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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 While the arXiv paper with the exact solution has not yet been peer reviewed, the preceding paper by Mersini-Houghton with the approximate solutions was published in Physics Letters B.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."
Why is this marked +1 informative? It should be +1 funny.
A follow up. The abstract for the second paper is linked in the summary, and the conclusion of the paper I'm referencing above suggests that the second paper(which we only have the abstract to) will attempts to address some of the concerns of simplistic assumptions. I think I'd need to do some really hard math, and pay for the full paper to determine if I personally agree with it justifying those assumptions, which I think is better left to experts who aren't supposed to be doing some programming right now.
The headline-- black holes don't exist-- is at odds with the actual article.
The article doesn't say the mathematicians said that black holes don't exist: it says they showed black holes aren't formed by the collapse of massive stars. Black holes such as the ones at the nuclei of galaxies may very well be formed by other processes.
--even if it were true that black holes don't exist, by the way, it doesn't solve the problem of the incompatibility of general relativity with quantum mechanics. At best it would solve the black hole information paradox; but since it still incorporates Hawking radiation in the solution, it doesn't even solve that.
http://www.geoffreylandis.com
It's not that gravity "overcomes" the speed of light, per se... but the fact that light always travels in a straight line, and that gravity can actually bend space, affecting what straightness actually is in that reference frame. Black holes, therefore, would bend space within a volume of space referred to from outside of it as their event horizon such to an extent that any straight line within the volume defined by the event horizon never actually leaves that volume.
File under 'M' for 'Manic ranting'
you can however observe stars orbiting Sgr A* at speeds that indicate something with 4 million solar masses is contained within a very small volume, and that no "star" is there.
While this calculation may help convince about some aspects of some arguments, it isn't necessary for the headline claim. There was always an old issue non-formation (or more accurately partial realization in finite-time or general paradox/etc) because of the coordinate singularity at the event horizon (time slows to a stop). There is even a book called Frozen Star by Greenstein from the 1980s if you are interested in the history of this.
The reason what the article of this thread says may cause controversy or confusion is because of the cultural way the resolution of the original issue got converted into a "talking point"/recurring example/"de-confused". In free falling coordinates, crossing the event horizon is no more special than walking across Earth's North Pole. There is no "problematic" infinity until the actual center point (which is what the Hawking-Penrose singularity theorem is about, but that theorem in essence assumes non-evaporation). That theorem itself was in response to speculation of some process intervening to "bounce" collapsing stars and censor black holes from the universe.
All these statements are fine and still correct as far as they go, but one has to be careful about the background assumptions embedded in analyzing things in free fall coordinates. A long history of poo-poo'ing the coordinate singularity or some hypothesized bounce process as "unreal" or "unphysical" led to a tradition of always analyzing things in free fall coordinates (as the arXiv paper in the OP does!). The validity of this transform does have implicit requirements, just not in the pure math of the general relativity transforms but in the physical context. E.g., it requires an infinite background future (i.e. no Big Crunch) which seems to be implied by data these days but was in great doubt for decades. It also assumes a non-evaporating situation which has been in doubt since the mid-1970s with Hawking Radiation.
Here's the important point which I cannot emphasize enough: WHAT ACTUALLY TRANSPIRES IS REFERENCE-FRAME INDEPENDENT. At some (maybe far) future time, a mass concentration is either there or it isn't. Period. Reference frames change observed rates/the clocks/positions maybe but not the actual core situation. If a distant, non-freefalling observer can see a Black Hole evaporate to nothing in a finite-time, then at the end of the day [ or the hole ;-) ] it will have taken less time to evaporate than to form in both the freefalling frame and the distant observer frame. That is just another way of saying it just didn't finish forming. That's it.
People have been speculating about micro-black holes evaporating into nothing ever since Hawking's initial result. In that light there is no news younger than 40 years old here.
To be sure there are some specific dynamics to be modeled here and what this paper does is model them in free fall coordinates. All those details are surely important to pro physicists. The zinger headline of non-formation doesn't rely on such details. It only relies upon any mass-energy transfer from within the hole to a great distance away and enough time in the heat death to have evaporation be the dominant process (or else a small enough black hole that it doesn't need much time). Hawking Radiation is but one such process, though a theoretical one. Most think (on similar general theoretical grounds) that any quantum gravity will have ways for strong gravitational fields to decay. So, it seems likely that there will be some process, but sure, sure, evidence is needed, too.
Logically, though, reference frame independence of what actually happens means that any argument against non-formation is translatable to an argument against Black Hole decay. Contrapositively, any argument for black hole decay is an argument for only incomplete black hole formation. There may be possible glitches in last-moment of existence type stuff, but that truly is blind-leading-the-blind territory. I actually tried to raise this in 1988 with my freshman relativity professor but I don't think he understood my point and he mostly poo'poo'd about how Hawking Radiation would break down at the last moment of decay or something.