4 ms·

From the external view you never enter, just get dimmer as you approach the speed of light and the time dilation keeps increasing. From the viewpoint of the on

by sliken 2y ago

From the external view you never enter, just get dimmer as you approach the speed of light and the time dilation keeps increasing. From the viewpoint of the one falling in, you just fall in and cross the horizon without noticing. Does make you wonder if time dilation gets so extreme, could another black hole wonder by, offset the gravity of the black hole, and let you escape. Even if it takes a billion years.

evo 2y ago
I suspect that would fall under the rule that if two black holes’ respective event horizons ever cross, they merge and initiate the eventual merger of the two respective black holes.
- sliken 2y ago
  I've seen this vaguely referenced, but when I dig in I don't find support for it. It's far from obvious that just because the event horizons (which is just a mathematical concept and a 3D area of space) should control the trajectory of the singularity. With two identical blackholes, with a event horizon of radius R, why should a singularity 2R away be unable to escape?
rthnbgrredf 2y ago
> Does make you wonder if time dilation gets so extreme, could another black hole wonder by, ... Even if it takes a billion years. This could even be the most likley scenario, since ultra massive black holes eats vast amounts of smaller over the course of billion years.
pavel_lishin 2y ago
Once you've crossed the horizon from your point of view, there is no escape. If another, larger black hole passes by, at best you'd be within a larger event horizon comprised of both, I think.
- sliken 2y ago
  Right, but say you end up half way between two equal mass blackholes, under zero gravitational force. Are those two black holes definitely going to merge? If they were going near light speed in opposite directions could they not merge and free you as you stay equidistant from both?
  - pavel_lishin 2y ago
    Well, if you're halfway and outside of hte event horizon... I don't know. But you definitely can't escape an event horizon. I don't know what would happen if two event horizons overlapped briefly, as two black holes passed by each other at significant speeds. That's definitely above my paygrade :P
    - sliken 2y ago
      Well imagine you are X distance from the singularity, and time dilation is hugely slowing down time from an external observer. As blackholes approach each other, the distance between the singularity and the event horizon significantly decreases. They become kidney shaped before the blackholes merge. The trick is can a blackhole approach quickly enough to catch you as you keep dropping as you past horizon. Normally I'd say no, but the time dilation significantly complicates things.
Filligree 2y ago
The time dilation does not act in that way. You will not experience the outside universe speeding up, at least not by very much; the reason for this “paradox” is primarily that photons coming off you take longer and longer to climb out, and the ones from right when you crossed the event horizon never will.

by sliken 2y ago

evo 2y ago

I suspect that would fall under the rule that if two black holes’ respective event horizons ever cross, they merge and initiate the eventual merger of the two respective black holes.

sliken 2y ago
I've seen this vaguely referenced, but when I dig in I don't find support for it. It's far from obvious that just because the event horizons (which is just a mathematical concept and a 3D area of space) should control the trajectory of the singularity. With two identical blackholes, with a event horizon of radius R, why should a singularity 2R away be unable to escape?

rthnbgrredf 2y ago

> Does make you wonder if time dilation gets so extreme, could another black hole wonder by, ... Even if it takes a billion years. This could even be the most likley scenario, since ultra massive black holes eats vast amounts of smaller over the course of billion years.

pavel_lishin 2y ago

Once you've crossed the horizon from your point of view, there is no escape. If another, larger black hole passes by, at best you'd be within a larger event horizon comprised of both, I think.

sliken 2y ago
Right, but say you end up half way between two equal mass blackholes, under zero gravitational force. Are those two black holes definitely going to merge? If they were going near light speed in opposite directions could they not merge and free you as you stay equidistant from both?
- pavel_lishin 2y ago
  Well, if you're halfway and outside of hte event horizon... I don't know. But you definitely can't escape an event horizon. I don't know what would happen if two event horizons overlapped briefly, as two black holes passed by each other at significant speeds. That's definitely above my paygrade :P
  - sliken 2y ago
    Well imagine you are X distance from the singularity, and time dilation is hugely slowing down time from an external observer. As blackholes approach each other, the distance between the singularity and the event horizon significantly decreases. They become kidney shaped before the blackholes merge. The trick is can a blackhole approach quickly enough to catch you as you keep dropping as you past horizon. Normally I'd say no, but the time dilation significantly complicates things.

Filligree 2y ago

The time dilation does not act in that way. You will not experience the outside universe speeding up, at least not by very much; the reason for this “paradox” is primarily that photons coming off you take longer and longer to climb out, and the ones from right when you crossed the event horizon never will.