Inquiring Minds


Questions About Physics

General Theory of Relativity and Black Holes

To a worker at fermilab,
I am not fully sure of the validity of my idea, but is makes a good deal of sense. Again, I am not sure if this has already been discovered. My idea is as follows: I think that the singularity of a black hole contains the mass of the entire star (or other large-mass object), simply at an infinite density. The event horizon of the black hole is the star (or other object) at the point that that object "froze" at its critical circumference. They are, therefore, in "different" time frames. If you are in a reference frame inside a black hole (if you could survive) you would see only the singularity. If you are in a reference frame outside the black hole you would see only the horizon (of course, since light, or anything else for that matter, can escape from inside the horizon). As an outline of this idea, the star imploded, froze at the critical circumference (according to a reference frame far away from the star). According to a reference frame on the surface of the star, though, it would continue to implode to a singularity without sign of the horizon. This still does not permit a naked singularity, though, because according to an outside reference frame, (the only frame a naked singularity would even effect) there is still a horizon cloaking the singularity.

If you are unclear of the details of my idea, please notify me. I must credit the work of Kip Thorne for giving me the base information I needed. Please respond as quickly as possible to tell me whether this idea is even possible, let alone likely. Again, I give you my deepest thanks.

From,

Nicholas G.


Dear Nicholas,

Your ideas are pretty much in keeping with the predictions of general relativity about what happens in the vicinity of black holes. If you are a long way away, watching a space ship falling into a black hole, you never see it cross the event horizon, no matter how long you wait. Radio and TV signals that it sends you just go slower and slower and slower as the ship approaches the event horizon of the black hole. What you observe doesn't freeze, exactly, but it does go slower and slower.

If you are on the ship, on the other hand, the situation looks very different. In a finite amount of time by your ship's clock, you cross the event horizon, without noticing anything funny happening. Once you are across the event horizon, however, your ship is drawn inexorably toward the singularity and no force known to current science can stop it.

What I've said so far is well understood in current theory. By that I mean that we can use the equations of gravity (i. e., general relativity) to make numerical predictions about exactly how it seems that ship's time is slowing down when viewed by an outside observer, etc. When the ship gets into the singularity, however, current scientific theory fails us and we don't know how to make numerical predictions. This is because at the singularity, quantum mechanics as well as gravity is important, and we don't yet have a theory of quantum gravity.

Yours truly,
Paul Mackenzie

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last modified 4/8/2000   physicsquestions@fnal.gov