Expert: James Gort - 3/3/2007

Question
Is it posible that as the universe ages black holes become more numerous and or grow larger & collide/merge with other black holes producing super-massive black holes.As the expansion of the universe slows and stalls the black holes (especialy the super-massive ones) begin to be drawn towards each other untill they collide/merge becoming larger & more powerful.The matter,ect that has stopped expanding begins to be pulled toward and spiral into the black holes untill the scale is tipped and ALL of the black holes merge becoming so powerful that all of he matter,ect is swallowed and it all implodes then explodes ouward producing the big bang?  

Answer
Hi Brad,

You've asked a very profound question.  But the short answer to your question is "yes", what you propose is possible.  In fact, it's one of the current theories of cosmology!  As stars age and heavier elements are produced, it becomes harder to have self-sustaining objects.  Beyond iron, energy is no longer released by the fusion process (no matter how massive the object), so the object must collapse.  The most massive objects collapse into stellar black holes, while less massive objects collapse into neutron stars or white dwarfs.  If any of those objects combine through collisions (assuming the average density of the universe does not fall off so rapidly as to make collisions virtually impossible), they'll eventually form larger black holes.  

Just look at some of the masses (in terms of the sun's mass) and "Schwarzschild radii" of some black hole candidates.  
Earth: m = 3 x 10^-6 mass of sun, r = 9mm.  So if you could shrink the earth to less than 9mm, you'd have a black hole.  
Sun:  r = 3km.  
Galaxy: m = 10^11 mass of sun, r = 0.03 light years
For the universe itself, it becomes more tricky, because we don't know the total mass.  If we assume m = 10^22 mass of sun, then r = 3 x 10^9 light years (somewhat less than the assumed radius of the current universe).  But if we assume m = 10^23 mass of sun, then r = 40 x 10^9 light years!  We could already be inside a giant black hole!  And that's why we can't communicate outside of our universe - photons just can't get out of our black hole universe.

There's many books on the subject, some of which are too technical for most people and some are not written by experts.  For your question, I'll recommend a little book by black hole specialist Jean-Pierre Luminet entitled "Black Holes", available for as little as $4.00 from http://used.addall.com  Chapter 19 is entitled "The Black Hole Universe" and describes this very theory.

I hope you'll continue to think through these mind-boggling problems and ask the thought-provoking questions.  As you can see, you've already come up with one cosmological theory on the oscillating universe.  Keep it up!

Prof. James Gort