Slashdot Mirror
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 While the arXiv paper with the exact solution has not yet been peer reviewed, the preceding paper by Mersini-Houghton with the approximate solutions was published in Physics Letters B.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."
Respectable mad scientists have known for years that supposed 'black holes' are really just wormholes to the goatee universe.
How can I believe you when you tell me what I don't want to hear?
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.
If it emits Hawking radiation as it's collapsing, it doesn't become a black hole, it becomes a Hawking hole.
Get free satoshi (Bitcoin) and Dogecoins
I felt a great disturbance in the Force, as if millions of CGI Artists for science documentaries suddenly cried out in terror, and were suddenly silenced.
this scenario brings these two theories together, into harmony."
and into direct conflict with observations. I'm going to guess your math is wrong, not that black holes don't exist.
Tic-Tac-Toe, Global Thermonuclear War, and relationships all have the same winning move.
In the true spirit of /. I only read TFS but from it I see that only the "collapsing star" method of creating a black hole is covered. So there must be other methods for obtaining a black hole which won't violate mathematical simulations.
...gis sdrawkcab (usually not responding to ACs; don't bother posting as AC)
and actually, as an addendum... whether right or wrong, she also clearly has massive cojones to put this out there. kudos to her.
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.
Just fine. Thanks for asking.
Lost at C:>. Found at C.
Perhaps you're observing phenomenon that appear to be Black Holes but are really gravstars or other normal stellar phenomena that don't require exotic and contradictory explanation and you don't realize it.
After all, just because you learned something growing up as a child doesn't mean it's true.
You are after all doing remote observation on objects that are 100's to billions of light years away.
The Colonel is dead, yet we still eat his chicken.
Play Command HQ online
No, you indirectly observe what are supposed to be black holes, or better yet, you directly observe instrument readouts that you interpret as indicating the existence of black holes. If this paper is correct, perhaps a different interpretation is in order, and exciting science can be done.
IAAASBH (I am an astrophysicist studying black holes): Yeah, um, no.
So... The science is settled then? OK...
"File to fit, pound to insert, paint to match" - Aircraft Maintenance 101
Microscopic invisible critters living on magnets shoot out invisible rubber band tethered harpoons at anything metal they see nearby. These beings are known as Magtonians. They feed on metal, but since they're microscopic you'll never actually see the damage. You can prove this by holding a magnet in your fingers and getting it close the metal, you can feel the rubber bands stretch and snap as you move the magnet close to metal and pulling it away. Some of the Magtonians can shoot their harpoons further than the others, that's why the pull increases as you get the two objects nearer to one another. More Magtonians successfully launch and attach the closer the magnet gets to metal.
There's another interesting fact about Magtonians. The males live on one side of the magnet, and the females on the other. However when the two are separated the females stay on one side and the males on the other. They're horny little bastards. This is why the pull of the harpoons are stronger when you use two magnets instead of just metal as both genders are launching their harpoons towards the others land.
Magtonians are not gay however and don't like the introduction of other Magtonians of their own sex into their group. When you try to introduce two male sided Magnets to one another or two female sided magnets to one another instead of harpoons they will try to keep themselves apart by extending poles pushing the two magnets apart. This is where the term "polarity" comes from. These crafty Magtonians are even fairly good at flipping the opposing magnet over with their harpoons and poles. Try it, try setting one disk magnet on top of the other with same sex sides facing, they will usually flip in mid air pole induced flip then quickly harpoon together.
Rubbing a magnet on a piece of metal will cause some of the Magtonians to fall off off and take up new residence on their food source, thus creating a new home for them and turning what was once a simple piece of metal into a new magnet.
The preceding post was not a Slashvertisement.
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.
I don't think we can just assume something is fact because it fits with what we know right now. Modern physics was built on quashing the assumptions that infinities and infinitesimals exist. We cannot go arbitrarily fast, and we cannot chop things up infinitesimally small, or measure to an arbitrary accuracy. These ideas were built in to classical mechanics as deeply as black holes.
To be clear I am not saying that black holes do not exist and what we observe and call black holes are not black holes. Just that when we are dealing with artifacts of mathematical models, time could identify them more as artifacts of the model rather than the most useful representation of the observable universe.
"She's a scientist and a lesbian. She's not going to let it slide." Orphan Black
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
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.
"After all, just because you learned something growing up as a child doesn't mean it's true."
Or perhaps the sensationalist non-peer reviewed paper making wild claim about the nature of the universe will wilt under scrutiny?
I generally don't throw out everything I learned as a child the first time I hear a contradictory claim, I perk up my spidey sense and look for extra info pro/con and decide if it is time to adjust my mental model of the world around me. Often it turns out that wild claims are a load of bunk from crackpots (shocker!).
My favorite early formative experience like this from my teenage years was a guy at a cafe who, after overhearing my step-dad and me talking engineering, and posed a riddle about a piece of string wrapped around the earth, and if by adding some length (I forget now) while evenly raising its height above the ground, could a poodle walk under it? Turns out that simple analysis showed his answer was completely wrong and BS (he claimed it took miles, while it takes 2*pi*poodle). My take-away was to be skeptical of crack-pots making wild claims about the world, they are often either idiots or wrong (especially if they clearly have an anti-science agenda).
