timo

I wonder how big 2 kg of lead in a cylindrical form with rounded ends would be ...

Just for info: For the last ~10 posts you guys have been giving advice to someone whose first and last activity on this forum is three and a half years in the past.

Have you really been given this homework assignment in a university course on Quantum Physics?

I think when asking "what is your result" CraXshot was addressing neo007 (who started this thread), not the general audience. And CraXshot is indeed not supposed to provide an answer for neo.

Any result without physical units is definitely wrong. 5.5 * 10^-7 parts of daylight time may be roughly correct, depending on season.

As a matter of fact, this is a (if not the) requirement for a potential energy to be properly defined.

[math] \pi = 3 \Rightarrow \sin(\pi) < 3 \Rightarrow \sin x \leq 1 \ \forall \, x[/math]. If that doesn't help then you may have to be a bit more specific what the "proof of fourier series" is .

A gas is some large quantity of usually small objects moving around, each having a kinetic energy that is usually non-zero.

I doubt that's going to have a significant impact on the result.

But if I add bricks on top of a wall then the wall becomes higher, which I can continue until I have no brick left. Therefore a brick must be pure tall!

Perhaps there is a typo in your rules? Where did you get them from? And are you sure that A and X are arbitrary matrices or at least allowed to be symmetric and antisymmetric, respectively?

No, it doesn't even require a gas. But I fail to see how that has anything to do with your original question. It would be nice if you told us whether your original issue has been resolved or not.

I don't know what the potential energy of gas/liquid/solid is supposed to be. But these substances certainly have something called binding energy (which is often computed from pair potentials, so that's probably what the book means with "potential energy"). It is common to count binding energies as negative for a bond holding particles together (the stronger they are bound the more negative the values, i.e. the smaller the value). For a gas the binding energy is about zero, which is negligible. For liquids and solids it is some non-zero negative number and not negligible anymore.

My Settings -> Change Display Name may do the trick. Asking Capn to do it certainly does.

It's funny that Wikipedia cites a different article from the same journal and same volume with an almost identical title: TASSO Collaboration: Evidence for planar events in e+e− annihilation at high energies, Physics Letters B Volume 86, Issue 2, 24 September 1979, Pages 243-249 Service: the article linked by ajb is called Evidence for gluon bremsstrahlung in e+e− annihilations at high energies.

Perhaps you are mistaking gluons for something else. It's common to take their existence as granted, and the have nothing to do with extra dimensions or "extra dimensions of folding" (by which I assume you mean small extra dimensions). You can consider any particle of the Standard Model as "only theory" since the Standard Model is a theory, but that line of doing science is about as promising as "maybe reality is just an illusion". Usually, you measure processes, and when you measure a process that could not have happened in the absence of the theoretical particle then you say that the particle really exists.

Of course it is possible. There are several levels on which you can adjust the colors. I'm not an expert, but maybe the header of my latest talk (in which I do play with colors) is a help for you; the places in which colors are modified are commented. \documentclass[xcolor=dvipsnames]{beamer} \useoutertheme{infolines} \usetheme[height=4mm]{Rochester} % Colors theme \usecolortheme[RGB={20,60,70}]{structure} \setbeamertemplate{blocks}[rounded][shadow=false] \setbeamertemplate{items}[ball] \setbeamertemplate{navigation symbols}{} % A customized alertblock (hand-picked colors, used with \begin{altertblock} ... \end{alertblock} ) \setbeamercolor{block title alerted}{fg=white,bg=black} \setbeamercolor{block body alerted}{fg=white,bg=black}

I believe the proper way to deal with these problems is using the ignore list. If someone consistently isn't capable of communicating at the level you'd expect from a discussion partner then don't discuss with him/her. Sure, you may be missing part of the discussion. But you're missing the parts that you consider moronic anyways, so why care? All sections of this forum are better served by picking up interesting points worth discussing rather than pointing towards the really stupid ones and discussing them to death. I strongly believe that stupid and obviously incorrect statements speak for themselves and don't always need to be commented, and I have yet to regret a single entry to my ignore list. It's admittedly not an answer to what you asked about. But perhaps the "ask what you can do for your forum" way of looking at things is also an interesting perspective.

It's true that in Germany you'd "rather not" go to a pub in work clothes. But I believe that's more because it is uncommon to go to a pub directly after work without going home first (the dedicated "after work" events mentioned by CharonY exist, though - I just never went there). Not letting strangers around you know that you work with your hands sounds like a strange reason to me, I've never heard of people who'd have a problem with that. People usually would just as well not go to a bar in the suit they wear at work.

