timo

I´d like to add that the clue about quantum computers is not that they are faster in the sense of "more operations per second". The clue is that losely speaking they base on a different mathematical model. That enables algorithms which are not possible with normal computers. The interest in quantum computers lies in these new algorithms which are not possible with normal computers, not in that they are seen as the solution to build a 20 GHz Pentium8.

Doesn´t it, in the end? By "perpetual motion" I´d think of a system that reaches it initial state after some time (so I wouldn´t count an asteroid flying in a straight line through void). In the case given here, we´d have air resistance. The energy lost through it cannot brought back to the system. An example without air resistance could be a planet orbiting a sun. Now, I´ve never seen or even done the actual calculation but I think there was the prediction that massive objects orbiting each other emit gravitational waves so you´d lose energy over time. Same goes for an electron orbiting a nucleus when viewing it classically (EM waves here, of course) - using QM won´t help unless you have a good argument why you call a groundstate "motion". I assume you´d even have some loss of energy due to gravitational waves in the case of the yoyoing train through earth. I know that wasn´t your point, but I am not really sure that when you take all physics effects into account, perpetual motion (in the sense of above) can really exist - not even in idealized models such as "no air resistance". But I cannot proof that they cannot, either (might be possible by using thermodynamics, though). One perpetual motion system in above sense I could actually think of (even if it´s very far-fetched): An asteroid moving through an otherwise completely empty universe with a toroidal topology

I dunno what you call "terminal velocity" but saying that if acceleration (gravity) is zero, then velocity is zero at least needs some further comment as it´s not obvious without knowing how the statement is meant or in what context it appears. Assuming terminal velocity is supposed to be the velocity which you´d reach the center of earth, then your statement is wrong, for example. I still don´t know what you call "terminal velocity" but I think we can safely assume that the velocity at the surface shall be zero, which certainly is not the velocity with which you´ll pass by the center of earth. Correct (felt like I should say something non-destructive ). Note: Yoyoing back and forth forever without having to put in any (or very little) energy would be a great improvement for long-distance travels (in comparison for cars and planes, for example).

But 2+2 = 4. And since his period has a length of 9, you would expect the 7th entry to be there, which in fact is 4. I wouldn´t be too surprised if that periodic behaviour indeed exists and I don´t think it is too hard to proof it, either.

I had some trouble finding out that you are talking about two rather disconnected things - a review in SciAm and a review in Time ... well, I should probably have read more carefully. I didn´t bother looking for informations on the SciAm review (perhaps you could post some information about it or about the book itself) but I read the Time article you linked. I must admit I was quite disappointed by that article. Except for some very questionable statements (like " any university that doesn't have at least one string theorist on the payroll is considered a scientific backwater") I fail to find any information in the text. What does the article say?

No you´re not missing anything. Strictly speaking one could argue whether the acceleration is infinite or simply not defined/existant but that supposedly wasn´t your point. Not all functions have properly defined derivatives and also acceleration does not need to properly exist in physics problems. One classical example where acceleration is not defined is in idealized collisions where the collision takes place at a single time (not over a time period). Within that idalized model, at the point of collision you cannot properly define forces and accelerations. You normally use conservation of momentum and energy plus a geometric assumption to solve the problem, then.

Too bad that afaik neither Israel nor Libanon and especially not the federal republic of Hisbollah managed to qualify for the tournament.

I didn´t read all you wrote so sry if I´m completely off here, but there´s an article including a very short explanation on wikipedia: http://en.wikipedia.org/wiki/Mystery_Spot

I suppose the cause is trying to understand (often in the sense of explaining) the world we are living in. As for the lot of effort you mentioned. I doubt that it´s so much effort. Giving a good starting idea I think I could give you a relativityiswrong-model with calculations supposedly proving it within a few days. Try learning relativity within a few days...

Gravitational attraction only applies in the up/down-dimension More seriously (but the same just in more confusing words): If you´d "extend" the mechanism by a projection on those dimensions that your physical laws shall exist in, then you can apply the law in all dimensions because those that it wouldn´t work in would be projected out. Do the laws apply, then because you can apply them or don´t they because they are projected out?

