Timeline for How do light rays move parallel at the event horizon and why is this necessary?
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| Sep 19, 2023 at 9:05 | comment | added | Nadav Har'El | @anna-v very interesting observation. Individual photons, even if they have a lot of energy, cannot transform to pairs of particle and anti-particle (see for example physics.stackexchange.com/questions/22916/…) pair a pair of interactive photons can. | |
| Jan 4, 2019 at 17:19 | comment | added | anna v | @ElioFabri it has to follow a zero mass geodesic. I am saying that photon paths must not interact and thus move in parallel. Light is a classical concept, photons are quantum mechanical components of light. I do not know how the light ray is built up by photons, but I strongly expect that parallel photons will make parallel light rays. And all classical emerges from quantum, is the current expectation of physics afaik. | |
| Jan 4, 2019 at 17:05 | comment | added | Elio Fabri | @annav. You wrote that the classical description of light (be it waves or rays) emerges from the superposition of the complex wavefunction of each individual photon with the zillions that compose the classical electromagnetic wave. And then? How can one understand a lightike geodesic along this way? Surely we may not say that a single photon follows a lightlike geodesics in spacetime. | |
| Jan 4, 2019 at 17:05 | comment | added | Elio Fabri | @annav. I know you like to reduce everything to elementary particles. I have the opposite view. GR is a classical theory and knows nothing of photons. Moreover I find dangerous to bring up a concept so liable to misunderstandings. Photons are quite different things from what most layman would think. They aren't tiny particles of light, like minuscule grains of sand. Photons are quantum particles whose properties are very far from common sense. | |
| Jan 3, 2019 at 19:11 | history | edited | anna v | CC BY-SA 4.0 |
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| Jan 3, 2019 at 19:09 | comment | added | anna v | @TheCodingWombat I explicitly stated that it is a handwaving argument. The hypothesis / statement is that light rays are parallel. ,I take it to photons, that is all.. Geodesics are a matter of calculations, mentioned at the link of a similar question by the OP. Photons can be on the same path, but as point particles theoretically an infinity of geodesics is available, they just should not cross. and interact. | |
| Jan 3, 2019 at 18:07 | comment | added | The Coding Wombat | Also, does this mean that the oribiting photons have to lie on a geodesic of the event horizon, and thus the only way for them to run in parallel, would be that they "follow" each other, or thus that their paths coincide? Or can they also follow shorter circles around the black hole? | |
| Jan 3, 2019 at 17:55 | comment | added | The Coding Wombat | "It will either keep on going down" - do you mean toward the singularity, so toward the center of the black hole? What does going around the black hole on the event horizon mean? If it can go around with the speed of light and not get pulled in by gravity, doesn't that mean that a photon already over the event horizon and thus in the black hole that moves in a normal direction to the surface of the black hole escape because that has a greater outward velocity than the photons going round? | |
| Jan 3, 2019 at 15:40 | history | answered | anna v | CC BY-SA 4.0 |