Discussion in 'Physics & Math' started by hardalee, Sep 16, 2015.

1. ### paddoboyValued Senior Member

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Something like that IMO.
But in reality the expansion is accelerating and we call the cause of that acceleration the DE, simply because as yet we do not know the nature of this energy that is at work....The CC of Einstein fame? ZPE?
The constant nature of this force acts over all spacetime and against the ever diminishing mass/energy density within the Universe and consequently gravity...hence we now observe an acceleration phase.

Last edited: Oct 5, 2015

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3. ### hardaleeRegistered Senior Member

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Hardalee unique congecture ,HUC, I like it but don't think it's mine. Math does work, negative mass not necessary, BH looses energy, tunneled particle escapes, everyone is happy. Anyway I'm happy and on to the next puzzle of what I don't understand.

Best to all.

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5. ### Q-reeusBannedValued Senior Member

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A quick search and this article lists 4 different scenarios for HR production: http://www.mathpages.com/home/kmath591/kmath591.htm
Tunneling from inside an EH is among them, but none corresponds to your position. You can provide a link to 'scenario #5'? Not that I care much for any of them. Especially given the violently differing BH scenarios ranging from classical BH to 'firewall' and 'fireworks' models, this is just a theorists playground. The chances for actual definitive observational evidence being somewhere between nil and zero.

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7. ### paddoboyValued Senior Member

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There are a number of aspects of cosmology where definitive observational evidence will never be forthcoming.
That does not mean the theory is any the less insecure.........

http://arxiv.org/abs/1009.4634

ABSTRACT:
Event horizons of astrophysical black holes and gravitational analogues have been predicted to excite the quantum vacuum and give rise to the emission of quanta, known as Hawking radiation. We experimentally create such a gravitational analogue using ultrashort laser pulse filaments and our measurements demonstrate a spontaneous emission of photons that confirms theoretical predictions.

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Very short GRBs may be Hawking radiation source A particular group of gamma-ray bursts, those of very short duration, have characteristics that suggest they may be the signature of an evaporating primordial black hole – the Hawking radiation proposed by Stephen Hawking in 1974. Very short gamma-ray bursts (VSGRBs) last less than 0.1second and have been detected by several GRB instruments including the BATSE experiment on the Compton Gamma Ray Observatory, the KONUS experiment, and NASA’s Swift gamma-ray burst mission. The evaporation of primordial black holes was postulated as a possible high-energy source for GRBs as a whole, but these events do not in general fit the characteristics of such an event. Hawking, in collaboration with Bernard Carr, proposed that the evaporation of black holes left over from the early universe would produce a burst of energy; GRBs in general are too bright and too uniformly spread over the sky to have come from primordial black holes. Now David B Cline and colleagues from the University of California in Los Angeles argue that these VSGRBs are a distinct population that does fit the characteristics of primordial black hole evaporation, notably their anisotropic distribution in the sky and lack of significant afterglows. Cline presented these results to the GRB2010 meeting in November.http://www.physics.ucla.edu/hep/vsgrb/ vsgrb_ichep2010.pdf

http://arxiv.org/abs/1401.6612

Has Hawking radiation been measured?
W.G. Unruh
(Submitted on 26 Jan 2014)
It is argued that Hawking radiation has indeed been measured and shown to posses a thermal spectrum, as predicted. This contention is based on three separate legs. The first is that the essential physics of the Hawking process for black holes can be modelled in other physical systems. The second is the white hole horizons are the time inverse of black hole horizons, and thus the physics of both is the same. The third is that the quantum emission, which is the Hawking process, is completely determined by measurements of the classical parameters of a linear physical system. The experiment conducted in 2010 fulfills all of these requirements, and is thus a true measurement of Hawking radiation.

8. ### hardaleeRegistered Senior Member

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384
I would suggest that the energy used to creat the virtual pair was already existant in the BH leading to a net loss since when one particle leaves the BH, the created pair, the particle and antiparticle, both have positive mass.

No link, just me thinking about it. That's all I have to support HUC. (I really do like the name.)

9. ### Q-reeusBannedValued Senior Member

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4,695
OK then. Sort of a hybrid of models (2) & (3) in that article I linked to. If adopting it lets you sleep well at night, guess that's not a bad thing.

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10. ### SchmelzerValued Senior Member

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Thanks for the link to http://arxiv.org/abs/1401.6612

It provides a nice illustration of my reason for reject Hawking radiation as pseudoscience (emphasis my):
So, the question which Unruh asks is also my question:
He gives a positive answer - based on some considerations which I do not accept as decisive. Why I do not accept them as decisive is, unfortunately, more difficult to explain to laymen. If there is some interest, or if I simply find some more time later, I may try, but not today.

