Timeline for Question about light orthogonal to an event horizon
Current License: CC BY-SA 4.0
11 events
| when toggle format | what | by | license | comment | |
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| Sep 9, 2021 at 21:35 | comment | added | BowlOfRed | Difficult to understand if you're thinking of normal 3D (flat) space, but inside the event horizon, there is no spatial direction that will point to "outside". All directions point toward the singularity. We can't use the same coordinates (like distance from the singularity) that are used outside to make sense of the location and motion inside that region. | |
| Sep 9, 2021 at 21:25 | comment | added | Árpád Szendrei | Really nice answer. Can you please elaborate on this: "No, the light never "reverses" directions the way a ball might when thrown upward." If you shine light towards the horizon from inside, where does light initially move, outwards or inwards? I know it has to stay inside the horizon, but otherwise can it move outwards while staying inside? | |
| Sep 9, 2021 at 7:39 | comment | added | j4nd3r53n | @EricTowers Indeed, what does 'exactly' mean in QM? But then spread it out a bit on each side of the event horizon. Would it split into two? | |
| Sep 8, 2021 at 20:22 | comment | added | Jaquez | @j4nd3r53n I am no expert, but my understanding of the fate of a photon on the event horizon is that it would endlessly travel around the black hole on the event horizon until the mass of the black hole changed. It would either become more massive, pushing the event horizon further out and capturing the photon, or the black hole would evaporate slightly and the photon would escape. In practical terms, a photon would not find itself on an event horizon for very long since it would be such a delicate balance. | |
| Sep 8, 2021 at 17:33 | comment | added | Eric Towers | @j4nd3r53n : A photon is not a point, so what does "exactly at" mean? | |
| Sep 8, 2021 at 9:07 | comment | added | j4nd3r53n | What I'd like to know is, what if the photon start exactly at the event horizon? | |
| Sep 8, 2021 at 4:11 | comment | added | BowlOfRed | Spatial directions for a light beam, which would allow you to enumerate all possible lightlike paths with that event as an origin. Outside the horizon, some spatial directions intersect the singularity. Inside the horizon they all do. | |
| Sep 8, 2021 at 2:33 | comment | added | Adam Herbst | Just checking...that's really "all timelike directions", correct? Or do all spacelike directions get eaten up too if you're close enough to the singularity? | |
| Sep 8, 2021 at 0:47 | comment | added | Charles Averill | Great answer. Thank you! | |
| Sep 8, 2021 at 0:47 | vote | accept | Charles Averill | ||
| Sep 8, 2021 at 0:45 | history | answered | BowlOfRed | CC BY-SA 4.0 |