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FQXi FORUM
May 23, 2019

CATEGORY: Questioning the Foundations Essay Contest (2012) [back]
TOPIC: Hawking Versus Unruh Temperature as a Measure of the Health of the Equivalence Principle by Douglas Alexander Singleton [refresh]
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Author Douglas Alexander Singleton wrote on Aug. 20, 2012 @ 14:31 GMT
Essay Abstract

The equivalence principle is the conceptual basis for our best theory of gravity, general relativity. To date there has been no definitive, experimental evidence for a problem with general relativity as the proper theory of gravity. In this essay we present a thought experiment, involving the quantum effects of Hawking and Unruh radiation, which indicates a violation of the equivalence principle. The way in which the equivalence principle is violated by this thought experiment points toward a possible way to resolve some of the short comings of general relativity - the lack of a consistent quantum theory of gravity and the existence of singularities in black hole space-times.

Author Bio

The author completed his SB degree in physics at MIT and obtained his PhD from the University of Virginia. He taught physics for one year at a high school while also working as a parking garage attendant, before moving to Virginia Commonwealth University for three years as a lecturer. In 1998 he moved to California State University, Fresno. He has held visiting faculty positions at Peoples' Friendship University Russia in 2004 and 2009 and at the Universidad de Costa Rica in 2005. His recent work has focused on quantum fields in gravitational backgrounds.

Download Essay PDF File

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Azzam AlMosallami wrote on Aug. 20, 2012 @ 23:29 GMT
Dear Dr. Douglas Alexander Singleton

I really want to thank you more than words for your great essay. You discussed an important issues regarded my essay http://fqxi.org/community/forum/topic/1272, the equivalence principle in SRT, the relative velocity in SRT, and the reciprocity principle. You illustrated my interpretation to the length contraction and the time dilation in my MSRT which depending on the concepts and principles of quantum theory is right, and thus my interpretation to faster than light and quantum tunneling, Casimir effect and entanglement is right. In my theory, in the case of measuring faster than light there is no violation for Lorentz transformation or causality. Wormholes in GRT can be interpreted according to my theory same as quantum tunneling and entanglement. I hope to read my essay and then discuss more details.

AZZAM

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Douglas Singleton replied on Aug. 22, 2012 @ 17:19 GMT
Dear Azzam,

Thanks for reading my essay and for your comments. I will try to fully read you essay and send comments.

Best,

Doug

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Jayakar Johnson Joseph wrote on Aug. 21, 2012 @ 17:28 GMT
Dear Douglas Singleton,

When gravity emerges from an eigen-rotational string, that gravity is proportional to the total mass representational by that string which includes inertial and gravitational masses of the objects in that string; and thus consistency of quantum gravity is expressional in this paradigm.

With best wishes,

Jayakar

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Douglas Singleton replied on Aug. 22, 2012 @ 17:21 GMT
Dear Jayakar,

Yes string theory may have something interesting to say about the EP. Thanks for your post and for reading my essay.

Best,

Doug

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Lawrence B Crowell wrote on Aug. 22, 2012 @ 02:36 GMT
Dear D. Singleton,

I think there might be some problems with this. The substitution of the gravitational acceleration g = (1 - 2m/r)(m/r^2) into the Unruh temperature equation may only apply in the near horizon condition where r = 2m + d, d

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Lawrence B Crowell replied on Aug. 22, 2012 @ 13:15 GMT
Dear D. Singleton,

I forgot that this system does not like backwards facing carrot symbols, and it cuts things off. So I repost this with I hope things fixed.

I think there might be some problems with this. The substitution of the gravitational acceleration g = (1 - 2m/r)(m/r^2) into the Unruh temperature equation may only apply in the near horizon condition where r = 2m + d, 2m >> d. The question is whether this is really a violation of the equivalence principle or a breakdown in the appropriate approximation for this substitution.

It is further difficult to know what is meant by Unruh effects in the region 2m > r. There is no comparable physics for the Unruh effect at a distance d = c^2/g, for d outside the Rinder wedge, or 0 > d.

I will try to give this some thought, but I think there is a question of whether this represents a real departure from the equivalence principle or whether this reflects T_H =~ T_U is correct only with the near horizon approximation.

