An argument against Background Independence

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Main Question or Discussion Point

We know that in QM and QFT, spacetime is given, fixed, nondynamical stage.

We know that gravitons framed as a QFT can give rise to GR as an effective field theory.

how do we know that spacetime geometry is dynamical independent of its effects on fermions and bosons? perhaps gravitational lensing is not the result of curvative but gravity-particles.

What's the difference between stating that gravity is a manifestation of local spacetime geometry, and

gravity is a particle field of gravitons, moving across an eternal, timeless, shapeless, non-dynamic, inert minkowski type background, that interacts with everything, including matter and energy, in a curved-path manner? time dilation is the result of gravity fields interacting with fermions/bosons, not curved spacetime.

Therefore, Smolin and LQG's quest for BI is wrong and misguided. Gravity is a field, that interacts with other fields, that exist as a part of spacetime, not spacetime itself, and is not quantized. Lorentz invariance holds below the subplankian regime, it is only the discrete nature of matter-energy that prevents it from being explored, but there is an infinte continuous space below the subplankian regime.

Gravity effects the motion of particles, but not time itself, which is absolute and flows everywhere.

QM is more fundamental than GR, QM's ontology is more fundamental than GR"s ontology, and GR's properties are an emergent property, an illusion of a field that interacts with all other fields and fermions, not spacetime itself.

The LQG project is doomed to failure.
 
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  • #2
selfAdjoint
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We know that in QM and QFT, spacetime is given, fixed, nondynamical stage.

We know that gravitons framed as a QFT can give rise to GR as an effective field theory.

how do we know that spacetime geometry is dynamical independent of its effects on fermions and bosons? perhaps gravitational lensing is not the result of curvative but gravity-particles.

What's the difference between stating that gravity is a manifestation of local spacetime geometry, and

gravity is a particle field of gravitons, moving across an eternal, timeless, shapeless, non-dynamic, inert minkowski type background, that interacts with everything, including matter and energy, in a curved-path manner? time dilation is the result of gravity fields interacting with fermions/bosons, not curved spacetime.
At this point you shift from asking a legitimate question to asserting your personal theory. You even break rules of English grammar to do it. Recall that we don't allow personal theories here. Now the points you raise are sometimes offered by string theorists in refutation of non string theories of QG. But that has proved a weak reed, even string theorists can see the advantages if dynamic spacetime and diffeomorphism invariance. More recent criticisms go to technicalities about Hilbert space construction and the role of anomalies. As far as I am concerned, the rest of your post is just ignorance in action.
Therefore, Smolin and LQG's quest for BI is wrong and misguided. Gravity is a field, that interacts with other fields, that exist as a part of spacetime, not spacetime itself, and is not quantized. Lorentz invariance holds below the subplankian regime, it is only the discrete nature of matter-energy that prevents it from being explored, but there is an infinte continuous space below the subplankian regime.

Gravity effects the motion of particles, but not time itself, which is absolute and flows everywhere.

QM is more fundamental than GR, QM's ontology is more fundamental than GR"s ontology, and GR's properties are an emergent property, an illusion of a field that interacts with all other fields and fermions, not spacetime itself.

The LQG project is doomed to failure.
 
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Posting a rash comment in a field that you are not familiar with is not a good idea. At least look up the definition of 'Minkowski spacetime' in Wikipedia first.
 
  • #4
josh1
The LQG project is doomed to failure.
Oh well, I guess LQG is correct after all.:tongue2:
 
  • #5
vanesch
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We know that in QM and QFT, spacetime is given, fixed, nondynamical stage.

We know that gravitons framed as a QFT can give rise to GR as an effective field theory.
I'm not even sure that that is correct. What gravitons do in QFT is to allow for the linearized dynamical field equations of GR to be quantized (and unfortunately this turns into a non-renormalizable QFT). But I'm not sure that even if that would work out somehow that you would get the non-linear stuff with it (in other words, that gravitons could describe strong curvature).

how do we know that spacetime geometry is dynamical independent of its effects on fermions and bosons? perhaps gravitational lensing is not the result of curvative but gravity-particles.
All options are open to speculation of course.
 
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I strongly disagree with the bananan's style of presentation, in which he presents his own beliefs as definite facts.
Still, I agree that some of his ideas could be correct. Moreover, some of these seem quite viable to me.
 
  • #7
Gravity is a field, that interacts with other fields, that exist as a part of spacetime, not spacetime itself, and is not quantized. Lorentz invariance holds below the subplankian regime, it is only the discrete nature of matter-energy that prevents it from being explored, but there is an infinte continuous space below the subplankian regime.

Gravity effects the motion of particles, but not time itself, which is absolute and flows everywhere.
Bananan, is this interpretation of general relativity connected to the Whitehead theory of gravitation?
 
  • #9
CarlB
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I don't believe in "background independence" either. But I don't think that the foundations of physics should be based on symmetry principles either.
 
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I strongly disagree with the bananan's style of presentation, in which he presents his own beliefs as definite facts.
Still, I agree that some of his ideas could be correct. Moreover, some of these seem quite viable to me.
I'm playing devil's advocate here I want to explore ramifications.
 
  • #12
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Recall that we don't allow personal theories here.
I do not understand this. Does it mean that we are allowed to discuss a theory of Witten, but Witten himself is not allowed to discuss his own theory? :eek:
 
  • #13
selfAdjoint
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I do not understand this. Does it mean that we are allowed to discuss a theory of Witten, but Witten himself is not allowed to discuss his own theory? :eek:

Sigh. By "personal" I mean (and this is the sense of our guidelines, which you did sign off one),
1. Not published in a peer reviewed journal and/or
2. Not by a recognized professional who normally publishes in peer reviewed journals but is here exposing a work-in-progress.

"Recognized professional" for me means qualified to post on the arxiv; ZapperZ perhaps would have a narrower definition.

In any case, somebody who just shows up here with a theory he brewed at home does NOT qualify. If the theory is minimally coherent you might try it on our Independent Research (IR) formum up under the General Physics subforum. Be warned this is our substitute for peer-review, and like all good peer-review, (a) it's tough and (b) it's apt to take a long time.

If your ideas don't meet even this standard, they will most likely be deleted, or maybe moved to General Discussion. If you persist in pushing them here in spite of our clearly stated guidelines you will be banned.
 
  • #14
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OK vanesch, it is all clear and reasonable. I was only confused with the word "personal". :-)
 

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