Saturday, November 15, 2014

Black holes: Initial thoughts

I watched the movie Interstellar (and liked it very much).  They get lots of stuff right and lots wrong.  A black hole features prominently in the storyline which made me think about the event horizon problem.

Interstellar


Image from Wired

This event horizon problem is a matter of debate among the greatest minds of all time in physics and no satisfactory answer has been found.  All potential solutions to the problem results in breaking some basic building block of physics as we know it.  So my meanderings pick out just some of the facts that I value most and ignore the problems my solution causes :)


Graphics generated using real equations for matter and light around a black hole.  The light circle around the hole is from gravitational lensing of the accretion disk light from the other side of the black hole.

Reputedly the properties of a black hole are mass, charge, and rotation and all other information inside the event horizon is lost.  This has always troubled me.

So first of all, charge (as part of electromagnetism) is transmitted by its force particle (the photon).  If photons can't escape the event horizon, then charge should not be detectable outside the event horizon.

This implies that if gravitons do transmit the force of gravity, then black holes can't exist (because gravitons couldn't escape either) -OR- alternatively, gravity is not transmitted by a force particle.

Another problem is introduced by gravity mappers.  We can detect variations in the Earth's gravity field by lumpy mass distribution through gravity mapping satellite pairs.  Presumably we could do the same with a black hole.  Even if all mass is eventually compressed into a singularity, we should be able to map masses falling into that singularity with the use of gravity mapping satellite pairs.  Which means we can find information inside the event horizon and cosmic censorship is out.

Finally, from the perspective of an outside observer we can use the equations from general relativity to prove that masses never fall through the event horizon.  As it approaches the event horizon, velocity asymptotically -> c but time asymptotically -> zero.  Eventually the delta distance approaches -> Planck length.  Once it does, then no further progress (for mass or information) can be made towards the black hole.  To the outside observer, the mass always achieves this stalemate prior to reaching the event horizon.  I suspect but can't prove that the outside observer is theoretically capable of observing this but that the red-shifting of the light makes it impossible in practice.

d = v * t
When v -> c and t -> 0, this collapses to d = 0 and to the outside observer, no further progress is made by the mass falling towards the black hole.

Ergo, from the outside observer perspective, all mass resides in a shell around the black hole.  The shell need not be symmetrical and mass need not be evenly distributed but that is the easiest case to envision and solve for.

On another note, assuming all black hole mass resides outside the event horizon evenly distributed in a shell, (I think) an observer outside this shell (and to observe it only as a gravity mapper) could not distinguish it from a point mass / singularity inside the event horizon.

In my next post, I attempt to describe the faller's perspective.

Updated 3/24/2015:
As shown in the comments section, there are proofs showing my description to be false.  I'll write a follow-up post with corrections at some point.

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