1) First we shall define to exist, relative to an observer, to mean that "the object in question lies in the observer's past light cone" 2) We define a black hole to be an "area of sufficiently compressed mass such that an event horizon of non-zero radius exists" 3) Next we make the presumption that black holes exist today (for observers on Earth) 4) We recognize that all existing mass approaching this black hole currently will cross the event horizon at \(t_{crossing} = +\infty\) 5) We claim that the black hole was created at \(t_{creation}\) where \(-\infty < t_{creation} < t_{now}\) (i.e. some point in the finite past) 6) We recognize that an event horizon of non-zero radius requires mass to exist within it, by definition Therefore, in order for #3 to hold, at some point in time called \(t_{dubious}\) where \(t_{creation} <= t_{dubious} < t_{now}\), the Earth observers must be able to claim that mass crossed the event horizon of the black hole in question (in order to satisfy #6 and #1). However, for those same observers at and prior to \(t_{creation}\), \(t_{dubious}\) now resides in their future light cone, and will eventually reside in their past light cone, which contradicts #4. A contradiction indicates that one of our presumptions is incorrect. The conclusion is that either all black holes are eternal (which is the only way \(t_{creation}\) can reside in Earth observers' past light cones), or they cannot be said to exist for Earth observers.
Only from the coordinates of the remote observer. In the frame of the local observer, all mass crosses the event horizon in finite time.
What about Hawking radiation? Wouldn't that cause the black hole to lose mass and eventually evaporate?
Well I did ask about M87 in the other thread along with mentioning telescopes... This was a cute article http://www.rit.edu/news/release.php?id=47657 Which, among a plethora of other information, made me wonder of a clandestine motive for making such stupid claims.
Yes, and the smaller the BH, the faster it loses energy. A 3 solar BH will take about 60 TRillion years to evaporate.
Last time I checked, Stephen Hawking retracted his theory. They now think that all information could be stored at the event horizon, so there is no need for Hawking Radiation. It is part to do with Leonard Susskinds Holographic Principle. He had much debate with Stephen Hawking, but they think it is because there are two seperate frames where one of them would observe the black hole to store the information on the event horizon. But, if you ask me I think it comes from the failure to be able to make what goes on inside and outside the black hole to be the same thing in one single reality. It is said two completely different observations of what actually happens occur at the same time. I don't think this would be a problem if an accelerating frame could observe their own time to slow down. So I would think yes they are eternal, I don't even think the expansion of the universe could tear them apart as the effects of that have not been seen to be local.
I believe Hawking only retracted that information was destroyed (2004), but still maintains that it radiates away due to HR.
Hawking Radiation has been around much longer than that. There is no way he could have just discovered that information wasn't destroyed in 2004. The whole purpose of the theory was to explain a way out, so that information was not destroyed. Whoever told you that didn't know what they where talking about.
Hawking radiation was the cause of the "information paradox", not the solution. John Preskill - On Hawking's concession (2004)
It has been suggested, subatomic particles may indeed be ridiculously tiny black holes - if this was ever to be verified, stable varieties such as the electron would indicate great longevity on all scales.
That's not the reason Hawking radiation exists. It exists because pair-antipair creation happens all over the place all the time (i.e. the vacuum energy is not zero.) When it happens near the event horizon, there is a nonzero chance that one particle will escape and one will not. This represents a reduction in vacuum energy near the black hole which in effect is "filled" with mass from the black hole. Do that long enough and the black hole loses mass and evaporates.
Then how did I know that Stephen Hawking came up with Hawking Radiation in order to solve the problem of information being destroyed in a black hole almost 10 years before these events took place? Just because a reporter at some event just heard of it then doesn't mean that is when he came up with theory. I swear I saw it come right out of Susskinds mouth one day on youtube, I should have saved the link. He said that he was talking to Hawking like it normally does to try to talk him out of his theory, and then he got him to say it was wrong and that was because information was stored on the event horizon of a black hole relative to an observer outside of that black hole. Then that was what the hipe was about for him coming up with the Holographic Principal. I tried to go back and find it but it is no longer there or I just couldn't find it. There was just too many total crank vidoes searching for that and I just couldn't take it any longer.
