Preferred Observers in Quantum Gravity by Tanmay Vachaspati

Tanmay,

If a black star is not a transitional phase between a collapsing star and a singularity, what is it, and how do you know the difference when anticipating the study?

Jim

Tanmay,

In your abstract, you state: 'it is argued that the classical General Relativity notion that "all observers are equal" must be qualified in a quantum theory'

The assumption that "all observers are equal" has been demonstrated to be untrue, even in the classical realm.

The amount of a priori knowledge that an observer has, regarding what is being observed, has a direct, quantitative impact on the number of bits of information that the observer can successfully extract from an observation.

Since all observers do not have identical a priori information, they cannot be "equal", in the sense of being capable of extracting equal amounts of information, from an observation. Almost all modern communications systems exploit this phenomenon.

Failing to take this fact about observers into account, is the primary reason for all the supposed "weirdness" having to do with observers of quantum phenomenon.

Tanmay,

Interesting essay. Just to be sure I understand, I have a few questions.

1. You are saying that it is trapped horizons, not singularities, that imply preferred observers, correct?

2. I am trying to fit this into general ideas about covariance. In SR, covariance is a symmetry, and in GR, it is a local symmetry. Is the local symmetry still valid in your picture, since you are distinguishing only between asymptotic and infalling observers (who are necessarily separated)? Or is there a more radical "quantum covariance-breaking" going on?

The reason I ask is because I am interested in alternative interpretations of covariance, particularly those involving order theory. I discuss this in my essay

On the Foundational Assumptions of Modern Physics

In particular, covariance in the elementary setting of Minkowski space determines many of the properties of particles in QFT via representation theory, so it seems that any change in the covariance principle would be interesting in particle physics.

Take care,

Ben dribus

Robert,

Thanks for your comment. The observation capacity could indeed be different for different experiments and recording setups (which includes histories and amount of remaining disk space etc.). In General Relativity it is assumed that one can have the same setups located everywhere. Perhaps what you are saying is that one cannot put the same observing or recording capacity at different points in spacetime. This seems like an interesting idea to pursue!

Best,

Tanmay

Ben,

I saw your submission and will read it more carefully. In classical GR trapped surfaces lead to singularities according to the singularity theorems. So if one has an event horizon, there will also be an accompanying singularity. The real issue comes up when we include quantum evaporation because the outside observer only sees evaporation, while the inside observer sees a singularity.

By covariance I assume you mean invariance under coordinate transformations (diffeomorphisms). This will still hold.

Best,

Tanmay

Tanmay,

You point out that the asymptotic observer can see the infalling observer frozen just before entering the event horizon for a very long time while everything gradually evaporates. Does this allow the asymptotic observer to collect enough data to (in principle) reconstruct the time evolution from the point of view of the infalling observer?

Hello Saibal,

It isn't that there is missing data that prevents the asymptotic observer from finding out what happens to the infalling observer. The parallels between after-life and the black hole situation are extremely tight and help to understand that there are some questions that are not meaningful because they cannot be tested.

Best,

Tanmay

Hello to both of you,

It is relevant.

ps the singularities are all from the singularity.....

Regards

Tanmay,

Actually, I am saying something much more subtle. For example, do you believe that the words "Relativity", "relativity", "RELATIVITY", "rElEtIvItY" are the same word? In other words, am I using the standard 26 letter English alphabet, or am I using a much larger alphabet, in which "R" is not a capital "r", but a completely different letter? If you do not know the answer, a priori, than you may completely misinterpret any observed message written using an "alphabet" that bears some resemblance to another that you are likely to confuse it with.

Now imagine that the letters of the "alphabet" are encoded as short bursts of several simultaneous frequency tones, too closely spaced to be resolved, and that these "symbols" are distorted prior to being received, such that the same symbol never actually is observed to appear the same.

Techniques now exist that enable an entity, with a priori knowledge of the "allowable" symbol structures, the "alphabet", to almost perfectly reconstruct such a "message", in other words, to recover its information content. An observer without such a priori knowledge cannot. Indeed, such an observer may not even recognize the signal as a message at all - it may appear to be nothing but a burst of noise.

Unbeknownst to most physicists, observational limitations, such as the Uncertainty Principle, do not apply to such knowledgable observers. If one delves into the origins of the Uncertainty Principle, deep within Fourier Analysis, one finds that the derivation of the Uncertainty Principle implicitly assumes that observers have no such a priori information to exploit. The principle is not wrong, it is simply irrelevant, for such knowledgeable observers.

While such considerations may be of little impact for astronomical observations, in which an observer has little a priori knowledge of exactly how the signals being observed were created, the same cannot be said of laboratory experiments, in which the experimenter does know a great deal about the experimental set-up. Issues like "entanglement" will almost certainly be completely misinterpreted, by any observers that fail to even appreciate the existence of such observational phenomenon, much less correctly factor it into their interpretations of experimental results.

Dear Tanmay,

What is your opinion about Covariant theory of gravitation, in which black holes are not allowed? If to use the idea of strong gravitation at the level of particles there must be the black holes too. But nucleons are not black holes since their mass do not changed.

Sergey Fedosin

Dear Tammay

In my essay http://fqxi.org/community/forum/topic/1413

i used mass of Hawking black holes as a contra to nuclons.

This is just a hypothesis.

What is your opinion?

Tammay

As you see mass of nuclon 10^40 lesser than black hole mass

it is close to

Dirac large numbers hypothesis

http://en.wikipedia.org/wiki/Dirac_large_numbers_hypothesis

Dear Tanmay

I agree with you that there are preferred observers in realistic solutions of the Einstein Field Equations. It is a significant effect.

I make the same point in a different context in a paper on the nature of time here .

George Ellis

Oops: here

Hope that works

George