4 ms·

How long does it take a infalling observer to cross the event horizon of a black hole?

• EA-3167 3y ago
  From the perspective of the person falling, it happens from one moment to the next. You as the person being accelerated don't notice any change in your own proper time, only distant observers will see that.
• magicalhippo 3y ago
  If you were to fall radially inwards towards a non-rotating black hole, that is not spiraling around it but "straight in", it would be the same as with plain Newton's law[1]. There's a nice graph in the midde of this[2] page that shows the difference between the proper time and the aparent time observed by the outside observer. At r = 2m you can see the aparent time goes to infinity and the quickly back again. [1]: https://physics.stackexchange.com/questions/718222/proper-time-of-fall-in-schwarschild-metric https://physics.stackexchange.com/questions/718222/proper-ti... [2]: https://www.mathpages.com/rr/s6-04/6-04.htm https://www.mathpages.com/rr/s6-04/6-04.htm
  • Zamicol 3y ago
    Thank you for the response and links. The second link is particularly helpful. I'm surprised that Newton is equivalent here, but the reason appears simple: although the inbound observer's time slows, their velocity does not. A distant observer is unable to perceive them as they approach the event horizon as the inbound actor grows infinitely dim thanks to time dilation.