All Questions
28
questions
0
votes
2
answers
645
views
Can we regard metric as the Higgs field of gravity?
The longer version of the question is: should we regard special relativity just as a spontaneous symmetry breaking phase of general relativity, driven by the non-zero vacuum expectation value (VEV) of ...
- 4,452
7
votes
2
answers
1k
views
How can the graviton be both massless and self-interacting?
Gravity is non-linear, so if it is mediated by gravitons, gravitons must interact with each other. On the other hand, the effects of gravity moves with the speed of light, so if it is mediated by ...
- 525
0
votes
1
answer
56
views
Non-minimally coupled inflation
In Wikipedia you can read under the Keyword Inflaton , the Formula:
What do the individual formula symbols mean in the following formula:
$$S=\int d^{4}x \sqrt{-g} \left[\frac{1}{2}m^2_{P}R-\frac{1}{2}...
- 11
3
votes
0
answers
118
views
Why is the Weyl tensor square gravity non-unitary?
I want to understand constraints of unitarity in quantum field theory. There is quite folklore statement:
gravity with a Weyl tensor square term is non-unitary
How to understand this? (I think that ...
- 5,707
13
votes
1
answer
326
views
Does the Gibbons-Hawking boundary action have an anomaly inflow interpretation?
The Einstein-Hilbert action on a manifold $M$ with boundary is
$$\frac{-1}{16\pi G}\int_M d^n x \sqrt{-g} R +\frac{1}{8\pi G} \int_{\partial M} d^{n-1}x \sqrt{|h|} K$$
where $K$ is the extrinsic ...
- 1,982
0
votes
0
answers
205
views
Are gravitons Goldstone bosons?
This question is inspired by Are Photons Goldstone Bosons?. And recently in Generalized Global Symmetries, photon was interpreted as Goldstone boson for generalized symmetry (see also my answer for ...
- 5,707
4
votes
1
answer
134
views
ADHM construction of gravitational instantons
Is there a ADHM-like construction for gravitational instantons?
Could somebody explain why there is not such construction?
- 5,707
0
votes
1
answer
99
views
Are there mainstream quantum level physics models that use the idea of positive and negative energy balancing one another? [closed]
One interesting example of a mainstream cosmological physical model using the balancing of positive and negative energy is that of a charged black hole. Here, positive electromagnetic energy and ...
- 3,108
0
votes
1
answer
256
views
What are details of this claim of Penrose about gravity and QFT being at odds with each other?
Question
Can someone flesh out the details of the argument Roger Penrose makes in this video of a lecture he gave on twistors (starting around 1:25:15) or recommend me the appropriate literature (...
- 1,389
1
vote
1
answer
274
views
Can we visualize the standard model fermions as a 5-dimensional matrix with only the first 3 dimensions gauged?
Standard model fermions are usually represented by columns. However the column can carry different connotation depending on the matrix operator acting on it. For example, the Dirac spinor 'column' and ...
- 4,452
8
votes
0
answers
383
views
Definition of gravity path integral?
In a non-abelian gauge theory there is a "fundamental" gauge field $A_\mu^a$ with gauge index $a$ often called connection. Although $ A_\mu^a$ is not gauge invariant, gauge invariant quantities can be ...
- 322
4
votes
1
answer
354
views
S-duality of Einstein-Maxwell-Dilaton theory
Consider theory with action
$$S = \int d^D x \sqrt{-g} (R - \frac{1}{2} \partial_\mu \phi \partial^\mu \phi - \frac{1}{2k!} e^{a \phi} F^2 _{[k]} ) $$
where $\phi$ is dilaton and $F_{[k]}$ is ...
- 546
2
votes
0
answers
119
views
Isn't is far more likely that general relativity, and not QFT, is "wrong?" [duplicate]
At the risk/certainty of both sounding super ignorant and talking out of my arse, I have always wondered why there is some big mystery about why there are contradictions between the predictions ...
6
votes
1
answer
322
views
How do gravitons transmit gravity to occulted bodies?
If matter feels gravitation by way of absorbing gravitons, how is it that gravity passes through matter unfettered?
For instance during a solar eclipse, should not the Moon block at least some of ...
- 173
0
votes
1
answer
2k
views
We Don't NEED Quantum Gravity because Gravity isn't Even A Force! [duplicate]
Now, I understand the motivation for quantum gravity. I honestly want to work on a theory myself. However, gravity, according to General Relativity, is not a fundamental force of nature. To me, it's ...
- 469