to the error. As far as error figures are concerned: in German newspaper I hardly see them given. Simon A. 20:12, 10 November 2006 (UTC)

I suspect the university has you do the surf\veys so they can imply that they are "scientific surveys". If I were you, I would insist on a big fat disclaimer on all those surveys saying "This is NOT a scientific survey, and is only to be used for entertainment purposes". StuRat 20:57, 10 November 2006 (UTC)

In a related question, how is lying on the survey handled ? Is any margin added to account for the percentage which can be expected to lie ? If niether of these are accounted for, I would expect survey results to be highly inaccurate. In cases where they can actually be checked, like voter surveys, I would expect many election results to fall outside the margin of error. StuRat 21:02, 10 November 2006 (UTC)

The margin of error on a survey, by definition, covers only the error that is likely to take place due to random sampling. If you ask 1000 people out of a much larger population about something, your error due to the fact that you didn't ask the entire group is going to be about 3%. Other possible sources of error are not accounted for in the margin of error, simply because that's how the margin of error is defined. As such, the margin of error of a survey is not necessarily a good measure of how far off the survey is actually likely to be from the true value you would get if you asked everyone, and everyone responded truthfully. Chuck 23:30, 10 November 2006 (UTC)

In that case, the term is thoroughly misused by the public, and those doing amateur surveys, to mean the total maximum error. StuRat 02:32, 11 November 2006 (UTC)

There are lots of corrections and that is why there are lots of polling organizations. The first correction has already been touched on and that is a sample of the real population will always have a margin of error. But as polls develop and they are compared to the actual results, the errors associated with systemic bias are corrected from historical analyses. For example, it is known polls are more likely to garner a response from Democrats than from Republicans. This is true for both phone polls and exit polls. Since pollsters know this, they correct for it. There is also differences based on age, gender, education, region of the country, etc. These are all put into a fudge factor that they use to weight the poll. This is why Zogby and Gallup get different results even though they ask the same question: they have different weighting factors. It is also how exit polls can exceed the margin of error. --Tbeatty 02:54, 11 November 2006 (UTC)

US Congressional Election results vs Voter Surveys

Is there any analysis of how accurate survey results were, in relation to the actual election results ? I'd be interested to know how well they did at predicting the results. StuRat 21:07, 10 November 2006 (UTC)

At [2] you can scroll down to "Rudimentary statistics" and see a nice explanation of statistical sampling theory. The site, although somewhat partisan in philosophy, also presents a nice compilation of all the published scientific polls regarding President Bush's approval rating over time, so you can get an idea of the central tendency and see which polls tend to produce higher and lower approval ratings, and compare his ratings to past 2 term presidents. One key point is adjustment: I will make up illustrative numbers: a polling organization may assume in their population model that the voters are, say 55% Democrat and 45% Republican. In a 3 day phone survey of 1000 respondents, they may have found 70% of those who answered the (random) phone call and completed the survey said they were Democrats and 30% said they were Republicans. A high % of the Republicans say they approve of Bush and a high % of Democrats will say they disapprove. Rather than reporting the actual observed percentages, the pollster is likely to adjust the observed Dem/Rep proportions to the ones espected, before computing the overall approval rating. They will make similar adjustments for black vs white, male vs female, to adjust for the fact that, say Republicans don't do phone surveys, or at work, or only use cel phones, or whatever skewed the sample percentages away from the population percentages. Thus it is an art as well as a science, and is hardly ever a pure exercise of random sampling. One pollster for a party admitted to absolute fraud: if the person hung up, the surveyor just made up responses. Amazingly the daya came out favorably for the party funding the poll. Edison 05:59, 11 November 2006 (UTC)

Mileage equivalent of raising a car.

I was wondering how far an average car might travel using the same fuel burned to get to the top of a 20m car park. Petrol has an energy content of 32MJ/l so assuming 8 miles per litre, 4MJ per mile. 1 Joule is the minimum energy to raise 1kg 10 cm, so assuming a 400kg vehicle, 80,000J would be required. Engine efficeny is 30% so this becomes 240,000 J, if we say 250,000J we get a distance of 1/16 mile which is approximately 100m. This seems silly, implying cars use only five times as much energy to move "up" as to move "along". Have I slipped a decimal point somewhere? Rich Farmbrough, 17:40 10 November 2006 (GMT).

HAve you taken into account the air resistance and rolling friction and other losses in climbing the hill? THe hill probably takes the sum of the two energies you calculated assuming the same speed of travel.--Light current 17:52, 10 November 2006 (UTC)

Yes these inefficincies arise, but they are low at low speeds. It may be that the answer lies in the car travel at 50-70 mph being incredibly infficient. Rich Farmbrough, 10:19 13 November 2006 (GMT).

