Originally Posted By: Bill
re: escape velocity - That is one of the poorer ways of describing the black hole horizon.


This is a derogatory classification of what you later more suitably describe as being one of the relatively simple ways to explain it.

I happen to agree with Einstein that we should keep things as simple as possible...unfortunately many people have the habit of latching onto new concepts such as 'black holes' and adding their own usually much more extreme aspects (such as worm tunnels) in attempts to have their name associated with such phenomena.

I believe that the person who "...reached the conclusion that a sufficiently large star could have an escape velocity greater than the speed of light." was the British astronomer the Rev. John Michell who, in the 1700's, reasoned that if a star had a strong enough gravity it would choke off its own light but I don't see this as suggesting that having been emitted by the star that light would then be pulled back into same but that the light would not escape in the first place.

In 'Einstein's Universe' Nigel Calder wrote (62, BBC, 1979):- "Light travels faster...toward the centre of gravity than away from it."

The stronger the object's gravitational field the greater that variation and on that basis - as a star collapses the rate of departure of a beam of light traveling away from that (fixed location) source gradually reduces to zero in some cases.

This is, of course, from the point of view of a far distant observer whereas a local observer (located alongside the light source) would determine c for both beams however this is solely due to the fact that his measuring rods and clocks are physically distorted by that field.