Re: Black hole question

From: Spike Jones (
Date: Sun Feb 13 2000 - 17:12:06 MST

> Jeff Davis wrote: Just a quick question, sans florid embellishments.

But Jeff, we *live* for your florid embellishments. {8^D

> If a black hole has an event horizon from within which nothing can escape,
> then how can the mass within the black hole exert a gravitational
> attraction on anything outside the event horizon?

The mass of the black hole bends or curves spacetime. Nothing need
escape from within the black hole to exert a gravitational influence on
stuff outside the event horizon.

> How can anything *orbit* a black hole?

Anything follows a geodesic thru spacetime, which is curved by mass
the same, regardless of its black holedom. If some blue meany
were to somehow compress our sun to a black hole, the earth would
keep orbitting one rev per year as before.

> Doesn't the indisputable fact of gavitational influence by the foremost
> candidates for black holedom suggest that either they are not black holes,
> or that the theory of black holes is flawed?

No. I see no contradiction here, but perhaps Amara or one of the
other professional astronomers will weigh in on it. Hawking's Brief
History of Time covers this topic. {8-] Hope this helps. spike

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