Unanswered Questions
1,161 questions with no upvoted or accepted answers
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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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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 ...
- 207k
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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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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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Situation after Saini & Stojkovic's paper on unitarity in gravitational collapse and non-formation of black holes?
In their paper, Anshul Saini and Dejan Stojkovic [1] claimed that by calculations it is possible to demonstrate that in a gravitational collapse of a disk, an event horizon is never made for a far ...
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Hayden-Preskill informational mirrors and decryption
I do have a question about an assumption made in the very interesting Hayden-Preskill paper of black holes as informational mirrors. Alice throws her top secret quantum diary which is $k$ qubits long ...
CommunityBot
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Could harm due to spaghettification be mitigated by entering a black hole at almost the speed of light?
Say that we wanted to send a probe into a black hole, perhaps hoping to see if it's actually a wormhole that might transport the probe elsewhere.
Upon approaching a black hole, the probe would undergo ...
CommunityBot
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6
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Black Holes and QED
So, in quantum electrodynamics (at least to my rudimentary knowledge), the electromagnetic force is mediated by photons.
On the other hand, in classical general relativity, the Kerr Black Hole ...
- 234k
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Is the Schwarzschild singularity a limit of the Kerr singularity?
In a Schwarzschild black hole, the singularity is spacelike. In a Kerr black hole, it is timelike.
Is there any continuous transformation between those solutions? Can the Schwarzschild solution be ...
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Entanglement island distance = quantum width of BH horizon?
In this recent paper, Bousso and Penington (B&P) finds that the protrusion distance outside the horizon of an entanglement island from a 4D Schwarzschild black hole is $\sqrt {l_P r_{hor}}$, where ...
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What is the volume inside the inner event horizon of a Kerr black hole?
(Dokuchaev 2011) found periodic orbits of particles and photons inside a Kerr-Newman black hole with a maximally extended global geometry. They orbit inside the inner horizon $r<r_-$ where the $r$ ...
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Kinnersley’s “photon rocket” and gravitational radiation
In this paper by Carlip, a comparison is made between electromagnetic and gravitational aberration.
For the latter case, he takes as a study subject the Kinnersley’s “photon rocket”, an exact ...
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On the embedding of the Schwarzschild metric in six dimensions
At every point of the 4-D space-time, it's metric, being a symmetric 2-tensor, has $\frac{D(D+1)}{2}=10$ independent components. From this we can subtract four degrees of freedom according to the four ...
- 207k
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Can one distinguish between near and far field for gravitational radiation?
For electromagnetic radiation one usually distinguishes between near and far field. The wave equation for the far field are based on Maxwell equations for the vacuum and predict that the radiated ...
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