timo

If the very text you quoted doesn't answer these questions for you, then I don't think we have a basis for discussion.EDIT: And I also didn't say that the US has a worse reputation that the Democratic Republic of Kongo. I said the international reputation suffered during the Bush administration, which by the way happens to be related to the topic of this thread. EDIT2: vv omg vv

While it doesn't completely fit into the US-inner-politics-only list, the international reputation of the US would come to my mind on the "loss" side. While starting wars around the world wasn't exactly new, kidnapping foreign citizens to lock them away without a trial, secret prisons in eastern Europe (and presumably non-European states like Saudi Arabia, too), employment of mercenaries, mistreatment of prisoners, and of course torture kind of was.

Welcome to drawer number one.

A nasty workaround is the nasty math tags: [math]©[/math], or even [math]\text{©}[/math] for the type-a-lots.

I don't think you are particularly lucky. I did several installations of Ubuntu variants on different computers and did, except for the WLAN not being detected properly, not experience any problems. But installing Windows doesn't seem to be any more trouble than installing the Ubuntus, either. The only advantage of Linux I see (from the ease-of-usage point of view) is when you need quite a lot of standard extra programs. Installing them via packet managers is much more convenient than downloading installers from a variety of webpages or juggling around with CDs/DVDs. I'm not sure to what extent that would count as the OS itself being "easier to use", though.

First off: I am not an astrophysicist. I did some work on relativity and exotic matter as a physics student, but did not follow the developments in astrophysics for about the last 4 years. So take all below with a grain of salt. The cosmological constant: When you write down the equation for the dynamics of the gravitational field, the Einstein equation, this equation turns out not to be unique. Rather, there is a free real-valued parameter in there, i.e. the value of the parameter is not determined from the theory. This parameter is usually called the "cosmological constant [math]\lambda[/math]". What you can do about this parameter is that you compare the theory predictions for different values of this parameter to experimental results and fit this parameter. For most applications, [math]\lambda=0[/math] is an excellent approximation. For one case, however, it is expected that a tiny non-zero [math]\lambda[/math] is important. That is the measurement of the universe's expansion. Now for your actual question: it can be considered somewhat inelegant to have a mathematical term in one of your most basic equations that is just a fit parameter without physical interpretation. So it is tempting to assume there is a physical reason why this term is there (assuming it is non-zero, of course). "Dark energy" is the idea that this term is the contribution to the energy density (**) which is caused by some unknown physical object (say an unknown form of matter). If you go beyond the explanation I just gave and analyze the structure of normal matter contributions to the Einstein equation and compare that to the contribution from the term with the cosmological constant, then you can also make some assumptions about the properties of this yet-unknown physical object. These properties are -assuming I recall that correctly- quite weird when compared to normal matter. In essence: At the current state, depending on your personality you can consider dark energy to be either - another name for the cosmological constant, or - a yet-unknown physical object with very exotic properties. (**): Strictly speaking not only the energy density, but I think my reply is already complicated enough.

By using Google to find it out, e.g. http://www.phys.ethz.ch/phys/students/prospective/ If there are still open questions after you read through the webpage extensively, write them an E-mail. The extensive search on their homepage should at least yield a contact address. I doubt that anyone on this forum happens to be a bureaucrat at ETH.

I did not mean to offend you. But I don't think you're helped if I am pseudo-encouraging rather than realistic. See it this way: physicists take about 4-5 years of university training to get a basic degree. Believe me: after those 4-5 years they still know preciously little about how particle physics works - even those that specialize in that field (I know what I speak of ). In that view, I simply don't consider it an offense to tell someone who obviously doesn't have this basic training that they don't have a proper understanding of a quantized field. And that non-understanding is definitely not going to change if you're being pissed by that statement rather an acknowledging that I gave you a hint how to think of it.

It is (again in my opinion) absolutely wrong to say that mass has no effect on how fast something falls (in the presence of friction). Assume two bodies with the same shape but different densities, and a friction force which only depends on the objects' shape and velocity (the latter should serve as a very good approximation for many cases). In this case, the object with the greater mass will fall faster. My statement about "depends on many things" is much more involved than you might think at first glance. Perhaps forget about it (in which case the "in my opinion" parts become "that's how it is") and just focus on the two example in the previous paragraph and the little calculation I quoted above - and possibly the thread I linked. There, it is clear that an object with larger mass will fall faster when air resistance is non-negligible. If you are seriously interested in understanding it, I strongly advice to understand the calculation steps, why I showed them, and what they do mean (there is a bit more to it than a simple rearrangement of terms). Also, try to first understand in terms of equations why all objects fall at the same rate when there is no friction.

