Ros, A mechanic must consider all the effects. I should have mentioned tidal effects as a cause of current day length.
but I intended to remark on something that could be observed. (Not the first thing that I fixed that didn't work as intended
Consider Meteorites, Space dust, and even the solar wind. Most of these will act to slow orbital motion. It won't happen tomorrow but eventually all orbits will decay. (if something else doesn't happen first
I suspect the same "mechanisms" are at work in the Galaxy.
Second point (sorry my quoter refused to quote some time ago)
With sufficient energy applied it will no longer be a black hole.
Whether it blows up or emisses away is of little interest. (Stephen Hawkings has remarked that it is possible for a black hole to emit radiation)
With sufficient energy applied to your autos motor it will no longer be a motor. Whether it blows up or melts first is of little interest. There are ALWAYS some mechanical limits, somewhere.
(Hawkings also comments that although we have not observed a primordal black hole there is fairly general agreement that IF we did it would have to be emitting a lot of gamma and x rays)
Hence my thoughts that in some cases a gamma burst may indicate the birth or death of a galaxy.
Further thoughts (all theory or BS whichever you prefer
Since it seems entirely possible (probable
) that all "anything" in a black hole is reduced to quanta then I would expect a "Galactic"burst to be very brief as opposed to a star source which has a much larger dimension. The speed of light (or gamma rays) precludes an instantaneous burst from a star but it may be possible for a black hole to emiss completely in a matter of seconds.
(Hawkings-A brief History of time Bantam Jun 1990, ppg 112.)
He has also mentioned it (emmisivity of a black hole) in a couple other books. I don't remember ( a common occurrence
) which one he explained the math in
Fun to think about anyways, Best Mech