Is Quantum Geometry the Zero Point Energy?

[Careful]

**
Would you confirm my interpretation of the idea of inertial observer as an unmoving observer, that is, an observer in a preferred reference frame? I am aquainted with the idea that there is no preferred reference frame, no unmoving observer, but I would like to verify that this is what is implied by inertial observer, and your assertion that the concept of inertial obseerver is rejected. **

Well what I meant is that Einstein concluded from this is that the laws of physics should be defined irrespective of some special reference frame. Obviously, inertial observers still exist but we earthly inhabitants are definately not inertial.

** Gravity is an acceleration, which has time squared in the denominator, and so is graphed as a curve, right? **

Gravity is an acceleration which cannot be undone by a coordinate transformation. As the rocket thought experiment pointed out, an accelerating (in the Newtonian sense) observer in empty space (with -g) is still in empty space. You really have to understand tensors well in order to appreciate this idea.


** I will have to look up Fock vacuum. However you seem already to think that it is not sufficient for QG and "it leads to the notion of non-equivalent vacua." **

It is known that the Fock vacuum is not suitable, finding a Hilbert space representation of the constraint algebra and getting out semiclassical states is probably the most difficult issue in LQG.

**As to Lorentz and Minkowski, I think you will agree that the Lorentz metric is fine locally but breaks down or blows up at extrema, such as horizons. **

Nope, the accelerating observers are Killing observers and actually leave the Minkowski metric invariant. It is the coordinate transformation (from inertial to accelerating observers) which is singular at the bifurcation horizon.

** But back to Unruh,
"Such local coupling however will put a restriction to the accuracy up to which long wavelengts can be distinguished depending on the sensitivity of the receptor cells."(Careful)
Will it not also imply that there is a maximum wavelength detectable by any receptor? And is this not the same as the cosmic event horizon? **

Well, there is certainly a limit to the wavelenghts which can be detected, but this can be resolved by building bigger and bigger telescopes.
But I have no problems with event horizons, you know. It is just that local physics cannot depend on them, implying that the derivation of the Unruh effect does not necessarily mean at all that a thermal spectrum is to be observed. That's all I said.

**, you will experience an increase in temperature. **

Here I think you misunderstood Unruh, these virtual particles become only ``real´´ when they interact with a detector which will merely thermalize (again, this is not for sure ).

** In fact, spacetime then becomes "solid" as a test probe approaches light speed, consistant with the idea that light speed is a constant and cannot be exceeded. **

Well, you seem to say that a large mass density could be created from the vacuum through some inertial effect. First of all the state of the radiation field will also change when energy is withdrawn by the detector (there is a nice paper about this by Wald and Unruh 1984), second it costs also energy to accelerate mass in Minkowski spacetime (think about the rocket fuel) so some form of equilibrium has to settle in eventually and looking at the value of the Unruh temperature, my guess is that the fuel will just burn out, the rockets will stop accelerating and the minkowki vacuum state will have become slightly thermal (due to the heat caused by the fuel), but the Unruh effect will not have been important at all (it is just waaaay to insignificant for all that)

Anyway, gravity is the most important force on the cosmic scale, you cannot replace it in the way you seem to be suggesting.

Cheers,

Careful

 

[rtharbaugh1]

Thanks for the discussion.

R.

 

[Careful]

Thanks for the discussion.
R.

Hi, I updated my second last post since I might have been a bit unclear about the covariance issue. Now, concerning these detectors: it is a funny story. There has been quite some argument about wether a detector would register something or not and people have been busy constructing models in which there would be no response as otherwise (it all depends upon the coupling between the detectorfield and the KG one - and the evolution of the detectorfield) Anyway, I do believe there might be some response in principle but doubt whether it would be thermal.

 

[Mike2]

Hi, I updated my second last post since I might have been a bit unclear about the covariance issue. Now, concerning these detectors: it is a funny story. There has been quite some argument about wether a detector would register something or not and people have been busy constructing models in which there would be no response as otherwise (it all depends upon the coupling between the detectorfield and the KG one - and the evolution of the detectorfield) Anyway, I do believe there might be some response in principle but doubt whether it would be thermal.

