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  • 0 posts edited
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  • 35 votes cast
Apr
10
comment The change in gravitational potential energy of a meter stick that swings through the vertical starting at rest from the horizontal
Your centre of mass idea is right, but its the full mass 0.180 kg over 0.5 metres. Which is the -0.882J you need.
Apr
3
comment Are there any QM effects where charged particles are not intimately involved?
Photons are simply charges communicating, which is another hint that charge and QM are somehow interconnected. The only reason photons diverge at the slit are charges - which interact absorbing the light in the wall, or deflecting it. I was looking for some quantum effect on say neutrino - neutrino interactions - which while predicted cannot be observed with current experiments. I agree fully that the framework of QM is independent of electric charge, but QM effects are never observed in truly uncharged interactions.
Mar
29
awarded  Enthusiast
Mar
26
comment Do all massless particles (e.g. photon, graviton, gluon) necessarily have the same speed $c$?
The speed of light is a postulate. That means that its just a rule which no one understands. A real move forward - true unification - would show that the speed of a photon is the same as a graviton because they are both the 'same thing' - postulate not required.
Mar
24
awarded  Yearling
Mar
24
answered Gravitational waves from an oscillating mass
Mar
24
answered warp drive with gravitational waves in the nonlinear regime
Mar
19
awarded  Revival
Mar
19
answered Does the existence (now proved) of gravitational waves imply the existence of Gravitons?
Mar
8
comment How does the propagation of gravity work for photons?
Photons certainly have gravitational fields. Any energy will affect spacetime. The calculation is simplest when there are two lasers facing each other, as the amount of energy in any single volume is well defined.
Mar
5
comment Do photons generate gravitational waves since they affect with their energy the stress tensor?
Interesting. While gravitational waves require a quadropole, any disturbance will cause some effect. Since Gravity is non linear that means some energy should be dissipated. A very tiny amount!
Mar
3
comment Is there a path to go from GR, to Gravitational Waves, to Gravitational Particles (Gravitons), to Quantum Gravity?
I'm not sure the OP was only referring to astrophysical objects. My take on the OP's Question: Take an atom or a protein - every motion should radiate GR waves (however little). Since these structures are stable - we can thus say that gravity is quantized.
Mar
3
revised Why there is no dipole gravitational wave?
deleted 91 characters in body
Mar
3
answered Why there is no dipole gravitational wave?
Feb
22
comment How much energy can be radiated as gravitational waves from black hole merger?
The amount of energy radiated was well above the efficiency of any fusion or fission power source. Also the density of energy in the radiation zone at emission time was 15 orders of magnitude higher than possible energy densities achievable with electric fields. Even at 1.3 billion light years away, the earth had 2.3 Terawatts of power pass through it from GW150914. There is so much power created in a merger like this that it goes beyond mere mind boggling.
Feb
13
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.
Feb
13
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