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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 While the arXiv paper with the exact solution has not yet been peer reviewed, the preceding paper by Mersini-Houghton with the approximate solutions was published in Physics Letters B.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."
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.
How does mathmatically disproving the existence of black holes bring gravity and quantum mechanics into harmony if you're essentially removing something that contradicts these theories rather than explaining how it works?
If it emits Hawking radiation as it's collapsing, it doesn't become a black hole, it becomes a Hawking hole.
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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.
that girls are bad at math.
P.S. this is a JOKE. even if the conclusions are proven incorrect upon peer review, im sure that that prof. mersini-houghton is many orders of magnitude smarter than me, and most male homosapiens for that matter.
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)
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.
... slashdot doesn't exist, either as it fell below the noise level of web traffic long ago. But yet here we are using it.
Damn_registrars has no butt-hole. Damn_registrars has no use for a butt-hole.
..that Hawking has just been a puppet all this time - no different from a politician other than the level of control over his actions the puppeteers where willing to entrust him with.
Go home everybody. Nothing to see here.
Does he throw a fit if you divide by zero?
Table-ized A.I.
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.
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
They look lke black holes from the outside, but are not singulaties. Matter collpses to highest quantum density possible- one plank mass per plank volume- bbut not infinitely small.
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
It wasn't that long ago that the scientific community claimed that a common bumble bee could not fly according to known laws of science. Black holes seem to be present and common place. When observations do not match equations bet your dime on the observations.
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).
Clearly the only way to solve this issue is to send a manned expedition into the black hole to see what we find!
Beware of bugs in the above code; I have only proved it correct, not tried it.
Just means that the choice of word should change:
His precise words were: "The absence of event horizons mean that there are no black holes -- in the sense of regimes from which light can't escape to infinity."
It seems clear. There are no forever and ever holes of blackness. There is always the chance that light might emerge.
Hawking continued, however: "There are however apparent horizons which persist for a period of time. This suggests that black holes should be redefined as metastable bound states of the gravitational field."
The G
He forgot to carry the 2....
No, that's not possible. Per definition a black hole cannot be observed. If it could, it would have to allow light to escape its event horizon.
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.
I always thought that the laws of physics as we understand them probably breaks down in the extreme case of black holes and that they therefore are more likely very heavy and dense stars, akin to neutron stars, but not necessarily singularities.
Excuse me, but please get off my Pennisetum Clandestinum, eh!
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.
To take what is probably the strongest example of an observed phenomenon that can be explained as a black hole and not much else. Even Hawking gave in and paid off his bet with Kip Thorne.
Based on the arxiv summary, it sounds less like "we don't think black holes exist" than like "when we add hawking radiation to our model, it doesn't collapse down that far, wtf", leading to (in my mind) the questions "well, do we see anything that looks like what this model is saying" and "in that case where do the things that look like black holes come from". (I suspect the answer is going to be "there's a bug in this model right _here_", but we shall see :)
If you happen to read the whole paper and feel like updating this thread with more description, I for one would love to read it.
> Black holes such as the ones at the nuclei of galaxies may very well be formed by other processes.
Black holes are formed by civilizations building particle accelerators of sufficient magnitude and then turning them up too high.
A challenge! Trial by stone!
That's not what those words mean!
Required reading for internet skeptics
http://french.ruvr.ru/2014_06_30/Les-trous-noirs-n-existent-pas-Partie-1-8534/
For many years, some scientist including Jean-Pierre Petit tries to publish details about that ideas and the mathematical model behind it, but is constantly refused by referee, since it's out of general acceptance. This is how science works.
Why are some black holes "supermassive" and others just regular?
Could we expect what's left after a supernova to, at some point billions of years later, explode again once it's reached that critical mass?
Could neutron stars turn back into regular stars?
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
Just a normal star... with a huge mass in quite a small volume, and that does not emmit light.
