Recent content by fengqiu

Consider a 4 current J^\mu and a metric g then conservation laws will require \del_\mu J^\mu = 0 my lecturer gave me a brief problem and I think I'm missing some understanding of it he writes What I'm not understanding is, where he states, if we choose B to be the time slice between etc...

Ahhh right I see, that makes sense! thanks for the help guys

I think it should, but I can't get it to work out. The operator is given in the question in the textbook.

Thanks for that, but I don't understand why you do this?

Hmmm, how do you mean? do you mean I need to normalise ##U\cdot U## with itself?

There's a question in Schnutz - A first course in special relativity Consider a Velocity Four Vector U , and the tensor P whose components are given by Pμν = ημν + UμUν . (a) Show that P is a projection operator that projects an arbitrary vector V into one orthogonal to U . That is, show that...

you, Orodruin are the man! thanks for your help it turns out that we get the same equation for energy equivalence and invariant mass that makes a lot more sense

i'm just crunching through the calculations now, I'll get back to you if i get the right answer, sorry one more question is that how do you know the pions are going at equal velocities?

oh okay... so if they have the same velocity... that makes a bit more sense... OKAY I'm still confused about the energies. could i not just solve the equation by equating the energies? Cheers\ Adam

Okay so i have a question for you guys if I have a positron striking an electron at rest to create 2 pions( + and -) and I want to calculate the minimum kinnetic energy that the electrons can possesses to create these pions... then the created pions will be at rest correct? so this gives me two...

yes, right, So I plug in x1=x2, so.. the limits of the integration don't matter? or.. the limits are from -a to pos a.. RIGHT any place in the well.. as long as they're together Thanks that makes sense

OHH I see what you mean, so operate on the free particle wave function THEN find derivative? Cheers

Yeah, the modulus across x. so... would I integrate wrt d(x1-x2) with limits 0?

Oh ok, that sounds right, how do I find the probability that the particles are at the same location? Do I just integrate between two arbitary numbers?

Yes but I'm not given x(t) so how would I find it's time derivative to average? Cheeeers