Carolina’s Laura Mersini-Houghton shows that black holes do not exist
http://uncnews.unc.edu/2014/09/23/carolinas-laura-mersini-houghton-shows-black-holes-exist/
(Chapel Hill, N.C. – Sept. 23, 2014) Black holes have long captured the
public imagination and been the subject of popular culture, from Star Trek
to Hollywood. They are the ultimate unknown – the blackest and most dense
objects in the universe that do not even let light escape. And as if they
weren’t bizarre enough to begin with, now add this to the mix: they don’t
exist.
By merging two seemingly conflicting theories, Laura Mersini-Houghton, a
physics professor at UNC-Chapel Hill in the College of Arts and Sciences,
has proven, mathematically, that black holes can never come into being in
the first place. The work not only forces scientists to reimagine the
fabric of space-time, but also rethink the origins of the universe.
“I’m still not over the shock,” said Mersini-Houghton. “We’ve been studying
this problem for a more than 50 years and this solution gives us a lot to
think about.”
For decades, black holes were thought to form when a massive star collapses
under its own gravity to a single point in space – imagine the Earth being
squished into a ball the size of a peanut – called a singularity. So the
story went, an invisible membrane known as the event horizon surrounds the
singularity and crossing this horizon means that you could never cross
back. It’s the point where a black hole’s gravitational pull is so strong
that nothing can escape it.
T
he reason black holes are so bizarre is that it pits two fundamental
theories of the universe against each other. Einstein’s theory of gravity
predicts the formation of black holes but a fundamental law of quantum
theory states that no information from the universe can ever disappear.
Efforts to combine these two theories lead to mathematical nonsense, and
became known as the information loss paradox.
In 1974, Stephen Hawking used quantum mechanics to show that black holes
emit radiation. Since then, scientists have detected fingerprints in the
cosmos that are consistent with this radiation, identifying an
ever-increasing list of the universe’s black holes.
But now Mersini-Houghton describes an entirely new scenario. She and
Hawking both agree that as a star collapses under its own gravity, it
produces Hawking radiation. However, in her new work, Mersini-Houghton
shows that by giving off this radiation, the star also sheds mass. So much
so that as it shrinks it no longer has the density to become a black hole.
Before a black hole can form, the dying star swells one last time and then
explodes. A singularity never forms and neither does an event horizon. The
take home message of her work is clear: there is no such thing as a black
hole.
The paper, which was recently submitted to ArXiv, an online repository of
physics papers that is not peer-reviewed, offers exact numerical solutions
to this problem and was done in collaboration with Harald Peiffer, an
expert on numerical relativity at the University of Toronto. An earlier
paper, by Mersini-Houghton, originally submitted to ArXiv in June, was
published in the journal Physics Letters B, and offers approximate
solutions to the problem.
Experimental evidence may one day provide physical proof as to whether or
not black holes exist in the universe. But for now, Mersini-Houghton says
the mathematics are conclusive.
Many physicists and astronomers believe that our universe originated from a
singularity that began expanding with the Big Bang. However, if
singularities do not exist, then physicists have to rethink their ideas of
the Big Bang and whether it ever happened.
“Physicists have been trying to merge these two theories – Einstein’s
theory of gravity and quantum mechanics – for decades, but this scenario
brings these two theories together, into harmony,” said Mersini-Houghton.
“And that’s a big deal.”
-Carolina-
Mersini-Houghton’s ArXiv papers:
Approximate solutions:
http://arxiv.org/abs/arXiv:1406.1525
Exact solutions:
http://arxiv.org/abs/arXiv:1409.1837
...
Harry
