Will a Photon Inside a Perfectly Reflecting Box Eventually be Detected?

[Fra]

These are great reflections. I am also quite convinced that there is some kind of connection between gravity and information updates (collapses), but I do not share Penrose exact ideas.

He tries to explain the collapse objectively, by using gravity (somehow).

I personally find gravity to be far more "mysterious" than and information update, so for me, I think the more natural path of inference is to rather post-dict gravity, from mutual information updates. Gravity could somehow be some particular "DC-component" in an ambient chaotic HF information update. In this sense, perhaps the notion of a physical graviton in the ordinary sense is a doubtful, since ALL information carriers in a sense universally enters this abstraction. The universality of gravity, would then relate to the universality of information capacity. All information needs to be encoded in physical degrees of freedom, and the "inertia" of information update, might be related to "gravitational forces".

But I doubt the main objective of Penrose, to restore "OBJECTIVITY".

I'm curious to hear more about Dmitry's further ideas since I know we have drastically differing views of realism.

/Fredrik

 

[Demystifier]

Is gravitational field from the photon is contantly changing (because it is moving, bouncing back and forth) or constant (because it forms a static wavefunction in cavity)?

It depends on how photon interacts with the environment. If the environment destroys the coherence, then a static wave function is not formed in the cavity, in which case the gravitational field is changing.

 

[Demystifier]

Electric charges can be cancelled. We can pass electrons thru neutral material (sonsisting of e- and p+). As there is no interaction (or it is cancelled) then there is no decoherence

gravity is like having all matter positively charged and conducting experiments on the electrons.

But the difference is not so much between gravity and electromagnetism, but between the SOURCES for gravity and electromagnetism. If gravitational sources with negative energy existed (e.g., the Casimir effect is believed to represent such a source), then gravity could be killed too, at least in principle.

 

[dmtr]

Now I understand your motivation, thanks!
Anyway, I don't think that gravity is so special and I don't buy this Penrose suggestion at all.

Why?

It looks like gravity couples this photon with the environment. You can't shield from gravity. So if you let some time pass there would be some loss of information from the system. As a result instead of seeing 50/50 distribution of pure states sometimes you'll see some mixed states (i.e. you'll be able to detect the photon on both paths or not been able to detect the photon at all).

The only argument against it (that I could see, from a layman point of view!) is that the gravity is too weak, to create enough information loss/decoherence (to explain the wavefunction collapse/time arrow).

 

[Demystifier]

Dmtr, see my post #33.

 

[Demystifier]

The only argument against it (that I could see, from a layman point of view!) is that the gravity is too weak, to create enough information loss/decoherence (to explain the wavefunction collapse/time arrow).

Decoherence explains neither the wave function collapse (except in MWI) nor the time arrow.

 

[dmtr]

Dmtr, see my post #33.

What if we, for a minute, forget about the negative energy and possibility of canceling the gravity. Would we be able to outline the explanation of the appearance of the wavefunction collapse for macroscopic objects/time arrow via this 'gravity-induced decoherence' mechanism?

Decoherence explains neither the wave function collapse (except in MWI) nor the time arrow.

Uh. Ok. And if we assume MWI?

 

[Demystifier]

What if we, for a minute, forget about the negative energy and possibility of canceling the gravity. Would we be able to outline the explanation of the appearance of the wavefunction collapse for macroscopic objects/time arrow via this 'gravity-induced decoherence' mechanism?

Uh. Ok. And if we assume MWI?

If we assume MWI and take decoherence into account, then we don't need gravity to explain the appearance of the wave function collapse. The electromagnetic interaction is sufficient (and dominating) for most purposes.

Of course, MWI has the problem of explaining the Born rule, but that's another story, and gravity certainly does not help in it.

 

[Dmitry67]

I personally find gravity to be far more "mysterious" than and information update, so for me, I think the more natural path of inference is to rather post-dict gravity, from mutual information updates. Gravity could somehow be some particular "DC-component" in an ambient chaotic HF information update. In this sense, perhaps the notion of a physical graviton in the ordinary sense is a doubtful, since ALL information carriers in a sense universally enters this abstraction. The universality of gravity, would then relate to the universality of information capacity. All information needs to be encoded in physical degrees of freedom, and the "inertia" of information update, might be related to "gravitational forces".

I don't think that gravity is that mysterious.
And I don't agree with Pensrose because I think gravity does not give a solution to collapse, as I believe in MWI
But to some extent it is special.

 

[Dmitry67]

But the difference is not so much between gravity and electromagnetism, but between the SOURCES for gravity and electromagnetism. If gravitational sources with negative energy existed (e.g., the Casimir effect is believed to represent such a source), then gravity could be killed too, at least in principle.

But even from the MWI perspective... Dont you see it strange...

Say, I measure some QM event. Based on the outcome, I can press the button (in another branch i don't do it). The button launches a rocket into a neutron star which has ALMOST collapsed, adding more mass and creating a black hole.

So black hole exists in one branch only.

So the whole background for QM becomes different... The whole arena for the "omnium" and wavefunctions... Space is differently curved... Nothing similar happens with electromagnetism.

 

[Demystifier]

Dmitry, I see nothing strange about it.

 

[dmtr]

But even from the MWI perspective... Dont you see it strange...

Say, I measure some QM event. Based on the outcome, I can press the button (in another branch i don't do it). The button launches a rocket into a neutron star which has ALMOST collapsed, adding more mass and creating a black hole.

So black hole exists in one branch only.

So the whole background for QM becomes different... The whole arena for the "omnium" and wavefunctions... Space is differently curved... Nothing similar happens with electromagnetism.

I don't know about strange, but it is likely to be very complex. I take it some kind of "sum over geometries" approach can be used for that. With the math well above of the level of GR/QM/QFT...

 

[dmtr]

The same mechanism which is responsible for Hawking radiation (created by a COLLAPSING black hole) is also responsible for radiation from ANY time-dependent gravitational field. The horizon is responsible for the thermal spectrum of the radiation, but not for the creation of radiation itself.

So would this box radiate or not? And if it would, with what spectrum and for how long? I'm not asking for a precise answer, just your best guess.

 

[Dmitry67]

Yes.
In MWI, even "worlds" lose an ability to communicate, non-diagonal elements of the matrix are not exactly zero, just very small.

So theoretically there is some communication. It is easy to imagine it in flat spacetime. But if in one branch spacetime is flat while in another there is a black hole... wow...

 

[Demystifier]

So would this box radiate or not? And if it would, with what spectrum and for how long? I'm not asking for a precise answer, just your best guess.

It would probably radiate. Almost anything that has a temperature or any form of activity radiates, at least a little bit.