You all are aware that my comment quoted in the initial post was incomplete and not about sfn, are you? I mean, this place is called "science forums and debate". People come here to talk about science (well, some come to discuss politics ...) and actually expect that people tell them when/where/why they are wrong or correct. So: I suspect/hope that´s an appropriate description for most members in here.

Sorry if I am off topic but I have a stupid question: I have read about the leaflet-thing for at least the second time but I don´t really understand it. Isn´t it a bit counter-productive to the cause of destroying enemy missiles (that´s the reason for the bombing, afaik) to drop leaflets saying "Dear Hisbollah, we have located some of rockets at X. We have scheduled a bombing for tomorrow night 10 PM. If that date is not ok for you, please write an email to info@bombing.net or -in case we already destroyed all you telephone connections- shoot a message in a rocket towards Haifa harbor. Our navy will fetch it up and pass your message to the central bombing planning." EDIT: Ah, it was Bettina´s post #61 where I read that leaflet-thing before.

Penguins. Nice little sociable and completely stupid guys.

No, there´s no such thing. An idea would be to use the preview button as it already shows the result without making a post.

I would suppose so. For example, driving a car is -under normal conditions and with normal speed- nothing I really do counciously. Same with writing: I don´t think "now move your hand vertically and then horizontally to write a T", I rather think about the whole sentence I want to write and the words somehow appear on the paper. In neither case I have the feeling that my mind is switching back and forth between different tasks.

Skooter, if you want to discuss that definition of infinity, why don´t you do that on usapatriotsamerica directly and exchange a few watts of information with USAPatriot? I see no discussion value here, no halfways-scientific statement in the post on usapatriotsamerica and no connection to astronomy and cosmology. So I´m inclined to report this thread to ask the mods to either close it or move it to some other forum ("design&arts" seems to be most fitting, sadly we don´t have such a forum).

Lincoln.

I would suppose "havn't picked my options yet" means that the courses listed are that which are offered for him for the semester, not that he´s taking them all.

Magnetically charged?!? On topic: I completely fail to understand the news (by which I mean the article linked in above, not 5614´s post). My problems start at some trivialities: What is that radiation the ionized hydrogen gas shall protect against? Assuming that the cosmic radiation does not only consist of one single particle type: Is it effective against all types or just against the most common ones or just the most unhealthy ones? Due to not knowing what the whole issue is supposed to be about at all, the next problem naturally comes quite quickly: By what mechanism shall the shielding work? I cannot really believe that the mechanism shall be the magnetic field created (by whatever means) by a current in the plasma. If it was, then I ask myself what -especially considering that superconductors are supposed to be used anyways- prevents me from simply creating these currents with wires?

Ten bucks you don´t have the guts to go into an exam saying "I have no idea about QM, which is great because ...".

While we´re on tranlating the initial post: What´s 5, BC and AB subscore? EDIT: Ty@Luke

Forget heat when you talk about entropy. dS=dQ/T is for chemicists. S=k ln(W) is the definition to go with when you want an understanding of the concept. There is simply more ways to arrange the balls such that they are disordered than there is to have them ordered. Therefore if any arrangement is likely probable, the chances to find the balls disordered are higher than to find them ordered. The ratio of the probabilities increase as the number of balls increases. Thermodynamics is defined in the limit of an infinite number of particles where the probability of finding the balls ordered goes to zero. Important point once more: Thermodynamics is defined in the limit of infinite particles (10^26 = inifinite ), so your statements about "there still is a chance to find them ordered" are absolutely correct, but asymptotically irrelevant.

Temperature and the other thermodynamical quantities are defined in the limit of a huge amount of particles. The construct called Thermodynamics doesn´t apply to single atoms with definite position and velocity. As for the question: The atom will move according to the movement equations. If there´s no force, then it will remain in its current state of movement (for example at rest). If there´s any kind of forces working on it (like a cloud of gas giving gravitational attraction), then it will accelerate as a result of the force.