Cheers LC

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Douglas Singleton replied on Aug. 22, 2012 @ 17:18 GMT
Dear LC,

Thanks for reading my essay and your questions. You are correct that inside the horizon there are difficulties. However I do note this by saying that on crossing the horizon the analysis will proceed by heuristic arguments and conjecture. One point is that at and inside the horizon one can not "stand still". This is already indicated by the fact that the local acceleration for an observer who is at rest near the horizon approaches \infty as one goes to the horizon.

But outside the horizon one is in a regime where one can trust the calculation of the local acceleration. For an observer at a fixed distance from a gravitating object one can straightforwardly calculate the local acceleration. Then taking this finite acceleration one can think of a Rindler observer with this acceleration. In turn this Rindler observer will detect an Unruh temperature proportional to a=(GM)/R^2. This temperature will be lower than the Hawking temperature of an observer in the field of a gravitating body. Thus the tow observer will measure the same local acceleration but will measure different temperatures.

Best,

Doug

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Lawrence B Crowell replied on Aug. 22, 2012 @ 23:19 GMT
I am thinking of bending some metal on this. I would feel better if my concern over whether this reflects a breakdown in an approximation is answered.

The accelerated frame near the event horizon observes the outside world “speed up,” for units of proper time on this frame correspond to very large units of time is asymptopia. As the accelerated frame approaches the horizon, which requires a larger acceleration, we may think of adiabically moving this situation to the stretched horizon. The distinction between this frame and the frozen appearance of a freely falling frame on the stretched horizon as observed from the outside are indistinguishable. This flies in the face of some standard physics, where physics is written according to inertial frames. There is an asymmetry between inertial and accelerated frames, which I think is in greater generality removed. I reiterate what I wrote the other day on the accelerated frame below.

For the accelerated observer the life time of the exterior world races by in a flash. For a stellar mass black hole it requires billions of g-forces to remain a few meters from the horizon, and to get within centimeters requires about a billion billion g's of acceleration. If by some means an observer could do this the outside world would be racing by, say for a small proper time with t = g^{-1} cosh(gs). So the proper time element is s ~ g^{-1}ln(gt) for a time unit t outside. As a result for t the lifetime of the black hole ~ 10^{67}year, g in units of distance ~ 1cm ~ 10^{-10} sec ~ 10^{-17}year the proper time the observer on the accelerated frame observes the BH to evaporate is



s ~ 5x10^{18} years.



This is much shorter than the BH life time measured by the exterior world. Assume you get that acceleration up to 10^{33}cm^{-1} or 10^{43}sec^{-1} or 10^{50}year^{-1}, then you are hovering practically on the stretched horizon. The BH evaporates in about 10^{-42} seconds, or close to the Planck unit of time! Bang!; which means all that ingoing and outgoing radiation which interacts with the black hole hits you at once is a colossal thunderclap. The event horizon appears for larger g close in to be more of a singularity, or a surface region of huge energy density that is radiating and absorbing energy at a ferocious rate.

Cheers LC

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Vladimir F. Tamari wrote on Aug. 22, 2012 @ 05:09 GMT
Dear Douglas,

Although the technicalities of comparing Hawking and Unruh's results are beyond me, I would like to comment on two things in your interesting essay: If one sets aside Einstein's rather arbitrary decision in SR to have c constant and the resulting spacetime concept, the Equivelance Principle in GR reduces to the curvature of the energy streamlines (or of the equipotential surfaces). This reduces it to simple refraction with variable speed of light in a region of gradient index of refraction (Eddington 1920). In other words the mechanics of classical deceleration resulting in curvature!

My other point is that in my theory the Holographic Principle can be explained as the resultant of physical node-node inductive forces within the ordered ether lattice of space, including a black hole. See attached Fig. 27 of the following paper to illustrate GR as refraction, and Fig. 11 to show the mechanism by which the Holographic Principle can be understood. Beautiful Universe Theory I hope these two concepts will somehow one day mesh in with your interesting research. If you have time I hope you will also have a look at my fqxi essay Fix Physics!

With best wishes,

Vladimir

attachments: 1_BUFIG11.jpg, BUFIG27.jpg

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Douglas Singleton replied on Aug. 22, 2012 @ 17:25 GMT
Dear Vladimir,

Thanks for reading my essay and your comments. I will try to read your essay and send comments as well. The illustrations look very nice.

Best,

Doug

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Steve Dufourny wrote on Aug. 23, 2012 @ 19:21 GMT
Hello Mr Singleton,

And if we arrive to put a light near this BH and if we superimpose the holographic concept ? we could see it :)

You know I beleive strongly in the equivalence principle. It is an important parameter at all scales you know.