I've thought about this issue myself, as I used to drive 15 minutes to get to a parking structure, then I would drive another 15 minutes within the structure, waiting in lines and searching for an open space. I'm sure most of my gas was wasted in that damn thing. If there was a way to reclaim the gravitational potential energy, say by regenerative braking, much of this waste could be eliminated. StuRat 18:32, 10 November 2006 (UTC)

Cos is Regenerative braking--Light current 18:35, 10 November 2006 (UTC)

Only five times as much? Ideally, it would be infinitely much more, because when lifting a car, actual work is done in the sense that there is a difference in the energetic state. When moving a car horizontally, that is not the case. So if there would be no resistance to overcome and the acceleration at the start of the trip would be regained during breaking at the end, there would be no consumpton of energy at all. That cars still use one fifth of the energy for horizontal transpor tis an indication of how horribly inefficient they are. Take a very smooth cannon ball. How much energy does it take to lift it to a height of 2 m? And how much energy would it take to make it roll 2 m over a smooth surface? For something closer to home, take a baseball. You'd have to give it a really minor push (with your pinky) to prevent it rolling more than 2 m. And the major reason it will stop at all is that the surfaces aren't smooth enough. DirkvdM 08:50, 11 November 2006 (UTC)

And an idling car uses an infinite amount of energy per distance moved ! StuRat 20:31, 11 November 2006 (UTC)

Yes thats why you should turn off your engine whilst waiting.

That depends on how long you wait, as there is inefficiency from starting and stopping the engine constantly. StuRat 23:30, 11 November 2006 (UTC)

The rule of thumb is 1 minute, but I believe in Germany there is a law forbidding idling over 20 seconds. Rich Farmbrough, 10:19 13 November 2006 (GMT).

Yes, I was expecting 20 or 100. Oh well. Rich Farmbrough, 10:19 13 November 2006 (GMT).

Is a solution defined as a mixture in chemistry

Prompted by an earlier question I wonder: Is a solution defined as a mixture or a compound in chemistry?--Light current 18:40, 10 November 2006 (UTC)

Why don't you read the article you linked to, solution. First sentence. Tuckerekcut 18:57, 10 November 2006 (UTC)

I did. It is confusing as it mentions homogenous mixtures.--Light current 19:02, 10 November 2006 (UTC)

Does the first sentence of chemical compound help? Could you prepare salt-water solutions in which you alter the the ratio of the components? DMacks 20:07, 10 November 2006 (UTC)

OK a solution appears to be a mixture . THanks for the solution to this problem 8-)--Light current 20:15, 10 November 2006 (UTC)

"There are three different types of mixtures: homogeneous mixtures (also called solutions), heterogeneous mixtures, and colloidal dispersions." from Mixture --`/aksha 03:04, 11 November 2006 (UTC)

Blindness & Nothingness

One can be fairly sure that it is nearly impossible to imagine nothingness. For when you are thinking of nothingness, you're still thinking of something. But nevertheless, I've tried. Today, I was closing my eyes, meditating, and I was trying to imagine what it would be like to be blind. Here is my question: does the mind of a blind person interpret the lack of vision as a sort 'blackness' - much like I do when I close my eyes - or does the mind of a blind person interpret the lack of vision as a complete absence of anything (i.e. no blackness, just nothing)? - R_Lee_E (talk, contribs) 18:42, 10 November 2006 (UTC)

There is actually a way to imagine nothingness (well my nothingness is actually black). As for being blind IDK--Light current 19:55, 10 November 2006 (UTC)

Don't know either. However, I remember an interesting piece of news. A museum made a completely dark room, where visitors has to use their tactile sense to orient themselves. The idea was to give seeing people an impression of what being blind was like. A spokesman of some German association of blind people commented that he considered the setup a bad idea: after all, a seeing person would feel frightened and disoriented due to the vivid impression of the blackness. From these feelings, the spokesman argued, the visitor would get a way too negative idea of how blind people experience the world, as under normal circumstances they feel as normal (i.e., secure and oriented) as normal people do, and they do not expeience any blackness or lack of sensation as long as their other sense provide usual input. Simon A. 20:20, 10 November 2006 (UTC)

Very interesting. - R_Lee_E (talk, contribs) 21:49, 10 November 2006 (UTC)

