Recent content by blue_sky

Yes, for not perfect fluid. blue

Where can I found an expressionfor the shear stress tensor in GR with some explanation about it? Thanks blue

If you ask me what time is I do not think I'm able to provide an answer. I do not think I'm able to define space too. The only think I'm able to say is the difference in space-time between time and space is that time flow in just 1 direction. blue

Well I guess you right from a math. point of view. In my opinion the physics is something different from math., i.e., math. is the "tool" we use to describe the universe through laws (physics). Personally I do not believe that BH exist also if they are a math. possibility. There are many...

The prob. is not what C is. You should write: \frac{mv}{\sqrt{(1-\frac{v^2}{c^2})^3}}+dU/dv=dE/dv blue

I tend to agree. Any 1 as a different view? blue

I agree with the exception of the total mass rest. Why we do need a total mass rest? This looks like a concept we are "importing" from classical phisycs. The question is: we do need it? blue

Nope, but if you can tell me where to look, I would appreciate. blue

Actually my thoght is that an integral over a finite 3 volume in full GR doen't make sense because c is finite and there is no rule which say how to relate 2 different point of the 3 volume (the 3 volume integral assume to make the integral at the same time for all the points... but this can't...

I'am startint to think thaf in full GR the integral over a finite volume don't have any phisical meaning; what is describing the full GR world are only the local equations. So in full GR is a non sense to define the mass of a body with finite dimentions. Any of you support this? blue

Pervect, my original question was also rised because also using the "simple" Schwarzschild solution you must use dV = 4 \pi r^2 dr Instead of the right formula for dV that u mentioned before to obtain the total mass. blue

Thanks garth... where can I read more on that subject? blue

Thanks... but this looks like that electromagnetism doesn't generate space time curvature. I got it correctly? blue

Energy---> space time curvature In general energy---> space-time curvature Any sperimental evidence that electromagnetism--->space-time curvature? blue

That make a lot of sense to me blue