Timeline for If the energy of the photon is conserved along a geodesic why is it redshifted
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25 events
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| Mar 4, 2021 at 20:06 | comment | added | Shashaank | @R.Rankin any simple reference for this ADM formalism for a beginner? My current knowledge in GR is till Black holes, Kerr metric etc and a bit of singularity theorems and I have never heard of this ADM formalism. Any book or notes for at a starting level? | |
| Feb 28, 2021 at 8:35 | history | edited | Shashaank | CC BY-SA 4.0 |
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| Feb 11, 2021 at 9:08 | history | edited | Shashaank | CC BY-SA 4.0 |
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| Feb 11, 2021 at 7:22 | history | edited | Shashaank | CC BY-SA 4.0 |
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| Feb 10, 2021 at 17:32 | comment | added | R. Rankin | Yes, energy is in fact still conserved, this is evidenced by taking the ADM energy. You find that while the gravitational energy is ill-defined locally, it still yields total covariant quantities when integrated over spacetime. This quantity changes when the E&M wave is included in closer proximity. This is where your missing photon energy goes | |
| Feb 10, 2021 at 14:38 | comment | added | Shashaank | @R.Rankin But the Schwarzschild metric has a timeline killing vector field, yet energy is not conserved. Any comments? | |
| Feb 10, 2021 at 8:32 | comment | added | R. Rankin | @Shashaank If our universe had a timelike Killing vector photon energy would indeed be conserved. Such spacetimes are known as stationary spacetimes. Ours is NOT one. This is because space is expanding over time, which rules out timelike Killing vectors. One can obtain a conformal Killing vector though. | |
| Feb 10, 2021 at 7:32 | history | edited | Shashaank | CC BY-SA 4.0 |
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| Jan 8, 2021 at 14:18 | vote | accept | Shashaank | ||
| Jan 8, 2021 at 14:18 | vote | accept | Shashaank | ||
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| Jan 8, 2021 at 14:18 | vote | accept | Shashaank | ||
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| S Jan 7, 2021 at 22:36 | history | suggested | jng224 | CC BY-SA 4.0 |
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| Jan 7, 2021 at 21:10 | review | Suggested edits | |||
| S Jan 7, 2021 at 22:36 | |||||
| Jan 7, 2021 at 21:05 | history | edited | Shashaank | CC BY-SA 4.0 |
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| Jan 7, 2021 at 18:00 | answer | added | Mike Serfas | timeline score: 1 | |
| Jan 7, 2021 at 16:29 | history | edited | Shashaank | CC BY-SA 4.0 |
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| Jan 7, 2021 at 16:06 | answer | added | Andrew Steane | timeline score: 15 | |
| Jan 7, 2021 at 15:20 | answer | added | user284984 | timeline score: 3 | |
| Jan 7, 2021 at 5:52 | comment | added | Shashaank | @RedGiant I understand that energy is conserved along a geodesic and for the reason please see the comment I have just made above. | |
| Jan 7, 2021 at 5:51 | comment | added | Shashaank | @Eletie But Caroll says that though the geodesic eqn (or rather by just solving the Euler Lagrange eqn for the time coordinate) you have $(1-R/r) \dot{t} =constant$ and the constant is interpreted as the energy. So I understand that energy is conserved along a geodesic and hence the question of photon getting redshifted and loosing energy. | |
| Jan 7, 2021 at 0:18 | answer | added | stuffu | timeline score: 1 | |
| Jan 6, 2021 at 23:20 | review | Close votes | |||
| Jan 11, 2021 at 3:04 | |||||
| Jan 6, 2021 at 23:02 | comment | added | Eletie | Does this answer your question? Are photon energies conserved in general relativity? | |
| Jan 6, 2021 at 22:13 | comment | added | RedGiant | Do you know that energy conservation law does not hold in GR? | |
| Jan 6, 2021 at 21:00 | history | asked | Shashaank | CC BY-SA 4.0 |