Do Black Holes Evaporate Despite Cosmic Microwave Background Radiation?

[Lapidus]

An outside observer never sees stuff heading towards a black hole crossing the event horizon. How then do black holes form? If I would have watched region in spacetime where today exists a black hole for the last two billion years, how did the black come into existence?

Is it true that bigger black holes do not evaporate, since the cosmic microwave radiation is hotter than them? Why then then all the fuss about the information loss problem?

thank you

 

[Bill_K]

Just because I never see it does not mean it never happens. I see the collapsing matter getting closer and closer to its Schwarzschild radius, redshifting itself into oblivion. Eventually there is mass m within a radius r=2m (almost), and for me there is no practical difference. Stars will orbit it like crazy, light will suffer an infinite amount of redshift trying to escape, and I myself had better not get too close!

 

[Naty1]

An outside observer never sees stuff heading towards a black hole crossing the event horizon. How then do black holes form?

That's the view of a stationary distant observer...but a free falling observer does see stuff crossing the hypothetical event horizon in a "normal" everyday manner, no time delay for example, and the free falling observer also passes the event horizon without incident.

 

[khemist]

An outside observer never sees stuff heading towards a black hole crossing the event horizon. How then do black holes form? If I would have watched region in spacetime where today exists a black hole for the last two billion years, how did the black come into existence?

Is it true that bigger black holes do not evaporate, since the cosmic microwave radiation is hotter than them? Why then then all the fuss about the information loss problem?

thank you

Black holes are believed to radiate Hawking radiation.

The black hole came into existence because a star collapsed under its own gravity after the pressure from the nuclear reactions inside the star subsided.

 

[Naty1]

Is it true that bigger black holes do not evaporate, since the cosmic microwave radiation is hotter than them?

yes. They will radiate in the future when the universe cools enough. Hawking radiation is not observable now.