Every particle in an accelerating body requires energy from somewhere to accelerate with the rest of the body. Therefore there are at least photons striking each and every accelerating particle (or it wouldn't be getting the energy to keep up with the rest of the particles). The question is where do these photons come from, and is their orientation of a statistical nature. If they are of a statistical nature, then perhaps this is the Unruh radiation, right?

 

[Careful]

Every particle in an accelerating body requires energy from somewhere to accelerate with the rest of the body. Therefore there are at least photons striking each and every accelerating particle (or it wouldn't be getting the energy to keep up with the rest of the particles). The question is where do these photons come from, and is their orientation of a statistical nature. If they are of a statistical nature, then perhaps this is the Unruh radiation, right?

I explained you that the Unruh effect is too small to serve as an ``engine´´. Moreover, what is detected all depends on the dynamics of the detectorfield and the coupling to the KG field. I told you that there are ``silent´´ detector models as well as those which register ``something´´. I cannot tell you anything more since AFAIK, no further results on this topic are known (and I am not going to throw some wild speculation into the air).

Cheers,

Careful

 

[Mike2]

I explained you that the Unruh effect is too small to serve as an ``engine´´. Moreover, what is detected all depends on the dynamics of the detectorfield and the coupling to the KG field. I told you that there are ``silent´´ detector models as well as those which register ``something´´. I cannot tell you anything more since AFAIK, no further results on this topic are known (and I am not going to throw some wild speculation into the air).
Cheers,
Careful

I'm not even sure I was talking about "Unruh radiation". I was merely commenting that when a body is accelerated, there is energy/photons given to each particle throughout the body. Suppose we accelerate a single particle with a laser? Would the particle always get only energy in one direction? Or would the particle begin to heat up because of the statistical nature of the laser light? Each photon cannot always hit the particle dead on, right? But on average it will accelerated in one direction. So the off-center hits would accumulate and effect the particle as if thermal radiation, right? I suppose the uncertainty principle would tell us how likely we could hit the particle dead on. If we did hit it dead on every time, then there would be complete uncertainty about the momentum of the photons, right. And the particle would appear to oscillate/heat in the direction of motion. But if we could control the momentum, then we would lose certainty about direction and the particle would heat up in the direction transverse to acceleration. Is there a relation that tells us what the particle will heat to for a given acceleration? Is this independent of the accuracy of the momentum or direction of the incident photons? Is this the Unruh effect? Thanks.

 

[rtharbaugh1]

"there is another way to look at this which I have been trying out. The force of gravity may not be a real force at all.

The universe is known to be expanding. The usual interpretation of data is that local objects, planets stars and galaxies, are not expanding. But what if they were? Two expanding solid objects would push each other apart. Two expanding solid objects in free fall would seem to approach each other. Can this push explain the force of gravity, and solve the heirarchy problem? I don't know.

But if this line of thought holds, objects in free fall are not accelerating." (Richard T. Harbauagh)

I don't wish to belabor this idea, but I do want to find out where, or if, it fails. It has occurred to me that, if it were stated as a theory, it would be falsifiable, however not in an entirely satisfactory way, since it would, at this point, only be by a lack of evidence.

If gravity waves or gravitons are shown to exist, then the idea is false. The idea that gravity may be regarded as a pseudoforce, due to local expansion of the universe from every defined point, woud not require gravitons or a gravity field (in the sense of a quantum field or EM field).

It would have the advantage of removing the need for a big bang singularity, it would lead to a way to reconcile the heirarchy problem, and it would be, AFAIK, consistant with both GR and QM, so would lead to a geometry that would contain both theories.

I am not asserting this idea as a fact, but only as fully falsifiable. I do have some ideas about attainable (even cheap) apparatus for further testing, but would like to fly the idea for a while in the hope that someone can shoot it down.

Thanks,

Richard