On: Stephen Hawking: 'There are no black holes'

[lmm]

By that logic neutron stars should be black holes. But they're not.

[ck2 → lmm]

Sorry I didn't mean the sol sun, I mean a sun with enough mass to become a black hole.

Neutron stars are in a sense "failed" black holes because of not enough mass. I wonder if they could eat more mass and achieve that status though.

[venomsnake → ck2]

That is one of the standard candles - type 2 supernova IIRC - when neutron star in binary system is eating the other star and turns nova very predictably.

[splat → venomsnake]

The standard candles are Type Ia supernova which are when white dwarfs exceed the Chandrasekhar mass and become neutron stars. It is thought that when neutron stars exceed the maximum mass of a neutron star (which is not well known, by the way) they form a gamma-ray burst.

[kevinastone → splat]

The TOV Limit for those following at home. It's when the star's gravitational pressure exceeds neutron degeneracy pressure and collapses into a black hole.

http://en.wikipedia.org/wiki/Tolman–Oppenheimer–Volkoff_limi...

[larubbio → venomsnake]

I think it's type 1a. There was a discussion on this recently after a new supernova observation.

https://news.ycombinator.com/item?id=7104056

Basically it's unknown if it is a two star system where the neutron consumes the partner, or a three star system where two neutron stars collide head on.

[Dylan16807 → lmm]

You just didn't squeeze them enough. The amount of matter you need for a stable black hole is moon-ish.

[lmm → Dylan16807]

Right, but you need to squeeze it smaller than "a few miles".

[Dylan16807 → lmm]

The sun has a Schwarzschild diameter of 3.7 miles. You're being too picky.