I think it depends whether the person has been blind from birth or could once see and has been blinded. See also Eigengrau. —Keenan Pepper 20:30, 10 November 2006 (UTC)

I expect the latter. Consider a curious bat wondering what it's like for people who don't have a sonar-type sense. Do people specifically notice that they don't have this sense? Or consider the similar question a monkey might ask of people without a prehensile tail: do people try to move their tail to grab things only to constantly notice they don't have a tail? Essentially animals (humans included) have a set of inputs and outputs, if you like, that we learn to use at the appropriate times. If you've never had a particular sense or limb, you'll never feel inclined to use it or to even notice it isn't there (obviously the case of a person who has only recently lost their sight is a different matter), I expect. digfarenough (talk) 22:53, 10 November 2006 (UTC)

If they were born blind, they would have never devolved the neurons to interpret vision in the first place. Check out this article Wiesel and Hubel 28 (6): 1029. (1965) --Cody.Pope 23:09, 10 November 2006 (UTC)

A blind person wouldn't be "thinking of nothingness", they'd still build up an 'internal' interpretation of what the world is like based on their other senses.

Trying to "blank" your mind and not have any thoughts at an instant is a completely different thing. Complete clearing of the mind of thoughts is supposed to be a skill learnt by some forms of meditation, and supposedly not easy either. I personally can't imagine how someone could be consicencly awake and not have any thoughts (heck...your mind's thinking and working even when you're not consciencely awake), but some people (like buddist monks and stuff) claim they can completely clear their mind of thoughts during meditation. --`/aksha 03:04, 11 November 2006 (UTC)

YEs its not easy. You let thought come and let them go with out holdnig on to them. Finally thoughts are more rare and eventully stop--88.110.36.197 03:43, 11 November 2006 (UTC)

If you are what you think then to stop thinking would mean to stop existing. Think on that (or not). DirkvdM 18:17, 11 November 2006 (UTC)

I dont think so!--Light current 18:24, 11 November 2006 (UTC)

I tend to ignore people who don't exist. Who do you think you are, God? DirkvdM 09:22, 12 November 2006 (UTC)

Is there a Braille version of Wikipedia? JackofOz 23:13, 12 November 2006 (UTC)

I don't see why there shouldn't be one. DirkvdM 09:28, 13 November 2006 (UTC)

Plasma

How Hot would it have to get for water to turn into a plasma and if it was hot enough would it actually be Hydrogen and Oxygen gas?67.126.140.134 20:31, 10 November 2006 (UTC)

Yes, it would split into oxygen and hydrogen first. StuRat 20:45, 10 November 2006 (UTC)

And then into a lot of ions?--Light current 20:54, 10 November 2006 (UTC)

Thank You StuRat I thought that,but anyways is there a formula for how much volume, lets say a liter of water, would take up when it is turned into a gas?

Depends on the volume its allowed to expand into. PV/T is a constant. I think plasmas act like a gas.--Light current 21:00, 10 November 2006 (UTC)

Plasmas definitely don't follow the ideal gas laws, but you can use them for back-of-the-envelope calculations. —Keenan Pepper 21:07, 10 November 2006 (UTC)

Im sure my answers will be sufficiently accurate for the purposes of the OP 8-)--Light current 21:09, 10 November 2006 (UTC)

According to my calculations, at atmospheric pressure, water is halfway dissociated into H₂ and O₂ at about 4000 kelvin. —Keenan Pepper 21:18, 10 November 2006 (UTC)

Of course, blood plasma is mostly water. :-) StuRat 21:45, 10 November 2006 (UTC)

...with dissolved oxygen gas! Though as far as hotness...um, I didn't make the cut for the Under The Labcoat 2006 calendar. DMacks 22:03, 10 November 2006 (UTC)

18 mL of water (1 mole) will expand to fill 22.4 L of space as a gas at 1 atm (the usual caveats of the ideal gas law apply). and if you dissocate the water back to monoatomic ions, it follows that 1 mol water -> 3 mol of ions, so a (reasonable?) guesstimate is 18 mL of water will expand to 67.2 L of gaseous ions at 1 atm. so you probably want to operate this device outdoors ;-) Xcomradex 09:12, 13 November 2006 (UTC)

Things to be discover

What do you think are the next more important discoveries to be done? I suggest: cure for AIDS, cheap clean energy, cheap space travel, light computation??Mr.K. 22:32, 10 November 2006 (UTC)

I picture programmable hunter-killer viruses. For example, a patient's cancer cell can be extracted, then a hunter-killer virus is programmed to destroy any cell with that exact DNA sequence. It's placed back into the body of the patient, and infects and destroys any cells with that DNA. After all the cancer cells are dead, the virus loses the ability to reproduce, and dies off, too. StuRat 22:37, 10 November 2006 (UTC)