There's no reason to assume those things are black holes. That's jumpping to conclusion.
Rethinking email
Typo correction... sorry (Slashdot should allow edits!)
Because of this alone, physicists pretty much already knew singularities probably were real
should be
Because of this alone, physicists pretty much already knew singularities probably weren't real
haven't read the orignal article yet, but:
It reminds me of the early days of black holes. Einstein, Weyl etc. knew there were degenerate solutions of the Einstein Equations.
Einstein went on to prove that radially collapsing material could never form a black hole. At the same time Oppenheimer was proving that rotating stars would form black holes.
It's articles and discussions like this that make me want to quit my sys engineer job and go back to school and earn a Ph.D in astrophysics. *Sigh* but I can dream...
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--- Most topics have many sides worth arguing, allow me to take one opposite you.
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?
Originally, yes. A very definite concept which wreaks havoc with physics, has since been shone to be almost certainly impossible in the simplistic form initially proposed, and for which a more nuanced and non-contradictory formal description has yet to be widely accepted. Moreover many of the candidate descriptions weaken or eliminate the event horizon - the defining quality of the original concept.
It's not quite the "here there be dragons" of dark matter (much less the "we're not even sure about the dragons" of dark energy), but it's not such a huge stretch. It's a theoretical construct which is predicted to have certain general properties that are consistent with some indirect observations, but whose details elude us and which it may be physically impossible to ever observe directly. Not really all that different than dark matter at all when you think about it. Or perhaps you're unfamiliar with just how definite a description of dark matter we have? It's a kludge that's never been directly observed, but our indirect observations are roughly as conclusive as those for black holes - to the point where we can make a pretty good estimate as to exactly how much dark matter is in the room with you right now, even if we have almost no idea what it is. But then we don't really have much idea what quarks are either, and yet a big pile of them is managing to type this post just fine.
--- Most topics have many sides worth arguing, allow me to take one opposite you.
(he claimed it took miles, while it takes 2*pi*poodle)
I believe 4*pi*poodle is the correct answer, you have to add the height of the poodle twice to the diameter of the earth.
I'm pretty sure it's 2*pi*poodle. Consider the thin circular slice of the Earth at the equator. Let it have radius r and circumference c = 2 * pi * r. The raised string describes a circle having circumference c + dc and radius r + dr, where dr = poodle and dr is much smaller than r. Using calculus, dc/dr = 2 * pi, so dc = 2 * pi * dr. But dc is simply the amount of string that must be added. qed.
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.
Actually you have that wrong.
Black holes are a mathematically predicted consequence of the theory of relativity, which have been confirmed to exist by observation (Their discovery was one of the major wins for relativity over competing modifications to classical mechanics).
We also had a theory for how a black hole might form (collapse of a sufficiently massive star). We have not yet (as far as I know) managed to observe the creation of a black hole. This paper is supposedly showing that there are mathematical errors in that theory, which would imply black holes must form in some other manner (or this paper will turn out to be flawed in some way).
>Indirect observation is still observation
All observation is indirect observation, except maybe when you define what you're observing as being what your brain perceives from its inputs.
I should use this sig to advertise my book ISBN-13 : 978-1501515132.
Are we talking about a spherical poodle?
the science was settled...
As long as we don't have to add 4*poodle*pi, I'm happy. I doubt even a single poodle would taste very good in pi.
Other than that, I get
\Delta C = C' - C = 2\pi(R+\Delta R) - 2\pi R = 2\pi \Delta R
where \Delta R is one standard poodle, which is (curiously enough) 0.314159 meters when converted into metric. That is, a one tenth of a pi poodle.
rgb
Even when the experts all agree, they may well be mistaken. --- Bertrand Russell.
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
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.
/o For the people who are still alive... o/
No, the science isn't settled.
http://www.worldcat.org/title/...
But the metric being wrong means that black holes fail to satisfy conservation of energy. Assume that conservation of energy is satisfied and fix the metric -- you'll find that a cross term was dropped -- and it all works out.