The works of hawking are indeed relevant about the hawking radiations correlated with heat and temperature.If I could, I will say him(Mr Hawking) that it is possible to see what is really our BH. first , what is really our central BH of our galaxy. we cannot really see what are their productions. I beleive that they are productors also of complementary matters.But we cannot see them just due to their mass. My equations are relevant. I ask me how we can see it really. I think that we can lighting up it. Of course it is not really easy.But it is possible.

The violations of the equivalence principle are not really rational you know.

That said, I liked to read your essay.

Regards

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Douglas Singleton replied on Aug. 24, 2012 @ 17:59 GMT
Dear Mr. Dufourny,

Many thanks for your comments. You are correct that from the thought experimetn I present in my essay one could as well take the stand that the EP is correct and then the implication would be that there is something "wrong" with Hawking/Unruh radiation (e.g. Hawking radiation does not exist, or does not have the form given by Hawking). In fact there are researchers who questin the existence of Hawking radiation. For exmaple

"Do black holes radiate?"

by Adam D. Helfer Rept.Prog.Phys. 66 (2003) 943-1008

e-Print: gr-qc/0304042 [gr-qc]

also there are researchers who question the existence of the Unruh effect

"An Example of a uniformly accelerated particle detector with nonUnruh response",

by A.M. Fedotov, N.B. Narozhny, V.D. Mur, V.A. Belinski

Phys.Lett. A305 (2002) 211-217

e-Print: hep-th/0208061 [hep-th]

Thus if one wanted to take the EP as exact under all conditions then my thought experiment would be an argument (along the lines above) of the non-existence of Hawking/Unruh radiation.

However, my choice was to assume the EP was violated and look at the consequences.

Best regards,

Doug

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Steve Dufourny replied on Aug. 26, 2012 @ 11:08 GMT
Hello ,

Is it necessary to invest in already knwown results ? the monney is a tool and it must be utilized witht he biggest wisdom.

The violations are not really foundamental you know.

The Bh radiates probably but their motions are above the fermions at my humble opinion.In fact the real interest is to fid the fractal above the weak and the strong int. more the electromagnetism. I beleive that the volumes of spheres are the secret......see the stabilities of informations.

In fact the aim is to class the BH and the volumes of stabilities. I beleive that the works of Hawking are relevant considering a pure thermodynamical correlation. The BH can be classed. The BH have a lot of properties correlated with the rotating spheres. The kinetic energy and the potential energy are always relevant.

In fact, these BH are like the stars, they produce the matter with all its fractalization and its complexity. The quarks, the neutrinos, the gravitons,muons,.... but not bosons at my humble opinion. In fact they are above the SR. It is intringuing considering the sortings and the synchronizations of informations in a pure general point of vue.

I beleive strongly that the volumes of BH increases more we go towards our main central BH of our Universal sphere. It is relevant considering the other productions of matters from these central spheres. The steps appear when the volumes and the rotations are inserted. The pure heat and thermodynamics can showing the road towards these central spheres. The system is a finite serie.

Regards

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Pentcho Valev wrote on Aug. 23, 2012 @ 19:55 GMT
Douglas,

The equivalence principle is quite useful in that it converts the gravitational redshift into Doppler shift and vice versa, as shown in this quotation:

http://galileo.phys.virginia.edu/classes/252/gener
al_relativity.html

Michael Fowler, University of Virginia: "What happens if we shine the pulse of light vertically down inside a freely falling elevator, from a laser in the center of the ceiling to a point in the center of the floor? Let us suppose the flash of light leaves the ceiling at the instant the elevator is released into free fall. If the elevator has height h, it takes time h/c to reach the floor. This means the floor is moving downwards at speed gh/c when the light hits. Question: Will an observer on the floor of the elevator see the light as Doppler shifted? The answer has to be no, because inside the elevator, by the Equivalence Principle, conditions are identical to those in an inertial frame with no fields present. There is nothing to change the frequency of the light. This implies, however, that to an outside observer, stationary in the earth's gravitational field, the frequency of the light will change. This is because he will agree with the elevator observer on what was the initial frequency f of the light as it left the laser in the ceiling (the elevator was at rest relative to the earth at that moment) so if the elevator operator maintains the light had the same frequency f as it hit the elevator floor, which is moving at gh/c relative to the earth at that instant, the earth observer will say the light has frequency f(1 + v/c) = f(1+gh/c^2), using the Doppler formula for very low speeds."