I like StuRat's idea, but it would be great for conservation. Something like that which could destroy Batrachochytrium dendrobatidis, and save many frog populations of the world. But, something needs to be done about climate change, or it would be all useless. --liquidGhoul 23:12, 10 November 2006 (UTC)

When StuRat mentioned programmable hunter-killer viruses, I thought of a computer virus that targets spammers... Vitriol 23:40, 10 November 2006 (UTC)

Oh, yes, please! DirkvdM 20:42, 11 November 2006 (UTC)

Viruses are one way to change DNA for gene therapy, but the problem is they are unpredictable, cannot be retracted, and are capable of mutation. Right now, it seems like RNAi is the future of gene manipulation. And you'd never believe where it comes from: worms. If you ask me, what scientist need to do next is to determine the exact etiology of disease (pick one...). If we know what goes wrong in the human body, precisely, only then can we hope to fix it. Tuckerekcut 23:48, 10 November 2006 (UTC)

RNAi doesn't come from worms... RNAi was first observed in plants (although it wasn't called RNAi then) and was then (and is now) used rather successfully for gene knockdowns with Caenorhabditis elegans (and is also used for gene silencing in transgenic plants). However we're simply taking advantage of a existing (still poorly understood) mechanism for gene regulation that occurs throughout the eukaryotes. Nil Einne 15:35, 11 November 2006 (UTC)

hunter-killer viruses would be a scary invention considering viruses pnchant for mutation. rechargeable battery technology for cars and other mobile appliances would transform the world. Stored energy with high enough density to enable flight and cars without burning fuel or toxic byproducts (or toxic accidents) would change everything. Climate Change is social problem, not a scientific one, meaning that current environmental goals of political organizaitons such as the UN and other states are geared towards wealth redistribution, not science. Climate change is a function of being on the planet. --Tbeatty 05:55, 11 November 2006 (UTC)

Climate change is a social science problem. Even if social science are in a state of protoscience, its their task to tackle this question. Mr.K. 22:23, 11 November 2006 (UTC)

I don't know why cheap space travel is so important. A cure for AIDS is but there are also a lot of other medical related issues which are major problems in developing countries. Malaria, TB and cholera are three that come to mind. Some would argue these don't require inventions others would say they do. Nil Einne 15:35, 11 November 2006 (UTC)

So we can leave the planet if things get too hot...Mr.K. 22:25, 11 November 2006 (UTC)

Understanding turbulence would be big, but probably nowhere near 'next'. When Einstein was asked what he would want to ask God, he said "Why turbulence?" (or something thereabouts). DirkvdM 20:42, 11 November 2006 (UTC)

Tbeatty, you say "Climate change is a function of being on the planet". Do you mean by that that it is an inevitable natural occurrence (which is true) or that human induced 'Climate change on steroids' is inevitable (which isn't true)? DirkvdM 20:42, 11 November 2006 (UTC)

The planet's climate change is an inevitable natural occurance. Natural variations far exceed any predictions about the human contribution. --Tbeatty 21:04, 11 November 2006 (UTC)

Only if you ignore the time scales. Yes, temps may have changed far more over the course of millions of years from natural forces than they will over the next century from man. However, the changes over the next century, due to man, will far outweigh any changes in the next century, due to nature (unless we are hit by a meteor as big as the one that killed the dinos). StuRat 23:27, 11 November 2006 (UTC)

And even the assumption that natural variations are much bigger is wrong. The predictions about temperature change due to human contribution range from 2 to 7 Celsius. The absolute worst catastrophy in Earth's history was the Permian-Triassic extinction event, which killed almost all life on Earth and was caused by a temperature rise of just 10 C, which in turn was possibly caused by a rise of a mere 5 C, which released methane stored in the ground (sea bed). Given that there are again such methane field under the oceans, the possibility of a rise of 7 C sounds pretty scary to me. Add to that that the Permian-Triassic extinction event took place over hundreds of thousands of years and the present change is predicted to take place over hundreds of years or possibly even mere decades, and it's quite astounding how much politicians ignore the whole thing. It's not like scientists predict it (which should be reason enough to stop and think), but it's actually happening. Temperature record after temperature record is being broken. Sorry about the rant, but if there is anything that deserves one, it's this (much more than Iraq or something pathetic like the 'threat' of terrorism). DirkvdM 09:42, 12 November 2006 (UTC)

Max Beerbohm said: "Anything that is worth doing has been done frequently. Things hitherto undone should be given, I suspect, a wide berth." JackofOz 23:23, 12 November 2006 (UTC)

This guy is not exactly a scientist. And why the hell you would not do/make something new?Mr.K. 21:28, 13 November 2006 (UTC)

"impossible Physics"

Can someone begin a "list" of the "impossible Physics" that our astronomers witness within visual space. Im interested in things that physically are "suppossed" to be impossible based off certain standards scientists have created throughout human history.

eg.. Black Holes, timing issues, etc...