Correct Horse Battery Staple: 72 bits of entropy. Enter "Correct H" into google. When it generates the phrase, that's
Just adding my own simple, non-calculus solution, to the mix.
When the radius of the earth is r we have...
Length of string around earth = 2*pi*r
Length of string around earth and poodle evenly = 2*pi(r + poodle)
Subtract former from the latter and it's 2*pi*r + 2*pi*poodle - 2*pi*r, so just 2*pi*poodle more.
Happy people make bad consumers.
So that's how science works now, huh? If you study something and hold an opinion on the topic your opinion becomes law? Sure, I can buy that. It sounds legit to me. The only thing I'm really left wondering is what happens when you have two astrophysicists studying the same topic and disagree? What then? It sounds like we might have a paradox on our hands.
whoops, forgot there's stuff on arxiv: just read this one:
http://arxiv.org/abs/0708.1008
Correct Horse Battery Staple: 72 bits of entropy. Enter "Correct H" into google. When it generates the phrase, that's
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
An observer watching object in stronger gravitational field sees time move slower in/for the observed object. So if I observe you go close to the event horizon and then you come back out, your clock would show less time had elapsed than mine.
Worth noting that outside observer, assuming they could see the redshifted light of you, would see you slowing and dimming (observed time between each photon emission increases) as you approached event horizon, never to quite reach it. But there is a time of last photon to be emitted that can get out, so things dim and wink out before being seen to arrive at event horizon.
But if you fell into hole you'd experience no slowing down of your approach to either event horizon or singularity (assuming hole big enough tidal forces don't pull you apart). In fact the event horizon would approach faster and faster until it reached lightspeed as it "touched" you and went by.
If you want to talk about wild, black holes are about as wild as they get. Collapse of matter into a singularity that not even light can escape? Seriously? I mean, there's some wacky stuff out there. But there's nothing quite as crazy as the singularity, which is 0 and +/- infinity all wrapped up into one thing.
It is a much less crazy universe without black holes. Occam's razor however, so far has favored it, in the same way that it's favored dark matter. That's all.
"If a nation expects to be ignorant and free in a state of civilization, it expects what never was and never will be."
Black holes do exist, I've seen one!
This was a thought I had when reading the summary. We have a lot of evidence that they exist. We see gravitational effects on nearby matter and the subtle but present gravitational lensing.
On the other hand, what I gather from this summary is that the status of a black hole becomes somewhat of a mathematical limit. Basically, matter still accumulates. Time still slows. Space still bends to the same extent that it would if the matter was in a singularity. However, from a distance, the concentration of mass within a volume of a few AU across could be indistinguishable from the same matter contained in a point that takes up exactly 0 m^3. Basically, for any volume, there is a distance that you can view it from that makes it look like a 0 dimensional point. Isn't this the idea behind relativity? From our frame of reference many thousands, millions or billions of light-years away, it looks exactly like our current model of a black hole... from a frame of reference within a light-year or so of the anomaly, it may look completely different, though it would have the exact same wide scale gravitational footprint.
Another thing to consider is as matter drifts towards a black hole, time slows down for it, until you hit the event horizon where time effectively (I suspect literally) stops. If time approaches the limit of 'static', then it is impossible for matter to actually become sucked into a black hole. It will simply get sucked ever closer to a limit it simply can't cross. This prevents the event horizon from ever forming.
I admit, this is all the speculation of a curious soul and has no mathematical foundation, but this is how I picture a black hole... I am partial towards this new theory because I never understood how anything ever enters a black hole if time approaches a stopping point as the object gets closer. Eventually, the time gets so slow that any forward movement becomes negligible as it approaches this limit. Therefore a black hole can't grow... and according to this theory, it can't even form.
