Could you pull someone out of a black hole?

  • Level: Graduate 
  • Thread starter Thread starter LowlyEngineer
  • Start date Start date
  • Tags Tags
    Black hole Hole Pull
Join the discussion
Registration is free. Start your own thread to ask a follow-up.
2 replies · 3K views
LowlyEngineer
Messages
1
Reaction score
0
Suppose you had a very, very large black hole, so large that the tidal forces at or near the event horizon were not fatal. If you lowered someone down via a very long indestructible cable past the event horizon, and you held your spaceship sufficiently far away from the black hole to ignore its gravity, would it be possible to pull the person back out? When you account for the effects of relativity, would the force required to do so be infinite?
 
Physics news on Phys.org
LowlyEngineer said:
a very long indestructible cable
An indestructible cable is no more compatible with relativity than a perfectly rigid rod.
 
The thrust that the rocket's engines must produce to keep this person at a constant distance from the event horizon goes to infinity as the distance goes to zero. So it isn't even possible to lower someone down slowly.