Wednesday, May 1, 2019

A counter-example to Birkhoff's theorem?

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Suppose that we have a symmetric shell of matter which is kept static by support props of some kind. Both the mass, and the pressure in the ...
Monday, April 29, 2019

Heating up the electromagnetic field of the vacuum - the fate of a wave close to an event horizon

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Let us model the electromagnetic field of the vacuum with a drum skin. We can produce an ordinary circular wave with our finger by pressing ...
Saturday, April 27, 2019

The merger of two black holes

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If we cannot get any signal from behind the event horizon, how can two equal-mass nonrotating black holes merge into one spherical black hol...
Friday, April 26, 2019

The Penrose diagram for a collapsing star

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Is the metric smooth at the point where the surface of the star descends below the event horizon? Assume that we have two rays of light ...
Wednesday, April 24, 2019

Are the black hole singularity models of Penrose and Hawking correct?

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In the 1960s papers and in the 1970 paper Roger Penrose and Stephen Hawking present proofs that singularities will inevitably form in a star...
Monday, April 22, 2019

An astronaut falling into a black hole never reaches the event horizon - there is no information paradox or a firewall?

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It is a popular belief that an astronaut falling towards a black hole will pass through the event horizon at the speed of light. This view h...
Thursday, April 18, 2019

The Dirac equation follows from "curvature" of space under a magnetic field?

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Let us start from the energy-momentum relation of special relativity:        E^2 = p ^2 + m^2. The usual interpretations of the correspo...