Assuming that my logic in this essay is somewhat valid, instead of seeing black holes such as we currently think exist, we would see extremely dense spheres that are literally kept from collapsing by the extremely slow passage of time. Again, this would look like a black hole from a distance, but it's a completely different, and Einstein approved monster.
Possibly. But if it is a 2*poodle*pi, it is probably disk shaped, possibly with delicately scalloped edges. A spherical poodle seems more likely to be a (4/3)*pi*poodle-cubed, and if nothing else, being cubed is very hard on poodles. Often they subsequently turn into e^{-poodle}, a decaying poodle or (if eaten) into ex-poodle-poo.
rgb
Even when the experts all agree, they may well be mistaken. --- Bertrand Russell.
Perhaps they mean a singularity? For example, you can have a black hole (space is curved such that light can't escape), but not a singularity...? (the center isn't an infinitely small point that nothing can ever reach---and can only fall towards forever).
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.
Right, except that if black holes don't exist (according to this paper) then something the mass of a super-massive black hole shouldn't exist, should it? It should have exploded and shed the extra mass.
Just a random thought: maybe dark matter fills some sort of void created by the explosion. I am not a scientist. :)
but it can't be proven one way or another
Well, maybe not right now, but -
They don't exist.
Oh. That was fast.
systemd is Roko's Basilisk.
Could someone please explain this finding to me using a car analogy?
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?
I think you resolve it by killing a cat.
Or maybe you don't.
Confucius say, "Find worm in apple - bad. Find half a worm - worse."
...String theory is bogus?
Nope -- no lift necessary. When you add 2*pi*(additional radius desired) to the circumference, it raises it by that amount all the way around the planet.
It's basic math: Circumference is 2*pi*r, so adding delta_r to the radius, you have 2*pi*(r+delta_r), or 2*pi*r + 2*pi*delta_r. 2*pi*r is what was already there, so you only need to add 2*pi*delta_r (in this case, delta_r is 1 poodle of height) to the circumference.
~Anguirel (lit. Living Star-Iron)
QA: The art of telling someone that their baby is ugly without getting punched.
You still wouldn't be observing the event horizon itself, just the stuff escaping from it and/or annihilating above it. Potentially very informative, but a far cry from observing the point where physics goes sideways, much less the singularity itself (or whatever else is happening on/within the event horizon).
Interesting tidbit though, if we could resolve details the size of the predicted Schwarzschild radius that would potentialy go a long way towards figuring out what we're looking at. As I recall, current observations of Sgr A* have established the existence of a non-luminesce "something" of roughly 4 million solar masses with a maximum radius comparable to Neptune's orbit - which puts the minimum density at something like a million times less than our sun. Black hole? Ultradense dark matter concentration? Your mom? Perhaps the EHT will tell.
--- Most topics have many sides worth arguing, allow me to take one opposite you.
UYHAAFTINBI (Unless you have an acronym for that, I'm not buying it.)
I still find unending amusement in the fact that we "know" so much based on observing distance objects. It doesn't take a scientist to see how much data is lost optically, just walk from one end of a large room to the other.
Worse, MMORPG.
Could neutron stars turn back into regular stars?
Generally speaking, no. I mean theoretically I suppose its possible, but it would require an enormous amount of energy input to overcome the gravity -- on the scale of something like a collision with another star. And after a collision like that it would be hard to say it "turned into" a regular star in any sort of direct sense.
well the synopsis says it would emit mass quickly enough that it would not have enough mass to stop light from escaping?
world was created 5 seconds before this post as it is.
Now just explain all the detected black holes and you're done.
The paper doesn't say black holes don't exist, it says they can't be created by a massive star collapsing. They may have been created in the big bang or perhaps by a neutron star growing or colliding or other unknown process. Lots of evidence for the existence of black holes but you never know what may be discovered.
https://en.wikipedia.org/wiki/Inverted_totalitarianism
Maybe he should have meant the following version which seems very counter-intuitive:
Suppose you wrap a string around the Earth's equator so that it fits tightly. Now suppose you add an extra meter in the length of that string. Surely, the string won't be tight anymore. So pinch it at a point and pull it upwards as high as you can. (Now, the string goes tightly around most of the earth, and forms a triangle elsewhere with the apex being the point you pinched and pulled.)
