was hawkings right?

There are no black holes?

http://phys.org/news/2014-09-black-holes.html
Researcher shows that black holes do not exist

http://arxiv.org/abs/1401.6562
Planck stars

Then, what is that "thing" at Sag A* ?

What a wonderful world!

In article , jacob navia
writes:

There are no black holes?

http://phys.org/news/2014-09-black-holes.html
Researcher shows that black holes do not exist

http://arxiv.org/abs/1401.6562
Planck stars

Then, what is that "thing" at Sag A* ?

What a wonderful world!

Not long ago, Stephen Hawking allegedly claimed something similar. A
quick internet search will shed much light on these claims. Basically,
it depends on the definition of "black hole". For all practical
purposes, astrophysical black holes continue to exist as they always
have.

Le 07/10/2014 08:57, jacob navia a écrit :
Well, one of my unscientific beliefs is that infinities do not actually
exist in nature. Black holes seemed to get to zero radius and infinite
density...

[Mod. note: no they don't! -- mjh]

???

Could you please tell me a paper to read about that?

Thanks

[Mod. note: Schwarzschild, K, 1916a,b and pretty much every paper on
the subject since then. The radius of a black hole is not zero and its
density consequently not infinite -- mjh]

jacob navia writes:
Well, one of my unscientific beliefs is that infinities do not actually
exist in nature. Black holes seemed to get to zero radius and infinite
density...

As the mod notes (somewhat cryptically), a black hole is defined by an
event horizon, which has a finite radius and hence contains a finite
density.

I am sure *something* stops the collapse sooner or later.

As I understand it, belief that something stops the collapse from
forming an actual singularity at the center of a black hole is pretty
mainstream, but that happens after the event horizon forms.

-dan

Le 07/10/2014 19:44, Dan Riley a écrit :
As I understand it, belief that something stops the collapse from
forming an actual singularity at the center of a black hole is pretty
mainstream, but that happens after the event horizon forms.

OK, the misunderstanding here is that when I say "black hole" I was
speaking about the matter inside the event horizon, and when astronomers
speak about a "black hole" they speak only about the visible part, i.e.
the event horizon.

Since we can't ever see what is inside the horizon it is logical to
speak about the visible part only I suppose. Excuse me for this
misunderstanding.

jacob

[Mod. note: quoted text trimmed -- mjh]