11. ### paddoboyValued Senior Member

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He is only one of many who gives a positive answer.....
Whether you accept them or not is of no real consequence, and further more, if as you say [and I'm not doubting you], It's too difficult to explain to a lay person, then why not explain it to Professor Unruh himself or one of the other professional experts.

It's very easy Schmelzer to come here and claim that certain generally accepted science concepts are wrong.....see www.atomsz.com . And of course there are many others that forums such as this need to contend with every day. That's the nature of science forums such as this, as I have told you before.

12. ### paddoboyValued Senior Member

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http://arxiv.org/abs/1401.6612
The experiment conducted in 2010 fulfills all of these requirements, and is thus a true measurement of Hawking radiation.

13. ### SchmelzerValued Senior Member

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Of course. But it is much more difficult to find in the articles posted by the opponents quotes which, essentially, are a copy of the claims one has made before. And not only in the content, but even in the emotional element, as naming the claim absurd. Not?

Of course, as I have written, Unruh finally rejects this position. And provides reasons for this. Which are worth to be evaluated - and you can be sure that I will do it. (A first look tells me that my counterargument to his counterargument remains valid, and the experiment in itself is irrelevant. What I can say here is that I do not doubt that the radiation itself will be thermal, and the temperature will be as predicted by Hawking - the disagreement is how much of it we will see, I think essentially nothing.)

But the point which even you can understand is that my position, even if rejected by Unruh in this paper, is one worth to be mentioned as a reasonable position, a position which one has to reject with a scientific paper. The usual crank nonsense is, clearly, nothing worth to write scientific articles, not?

Last edited: Oct 6, 2015
14. ### SchmelzerValued Senior Member

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Don't cry. (This is about bold letters.)

Then, let's look at the requirements. "The third is that the quantum emission, which is the Hawking process, is completely determined by measurements of the classical parameters of a linear physical system."

In other words, the experiment is a completely classical one. But there is some nice, purely mathematical, analogy between the classical and the quantum formulas. So, experiment by analogy, or so. All this combined with a second "experiment by analogy", namely, equating the theory of gravity with condensed matter theory.

Which is, by the way, the forbidden analogy for all those who hate the ether.

By the way, a nice illustration that your claims about some hidden "agenda" behind my rejection of Hawking radiation is completely off. It is, last but not least, not an accident that the guys who have cited my ether paper are from the "analog gravity" camp. Unruh is the guy whose papers have created this camp. So, if I would act based on my agenda, I would support this camp. I couldn't care less. I think Unruh is wrong here, point.

15. ### paddoboyValued Senior Member

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Good stuff. When and if you finally resolve your doubts, I hope you put out a scientific paper on it for appropriate peer review.
Not quite. And I'll believe you'll agree with me if you check out the clown posting in the science section at this time and claiming fact, plus the general nonsense in the alternative/pseudo sections.

16. ### paddoboyValued Senior Member

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You are entitled to think he is wrong.:shrug: The thing is to show he is wrong, and I don't believe that has been done. The nature of Hawking Radiation is still rather less than certain as per the near certainty of GR say, but again as I have said, appears as a rather logical extension imh of quantum theory.

17. ### paddoboyValued Senior Member

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http://arxiv.org/pdf/1005.4000v1.pdf

Testing Hawking particle creation by black holes through correlation measurements

1 R. Balbinota , I. Carusottob , A. Fabbric and A. Recatib

Abstract:
Hawking’s prediction of thermal radiation by black holes has been shown by Unruh to be expected also in condensed matter systems. We show here that in a black hole-like configuration realised in a BEC this particle creation does indeed take place and can be unambiguously identified via a characteristic pattern in the density-density correlations. This opens the concrete possibility of the experimental verification of this effect.

extract:
These conclusions are obtained considering the hydrodynamical (long wavelength) approximation of the BEC theory and exploiting the gravitational analogy. However a key point is to know whether in a BEC Hawking radiation and its features are robust, i.e. if they survive when a detailed “ab initio” calculation with the full microscopic theory is performed overcoming the transplanckian problem. The definitively positive answer to this fundamental question has been given in [9] and can be clearly seen in Fig. 2, where the result of a numerical computation based on the so called truncated Wigner method are presented. The spectacular appearance after the horizon formation of the two tongues neatly peaked exactly along the line x v+cl = x 0 v+cr as predicted by the gravitational analogy signals without doubts the actual presence of Hawking radiation in BECs. It has been also shown that the effect is still present and clearly visible even in the presence of a thermal background, always present in BECs

18. ### OnlyMeValued Senior Member

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A true measurement of Hawking radiation, or a similar radiative process, in an analogue model. But that model is not equivalent to the conditions predicted for the event horizon of a gravitational field.