I'm a bit surprised you apply a force to the rolling balls. Do you mean the gravitational force that pulls them down or are you applying another force? If I understood your scenario correctly, then that is somewhat correct. It's pretty much what I meant when I said You are mixing two things that are usually considered somewhat separately. First, "experiencing a greater force due to gravity" is the same as "greater effect of 'free fall'", since free fall is when 100% of the gravitational force goes into accelerating the object. Second, there is a force pressing the ball onto the ramp, which can determine the way the balls go down the ramp (rolling vs. sliding, and presumably mixtures of - that's also what DrRocket spoke about in his post). I was assuming your balls roll, in which case this force can usually be ignored. If you choose not to ignore it, then reduced pressure of the spheres onto the slope indeed is another reason strengthening the "goes down a steeper slope faster" effect. I believe you are best helped by trying to understand the "more freefall-like" reason first, since this is basic school knowledge (8-9th grade or so), whereas the other is already lower university level. You may be interested in reading forces on an inclined plane on Wikipedia, since this shows how the gravitational force is split into a force parallel to the direction of motion, and a rest.

Not exactly. Two different objects, say spherical ones, can roll down the same slope in a different way. That would be caused by different moments of inertia. The same object rolling down slopes with different angles in different ways is much more simple: There is a constant gravitational force pointing downwards towards the slope. This force can be uniquely written as the sum of two forces, where one of the forces is in the direction of motion and the other one is perpendicular to it. The force into the direction of motion is the one that is responsible for the motion (not too much of a surprise). The steeper the slope the larger this force, and hence the faster the object accelerates and rolls down.

There are times that I feel that I am having a conversation with a random text generator.

That's wrong. One of the largest physics experiments in the world (Tevatron) essentially does nothing else than colliding protons and antiprotons, and they do see quite a lot more than only energy being left. You seem to be incorrectly extrapolating the statement that electrons and positrons annihilate into pure energy (which is already wrong by itself) to "therefore every matter<->antimatter pair does the same". To answer your question: Proton-antiproton reactions are explained via the Standard Model of particle physics plus a lot of phenomenological tricks for the description of non-elementary particles. At least at very high energies you consider the quarks and gluons in the proton (their amount is obtained from fitting a curve to measurement data) as being pretty much free particles and describe the core of the process with perturbative Standard Model physics. Thereafter, some corrections are applied, but these are very tricky, and I think only few people (excluding me) understand these properly.

That is not completely fair. The original premise of this thread was that "the BBT(Big Bang Theory) defies conservation of mass energy" (correction to energy by me, because mass may be a complicated concept in this context). And as Dishmaster correctly says this is not the case. It is a common misconception people get from hearing the term big bang and reading popular scientific texts, or even reading scientific texts but without having the background to understand them. Saying that excluding the creation step from the big bang is just a trick is problematic: you are assuming that there is a kind of creation step. This is not assumed in the standard big bang scenario, where you trace backwards in time from today until you reach a point where you expect that your physics breaks down and that you cannot make any physical statements at and beyond this point. And there is also no scientific evidence for the existence of a creation step (that I knew of). Assuming that a creation step must have preceded the existence of the universe may seem natural to you, but comes with a few inherent assumptions that are not scientifically justified. I could name a few, but they all boil down to the same issue: you are using your intuition to extrapolate beyond the point where you expect your known physics to break down (and where you don't have a good intuition on, because early-universe conditions are probably a bit different from the Newton world you live in). There is, as far as I know, neither a logical nor a scientific reason to assume an event in which the universe came into being, even though I admit that it is not excluded and also very imaginable.

Thanks for the numbers, it's far from standard in this forum that people back up their statements with quantitative arguments. The profit indeed sounds more than I had expected. But to be fair you have to realize that the 7M Euro revenue seem to come with a 5M+ Euro operating cost (that's how I read the numbers - I'm not an economist). That motivates the following simplified assumption: if they were a non-profit organization then fees would be about 75% of what they are now. That still is ridiculously expensive, and far from free. EDIT: Incidently, I think I never read an article from Elsevier (I know the name, though). I checked with the publishers of my papers: most papers are free for download (IOP). Only one costs (AIP), but is of course also available on arXiv for free (and with better formatting ).