You don't think this analysis based on the equivalence principle should be abandoned do you?

Pentcho Valev pvalev@yahoo.com

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Douglas Singleton replied on Aug. 24, 2012 @ 18:14 GMT
Dear Pentcho,

Prof. Fowler was at UVA during my time there (and I think he still is). Great professor and researcher.

I have no problem with the example of the EP that you give. It is completely correct. But also it treats the photon classically. The suggested violation of the EP that I give in my essay occurs when one treats fields (inlcuding the E&M) field quantum mechanically. If one treats the E&M field classically then one would not have Hawking or Unruh radiation and my thought experiment breaks down. It is only when one treats the E&M field as a quantum field that the possible viiolation of the EP arises.

By the way there is a suggestion that the EP *is* violated even classically. In the article

"Nonequivalence of a uniformly accelerating reference frame and a frame at rest in a uniform gravitational field", Edward A. Desloge

Am. J. Phys. 57, 1121 (1989)

where Desloge writes down what he claims is a uniform gravitational field in 1+1 dimensions and then shows that the geodesics in this metric are not the same as in the 1+1 Rindler metric -- the metric seen by an observer accelerating through Minkowski (flat) space-time.

Best regards,

Doug

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Pentcho Valev replied on Sep. 1, 2012 @ 04:17 GMT
Doug,

The most important implication of the equivalence principle is that, in a gravitational field, the speed of light varies like the speed of any projectile. If, in Fowler's example, "the earth observer will say the light has frequency f(1+v/c)", then the same observer will say the light has speed c'=c+v. Do you agree?

Pentcho Valev pvalev@yahoo.com

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Pentcho Valev replied on Sep. 1, 2012 @ 04:33 GMT
Variable speed of light in a gravitational field - explicit derivation:

http://www.youtube.com/watch?v=ixhczNygcWo

"Relativity 3 - gravity and light"

Pentcho Valev pvalev@yahoo.com

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Author Frank Martin DiMeglio wrote on Aug. 25, 2012 @ 20:14 GMT
Hi Douglas. Quantum gravity (and the union of gravity and electromagnetism as well) definitely require observer and observed, instantaneity, and a fundamental balancing and equivalency of inertia and gravity. Balance and completeness and the combining, balancing, and inclusion of opposites is essential.

Ultimately, in a truly unified and FUNDAMENTAL understanding of physics, space must be shown as invisible, not visible, and visible in a balanced fashion in keeping with the above paragraph. Temperature is basically averaged [FUNDAMENTALLY] given such a unification.

What are your thoughts on this please? Thanks.

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Douglas Singleton replied on Aug. 26, 2012 @ 19:08 GMT
Hi Frank,

Thanks for your comments on my essay. I'm not sure I completely follow the question but let me give it a try. You seem to be saying that spatial dimensions should become "invisible" in a unified theory. Generally in things like string theory the trend goes the other way -- as one probes higher energy scales the extra dimensions which had been hidden, compactified or invisible "open" up and become visible. Thus in theories with extra dimensions like string theory more spatial dimensions open up/become visible as one goes toward the unification scale.

However, there is recent work which postulates that dimensions compactify or curl up at larger energy scales. This idea can be found in

"Detecting Vanishing Dimensions Via Primordial Gravitational Wave Astronomy",

Jonas R. Mureika, Dejan Stojkovic, Phys.Rev.Lett. 106 (2011) 101101

e-Print: arXiv:1102.3434 [gr-qc]

and the references therein. In this scheme (which is based on the causal dynamical triangulations of GR) the spatial dimensions reduce at larger energy scales.

Something along these lines might be what you had in mind?

Best regards,

Doug

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Azzam AlMosallami wrote on Aug. 25, 2012 @ 23:37 GMT
Dear Douglas Alexander Singleton,

I hope to discuss with my idea which is related to my MSRT http://fqxi.org/community/forum/topic/1272 and is related to your paper.

According to my theory, since time dilation and Lorentz factor is depending on the difference of the vacuum energy. Thus I found, in the case of the train moving with constant speed v, then for the stationary earth observer the vacuum energy of this train must be higher than the vacuum energy of the earth surface. Thus the temperature inside the boundaries of the moving train will be increased. And if the velocity increased also, the temperature will increase also. This increase in the temperature is because of the increase of the vacuum energy which is related to the velocity of the train. But according to my MSRT, there is no Unruh radiation, where I proof that. What is your opinion for my idea? I hope to hear from you.

