Expert: James Gort - 4/28/2007

Question
Hello Dr. Gort

I was reading your answer about the blackhole universe theory, and I was wondering if it would be possible for all (or majority) the stars in the universe to become blackholes, then slowly merge and eat over time into 1 super blackhole, which would now be the universe, and all the matter they have consumed is essentially "crushed" into energy, possibly light energy, then at that point, there would be enough energy for the blackhole to explode since the mass of the matter would be gone since its now all energy, so now we have all this energy expanding out into this new universe and this energy is spontaneously changing from light into matter giving us what we have today? just a theory i came up with basing off the blackhole universe theory, mine is different in that the blackhole doesnt exist anymore, i dont know if its possible at all since i dont know much about astrophysics, but I like to theorize about space and time.

Answer
Hi Adam,

For not knowing much about astrophysics, you just came up with one of the current theories on the future of the universe - termed the "Big Crunch"!

Unfortunately, we don't have a lot of data to support which theory might be the correct one.  If the density is right, the universe will stop expanding and start contracting, eventually becoming a large black hole.  From there, the physics is unknown, but a new "Big Bang" could result.  Current evidence, though, seems to support a universe that will continue to expand, perhaps forming small black holes along the way, but eventually becoming less and less dense until all stars die away.

Your idea about the majority of stars becoming black holes is not supported by theory.  Only the largest stars have enough mass to collapse into a black hole.  Of course, stellar collision could combine smaller stars into a black hole, but those are fairly rare.  And although the gravity very near a black h9ole is immense, at larger distances the gravity is no more than a star of similar mass has.  So the black hole will not "suck in" matter until the matter gets very close to it.

If you read one of my answers, you might have seen that the current known density and mass of the universe is very close to that needed to form a large black hole.  So we may already be inside a super black hole (no one really knows what goes on inside a black hole, since we've never seen inside one!).  Other universes could exist outside our "black hole" and we would never see them (because light can't escape from our "black hole".)

But to get back to your theory, we really don't know the ultimate fate of black holes, and they could "explode" and send matter and energy expanding out into space.  For this, we need a quantum theory of gravity.

I hope all this has given you some additional things to think about.

Prof. James Gort