Expert: Tom Whiting - 11/2/2010

Question
Hi Tom. Thank you for answering my recent question regarding what we'd see if we could run the universe backward.

As a follow-up question, let me ask this:

Light and matter that have entered into a black hole are captured by its gravity and can never escape. If we could run the universe backward and observe it, would a black hole be viewed as releasing the light and/or matter that it had captured during its existence?

Answer
Thought I was quite clear with my previous answer... in any case....
First, yours is an impossible hypothetical question as we cannot run the "universe" backward. Second, the reason we can't is because current science considers time a one-way arrow, always moving forward, not backward.  In other words, while forward time travel to the future is at least theoretically possible, backward in time travel is not. (We cannot take the square root of a negative number being the reasoning, not to mention that cause and effect become reversed... the ceiling light comes on before you throw the switch, and that is patently impossible.) There is even a good theological argument for impossible backward time travel... some unscrupulous person could go back in time and mess up the Crucifixion, or Mohammed, or Moses or Abraham, or Noah, or Buddha, or whomever you believe in; plus you could kill your grandfather, therefore you maybe don't even exist, another impossibility.
It's my understanding that once even light enters a black hole, nothing can escape. Therefore, I would assume that even your impossible backward running Universe could not be strong enough to "release the light" from a black hole, and/or the past captured matter either.
As I stated earlier, you can run the movie film backwards all you want to, but not the real Universe.  So my impossible hypothetical 'answer' is, "No, I don't think a black hole would disgorge captured light or matter..by definition of a black hole"...  to your impossible 'hypothetical' question.
(Of course, if you're writing a science fiction novel about such an event, then you can do, and write, anything you want, even if it's not true... politicians do it to us all the time.)
Clear Skies,
Tom