Azzam

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Douglas Singleton replied on Aug. 26, 2012 @ 20:11 GMT
Hi Azzam,

In the case you are considering (a train moving with constant velocity) you are correct -- there is not Unruh radiation. To observe Unruh radiation one must go to an accelerated frame. Also although there is no definite, undisputed evidence for the Hawking or Unruh radiation there have been recent claims that analog Hawking radiation has been detected in a system where ultra...

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Azzam AlMosallami wrote on Aug. 26, 2012 @ 22:51 GMT
Dear Douglas Alexander Singleton

Thank you very much for your previous comment.

In my theory (the equivalence principle) difference temperature is one term that affected on the difference of the vacuum energy, and thus affecting on the Lorentz factor. The other terms are the effective density and pressure. Most of the quantum tunneling experiments and entanglement are performed in a...

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Jeff Baugher wrote on Aug. 30, 2012 @ 02:40 GMT
Dr. Singleton,

I noticed your statement in the abstract :"To date there has been no definitive, experimental evidence for a problem with general relativity as the proper theory of gravity."

Although the following is not definitive, what is your opinion of the following statement?

"An alternative explanation of the accelerating expansion of the Universe is that general relativity or the standard cosmological model is incorrect. We are driven to consider this prospect by potentially deep problems with the other options." REPORT OF THE

DARK ENERGY TASK FORCE


Regards,

Jeff Baugher

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Douglas Singleton replied on Aug. 30, 2012 @ 04:22 GMT
Dear Mr. Baugher,

I agree with this statement. As I read the statement it says that we need to consider that GR and/or the standard cosmological model may be wrong. The current cosmological picture is that GR and the current cosmological picture are correct and that one only needs to add some field/fluid/stuff, which is generically called dark energy, to account for accelerated expansion rate of the Universe. But as well it could be possible that the accelerated expansion is due to some modification of GR. In some sense my essay leans in this direction although I focus on modification at short distances rather than cosmological distances.

And even if there is no *definitive* experimental evidence, currently, that GR is wrong there are plenty of hints that GR needs to be modified: (i) the inability to quantize gravity; (ii) dark matter (this might be due to some modification of GR at galactic distance a la modified Newtonian dynamics); (iii) dark energy (again this might be evidence for modifcation of GR rather than the existence of some substance with the odd properties of dark energy); (iv) the singularities at the center of a BH. Thus there is strong circumstantial evidence the GR will need to be modified at short and/or long distance scale.

Best,

Doug

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Jack replied on Aug. 31, 2012 @ 00:41 GMT
Doug,

The fact that Hawking radiation and Unruh radiation are different does not show any failure of the equivalence principle (EP). The EP is local, while Hawking radiation is generated in an extended region. If you are in a small elevator, and see radiation coming at you, you have no way of knowing whether it is Hawking radiation or radiation due to some other source. The EP only applies to what goes on within the elevator (local), not to what external boundary conditions the elevator is likely to have.

It is no different from the standard example of an observer standing on a planet (near 0 Kelvin). This observer observes no Unruh or Hawking radiation, but he feels a force on his feet.

Regards,

Jack

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Douglas Singleton replied on Aug. 31, 2012 @ 03:49 GMT
Hi Jack,

Your questions touch on some subtle issues that the essay format did not really lend itself to. However, the measurement of the Hawking and Unruh temperature that I have in mind is *local*. The "thermometer" to be used is an Unruh-DeWitt detector - this is a two-state quantum system which is placed into some curved space-time or moved along some space-time trajectory in flat...

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Jack Mallah wrote on Sep. 1, 2012 @ 19:44 GMT
Doug,

The measurement is local, but your interpretation of that measurement depends on your assumed knowledge of the situation over extended distances. You see radiation, so you assume that it's Hawking radiation; but you would see the same radiation if in place of a black hole there were a low mass object of the appropriate size and temperature there. The two situations are locally equivalent at the detector, and such a possibility is all that the EP requires.

If you put a radiation shield around the detector, that could block much of the Hawking radiation, so clearly what you are measuring is not independent of the situation external to the detector volume.

Physics within the detector volume still 'looks like' physics in flat space but with appropriate boundary conditions (with the usual caveats about tidal forces and so on if your detector has finite size). By contrast, suppose that an object within your detector had a gravitational mass that was that was not equal to its inertial mass. There is no set of boundary conditions which can be imposed external to your detector volume that could 'spoof' or cause you to falsely reproduce the set of measurements that could confirm this. It would therefore be a true violation of the local EP.