Hawking radiation had nothing to do with the information paradox. The theory was developed when Hawking and Bekenstein realized that BH's have entropy proportional to the area of the event horizon, and so must radiate thermodynamically. This was in the early 1970s Do you ever get tired of being wrong?
Into what? Another Black Hole? According to the Holographic Principal, time would stop for something go into a black hole, and then would lose its velocity and be frozen in time. (that is something I don't tend to agree with, but it would be hard to see how something could get stuck onto a black hole) The outer edge of a black hole would be completely jam packed with everything for a particle pair to really do anything. Neutron Stars are formed from dying stars that are not large enough to become black holes. The protons and electrons all get smashed into each other and form a star that is completely made out of neutrons. There is no way to know if particle pair creation even occurs on the surface of a black hole. The force of gravity on a surface that has completely stopped in time might not even have any room to form particle pairs. It would be competely smashed into neutrons. To tell you the truth there is no way anyone could know for sure what is on the surface of a black hole. I don't think either of them have the correct theory, but one thing is for certain they are in disagreement about what is happening there, and that is all there is science really has anything to say about that. I don't even think they are the right mass to be made of neutrons, but maybe closer to energy. Scientist could only guess what they are made of and have tried to show they could be made of neutrons with no success. The density of suppermassive blacks holes is too low, and scientist do not understand why they are less dense than neutron stars. I would guess they are made of mostly electrons, since they have around the same density of water and the electromagnetic force is strongest in water, and cannot be compressed easily.
You didn't know that, because it's not true. Perhaps your recollection is inaccurate, or you were misinformed, or you misunderstood what was said. What reporter? I linked you to John Preskill's own website. John Preskill is the physicist who bet against Hawking and Thorne. (See Wikipedia - Thorne-Hawking-Preskill bet) This is the text of the 1997 bet (from Preskill's site): Whereas Stephen Hawking and Kip Thorne firmly believe that information swallowed by a black hole is forever hidden from the outside universe, and can never be revealed even as the black hole evaporates and completely disappears, And whereas John Preskill firmly believes that a mechanism for the information to be released by the evaporating black hole must and will be found in the correct theory of quantum gravity, Therefore Preskill offers, and Hawking/Thorne accept, a wager that: When an initial pure quantum state undergoes gravitational collapse to form a black hole, the final state at the end of black hole evaporation will always be a pure quantum state. The loser(s) will reward the winner(s) with an encyclopedia of the winner's choice, from which information can be recovered at will. Stephen W. Hawking, Kip S. Thorne, John P. Preskill Pasadena, California, 6 February 1997
This sounds ridiculously similar to Nassim Haramein's Schwarzschild proton. And Haramein is a new age hippie ancient aliens bullshitter. Quite creative eh? Great for science-fiction, not science. :fart:
If you want to make this distinction, why not use the convention already provided by English grammar? Namely, "existed", "exists", and "will exist" to refer to the causal past, present, and future, respectively. If you can only make a conclusion look impressive by manipulating definitions, then your conclusion is really not that impressive and you are hyping it. I think a clearer definition is to define the black hole as the region of spacetime inside the event horizon associated with a singularity that will inevitably form by gravitational collapse. The event horizon is a light cone (actually the smallest light cone that completely contains the singularity), so this definition of a black hole is invariant. Stop here. By your definition above, black holes do not "exist" today according to GR. For an outside observer, any black hole is contained entirely in their causal present and future. So in English it's fair to say that black holes exist according to GR (they're "there" in the sense that you can fall into one), but they have never existed from your perspective as long as you steer clear of them. There's an analogy here with the situation for an accelerating observer I once described for you [POST=2631153]here[/POST].
Exactly my point. We cannot say black holes currently exist any more than we can say that our sun currently exists as a white dwarf because 'in theory we could wait around until it is in such a state'. If you have a reasonable definition of what it means "to exist" which doesn't involve using our imaginations to transport ourselves into the infinite future I wouldn't mind hearing it.
Into energy and matter. You would not want to be near one when it evaporated. Only to an outside observer. To an observer on that something time would proceed normally. The particle pair creation that gives rise to Hawking radiation does not occur on the "surface" of a black hole (and indeed that term doesn't really have any meaning.) It occurs near the event horizon which is not the same as the "surface." I think you are confusing compression as we know it with compression at atomic scales. They are many, many, many orders of magnitude different and have nothing to do with each other.
