Timeline for Can matter really fall through an event horizon?
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| Dec 31, 2020 at 3:34 | comment | added | george storm | Thank you for your comments - finally reached me!. I obviously wasn't clear about my add-on. The "if correct" bit was intended to imply incredulity. My expectation remains that we have effectively a continuum (each outside the previous) of enveloping developing event horizons that would, if left undisturbed, tend to a time singularities - but never actually get there. Clearly no matter can escape, but the cone of escaping light never closes completely. And the no-hair situation never develops: though I think it unlikely the difference is observable, even at evaporation | |
| Nov 8, 2019 at 18:19 | comment | added | safesphere | "certainly it should be possible for the infalling viewer to come up with an accurate assessment of what it observes" - Not at the horizon. The horizon is lightlike, so no frame of reference can be constructed at the horizon just like no frames exist moving with the speed of light. This is a restriction of the hyperbolic geometry of spacetime. Therefore an observer cannot observe anything at the horizon. His proper time stops there: $d\tau/dr=0$ and effectively ends, so his worldline is truncated at the horizon at a final proper time value, as you initially stated. | |
| Nov 8, 2019 at 18:11 | comment | added | safesphere | +1 for your initial answer, but your add-on is incorrect. "the size of the event horizon is expanded by the presence of mass outside the horizon" - Correct, but the following: "it would allow a 'real', event horizon to arise in finite time" - is incorrect. The expanding apparent horizon pushes matter away due to linear frame dragging (e.g. anothing on the way of a flying BH is not swallowed, but pushed by the horizon, as is obvious in the BH rest frame). So the true horizon never forms, as you initially stated. | |
| Jun 2, 2019 at 23:10 | history | edited | george storm | CC BY-SA 4.0 |
Response to comment
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| Jun 2, 2019 at 19:01 | comment | added | george storm | Thank you for the reply, including for reference to .../2449. I have to admit that found your comment potentially more helpful (see below) than the comments there, which seemd to me to range from the naive through the utterly obscure to the unhelpfully dogmatic. | |
| Jun 1, 2019 at 17:54 | comment | added | Terry Bollinger | george storm thanks! Oddly, this simple argument you just made was at one time the dominant interpretation of black holes, known as the "frozen star" interpretation. See e.g. astronomy.stackexchange.com/a/2449 for some discussion. Physicists now like to say that only the infalling viewer view counts, which is a bit odd to me, since she too must wait until the end of the universe before crossing the true event horizon. The real driver for saying matter crosses is assuming matter must start "in" a collapsing star... which is not correct; the absolute horizon starts as an interior point. | |
| Jun 1, 2019 at 11:40 | review | Late answers | |||
| Jun 1, 2019 at 11:41 | |||||
| Jun 1, 2019 at 11:23 | history | answered | george storm | CC BY-SA 4.0 |