The Double Life of Black Holes

Sugarman

Making Sugar
Joined
Feb 24, 2016
Messages
23,539
#1
There are astrophysical black holes, and then there are mathematical ones. Astrophysical black holes sit in galactic centers, emit jets of hot plasma, and on occasion swallow stars. You have heard of those. Mathematical black holes, on the other hand, serve as the focus of physicists’ thought experiments. They are not formed from collapsing stars, they have existed forever, and they sit in an empty universe. They may be infinitely large, have perfect mirrors around them, or extend into six dimensions of space. You have heard of those too, but maybe you didn’t notice.

The story of black holes began in 1916, when Karl Schwarzschild discovered a solution to Einstein’s equations of general relativity that is able to trap light. The characteristic property of Schwarzschild’s black hole — and of all black holes discovered later — is the presence of an “event horizon,” the surface of a region from within which nothing can escape. Once you cross an event horizon, you are trapped forever.
More At: https://www.quantamagazine.org/the-double-life-of-black-holes-20190129/
 

Clive2

Well-Known Member
Joined
May 23, 2017
Messages
115
#2
While it's highly unlikely that humans or current spacecraft would ever survive approaching or entering a black hole (radiation / heat / gravitational tides etc), it could be interesting if our descendants sent an unmanned probe on either a 'death-dive' or flyby into or past one, transmitting data until final moments.
The current drawback, AFAIK, is the vast distance / time in getting to the nearest (known) one, at the center of our MW galaxy!!
Not to mention the many centuries it would take for the powerful-enough radio data to relay back to Earth Mars.
 
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