All of the references presented so far, deal with classical analogues.

The reality of black holes and any associated event horizon remain a theoretical extension of GR to gravitational conditions we cannot observe and or test. None of the analogues discussed prove anything about how a black hole's event horizon might interact with vacuum energy. That doesn't mean that there is none only that it is not as certain as some here seem to believe.

Read any of the three papers in full and you will find that the authors understand the difference between their analogues and the black hole radiation predicted by Hawking... Even while the lay discussion here does not seem to.

19. ### paddoboyValued Senior Member

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Perhaps you need to read what I have said about Hawking radiation in counter argument against those that are saying specifically it does not exist.

And I also understand with regards to analogues, but again by the same token, if the results were reversed, then our deniers would be arguing with much more gusto.
They support the model, pure and simple...I have not claimed anything else.

20. ### SchmelzerValued Senior Member

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I disagree. The trans-Planckian problem shows that the original derivation by Hawking is not a derivation but an absurdity. Because it depends on absurd assumptions.

Now, Unruh argues that one can, nonetheless, show that Hawking radiation exists. Fine, but in this case, he has to show this. It is not me who has to show that he is wrong. For me, it is sufficient to show that the argument is not decisive.

The next point is to clarify that in some part of this I agree that it exists - namely, during the collapse and a very, exponentially, short time after the collapse. As well, I do not doubt at all that this exponentially decreasing radiation will be like Hawking radiation, namely, it will be the radiation of a black body with the temperature computed by Hawking. The disagreement is about the effective size of this black body. I think this size will exponentially decrease after the collapse. So, I do not claim that everything is wrong in Unruh's papers, not at all. All the computations which show that the radiation will be radiation similar to a black body of Hawking temperature are fine. I have no problem at all "acknowledging" that 1 sec. after the collapse the black hole will radiate like a black body of Hawking temperature of size $e^{-10^5}m$. As well, I have no problem "acknowledging" that during the collapse itself there will be Hawking radiation. Because above statements simply are what I think.

Then, there is a third point. The point is that in the hydrodynamic analogy there is no general covariance. Or, better, there is general covariance in the large distance approximation. But there is none in the fundamental, microscopic domain. But the microscopic domain is the relevant one. It is the domain where, following Unruh, the absurd assumptions are transformed into a more reasonable one.

In other words, the Hawking radiation following Unruh is Hawking radiation in an ether theory. General covariance no longer holds, thus, one can no longer apply the equivalence principle, except in the large distance approximation. What is indistinguishable in the large distance approximation - if the ether moves or is at rest - is distinguishable in Unruh's analog gravity. The velocity of the "ether" is, in this analog theory, simply the velocity of the liquid. And I have found in Unruh's earlier papers places where this point is accepted, that one has to make assumptions about the "preferred frame". And, in particular, he assumes the preferred frame to be that of an infalling observer.

This is, indeed, the preferred frame of the black hole analog. The liquid is flowing in such a way that it is initially in a normal range and, then, inside a nozzle, reaches supersonic velocity. And this is also the natural preferred frame during the gravitational collapse itself - all the matter is infalling, so, it would be natural to have an infalling ether too.

Unfortunately, this is not the natural frame for an ether after the collapse. There is no opening of the nozzle at the center of the black hole for a constant inflowing ether to go away. So, what one has to expect for the gravitational collapse is, after some time, a stable configuration of the ether. But if the ether is stable, there will be no Hawking radiation. This is well established and acknowledged - stable stars do not Hawking-radiate.

21. ### paddoboyValued Senior Member

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And I believe he has shown this.
I won't comment on the rest of your post and your ether as you know my thoughts, and the thoughts of the general mainstream academia on this matter, suffice to say, as I have mentioned before, the onus is on you to support your overall cosmological claims as against those generally accepted.

22. ### SchmelzerValued Senior Member

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You do not even understand that all the argumentation of Unruh makes sense only as an ether analogy. Even if he does not use the e-word.

23. ### paddoboyValued Senior Member

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I dare say even Professor Unruh would not understand that.