Physicists have long thought that the singularities associated with gravity (like the inside of a black hole) should vanish in a quantum theory of gravity.
It now appears that this may indeed be the case. Researchers in Uruguay and Louisiana have just published a description of a quantum black hole using loop quantum gravity in which the predictions of physics-ending singularities vanish, and are replaced by bridges to another universe.
Singularities, such as the infinitely strong crushing forces at the center of a black hole, in a physical theory are bad. What they tell you is that your description of the universe fails miserably to explain what happens as you approach the singularity. Tricks can sometimes resolve what appears to be singular behavior, but essential singularities are signs of a failure of the physical description itself.
General relativity has been summed up by the late John Wheeler’s phrase: “Spacetime tells matter how to move, matter tells spacetime how to curve.” Relativity is riddled with essential singularities, because gravity is both attractive and nonlinear – curvature in the presence of mass tends to lead to more curvature, eventually leading to trouble.
The result is rather similar to a PA system on the verge of producing a feedback whistle. If you whisper into the microphone (small gravitational fields) the positive feedback isn’t enough to send the PA into oscillation, but talking at a normal volume (larger gravitational fields) produces that horrible howl. Whispering is the comparable to the familiar actions of gravity that keep the planets and stars in their courses. The howl is the process that eventually leads to a singularity as the end result of gravitational collapse.
Let’s follow this analogy a bit further. On a PA system, the volume of the feedback is limited by the power capacity of the amplifier, so it can’t reach truly destructive levels (other than to our eardrums.) However, gravity as described by general relativity doesn’t have such a limit. Since gravity is always attractive, and eventually becomes stronger than all the (known) forces that normally give volume to matter, there is nothing to keep gravitational collapse from proceeding until the curvature of the spacetime tends toward infinity – i.e. a singularity.
Remember that this is the prediction of the classical theory of gravity, general relativity. Classical physical theories contain no fundamental limitation on mass-energy density or on the size of spacetime curvature. While this may be (and probably is) incorrect, we rarely run into a problem caused by this error, so have largely ignored the problem for centuries.
Then along came gravitational collapse and black holes. First proposed by geologist John Mitchell in 1783, a black hole is a region of spacetime from which gravity prevents anything, even light, from escaping.
The Latest on: Quantum black hole
THERION Singer LINNÉA VIKSTRÖM's QFT Project: Listen To 'Big Bang' Song
on April 16, 2018 at 2:08 pm
"Big Bang", the new single from QFT (QUANTUM FIELD THEORY), the solo project of internationally praised metal singer Linnéa Vikström, can be streamed below. The Big Bang, space travel, black holes, singularity, aliens, stars colliding and the inevitable ... […]
Stephen Hawking asked to have this complex equation on his tombstone, see if you can figure out what it means
on April 12, 2018 at 5:40 pm
Understanding the thermodynamics of black holes required the Cambridge physicist to apply quantum mechanics to these incredibly dense objects, and this led to the proposal of Hawking radiation. Black holes had entropy and a temperature. Hawking himself ... […]
Hawking defied ALS to become pre-eminent physicist
on April 8, 2018 at 4:22 am
and quantum theory. His success in turn transformed him into a massively popular scientist, one as familiar to the wider world through his appearances on prime time television shows as his work on cosmology and black holes. Hawking owed one part of his ... […]
Stephen Hawking, best-known theoretical physicist of his time, dies at 76
on April 8, 2018 at 4:21 am
He concluded that black holes have a temperature and eventually evaporate away ... “This was work that tied together quantum mechanics, gravity and the theory of thermodynamics. It just typifies his insightful approach to science.&rdquo […]
Is Dark Matter Made Up of Mini Black Holes from the Big Bang?
on April 6, 2018 at 4:51 am
But there may be another force at work, siphoning mass from these black holes: Hawking radiation. Stephen Hawking theorized that due to quantum effects, black holes emit particles and energy. Over time, Hawking radiation may cause them to completely ... […]
The Black Hole Information Paradox, Stephen Hawking's Greatest Puzzle, Is Still Unsolved
on March 29, 2018 at 7:08 am
Many physicists appeal to the holographic principle, noting that the information encoded on the black hole’s surface applies quantum corrections to the purely thermal Hawking radiation state, imprinting itself on the radiation as the black hole ... […]
Hawking’s final quest: saving quantum theory from black holes
on March 20, 2018 at 7:03 pm
When Albert Einstein died in 1955, he had spent decades on a lonely, quixotic quest: to derive a theory of everything that would unify gravity and electromagnetism—even though physicists discovered new nuclear forces as he worked. Stephen Hawking, the ... […]
Physicist Proposes Alternative to Black Holes
on March 19, 2018 at 2:00 pm
Neutron stars find a balance between the repulsive force of quantum mechanical degeneracy pressure and the attractive force of gravity, while more massive cores collapse into black holes, unable to fight the overwhelming pull of their own gravity. […]
via Google News and Bing News