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Physicist Claims Black Holes Mathematically Don't Exist
Koreantoast writes: Black holes, the stellar phenomena that continue to capture the imagination of scientists and science fiction authors, may not actually exist. According to a paper published by physics professor Laura Mersini-Houghton at the University of North Carolina and Mathematics Professor Harald Pfeiffer of the University of Toronto, as a collapsing star emits Hawking radiation, it also sheds mass at a rate that suggests it no longer has the density necessary to become a black hole — the singularity and event horizon never form. While the arXiv paper with the exact solution has not yet been peer reviewed, the preceding paper by Mersini-Houghton with the approximate solutions was published in Physics Letters B.
"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... 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."
"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... 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."
IAAASBH (I am an astrophysicist studying black holes): Yeah, um, no.
So, what are those big honking things seeing?
Is this a case where something has been mathematically proven to not exist after it's been observationally confirmed?
Lost at C:>. Found at C.
She's not saying the things are not "very very dense" rather just that they never collapse further than the state that gravity can overcome the speed of light. I believe she's saying a black hole's mass would be "evenly" (or not) spread out over the volume encompassed by the event horizon, rather than in a singularity.
We have two theories: quantum mechanics and relativity, and they disagree about what happens when really massive stars collapse (or relativity predicts a singularity and quantum mechanics doesn't have much to say about what happens at those energies). The relativity answer seems impossible because when you get infinity out of an answer in physics, your math is probably wrong. Quantum mechanics only covers the 3 other forces, not gravity. So really we know that we probably don't know what's going on with this phenomenon. The term "black hole" is a little bit like "dark matter". It's a placeholder for what we don't know. We have observed evidence that there are extremely heavy and dense objects affecting nearby stars, but we can't observe them directly. So, what we've observed is not necessarily exactly what relativity predicts is there. This paper is offering a different theory (which may or may not be more correct).
"I have never let my schooling interfere with my education." - Mark Twain
It is generally posited that a singularity is the result of a gravitational collapse resulting in a black hole. However an event horizon will form whenever sufficient mass density occurs, thus a 'black hole'. If the contention is that the Hawking radiation dissipates the mass before the singularity forms, so be it. Does not mean no black hole, just no singularity.
I have not read the article, so I don't know if this is reflective of her contention, however:
Imagine 2 observers, 1 falling into the black hole, one with great patience a safe distance away. Over time the distant observer will see the black hole eventually become isolated and cease to accumulate new mass (trillions of years perhaps). Thereafter, Hawking radiation begins to dominate and the black hole goes on a diet, eventually going out of existence with a hot bang.
Meanwhile the more adventurous observer is falling toward the postulated center of the black hole, but is experiencing greater and greater time dilation relative to the low density external universe. Thus at some point, before reaching the singularity state, the observer 'sees' the entire future of the external universe, including an ever increasing flood of Hawking radiation that results in the black hole evaporation. So incoming matter never gets to infinite density, no singularity occurs because the evaporation happens on a different time scale than the collapse. Black hole? Yes, Singularity? No
If this is not the equivalent of the cited paper, I am free to go to Oslo at any time.
Or, is it possible that he does observe Black Holes, and they do exist, but the formation method is something other than what we've always assumed (eg star collapse)?
Beware of bugs in the above code; I have only proved it correct, not tried it.
The authors propose a singularity is not created when a black hole collapse occurs. Instead, the suggest that the material falling into the gravity well forms a "Planck star". The mass does not disappear into a singularity, but remains as a form of matter compressed to the Planck scale. The Planck pressure (my term) stops the gravitational collapse, so no infinite mathematical feature is involved.
A Plank star has very similar characteristics to a conventional black hole. It has a Schwarzschild radius, so matter and energy are swallowed up in the same way. The difference is what happens inside the Schwarzschild radius and the long term fate of the star.
Two effects come into play: time dilation and Hawking radiation. Because of the immense gravity, time dilation makes events inside the Schwarzschild radius appear to take billions of years to the outside observer, although the happen rapidly in the frame of reference of the Planck star. As in-falling matter hits the Planck matter core, it bounces back. It does not simply collect at the core.
Additionally, Hawking radiation occurs. This means that energy can be released outside the Schwarzschild radius, which allows the star to loose mass. In this theory, about a third of the mass can escape via this mechanism. However, this process also takes a long period because of time dilation. (There is more complexity to this, but since I'm not certain how it works I'll not try and describe it.)
Eventually the radius of the expanding Plank star matter and the Schwarzschild radius intersect, and from the point of view of the external observer the formerly "black" hole explodes. This is different then the long term evolution of a classical black hole, which looses most of it's mass via Hawking radiation. The final evaporation of a classical black hole is not a big explosion since the final mass is relatively small, and no matter how big the black hole was, the final bang is the same size. For a Planck star, the size of the explosion depends on the mass inside the Schwarzschild radius.
This theory has some very nice properties. First, there is no infinitely dense matter. Classical black hole models have been trying to grapple with this issue for a long time. Also, since the final explosion can be massive, it could be the source of very high energy cosmic rays. Some have already suggested that gamma ray bursts may be the visible result. The theory predicts that the explosion can take about 14 billion years to occur to an external observer, so that fits in with the current age of the universe. Note that there are testable features relating to cosmic rays and other radiation coming from Plank stars, so observational verification is possible.
An important part of the theory is that it resolves the black hole information paradox. According to this article at Phys.org
This is potentially a big deal. If true it solves some troubling theoretical problems and man tie black holes and cosmic rays together. It would also present a huge challenge to string theory, because it gives credence to loop quantum gravity.
Why is Snark Required?