How high this apex would be from the surface? The answer turns out to be well over a hundred meters. See Image 1
(Apart from the actual number, the surprising part is also that the bigger the initial object - earth here - the higher you can pull the string even though you add the same extra length of 1 m in each case.)
Black holes do not exist
Jean-Pierre Petit
04/2014
ABSTRACT We reconsider classical features of Schwarzschild and Kerr metrics, which are the fundamental basis of the black hole model, through new space and time coordinates which transform the object into a space bridge linking two folds of the [...]
Parer available for download
The gist of the paper is to claim black holes, as we observe them, cannot form by collapse of a massive star.
Maybe we deserve this world ?
Because a black hole is understood as something with an event horizon. You don't get to define astrophysical terms; they mean what they're understood to mean by those versed in the art. My suggestion is that we go back to the old and just-as-relevant-today term "frozen star", but I'm not arrogant enough to push for it in the way you want to redefine terms just because you will it.
"Politicians and diapers must be changed often, and for the same reason."
If you really were an astrophysicist, you'd know that black holes are observationally indistinguishable from dark grey ones.
"Politicians and diapers must be changed often, and for the same reason."
Black holes are observationally indistinguishable from dark grey ones (the non-observational difference being whether there is an event horizon).
"Politicians and diapers must be changed often, and for the same reason."
You're discussing a paper by Rovelli and Vidotto, whereas this discussion is about an unrelated paper by Mersini-Houghton and Pfeiffer. They're unrelated because in the latter an event horizon never forms. Moreover, the Rovelli and Vidotto paper is garbage--see http://backreaction.blogspot.c...
"Politicians and diapers must be changed often, and for the same reason."
Or perhaps the sensationalist non-peer reviewed paper making wild claim about the nature of the universe will wilt under scrutiny?
Indeed, let his peers have a few months to comment too.
I appreciate the clarification!
What they showed is that black holes cannot form in *their model*, which includes quite a few simplifications to make the problem tractable numerically.
It might yet turn out that in another setting, the black hole can form.
"Long run is a misleading guide to current affairs. In the long run we are all dead." (John Maynard Keynes)
A wild black hole appears.
It attacks sun with gravity.
It's super effective.
"By the way if anyone here is in advertising or marketing... kill yourself." -- Bill Hicks
You're being pedantic too!
It's pedentry day!
No. That was yesterday. Until tomorrow.
I should use this sig to advertise my book ISBN-13 : 978-1501515132.
"I still find unending amusement in the fact that we "know" so much based on observing distance objects"
I know, huh? Things were better back in the old days when we "knew" the cosmos without all this painstaking observation and maths and stuff.
That's a small Schwarzschild radius. There are some "black holes" with enough mass that the Schwarzschild radius would be 87 AU. We've already discovered "black holes" with 100,000,000 solar masses that emits absolutely no light, except when they pass through the accretion disk of the parent 10.000.000.000 solar mass parent, which causes a massive flare up every few years.
How do you pack 100 million solar masses into a small area and not have it emit any radiation? You can't. So either the light is not making it to us at all or it's being red shifted below radio. It's going to take a lot of gravitational red shifting to bring x-rays and gamma rays below radio.
I was under the impression that a Neutron star could not (d)evolve into a black hole by just taking mass from another star, except possibly a merger of neutron stars. I thought the logic was something that as the matter falls onto the Neutron star, it creates radiative pressure from fusion that slows down more matter from accumulating, then it blasts away the extra mass and starts over. At no point can it accumulate extra mass fast enough to turn into a black hole.
Density is not the determinant a black hole. Large black holes have very low densities.
