Are there any physics nerds on here. Probably a huge long shot. I'm doing a PhD in particle physics and I am pretty much screwed and my supervisor is sodding useless.
Any remote possibility that anyone can help?
Long shot. Any hardcore maths/ physics nerds on here
Moderator: phpBB2 - Administrators
not my area directly, but i know a bit. My mate is a physics expert.
What are you doing for your PhD?
What's the issues?
Why don't you approach the head of department and try to sort stuff out. I've had a few friends who while doing PhDs had useless supervisors, or their supervisors just left the uni completely! In two cases they never even finished the PhD, mainly because they lost motivation; it'd be a shame for that to happen, especially with such a cool topic hehe!
What are you doing for your PhD?
What's the issues?
Why don't you approach the head of department and try to sort stuff out. I've had a few friends who while doing PhDs had useless supervisors, or their supervisors just left the uni completely! In two cases they never even finished the PhD, mainly because they lost motivation; it'd be a shame for that to happen, especially with such a cool topic hehe!
My physics is OK, but nowhere near your level.
Ok, you asked for itdnb wrote:Try me.
I don't want to give too much away obviously, and this is going to be hard without latex, but I'm flumoxed by this one and there is not much in the literature. Say I had scalar field phi(x) and evaluated the field at phi(x_G) where x ---> x_G is a finite isometry of the coordinates, say a rotation.
then phi(x_G)=exp(L)phi(x)=exp(X.\partial_x) phi(x)
where L is the lie derivative of the scalar field. I know that for a fact, it's just parameterising the isometry, and using the chain rule. This is like the 'exponential' of the directional derivative
Now say, phi wasn't a scalar, but say the components of a vector, or a spinor...does this still hold? So say if A was a vector, would the following be right?
A(x_G)=exp(L)A(x)
where now L is the lie derivative of the vector. Probably a little abstract.
I think....(do only think) I may have sorted this out.
No, I don't think it is the Lie derivative any more, I think it is simply the directional derivative but with \partial replaced with the covariant derivative \nabla.
Am a little bit worried about the exponential now in the scalar case. I can't see an error with my calculation, but the literature talks about the exponential map in connection with geodesics, but the flows generated by isometries are not geodesics. So now I'm worried about that.
No, I don't think it is the Lie derivative any more, I think it is simply the directional derivative but with \partial replaced with the covariant derivative \nabla.
Am a little bit worried about the exponential now in the scalar case. I can't see an error with my calculation, but the literature talks about the exponential map in connection with geodesics, but the flows generated by isometries are not geodesics. So now I'm worried about that.
