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 10h comment Scale invariance and stress energy tensor @ParthaPaul I suggest you use web-links rather than textual references. They are quicker to check out. After all the hypertext concept was invented/propelled by physicists at CERN. 10h comment Derivation of Euler-Lagrange equation from principle of least action @GiorgioComitini Peccato! I was hoping for an inside tip :-) I guess i will stick to Lyx for now. 11h comment Derivation of Euler-Lagrange equation from principle of least action @GiorgioComitini I also ask you: what kind of Tex editor (if any) did you use? 11h comment Derivation of Euler-Lagrange equation from principle of least action @GiorgioComitini I always support compactly supported arguments, so for me....+1 :-) 11h comment Derivation of Euler-Lagrange equation from principle of least action @123hoedjevan, Giorgio is correct. His answer is the rigorous statement and proof of the least action principle and EOMs. Nevertheless I do not think is useful to down vote your answer, but rather encourage you to change your arguments, so that your answer is correct too. I like your TEXing very much, what tex editor (if any) did you use? For me...+1 12h comment Construct an effective field theory of neutrino mass where is this text taken from? 1d comment Why is the covariant derivative of the determinant of the metric zero? We probably misunderstand each other, but -from what you write - it would seem that any polynomial function of metric components , such as $f=g_{00}^2$, is covariantly constant which is not the case. I do not think at the moment that there is a simple heuristic/intuitive justification for the constancy of the determinant. You just have to take the definition and make the calculations 1d comment Why is the covariant derivative of the determinant of the metric zero? Qmechanic I do not really understand your heuristic explanation. Following your logic it would seem that any simple product of metric components should be covariantly constant. But it's not Apr 20 answered Orthogonal of tangent vector in Rindler coordinates Apr 16 awarded Excavator Apr 16 revised What is the utility of ADM decomposition of the space-time metric? edited grammar Apr 16 suggested approved edit on What is the utility of ADM decomposition of the space-time metric? Apr 16 answered Does metric signature affect the stress energy tensor? Apr 1 comment Einstein wrote $x^4=ict$, where $c$ is the speed of light. Does this mean the fourth dimension is moving? this is obviously an April's fools question. It is amazing to see so many fine physicists scrambling to give an intelligent answer to a silly question. It is always wise to check the profile of the OP before answering. Mar 30 comment Do gravitational waves travelling through a medium produce sound? @ChrisWhite of course! but in principle the further the wave goes from the hole, the more gravitationally redshifted it will be. This is a gedanken experiment, so everybody is equipped with infinitely sensitive sensors....and hears. Mar 30 comment What is the explicit form of $\tau^{\alpha\beta}$ in the linearized Einstein field equations $\Box h^{\alpha\beta}=-16\pi\tau^{\alpha\beta}$? Can you please link the specific article in Wikipedia? Mar 29 answered Do gravitational waves travelling through a medium produce sound? Mar 29 revised Function to model deformed spacetime in 2D visualization of an Alcubierre drive edited whole answer Mar 29 answered Function to model deformed spacetime in 2D visualization of an Alcubierre drive Mar 26 awarded Explainer