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1d
revised Do the photons emitted along with the gravitational waves take more time to reach earth than the ones emitted after them?
edited for transverse linear waves.
1d
answered Do the photons emitted along with the gravitational waves take more time to reach earth than the ones emitted after them?
Jan
31
comment Shouldn't General Relativity Predict a Maximum Temperature?
So the maximum temperature limit goes up as the size of the hot stuff gets smaller. Most hot stuff still has most of the energy located in the mass of the particles, but its still a neat question. (e.g. - think of an electron - positron gas and the temp you need to go to see over 511keV of kinetic energy per particle).
Jan
31
answered Graviton detector thought experiment
Jan
21
comment Why does general relativity need space to be continuous?
Sorry I was thinking of the metric - space time is continuous, its just the metric which is not. - Concerning the Schwarzschild solution: "Clearly then, if our body has radius less than C then the exterior geometry will involve an r = constant hypersurface across which the metric is discontinuous and non-finite." math.unb.ca/~seahra/resources/notes/black_holes.pdf
Jan
19
comment Why does general relativity need space to be continuous?
If you look at the surface of a spherical planet, there are non - smooth changes in lots of GR fields at the surface. Like at the surface of a neutron star.
Jan
14
comment What is gravitational energy in general relativity?
The r.h.s is often a 'how you look at it' thing - as I pointed out you can put a dust of black holes on the r.h.s quite easily. If you want to put gravitational waves on the r.h.s - say in a universe model, you would add them as some average noise term. As in any universe model you need to approximate matter and energy with dust and radiation on the right. So its not a problem - same r.h.s for e&m wave noise as gravity wave noise. Energy is a pretty simple concept. Something carries energy - as gravitational waves certainly do if you can extract that energy out and perform work.
Jan
14
comment What is gravitational energy in general relativity?
Where do you get the notion that gravitational waves don't carry energy? Which authors say that gravitational waves don't carry energy? They certainly carry energy as you can use that energy to spin up a black hole or 'power' a gravitational wave detection. You could certainly put graviational waves on the r.h.s if it makes sense for the system you are looking at.
Jan
14
comment What is gravitational energy in general relativity?
You can build a universe made solely out of gravity and add items to the r.h.s. or the left hand side depending on how long you want to spend solving the equations, how much accuracy you need, etc.
Jan
10
comment What is gravitational energy in general relativity?
You can certainly put gravitational energy on the r.h.s. For example - think of a 'dust' of black holes in a model universe - the r.h.s can't tell the difference between the type of matter that makes up the dust.
Jan
7
answered What experiments and data have validated that the EM field contributes to the gravitational field?
Jan
7
answered Why does a light wave fade as it travels through space?
Jan
4
comment Can there be acceleration without velocity?
I don't see the connection to Compton scattering.
Jan
1
comment Can there be acceleration without velocity?
See also physics.stackexchange.com/questions/70915/… on that radiation problem.
Jan
1
answered Can there be acceleration without velocity?
Jan
1
comment Can there be acceleration without velocity?
Its not accepted that uniformly accelerating charges radiate. Feynman said "we have inherited a prejudice that an accelerating charge should radiate" mathpages.com/home/kmath528/kmath528.htm
Dec
31
answered What would be the implications for current theories if gravitational waves are not detected?
Dec
29
comment Why can't gravitational force have repulsive counter part?
ok, thanks for that.
Dec
29
comment Which physically acceptable quantum interpretations do not require the existence of any observer at all?
Penrose's idea is logically a complete rejection of QM, of course not in how well it works, but rather as QM then becomes - similar to Newton vs Einstein's gravity - a 'mere' approximation to another theory.
Dec
29
comment Which physically acceptable quantum interpretations do not require the existence of any observer at all?
The history of science is pretty clear. Where did I say that gravity or QM are not precious? Newton did not like his instant transmission, knew it was a problem, in the same way that people who study QM know it has some problems, measurement being the biggest one.