Sincerely,

Jack

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Douglas Singleton replied on Sep. 2, 2012 @ 07:02 GMT
Hi Jack,

If I understand correctly you are saying "If an observer feels an acceleration to the bottom of the Einstein elevator and measures a temperature there is no way to tell if the elevator is near a black hole and the observer is detecting Hawking radiation *or* if the observer is in the Einstein elevator near a gravitating body that is not a black hole (e.g. the Earth) and is...

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Jack Mallah replied on Sep. 12, 2012 @ 17:14 GMT
Doug,

Thanks for the detailed reply. I do find it interesting that the time correlation function is different for a thermal bath as opposed to the Unruh effect. What do you think is the physical reason for the difference?

However, that does not affect the point about equivalence. Of course a thermal bath is in no way equivalent to Hawking radiation, if only because Hawking radiation...

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Douglas Singleton replied on Sep. 13, 2012 @ 16:38 GMT
Hi Jack,

Yes it is interesting and important to the point I’m making that not only the temperature but the Greens function and as well the related transition rate per unit time depend on the situation one is considering (i.e. an Unruh-DeWitt detector in a Hawking background vs. Rindler background vs. temperature bath etc.) One does not have to look far for the physical reason for this....

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Pentcho Valev wrote on Sep. 1, 2012 @ 20:31 GMT
Doug,

You wrote: "Very nice YouTube video. From my brief viewing of this it seems correct. Note though that the author mentions that the derivation/motivation he gives is not rigorous."

Yet he derives the fundamental equation of Newton's emission theory of light, c'=c(1+gh/c^2), in the form dc/dh=g/c:

http://www.youtube.com/watch?v=ixhczNygcWo

"Relativity 3 - gravity and light"

That is, in a gravitational field the speed of photons varies exactly like the speed of cannonballs. This prediction of the emission theory is confirmed by the Pound-Rebka experiment:

http://www.einstein-online.info/spotlights/redshi
ft_white_dwarfs

Albert Einstein Institute: "One of the three classical tests for general relativity is the gravitational redshift of light or other forms of electromagnetic radiation. However, in contrast to the other two tests - the gravitational deflection of light and the relativistic perihelion shift -, you do not need general relativity to derive the correct prediction for the gravitational redshift. A combination of Newtonian gravity, a particle theory of light, and the weak equivalence principle (gravitating mass equals inertial mass) suffices. (...) The gravitational redshift was first measured on earth in 1960-65 by Pound, Rebka, and Snider at Harvard University..."

Pentcho Valev pvalev@yahoo.com

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Member Benjamin F. Dribus wrote on Sep. 3, 2012 @ 07:35 GMT
Dear Douglas,

I really enjoyed your essay! A couple of questions come to mind.

1. I am trying to understand how to frame your ideas in the context of the general principle of covariance. In SR, covariance may be viewed as symmetry under the Poincare group, which is also viewed as determining many of the properties of particles in QFT. In GR, covariance may be viewed as a local group symmetry. Would you say, then, that quantum effects break covariance? Or would you describe it in some other way?

By the way, I prefer NOT to view covariance as a local group symmetry, but as an order-theoretic concept; I explain this briefly in my essay:

On the Foundational Assumptions of Modern Physics

2. You mention that dominance of gravitation mass over inertial mass might be an alternative explanation to the dark matter hypothesis. What about dark energy? Here the relevant scale is even larger, so one might naively expect an even greater enhancement of the "gravitational force" (which is obviously not what we observe); however, in this case we are no longer dealing with a "central force" as in the case of a black hole or galaxy, so I'm not sure what to expect. What do you think about this?

Take care,

Ben Dribus

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Douglas Singleton replied on Sep. 5, 2012 @ 18:09 GMT
Hi Ben,

Thanks for reading my essay. Also very good/interesting questions. In regard to quantum effects breaking general covariance this is indeed the case. In a nice paper by Wilczek and Robinson

"Relationship between Hawking Radiation and Gravitational Anomalies"

Phys. Rev. Lett. 95, 011303 (2005).

they show that Hawking radiation can be thought of as arising out of...

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Avtar Singh wrote on Sep. 5, 2012 @ 18:35 GMT
Dear Douglas:

I enjoyed reading your well-written essay and a creative approach to resolve the black hole singularity in GR. Have you given any consideration to use the black hole evaporation concept to solve the singularity issue?

