Recent content by Rob Sfic

Many thanks to atyy.

Equivalence principle? Hello PAllen, I am completely in agreement with you modulo the definition of the volume element or volume integral we consider. I am always very surprised that in GR the definition of the volume 4-form is $\sqrt{-|g|}\,d^4x$ and not $\tfrac{1}{\sqrt{-|g|}}\,d^4x$ because...

The "physical tensors" My apologies to « atyy ». I felt a slipping slope and a spreading of the initial problem. Sorry. I have also to improve my english to find all the correct civil sentences. Now, the things remains not clear for me. « bcrowell » after « Sadraj » said that GR is...

The question Well, I think that we move away from my initial question. No clear or convincing replies. I would like to avoid things such that: "someone said that..." such as Mr. 't Hooft or others. I would prefer scientific answers... Thank you.

Volume 4-form Schwarzschild was wrong? Well! Anyway, in GR the volume 4-form is $\omega_S\equiv\sqrt{-|g|}\,d^4x$. But, on the one hand, under any change of frame expressed by the Jacobian matrix $J$, the volume 4-form $\omega_G\equiv\tfrac{1}{\sqrt{-|g|}}\,d^4x$ is invariant. Indeed...

Invariance Hello, I am agree, the signature of the metric $g$ is an invariant and changes of coordinates can change the value of the determinant $|g|$ of $g$. From the Sylvester’s law, the signature is an invariant under changes of coordinates. Besides, invariance is always defined with...

Hi, In his original paper, Schwarzschild set the "'equation of the determinant" to be: |g|=-1. In other words, he imposed the determinant of the metric to be equal to minus one when solving the Einstein's equations. Must we impose this equality systematically in general relativity and why...