Recent content by Michael_1812

Dear Sam, Many thanks for your time and help ! Now I understand this. Michael

Dear Sam, Many thanks! I agree with your derivation. You have built such an F that the sum Tγλ + ∂μ Fμγλ is both conserved and symmetrical. Now, suppose I go a different way and extract directly the symmetrical part out of the canonical SET: Tγλ = (Tγλ + Tλγ)/2 + (Tγλ...

Further to my question. I certainly understanding that TγλB should not necessarily be defined as (Tγλ + Tλγ)/2 . We are always free to add a full divergence. And we should add it, to make sure that the result be conserved Therefore it is possible that TγλB is defined not as (Tγλ...

Hi guys, Can anyone please help me to grasp a minor detail in the derivation of the Belinfante-Rosenfeld version of the Stress-Energy Tensor (SET) ? To save type, I refer to the wiki webpage http://en.wikipedia.org/wiki/Belinfante%E2%80%93Rosenfeld_stress%E2%80%93energy_tensor Using...

Dear vanhees71, dauto and Jano L., Thank you very much for your help ! Much food for thought, really

Thanks for the informative reference. I shall try to digest it, though it does not seem a simple piece of reading. I see that the author of that article had to resort to pretty advanced concepts, and I am trying to express this in simple words. From the author's equations (22 - 23), I see that...

Guys, Let me ask you the silliest question of the year. I am looking at the Maxwell equations in their standard form. No 4-dim potential A, no Faraday tensor F, no mentioning of special relativity - just the standard form from a college-level textbook. I know that the eqns are NOT...

Guys, May I now ask you a (presumably, silly) question. Why is SO(2) not a normal (invariant) subgroup of SO(3) ? Many thanks!

Dear atyy, Thanks for the interesting link. While it is indeed relevant, it still does not provide an immediate answer to the question: given an arbitrary twice-covariant tensor field, is it possible to build, on a *finite* patch, a coordinate grid, for which this tensor field act as a metric...

Suppose I have a manifold. I say that it can support a certain configuration of gravity field described by metric tensor \gamma. I do not write \gamma_{\mu\nu}, because that would immediately imply a reference to a particular chart. A tensor field, however, exists on a manifold unrelated to this...

Does this have anything to do with violation of the Strong Equivalence Principle?

a relativistic counterpart to the angular-momentum-conservation law?? Here comes an even more wicked question. Varying the Hilbert action with respect to gauge-like ripples of the metric, i.e., with respect to small shifts of the coordinate chart, we arrive at G^{\mu\nu}_{ ; \nu} = 0 ...

Anderson's line of reasoning has long been explored in detail by many. See for example the theories by V. I. Ogiyevetsky and I. V. Barinov. "Interaction field of spin two and the Einstein equations." Annals of Physics, 35:167-208, 1965. and S. Deser. "Self-interaction and gauge...

I have re-posted the latter two questions as new threads

Could someone please explain to me in simple words (i.e., without referring to forms on the frame bundle, etc) why the Bianchi identity is the relativistic generalisation of the momentum-conservation law? Here comes my hypothesis, but I am not 100% convinced that it is correct. In Newtonian...