Thanks 68.73.81.36 00:05, 11 November 2006 (UTC)

• Sending information faster than the speed on light via quantum tunneling. StuRat 02:28, 11 November 2006 (UTC)

• I don't think they've observed this, have they?--Tbeatty 02:45, 11 November 2006 (UTC)

• I believe that they have sent an audio transmission faster than the speed of light. StuRat 08:29, 11 November 2006 (UTC)

• I would like to see this. The only thing that I have seen that is faster than light is phase information. This isn't real information and can't be used to transfer real information. The other thing is coupled photons (I forget the real name). They are coupled and their existence is actually known before they are created but I think they still obey speed limit rules.--Tbeatty 08:50, 11 November 2006 (UTC)

• Here is the article: [3] and here is the relevant excerpt:

Professor Gunter Nimitz of Cologne claims he has transmitted Mozart across a 14 cm metal barrier at 4.7 times the speed of light. Professor Raymond Chiao of California has also measured transmission at 1.7 times the speed of light. This was reported in the BBC science program "Horizon". According to Einstein, faster than light travel is not possible, if one starts at below light speed; so these results are astounding. They rely on a mechanism called quantum tunneling, where a photon can be in several places at once. Some believe that the photon is really interacting with another one in a parallel universe, hence the weird effects seen when, for example, two photons sent through two separate slits, instead of forming two distinct bright spots, interact with each other, producing many dark and light bands. How one photon can be in so many places at once is for budding geniuses to explain.

StuRat 09:02, 11 November 2006 (UTC)

To clarify this. Prof. Nimtz is considered an annoyance by many of his collegues due to his insistance on this claim. The facts, as the majority of physicists in the field see them, are as follows: There is a well known paradox in quantum mechanics with respect to the phenomenon of quantum tunneling. The description of tunneling by means of the Schrödinger equation says that the time that a particle needs to tunnel through the barrier is independent of the length of the tunnel, and hence, a particle that travels through a very long "tunnel" appears to be travelling faster than light if you take the solution at face value. Nimitz set out to demonstrate this in the lab using the simplest possible realization of quantum tunneling: microwaves propagating through a wave guide (simply a conducting, hollow metal tube; here with square cross section and a few dozens of centimeter long) which is too small to conduct the waves (i.e. the width is (slightly) less then half the wave length). Then, classical electrodynamics say the the wave is exponentially dampened, i.e. only a tiny bit comes out at the other end. The tunneling solution also says that the wave comes out "too early". But how do you measure the time that the wave needs to traverse the waveguide? A wave is not point-like, but has some extension. Nimitz, it seems, looked at the "center of mass" of the wave packet, which indeed moves faster than light. However, the information that the wave packet carries, enters the wave guide already as soon as the leading flank, i.e. the first bit of the wave enters, and the it should be considered as arrived once the leading flank exits. Careful theoretical analysis of the solution of the Schrödinger equation shows that the leading flank, other than the "center of mass", does not travel faster than light, i.e. causality and hence special relativity is not violated. As far as I am aware, Nimtz agrues a minority position by claiming that his experiments are not covered by this theoretical analysis. Simon A. 10:59, 11 November 2006 (UTC)

I've just looked at Google scholar: I was unjust to Nimtz by making him appear stubborn. It seems that in his more recent publications, Nimtz now embraces the claim that "faster-than-light effects" in tunneling cannot violate causality. The debate is hence now no longer whether special relativity and its light-speed barrier is challenged by tunneling experiments (it is not), but rather how to correctly explain why it is not and whether it is proper to call it "faster-than-light" nevertheless. Simon A. 11:56, 11 November 2006 (UTC)

• Is this intended to be ammo for a ID vs. Evolution debate? ;) - R_Lee_E (talk, contribs) 03:33, 11 November 2006 (UTC)
• Hi, you might take a look at this page. I hope this template isn't deleted as I've found quite a few intriguing topics through it: http://en.wikipedia.org/wiki/Unsolved_problems_in_physics