Recent content by ChrisPhys

@Orodruin Thank you, that makes sense. I appreciate your help.

To address your last point: I just viewed the ##\delta## function as the limit of a Gaussian, whose derivative at zero is zero. Is that an error?

I can't convince myself whether the following functional derivative is trivial or not: ##\frac \delta {\delta \psi(x)} \big[ \partial_x \psi(x)\big],## where ##\partial_x## is a standard derivative with respect to ##x##. One could argue that ## \partial_x \psi(x) = \int dx' [\partial_{x'}...

Thanks @vanhees71 So my problem reduces to evaluating two functional derivatives: 1) ## \frac{\delta \sqrt{g} }{\delta g_{ij}} ##, which you evaluate above. Could you explain your result to me? 2) ## \frac{\delta g_{ij} }{\delta g_{ij}} ## which I assume is equal to 1 or otherwise some...

Hi @vanhees71 Thanks for your reply. Does your statement also hold for a Euclidean metric? Specifically, the problem I'm considering is on 3-D Euclidean space, where I guess all factors of ##\sqrt g ## are trivial, so my hamiltonian is ##H = \int d\vec x [\nabla \phi (\vec x) ] ^2 ##, with...

I would appreciate any help with the following question: I know that for relativistic field theories, the stress tensor can be obtained from the classical action by differentiating with respect to the metric, as is explained on the wikipedia page...