That is presumably because you guys don't know what a particle is within the context of particle physics. It's just not that little metal sphere that bounces around that one might imagine it to be. Could you see how say an electric field could cause attraction? I assume so. Consider particles being pieces of the fields.

I've heard those theoretical physicists are paid so good that they can afford a warm meal every day. EDIT: What the heck? you killed Zoidberg with the forum update!

That is a tricky statement because the acceleration due to air resistance depends on the mass It is also correct that an object with more mass experiences a larger gravitational force; only the acceleration due to gravity is the same for all objects. It is, in my opinion, absolutely correct to say that a book falls faster than a sheet of paper due to its larger mass. But beware that you are comparing books with papersheets here! A feather pillow might have more mass than a rifle bullet but I doubt it will fall down faster. Mass is not the only factor determining the speed of falling. You might be interested in reading this thread where I put a similar statement into a slightly more scientific form: http://www.scienceforums.net/topic/26055-galileos-expements/

It's somewhat refreshing to read such a nonsense without a reference to string theory (which no one here really knows what it really is about, while at the same time it certainly says what was just claimed).

Isn't it a rather obvious approach to look at the courses typically being offered as the next step beyond your current education level and try those topics, possibly by reading the books recommended for those courses?

"Superposition principle" is just saying that entities of the same kind can be (or maybe must be) added up to form a third combined entity. This can be amplitudes of two wavefronts in water, or forces, or solutions of linear differential equations. There is no such thing as THE superposition principle. One does not add up wave functions of electrons and photons since there is no reason to do so. I also wouldn't know how to do that since in standard representation the electron is a bi-spinor valued field while the photon is a vector-valued one, i.e. you'd have to do something akin to adding five to the unit vector in x-direction. There is no such thing as a wave nature of energy, btw.

Asking question is completely ok. Even for such easy question which you could as well have looked up on Wikipedia - at least in my opinion. Worse would have been This somewhat does serve as a starting point for a discussion. But a stupid one. And really bad would have been. No discussion, stupid, delusuionary.

The easiest way to think of a tensor is probably as a linear function over a vector space (for those a bit more familiar with tensors note that I did not specify the range is or the number of arguments). I have no idea why functions are useful but I am quite sure they are.

I guess that's a reason to congratulate you ... whatever ACS might be ...

Until you switch on gravity or possibly even other interactions. Then it is not so clear that you can put any number of photons in any volume. Regarding the question of interactions: if you shoot two photons onto another then in principle, the outgoing photons might have a different direction than the incoming (although I am not sure if this has been measured). So in this sense photons do interact with another.

Before . Guess the research at Memory Alpha Institute is even more advanced than I though .

That would be dark matter you speak of - yet another thing.

Keep in mind that a past-future communicator must have a certain size due to physical limitations: due to the Heisenberg uncertainty principle the more precisely you know the position of your chronotons, the less precisely you know their momentum. Hence, for being able to pick the correct multiverse brane, your device has to have a certain minium size, which is determined by the Planck units. Keep in mind that this is all very new and at the top of current theoretical physic research!

The trick is the input, not a program that has a variable. So you'll have to be a bit more specific there. Strictly speaking, your specification is fully satisfied with the following c++ code #include <iostream> int main() { for (int value(0); value!=-1; std::cin>>value) std::cout<<"value is now "<<value<<". Enter new value: "; } I somehow doubt it is what you were asking for, though.

It's kind of funny that my spontaneous thought is that if the non-existence of a graviton was proven (however that might happen), we'd have to rethink our ideas about (the application of) perturbative quantum field theory, not our ideas of gravity. Can't quite put the finger on what I mean by that, though.

Well, I must admit that I don't understand how parallel universes are physical, theoretical or hypothetical with m-theory (not that I knew what that is) or quantum mechanics (I've got a vague idea what that is). I'm only an average stupid little physicist - I don't understand all the cool stuff that non-physicists talk about in the Internet all the time. But I wouldn't mind if someone tried to explain it to me.