Mr Skeptic

My guess is that it is probably purer, and almost certainly far less used (so suffers from a lack of economies of scale).

If your classmates have one you could borrow it from them? Look for it in a library? If all else fails, maybe you can buy one and return it (you'll still probably have to pay for shipping).

You can levitate but unless you have some of the really strange stuff that ajb mentioned, you can't really use gravity to levitate. You can levitate things electrically or magnetically, on a cushion of air, etc. For example, if you have a ping-pong ball and a vacuum cleaner that can be set to blow fairly hard, you can have the ping-pong ball suspended in the air by the airflow. And also we have levitating trains: http://en.wikipedia.org/wiki/Maglev_%28transport%29

I suggest Wikipedia. It's not a textbook of course, but it is an excellent resource for filling holes in your knowledge. You can browse by category or search for a specific word or phrase. http://en.wikipedia.org/wiki/Category:Mathematics

Depends on whether your wife prefers to be jealously guarded, or to be trusted.

On that note... Most of us are OK with killing an embryo because it lacks the essential qualities of a human that require a sufficiently developed mind, for the simple convenience of the mother (granted, quite a big convenience). But what if instead of killing the embryo we performed brain surgery on it, sufficient to prevent consciousness from ever developing but not enough that it cannot perform the basic life functions. Thus, it could be born and develop into a brainless adult with organs large enough to donate. On the basis of brain development, it would still lack the essential qualities of a human, and via donation of organs could save or greatly improve the life of real people in need of organs. From a utilitarian perspective, that seems like the right choice, but it still seems distasteful.

An electrical current could destroy the chip but only if it passes through the chip. Electrically insulating the chip could make it easier for the current to pass through the dog's body (essentially like salt water) rather than through the chip. And the chip would need at least a little insulation for sure, otherwise it would get short circuited when placed in the dog. I'm not really sure how plausible the scifi idea of frying electronics embedded in a body without killing the patient actually is. I guess it would depend on the chip and method used.

Yes. This is part of how thermonuclear weapons work, though no doubt some of the x-rays leak through or get absorbed, a good portion of them get reflected. http://en.wikipedia.org/wiki/Thermonuclear_weapons#Two-stage_thermonuclear_weapons

Being unsaturated won't make them particularly polar, though I suppose it would at least help a little by making them more liquid. I don't really know but I would think that even with some dissolved some of it would still form micelles, in equilibrium with the dissolved lipid? Does your final product have to have the 10 mg/L dissolved or is it OK if some of it is in micelles? Is it OK if your product has a detergent/surfactant? In any case, heating will help in combination with pretty much any other method.

Salt can only melt ice at temperatures above about 0 Fahrenheit. (in fact, that was how Mr Fahrenheit got his zero temperature). Anything that dissolves in water will melt ice to some extent, but salt is so effective because so much of it can be dissolved and because both the sodium and the chlorine count for this, and more importantly because it is cheap. Like Moontanman said, don't go there with a salt shaker and expect to do anything. Shoveling the snow out will be quicker, at least if the snow is soft enough. Otherwise, a large bag of salt will eventually melt the snow and ice. The way it works is that salt water freezes at a lower temperature than fresh water, and basically the salt dissolves in the water formed by the melting ice, but the process is rather slow since the salt needs to dissolve in ice water and melting ice requires heat such that the temperature is lowered as it melts, and it has to warm up from the surrounding environment. But it will eventually melt it, and also it will make little holes and stuff in the ice which will make it less slippery.

http://en.wikipedia.org/wiki/Hosni_Mubarak#President_of_Egypt Mubarak has been "president" for almost 30 years now, and it seems the people are sick of him. http://en.wikipedia.org/wiki/2011_Egyptian_protests Definitely something to keep an eye on in the following weeks.

Well apparently they used to lick the radium paint brushes to get the brush tip into a nice shape or something. That turned out to be a bad idea. If you use alpha radiation, it is blocked by a sheet of paper or a couple inches of air, for beta radiation you'd need a sheet of tin foil or several feet of air. Basically they are very easy to shield but you don't want them right on your skin or in your body. Gamma radiation you need thick lead. For your light sources you need one that is easily blocked otherwise it would go right through your paint instead of energizing it.

Somehow I totally missed that you were suggesting a runway . It may be a good idea but you have to remember that the faster you go the longer the runway needs be for every second the craft is to spend on the runway. The craft will have to be strong enough to resist 1 g in another direction than just the engines, and more for the ski jump, which would add more structural weight for the ship and perhaps its cargo. The ski jump would have to be very tall considering the speed at which the craft would be going by then. All this translates to quite a bit of cost especially considering that we would be using it like 5 times per year. If you consider the possibility of sabotage, a giant runway is a huge security risk as well, and possibly a safety risk too. Ooh, and the runway also has to be able to survive being torched by shuttle exhaust, so asphalt is probably out of the question.

I assume that by "a factor of ten thousand" you mean "almost double"?

You cannot undo a relation that maps multiple numbers to one number. Thus your line of reasoning fails at the third step.

Yes, back in the day glass windows were not of uniform thickness. Usually when installing the window, the thicker part is placed on the bottom so that it isn't top-heavy. Some old installations have the thicker glass on top.

Sure, and your cell phone will create EMPs and use them to communicate. However when people talk about EMPs they usually mean ones powerful enough to fry electronics. An electromagnet really isn't going to do that.

