Unanswered Questions
1,969 questions with no upvoted or accepted answers
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Improving physics simulation of black hole accretion disk?
I have recently been working on software which uses ray tracing/marching to render a black hole in the Schwarzchild metric. I've implemented most everything that I originally set out to do, and I am ...
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Covariant derivative of the vielbein determinant
The vielbein postulate says that
$$\nabla_\mu e_v^{\,a}=\partial_{\mu}e_\nu^{\,a}+\omega_{\mu\,\, b}^{\,\,a}\,e^b_\nu-\Gamma^\sigma_{\mu\nu}\,e^{\,a}_\sigma=0.$$
$\nabla$ is the coordinate covariant ...
CommunityBot
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How does definition of event horizon imply that they are null?
I am familiar with the definition of a (future) event horizon as the boundary of the closure of the causal past of the future null infinity. I am aware that event horizons are null hypersurfaces -- ...
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Is there a physical interpretation of Poincaré duality?
Is there a known interpretation of Poincaré duality in terms of a physical equivalence between (maybe topological) sectors of different (probably susy) quantum field theories?
Edit/update :
If on a ...
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Writing the EL equations in the language of differential geometry
I want to explore generalised Noether currents obtained from $q$-form symmetries in an action.
The regular way we obtain Noether currents is fairly straightforward: We have a 0-form symmetry $\phi \to ...
- 207k
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Defining the covariant derivative on bitensors
Bitensors (tensors defined on two different points) are an extension of tensors found in some applications of general relativity, where objects such as the world function, parallel transport operator, ...
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Growth of apparent horizons and null convergence condition
An apparent horion ( S. W. Hawking & G. F. R. Ellis (1975). The large scale structure of space-time.) in General Relativity is a surface where all null vectors are pointing "inwards", i....
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What is torsion physically in the Einstein-Cartan theory?
In Einsteins theory of gravity the metric gives a unique torsion free connection called the Levi-Civita connection.
In the Einstein-Cartan theory we allow any connection compatible with the metric ...
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How can blackholes be fast information scramblers?
I noticed that there was already a post discussing the fast scrambling property of black holes. But it seems no satisfactory answer was given.
As mentioned by L. Susskind et. al, the fast scrambling ...
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Are there any SUSY black holes in D > 5?
Quoting from arXiv:0801.3471
Asymptotically flat BPS black hole solutions are known only for $d = 4,\,5$.
and I've seen this claim very timidly suggested in a couple of other places, but I couldn'...
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Rigorous treatment of Penrose diagrams
I'm looking for a rigorous exposition of Penrose diagrams (also called conformal diagrams in general relativity. By "rigorous" ("careful" is perhaps a more attractive word) I mean that it should ...
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Could the recently discovered "Dancing Black Holes" be the experimental signature of Hawking Radiation?
Science just reported two gravitationally bound massive black holes that are slowly receding from each other. Under normal circumstances two such bound black holes would be approaching each other as ...
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What does black hole formation and evaporation actually look like as viewed from far away?
Many people on Physics SE (myself included) have been confused about what black hole formation and evaporation look like when viewed from far away. For example:
Does any particle ever reach any ...
CommunityBot
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Where in fundamental physics are Lie groups actually important (and not just Lie algebras)?
I was wondering where in fundamental physics the global structure of a Lie group actually makes a difference.
Most of the time physicists are sloppy and don't distinguish groups and algebras ...
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What is Hawking Hartle vacuum state and why does the following Euclidean path integral gives the wave functional of it?
I am studying the wave function of black hole via the paper by Sergey Solodukhkin, Entanglement entropy of black holes,arXiv:hep-th: 1104.3712. In the paper, equation (53) is as follows:
$$\Psi[\psi_{-...
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