Based on recommendations here, I'm reading Kip Thorne's BLACK HOLES AND TIME WARPS which was somewhat uninteresting during the first 100 pages or so but then he redeems himself...here's some excerpts I found insightful and clearly stated (pgs 130-133) After noting that time moves more slowly at the surface of a star as viewed by a stationary distant observer he says:
So the overall explanation, I think, ties together a number of concepts....I'm wondering how others might explain the boldface phrase....sounds on one hand like time warps energy!!!! Or is it more correct to view this as only an analogy, with the real explanation being gravitational potential is behind the shift (both in time and wavelength)?One consequence of time warpage is the gravitational redshift of light emitted from a star's surface. Since the light's frequency is governed by the flow of time at the place where the light is emitted, light emerging from atoms on a star's surface will have a lower frequency when it reaches the earth than light emitted by the same kind of atoms in interstellar space. The frequency will be lowered by precisely the same amount as the flow of time is slowed...for a star whose actual circumference was the same as it's critical one (as predicted by Schwarszchild geometry) the flow of time at the star's surface is infinitely dilated; time does not flow at all...in modern language, the stars surface, with it's critical circumference is precisely at the horizon of a black hole...this infinite shift in wavelength, in effect, removes all the light's energy; and the light, thereupon, ceases to exist!