You may be interested in my paper - - -“ From Absurd to Elegant Universe” wherein I use the mass evaporation not only to resolve the black hole singularity but also the dark energy (Cosmological Constant) problem.

I would greatly appreciate your comments on my paper.

Best of Luck and Regards

Avtar Singh

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Douglas Singleton replied on Sep. 6, 2012 @ 12:48 GMT
Avtar,

Thanks for your comments and for looking at my essay. I will try to have a look at your essay. It may take a while since next week I'm traveling to a conference and must still prepare my talk.

I have not looked specifically at using Hawking radiation as a means for resolving the issue of the singularity of a Schwazschild BH, however in two recent papers with Sujoy Modak

"Hawking Radiation as a Mechanism for Inflation",

Sujoy Kumar Modak, Douglas Singleton,

e-Print: arXiv:1205.3404 [gr-qc]

and

"Inflation with a graceful exit and entrance driven by Hawking radiation",

Sujoy Kumar Modak, Douglas Singleton,

e-Print: arXiv:1207.0230 [gr-qc]

we propose using the Hawking-like radiation of FRW space-time as a possible mechanism for inflation. This model is along the line of the work by Prigogine et al

I. Prigogine, J. Geheniau, E. Gunzig, P. Nardone, Gen. Rel. Grav. 21, 767 (1989).

who consider generic particle creation models (rather than the specific Hawking radiation particle creation) as a means of driving inflation. These models in general do resolve the cosmological singularity problem (i.e. there is not cosmological singularity in Prigogine's model). Thus it may well be that the same kind of thinig would work for BH singularities. But I would need to think about this some more.

Best,

Doug

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Hoang cao Hai wrote on Sep. 19, 2012 @ 15:26 GMT
Dear

Very interesting to see your essay.

Perhaps all of us are convinced that: the choice of yourself is right!That of course is reasonable.

So may be we should work together to let's the consider clearly defined for the basis foundations theoretical as the most challenging with intellectual of all of us.

Why we do not try to start with a real challenge is very close and are the focus of interest of the human science: it is a matter of mass and grain Higg boson of the standard model.

Knowledge and belief reasoning of you will to express an opinion on this matter:

You have think that: the Mass is the expression of the impact force to material - so no impact force, we do not feel the Higg boson - similar to the case of no weight outside the Earth's atmosphere.

Does there need to be a particle with mass for everything have volume? If so, then why the mass of everything change when moving from the Earth to the Moon? Higg boson is lighter by the Moon's gravity is weaker than of Earth?

The LHC particle accelerator used to "Smashed" until "Ejected" Higg boson, but why only when the "Smashed" can see it,and when off then not see it ?

Can be "locked" Higg particles? so when "released" if we do not force to it by any the Force, how to know that it is "out" or not?

You are should be boldly to give a definition of weight that you think is right for us to enjoy, or oppose my opinion.

Because in the process of research, the value of "failure" or "success" is the similar with science. The purpose of a correct theory be must is without any a wrong point ?

Glad to see from you comments soon,because still have too many of the same problems.

Regards !

Hải.Caohoàng of THE INCORRECT ASSUMPTIONS AND A CORRECT THEORY

August 23, 2012 - 11:51 GMT on this essay contest.

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Douglas Singleton replied on Sep. 19, 2012 @ 19:53 GMT
Hi Hải.Caohoàng,

Yes the recent discovery of the Higgs-like particle could be relevant to the discussion of the local equivalence of inertia and gravity since the Higgs mechanism gives particles their inertial mass. On the other hand one might argue that to understand gravitational mass one would need to understand gravity at its natural scale i.e. the Planck scale. If one buys this hand waving argument (i.e. inertial mass is set at the Higgs scale ~ 125 GeV and the gravitational mass is connected with the Planck scale) then one has a puzzle of how two such different scales can lead to masses (inertial vs. gravitational) which are so similar. This is then just another form of the heirarchy problem.

Thanks for your comments and reading my essay.

Best,

Doug

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Member Gheorghe-Sorin Sorin Paraoanu wrote on Sep. 30, 2012 @ 11:43 GMT
Hi Doug,

I find the point that you raise in your essay extremely interesting.

I even went to read your PRL from 2011 to clarify for myself a few technical points.

