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#1
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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! |
#2
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was hawkings right?
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. |
#3
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To the moderator of sci.zdtro.research
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] |
#4
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was Hawking right?
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 |
#5
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was Hawking right?
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] |
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