Protip: Get a sense of humor. You are the reason why he had to qualify it.
Nice.
Please explain how this hypothesis fits with the observed effects of breaking a magnet in half, and with related theories of electromagnetism.
Magtonians are not gay however
Are you proposing this as an explanation as to why we have not been able to obtain evidence of monopoles?
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.
You're being pedantic. Indirect observation is still observation, and they're indirectly observing things that behave consistently with our theory of black holes. As for black hole formation, which is what the article is actualy about, I don't think they've ever observed such a thing.
--- Most topics have many sides worth arguing, allow me to take one opposite you.
Try re-reading your question, the answer is embedded in it. I'll clarify: Black holes are a theoretical construct which cause a contradiction between quantum mechanics and general relativity, if it's proven that they cannot exist, then the contradiction they create likewise doesn't exist.
A simpler example: The statements "All crows are black" and "This is a white crow" contradict each other. If I prove that white crows can't exist (maybe your "white crow" is actually a deformed pigeon) then the contradiction disappears - the second statement is shown to be false, and the apparent contradiction dissapears. It wasn't "resolved", it was shown to have never actually existed in the first place because it was based on a false premise.
Obviously the GR/QM contradiction is somewhat more subtle, but the principle is the same - if they only contradict each other within the context of an impossible scenario, then there is no actual contradiction.
--- Most topics have many sides worth arguing, allow me to take one opposite you.
How is it at odds with observations? We've (indirectly) observed some of objects consistent with our theories of how black holes would behave, but to the best of my knowledge we've never observed the *formation* of such an object.
The headline-- Black holes don't exist-- is at odds with our observations: we see things that appear to be black holes.
The actual summary is not at odds with our observations: the summary says that stellar collapse doesn't form black holes, and we don't have observations to say know how the black holes we seem to be observing were formed.
Now, you could go on and ask whether the things that we see which we are interpreting as black holes might be something else. But that would require a new theory that could explain how the massive, compact objects we see could exist, and not be a black hole. I don't believe that, at the moment, we have any other candidates.
With that said, of course we can't see a black hole itself. But we can see the stuff orbiting it, and that can tell us its mass and size, which is enough to tell what it is.
http://www.geoffreylandis.com
Let's look out 50k ly. We can see that something incredibly massive is sitting in an incredibly tiny region of space. We don't see stars there. In fact, we observe some x-ray bursts, which are consistent with models of an accretion disk. We also know the upper limit on the volume this mass resides in: Something about the size of our solar system. We know this because we can actually image that resolution at that distance - aka, we can see it. Do we see a black hole? No, but then again, those are almost impossible to image directly. Instead, you observe local effects, like gravitational lensing (http://arxiv.org/abs/1204.2103).
I would surmise that this paper is going to have a hard time in the peer review process unless it accounts for invisible, ultra-dense objects of some kind.
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.
Sooooo its something of huge mass that pulls things in like they're falling down a hole and it emits no light and therefore would appear to be black.
Why can't we call this thing a black hole again?
But I believe this paper isn't disproving that. I think its saying all of that mass doesn't go to a point of infinite density, due to other known phenomena that keep it from happening.
Are we talking about a spherical poodle?
Correct, but you don't need calculus.
c+dc = 2*pi*(r+dr)
substitute 2*pi*r for c & expand
2*pi*r + dc = 2*pi*r + 2*pi*dr
simplify
dc/dr = 2*pi
assuming dr>0. i.e. we are not dealing with a poodle singularity.
Which by remarkable coincidence have recently been shown mathematically to not exist
Third time's the charm: trying to come up with something you can just click-and-read:
This one's in html:
http://file.scirp.org/Html/1-7...
Correct Horse Battery Staple: 72 bits of entropy. Enter "Correct H" into google. When it generates the phrase, that's
Sensationalist? What are you talking about?
Not peer-reviewed? Mersini-Houghton's results were published this month in Physics Letters B, Backreaction of Hawking radiation on a gravitationally collapsing star I: Black holes? I don't expect you to read the existing literature, but the least you can do is check the indices to see if it exists.
Black holes as we conceive of them now would actually be easy to see.
Light originating from behind the black hole (from the perspective of the viewer), traveling in a direction toward the black hole (but not intersecting the event horizon), would be bent by the black hole. The result would be extreme gravitational lensing. When looking at the black hole, the effect would range from a general increase in brightness around the black hole, to an extreme brightness appearing to originate from the location of the black hole.
Objects of such mass and density have not been found. We have speculated that they exist at certain places, but we have not seen the requisite lensing effects akin to a kid using a magnifying glass outside (either just looking at shit or using it to burn shit).
Black holes, with the requisite lensing effects may exist, but they'd be easy to spot. What we seen so far, and have labeled as black holes, cannot be of the size and mass we think they are.
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?