From the size and mass, we can rule out pretty much all the other possibilities. (Small but massive dust clouds are gravitationally unstable.) So if it's not a black hole, it must be something else, and that something else is either new physics, or a manifestation of old physics that we've been insufficiently clever to figure out yet.
http://www.geoffreylandis.com
...
As for the stability of a dust cloud - if it's "stationary", certainly. But how about if it were orbitting an ancient neutron star or other massive non-luminous object in an organized manner? A "lynch pin" as it were to impose order on what would otherwise devolve into a chaotic system and collapse.
I don't know what you mean by "in an organized manner." You mean, what if a superior civilization put each grain of dust on exactly such a trajectory that dust/dust interactions don't destabilize the cloud? OK.
As for ordinary, non-"organized" dust clouds, if there is any interaction between dust grains, and no internal source of energy to keep it from collapsing, a dust cloud large enough to be self-gravitating is unstable.
As for new physics for a "solid" object of that mass - we wouldn't even have to go very far. All we have to do is [proposes altered version of General Relativity] ....
That would be new physics. General Relativity does, of course, account for the gravitational energy of gravitational fields; that's why it's nonlinear. On the face of it, your proposed revision to general relativity's equations violates conservation of energy. There may be some way to avoid that-- but if you do, this is new physics.
http://www.geoffreylandis.com
As I understand it GR does *not* factor in the energy within the gravitational field as creating it's own "secondary" field
It is built into the theory. This is why GR is a nonlinear theory-- which is precisely what makes it so difficult to solve.
- if it did gravity would no longer follow the inverse-square law near singularities,
Correct. Gravity only follows inverse square law in the weak-field limit. Orbits in 1/r2 potentials are ellipses. Orbits in Schwartzschild geometry are not ellipses. Right there you know that Einsteinian gravity differs from Newtonian 1/r2 gravity.
I actually would like to spend some time to elucidate how it is that nonlinearity in GR means that it incorporates the effect of gravity on gravity-- but I'm afraid I just don't have the time to spare at the moment.
... Bottom line, we have Einstein himself on record saying he chose to ignore the energy in a gravitational field as "double counting", are you really going to argue the point with his ghost?
Not only would I not argue, I would agree with him. Since the gravitational effect of gravity is already accounted for in general relativity, it would be double counting to count it again.
http://www.geoffreylandis.com
IT's hardly a novel or even fringe idea. Hawking proposed this solution as well and those who don't accept this solution have equally weird views about firewalls blocking information loss.
If you liked this thought maybe you would find my blog nice too:
>I actually would like to spend some time to elucidate how it is that nonlinearity in GR means that it incorporates the effect of gravity on gravity-- but I'm afraid I just don't have the time to spare at the moment.
Too bad, sounds like you may actualy know what you're talking about. I don't suppose you know of any good online resources for a gentle intro?
--- Most topics have many sides worth arguing, allow me to take one opposite you.
No, just perpetually trying to do my part to raise the level on conversation. All that is necessary for inanity to triumph is for interesting people to say nothing. Or something like that.
--- Most topics have many sides worth arguing, allow me to take one opposite you.
The abstract is explicit that their calculations (the details of which are way over my head) have a collapsing star "bouncing" before it's surface goes below the radius for it's event horizon. That's a finite radius, long before the singularity happens.
What I don't get is why they think that this prevents a black hole from ever forming, since there argument is based on the rate of emission of Hawking radiation blasting the infalling mass back into space - similarly to the Eddington limit to accretion rates on quasars. That would limit the rate at which matter could fall into the forming black hole, but I don't see how it would prevent a black hole forming.
Birds are not dinosaur descendants;birds are dinosaurs, for all useful meanings of "birds", "are" and "dinosaurs"
Which is what I said. You would watch the end of time behind you. To and outside observer time would stop for you. To you, the outside observer would age extremely fast.