Recent content by tunafish

Hi everybody! I'm going to make this quick, so i won't waste your time! SO: What are the proofs of the expansion of the universe?? And what were the firsts? Is the cosmological redshift a proof of that? A little more complicated one: From where, in the einstein equations, should i see...

Ok, i figured that out, my thanks to Bill_k and Kith! Kith, please tell me if this is correct (but I think it is): 1) It's \langle x|\psi\rangle=\sqrt{\frac{\pi}{a}}\sin(n\pi x) yeah, i can see why now. And i don't know why on Earth I've put that dx!2) The momentum wave function is indeed...

Thanks for the attention! But I still have some problem with the 2) part. Basically, when I have to solve the eigenvalue problem for a generic hamilonian H|\psi\rangle=E|\psi\rangle what exactly is the \psi I'm plugging in? I mean, I have to choose the representation (coordinate or momentum)...

Hi everybody! Two question for you: 1) Take a free particle, moving in the x direction. Its (time indipendent) wave function, in terms of the momentum is \psi(x)=\frac{e^{i\frac{p}{\hbar}x}}{\sqrt{2\pi\hbar}}. Now, i know the momentum of the particle: p. So i should not know anything about its...

Ok, but like mathman says there is a difference between n poins in space and a vector with n components! Could you explain to me what it is? And if I step into a function f:\mathbb{R}^n\roghtarrow\mathbb{R} how should I understand it, as a function of n points or a function of some vector??

Thanks friends! But your answers seems contradictory to me: aegrisomnia says that the example function i proposed may be wiewed ad a function on a vector SteveL27 instead says that there has to be some application, like the scalar product, to convert the vectors into numbers. I'd say...

Hi guys! I'll go straight to my question.. how come the lorentz group is not the gauge group of general relativity but it is instead the two sheet SL(2,\mathbb{C}) covering of it?? Thanks!

Hi fellas! Would you help me solve this problem I have? Let's take a function f:\mathbb{R}^n\rightarrow \mathbb{R}. And so f(x_1,x_2,...,x_n)=y; \;\;y\in \mathbb{R} It's of course a function of many variables, but can this be considered a function of a vector whose components are the x_n's...

Thanks for your time henry_m, I didn't expect a rensponse so fast! You obviously say that since the coordinate transformation (an consequentely the change of basis they induce on the manifold) does not affect any phenomena (physic is the same for all observer) the lorentzian group, the group...

Hi everyone! Two question for you (): 1) I know that General relativity may also be seen as a gauge theory, but which kind of gauge group is used there?? 2) In the gauge theory wiew the Christoffel symbols \Gamma^{\alpha}_{\mu\kappa} in the covariant derivative...