Linked Questions

0
votes
1answer
787 views

Does Stephen Hawking believe that General Relativity is wrong? [duplicate]

Stephen Hawking recently said that black holes do not exist. According to Wikipedia, black holes are predicted by General Relativity. So it would seem to follow that Stephen Hawking believes that ...
18
votes
2answers
2k views

So Black Holes Actually Merge! In 1/5th of a Second - How?

I've read a lot of conflicting answers in these forums. However, today saw the awesome announcement of gravitational waves. Two black holes merged: http://www.slate.com/blogs/bad_astronomy/2016/02/11/...
10
votes
2answers
2k views

When does a singularity start to exist during a black hole formation?

Excuse me if the question is naïve. I am not a physicist. Let's imagine formation of a black hole from a homogeneous collapsing star. At certain moment when enough of matter is inside of a small ...
18
votes
4answers
907 views

Doesn't the Schwarzschild metric combined with Hawking radiation imply that nothing ever gets past the event horizon of a black hole?

According to the General Theory of Relativity, the coordinate time distance per spacetime distance traveled by a particle freely falling into a black hole gets closer and closer to $0$ as the particle ...
2
votes
2answers
189 views

Spacetime geometry with a system of $n$ interacting black holes [closed]

The Schwarzschild metric is given by $ds^2=-\left(1-\frac{2GM}{rc^2}c^2\right)dt^2+\left(1-\frac{2GM}{rc^2}c^2\right)^{-1}dr^2+r^2d\Omega^2,$ for $d\Omega^2$ the round metric on the $2$-sphere, in ...
3
votes
4answers
2k views

How would one determine how old a black hole is?

Would different observers agree on the age? Or is this question nonsensical? e.g. what's north of the north pole? There are ways of estimating the ages of stellar bodies using various methods but is ...
4
votes
2answers
533 views

Do magnetic fields exist beyond the gravity of a black hole?

http://www.sciencealert.com/the-magnetic-field-just-outside-our-black-hole-has-been-studied-for-the-first-time reported strong magnetic fields escape out of black holes. Does that rule out photons ...
4
votes
2answers
785 views

Is there anything actually inside a black hole, do they actually exist?

When objects fall into a black hole, observers outside the black hole will never see the object cross the event horizon because the object's time slows down and will stop at the event horizon. The ...
3
votes
2answers
286 views

Why does an evaporating black hole always stay a black hole?

Stars can only collaps and form black holes if their masses are above the Chandrasekhar limit, $M>M_{\rm Pl}^3/M_{\rm hydrogen}^2$. When the universe eventually cools down enough, the black holes ...
3
votes
2answers
1k views

Does a black hole have enough time to actually form a singularity?

I am trying to wrap my head around black holes, singularties and hawking radiation. Physics.se contains many intresting questions and answers, but from none I could so far read about the interaction ...
3
votes
2answers
426 views

Why do black holes have to disappear?

I read about Hawking radiation in Wikipedia and understood black holes may disappear over a long period of time. But my question is why does it have to disappear, because after some time of radiation ...
1
vote
2answers
632 views

Are black holes “Immortal”?

Black holes are stars that are so massive, that when they die, they become so dense that not even light can escape. That means that a black hole is costantly adding mass and energy and thus making its ...
1
vote
4answers
163 views

Is there any evidence that matter and antimatter continuously appear and disappear on the edge of a black hole?

I heard Stephen Hawking got a Nobel prize for this, someone said there was no evidence for it which I find quite strange since he got an award for it.
4
votes
1answer
316 views

Is the new Hawking black hole all about photon launch angles?

The new Jan 2014 Hawking paper (arXiv:1401.5761v1) asserts on page 3: The absence of event horizons means that there are no black holes - in the sense of regimes from which light can't escape to ...
-1
votes
5answers
183 views

Origins of the wormhole and blackhole speculations [closed]

l just read about wormholes and blackholes. They're simply hypothetical structures in the universe predicted by physicists. My question is, what is the basis of their prediction? Who are the people ...

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