Glow-in-the-dark paint can be made such that it gets "charged" by light, and then visibly glows in the dark, but this glow will run out fairly quickly (an hour or less, I think). More permanently glowing paint could be made using radioactivity as the energy source; this was the original glow in the dark paint with radium used on old watches. Tritium is also used as an energy source for glowing things like some exit signs.

Spanish is a good choice. http://en.wikipedia....panish_language In 1999, there were 358 million people speaking Spanish as a native language and a total of 417 million speakers[10] worldwide. Currently these figures are up to 400[3][4] and 500[5] million people respectively. Spanish is the second most natively spoken language in the world, after Mandarin Chinese.[6] Mexico contains the largest population of Spanish speakers. Spanish is one of the six official languages of the United Nations, and used as an official language of the European Union, and Mercosur. Spanish is the second most studied language in the world, after English.[11][12] Also knowing Spanish has helped me understand a bit of other languages. When I visited Brazil I would speak Spanish to them and they would speak Portuguese to me and we could understand each other. This seems to be rather common: Spanish and Italian share a similar phonological system. At present, the lexical similarity with Italian is estimated at 82%.[156] The lexical similarity with Portuguese is greater at 89%. Mutual intelligibility between Spanish and French or Romanian is lower (lexical similarity being respectively 75% and 71%[156]): comprehension of Spanish by French speakers who have not studied the language is low at an estimated 45% – the same as English. The common features of the writing systems of the Romance languages allow for a greater amount of interlingual reading comprehension than oral communication would. Italian wouldn't be a bad choice either. It is less popular than Spanish but its also closer to French, and closer to the original Latin. If you're Catholic it would definitely be the best choice: http://en.wikipedia....talian_language Italian ( italiano (help·info), or lingua italiana) is a Romance language spoken as a native language by about 70 million people in Italy, Malta, San Marino and parts of Switzerland, Croatia, Slovenia and France,[1] and immigrant communities in the Americas and Australia. Many native speakers are native bilinguals of both standardised Italian and regional varieties.[2] In Switzerland, Italian is one of four official languages, spoken mainly in the Swiss cantons of Grigioni and Ticino. It is also the official language of San Marino, as well as the primary language of Vatican City.[3] It is co-official in Slovenian Istria and in part of the Istria County in Croatia. The Italian language adopted by the state after the unification of Italy is based on the Tuscan dialect, which beforehand was only available to upper class Florentine society.[4] Its development was also influenced by other Italian dialects and by the Germanic language of the post-Roman invaders. Italian derives diachronically from Latin and is the closest national language to Latin. Unlike most other Romance languages, Italian retains Latin's contrast between short and long consonants. As in most Romance languages, stress is distinctive. In particular, among the Romance languages, Italian is the closest to Latin in terms of vocabulary.[5] Lexical similarity is 89% with French, 87% with Sardinian, 85% with Catalan, 82% with Spanish, 82% with Portuguese language, 78% with Rhaeto-Romance and 77% with Romanian.[1][6]

Viruses require very specific security flaws in their target.

I'm pretty sure that the only reason to go horizontal is to make the most of wings (ie using the air as extra mass for propulsion). Given the wings on rockets are quite insignificant it's probably better off and safer to just go straight up most of the time. Computer models are only as accurate as they are made, and can ignore aspects of reality if the moddeler feels like it or doesn't know any better. For example the computer model might ignore the wear and tear aspects, or might ignore the problem that radiation can increase brittleness. The only way to know for sure if your model works is to compare it to reality, like is done with the climate modeling. Also consider that climate modeling is its own science and hardly anyone has expertise modeling gas core nuclear reactors.

The problem of course is that after infinitely many flips you might get someone with infinitely many tails. Turns out that that 2^infinite is infinitely bigger than infinite but even that is no guarantee when you compare to the series 1/2+1/3+1/4+1/5+... ajb basically gave you the answer. It's 2 minus something that gets smaller and smaller the farther you go, so if you go til that other term is infinitesimally small then you get left with 2. As he said though, no one proved it is actually true. (well I did but I'll let someone else do it if they want to. after all, many of you probably never proved something to be true for infinitely many things, right? It's easier than it looks!) OK, this is the claim that needs proving: [math]\sum_{i=0}^{n}\frac{i}{2^{i}} = 2 - 2^{-n}(2+n)[/math], The way this is usually done is prove that if the claim were to hold for some arbitrary number n=k, then it would also hold for n=k+1. If you do this remember that you can assume that it is true and also that you should put the k in the final answer into parenthesis as (k+1). Then prove that it does actually hold true for some n, typically n=1.

Distances in real life depend on how fast you are going. Going at almost the speed of light it would seem to you that the distances are almost zero. Time also gets distorted. These distortions are necessary for the speed of light to always be c for all observers despite them moving at different rates, as required by maxwell's equations and the principle of relativity.

People should know how to figure that out from the error message their compiler gives, and that should be far quicker too. Having a whole forum for asking about syntax errors is like begging for people to let us do their work for them. There might be an occasional syntax error that might be worthy of being discussed on a forum, but really most are quite trivial.

Stem cells share a property with cancer cells of being eternally young (they don't lose telomers like adult cells), and also of rapid reproduction (stem cells not as much as cancer ones of course). I've heard suggestion that most of our cancers might be caused by natural stem cells in our body rather than adult cells, but I don't know if there is enough evidence to support such a claim. http://www.nytimes.c...lth/21canc.html