Recent content by wasia

Derivation is really easy, you only need some vector calculus identities. However, the full thing is here.

In this case proper time is not a well defined concept, since you are considering a null curve. I cannot give you a formal definition, but I think of an affine parameter as something that parametrizes the curve under consideration in a good way - i.e. every point on the curve is in one-to-one...

Hello! Here and there I find that it is possible to make the Christoffel symbols vanish on a curve (e.g. lecture http://www.phys.uu.nl/~thooft/lectures/genrel_2010.pdf" by 't Hooft). The transformation law of the Christoffel symbols is relevant in this case...

Hello, I have read (wiki and physicsforums besides other sources) about how preparing an ohmic junction is hard on wafers in the clean room and that usually one gets a Schottky barrier instead, if one is not careful enough. This makes me wonder, how come that people used to get an ohmic...

Back to the topic: I believe Cambridge is the way to go if you really want to go abroad. I haven't experienced studies there firsthand, however, from what my friends tell me, Cam is pretty serious about maths. Again, I am a bit surprised that you do not consider Utrecht, as the double...

Do I understand correctly that you claim that the invariant matrix element does not depend on the angle?

Hello, First of all, it is not a homework question, just something I wonder about. The dominating electron-positron annihilation process at low energies is photon pair creation. What is the angular dependence of the total cross section? For some reason I expect the head-on collision to...

Well, this is exactly what I mean by cumulative - the different becomes more pronounced with time. But what do you mean "obviously isn't possible"?

Hello, I am sure this must have been considered before, but I haven't been able to find it. I would be most grateful to get a reference or the right keywords to search for. Consider a slowly rotating cylinder, which is brought into a gravitational field (say from space to the surface of...

After an extensive search it seems there is no easy way to customize this behaviour in Mathematica. It is defined by Item[KeyEvent["Right", Modifiers -> {Shift}], "SelectNext"], Item[KeyEvent["Left", Modifiers -> {Shift}], "SelectPrevious"] in the "KeyEventTranslations.tr" file. I was not...

Yes, I think it is correct. I find the list of what Maths one needs for Physics in 't Hooft's http://www.phys.uu.nl/~thooft/theorist.html" quite good.

I can only answer about 'practical' things and only approximately. After you graduate and start doing research, specialization prevails, hence one most likely does only experiments, or only theoretical work ~ calculations/modelling . However, in undergrad studies, a lot depends on the curriculum...

I think the abstract of the original paper answers questions 1-3: This was taken from Jönsson C,(1961) Zeitschrift für Physik, 161:454–474 (the paper itself is in German). Wikipedia also gives a reference to "Jönsson C (1974). Electron diffraction at multiple slits. American Journal of...

Most probably you should talk about plane waves. Also, one can discuss spin, which is a property of the particle that basically tells you which equation to use. As always, http://en.wikipedia.org/wiki/Free_particle" might be a good place to start.

I would say some neutrino is the "smallest" in the sense that it has a small mass and doesn't interact much with anything.