All Questions
Tagged with quantum-field-theory general-relativity
292
questions
3
votes
0
answers
56
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Are anyons non local?
Studying anyonic statistics in 2 dimensions, I naturally thought to ask the question of whether anyons are non local, since as we braid one around another, no matter the distance between the two, one ...
- 737
-1
votes
1
answer
315
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Research Proposal in Statement of purpose for integrated Phd Theoretical Physics [closed]
I wrote this following paragraph in my statement of purpose for my Integrated PhD Physics program in Theoretical physics at best research institute in India.
My research proposal in this field is to ...
- 195
6
votes
3
answers
552
views
Gravitational effect of negative energies in QFT
Within the formalism of QFT in curved space, we find negative energies to be unavoidable (theoretically). Even worse, all proposed Energy Conditions fail (in curved spacetime), not only within the ...
- 749
0
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0
answers
44
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Casimir Effects in Small Hyperspherical Universes, Small Wormholes and Small Black Holes
If there was a path in the geometry of space-time that 'looped around', it seems like any particles (real or virtual) in the loop would have to match the periodic boundary conditions of that loop.
It ...
- 1,911
14
votes
0
answers
437
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How to perform a derivative of a functional determinant?
Let us consider a functional determinant
$$\det G^{-1}(x,y;g_{\mu\nu})$$
where the operator $G^{-1}(x,y;g_{\mu\nu})$ reads
$$G^{-1}(x,y;g_{\mu\nu})=\delta^{(4)}(x-y)\sqrt{-g(y)}\left(g^{\mu\nu}(y)\...
- 3,691
2
votes
1
answer
1k
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Graviton Scalar interaction - Feynman rules
Having the interaction lagrangian for scattering between two scalars and the graviton $h$
\begin{equation}
\mathcal{L}_{\phi \phi h}=\frac{\kappa}{2}\left(-\frac{1}{2} h_{\mu}^{\mu} \phi^{2} m^{2}+\...
- 900
1
vote
1
answer
91
views
"Instabilities" in Quantum Gravity
As far as I understand, there is no notion of conservation of energy in GR: the Landau-Lifshitz Pseudotensor is not conserved in all possible coordinate systems, and thus such a notion of energy ...
- 749
5
votes
3
answers
717
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Are there fields (of any kind) inside a black hole?
It is said that nothing escapes from black holes, not even light. All particles are now thought to be excitation of different fields (electric field, electromagnetic field, photon field, etc).
Does it ...
- 137
0
votes
1
answer
269
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Spinors and Tensors: what is the form of spin transformation matrix?
The (covariant) vector transformation law is given by:
$$V^{'}_{\mu} = t^{\nu}\hspace{0.1mm}_{\mu'}V_{\nu} =\frac{\partial x^{\nu}}{\partial x'^{\mu}}V_{\nu} \tag{1}$$
where the transformation is ...
- 3,085
1
vote
1
answer
91
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What is the status of Newton's third law within the context of modern physical theories?
Newton's third law says that every action has an equal and opposite reaction. This is essentially the law of conservation of momentum. From conservation of momentum perspective, the law should be ...
- 165
1
vote
1
answer
524
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Do negative energies exist in the Standard Model?
As far as I understand, the Hamiltonian of QED and QCD are positive definite. The QED Hamiltonian in Coulomb Gauge is given by the following (credits David Tong QFT Notes):
$$
H=\int d^{3} x\left[\...
- 749
11
votes
3
answers
3k
views
Why is there a “problem of time” in Quantum Gravity?
It’s often said that the problem of time exists because time is treated as absolute in quantum mechanics but not so in General Relativity, see e.g. A list of inconveniences between quantum mechanics ...
- 2,123
0
votes
0
answers
55
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What is the relation of differential geometry to General Relativity and Quantum Field Theory? [duplicate]
We know that Yang Mills Theory forms the basis of the Standard Model of Physics, which describe the interaction of elementary particles at high energies, of course not including gravity. Yang Mills ...
2
votes
1
answer
208
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Scalar product of fields in Schwarzschild space-time
The scalar product of fields in curved space-time is defined by (Birrel, Davies)
$$\left(\phi_{1}, \phi_{2}\right)\equiv-\mathrm{i} \int_{\Sigma} \phi_{1}(x) \overset{\leftrightarrow} {\partial_\mu}\...
- 339
2
votes
0
answers
157
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Wilsonian Renormalization in Curved Spacetimes
One way of seeing the Wilsonian renormalization in flat spacetimes is to consider a quantum field theory in a lattice, where the spacings between the lattice elements depend on the energy scale under ...
- 1,056