Though I think the discussion above with Jack Mallah needs to be continued. I would like to reformulate a bit here what is at stake. Suppose that we are in an Einstein's elevator: the equivalence principle tells us that we cannot know if we are in an accelerated system or in a gravitational field - the physics that we "experience" is the same. Yet one can simply open the door of the elevator and check what is the actual situation: are we standing on some planet or are we in some accelerating spaceship, etc. Is the measurement of the Unruh versus Hawking temperature and correlations that you describe in any way different from the situation described above? Somewhat I would think that what happens is that you find a way to extract global information from a local measurement of the radiation. This is still interesting of course, but does it mean at all that the equivalence principle is broken? In some sense, there could be something more fundamental here that I am not catching, for example one would think that the Hawking and Unruh effects are a inescapable consequence of QFT, therefore the situation is different from just opening the door of the elevator and acquiring information about the surroundings. In this sense one can say that global information will inevitably be present in any local frame. Though I find this argument weak, because also with the Hawking/unruh radiation I can choose to shield them by "metalizing" my elevator (making it a Faraday cage).

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Douglas Singleton replied on Oct. 1, 2012 @ 11:45 GMT
Hi Gheorghe,

Thanks for reading my essay and as well the journal paper which was the basis of the first part of the essay.

In regard to your question " Is the measurement of the Unruh versus Hawking temperature and correlations that you describe in any way different from the situation described above?"

My contention is that it is different. The Unruh-DeWitt allows one to make local measurements of the temperature and transition rate. The physical picture I like to keep in mind for the UD detector is an electron in a magnetic field. This has two states and one can measure the rate at which the upper state gets excited in a particular space-time (e.g. Schwarzschild) or for a particular space-time path (Rindler observer). The conceptual reason for why the local measurement with an UD detector can obtain global information about the space-time or space-time path is that its transition rate depends on the field modes which depend on the global structure of the space-time or space-time path. Also QM in general has non-local features (such as entanglement) and the EP is local.

The question of shielding the radiation is interesting and I have not fully understood this. Certainly, under normal circumstances, one can shield the UD detector from Hawking radiation (By "under normal conditions" I mean at all points in the BH evaporation process except at the very end when it will emit gamma rays of increasingly high energy and short wavelength. At some point the wavelengths of the gamma ray photons emitted by the small BH will be much smaller than the interatomic spacing and it will not be possible to shield them).

On the other hand I am not sure if it is at all possible to shield an UD detector from Unruh radiation.

Best,

Doug

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Hoang cao Hai wrote on Oct. 3, 2012 @ 03:53 GMT
DEAR Douglas Singleton and TO ALL THE AUTHORS AND READERS WAS INTEREST.

Today, I am finished reading all of the essays in this topic.

First of all, thanks again to FQXi and the donors has facilitated for us to have the opportunity get contribute to science.

Next, would like to express to other author by the thanks for the comments that you have contributed to give me, and sincere apologies to those of you that I do not have specific feedback for your essay.The reason that is because:

The placing for issues and measures to solve for the problems of your offer is completely different from mine, so I can not comment when we do not have the same views on one matter, the purpose is to avoid the discussion became conflict of ideologies,it is will not be able to solve the problem which we are interested.

The end, I hope that : we ( who want the human to put their faith in science) will have the same fear: to someday,every people told each other that:

WAIITING FOR SCIENCE HELPS IS VERY LONGTIME,

LET PRAY TO GOD OR A CERTAIN DEITY SOMETIMES EVEN FASTER !

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Sergey G Fedosin wrote on Oct. 4, 2012 @ 06:51 GMT
If you do not understand why your rating dropped down. As I found ratings in the contest are calculated in the next way. Suppose your rating is
and
was the quantity of people which gave you ratings. Then you have
of points. After it anyone give you
of points so you have
of points and
is the common quantity of the people which gave you ratings. At the same time you will have
of points. From here, if you want to be R2 > R1 there must be:
or
or
In other words if you want to increase rating of anyone you must give him more points
then the participant`s rating
was at the moment you rated him. From here it is seen that in the contest are special rules for ratings. And from here there are misunderstanding of some participants what is happened with their ratings. Moreover since community ratings are hided some participants do not sure how increase ratings of others and gives them maximum 10 points. But in the case the scale from 1 to 10 of points do not work, and some essays are overestimated and some essays are drop down. In my opinion it is a bad problem with this Contest rating process. I hope the FQXI community will change the rating process.

Sergey Fedosin

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