
#19
May712, 01:13 PM

P: 334





#20
May712, 04:43 PM

Sci Advisor
P: 2,194





#21
May712, 06:02 PM

P: 334

As you already know, the Big Crunch theory postulated that universal expansion following the BB halts, matter reverses direction, collapses into a singularity and another Big Band occurs ad infinitum The mechanism behind this they did not know but simply tossed the idea around as feasible. As the black hole caused by the crunch grew its event horizon would expand to gargantuan dimensions thus accelerating the influx of material. Eventually all matter would be inexorably drawn in regardless of where that matter is located. Ultimately the whole infernal thing would collapse back into the infinitely small primordial cosmic egg that it had been and somehow Big Bang all over again. But since infinitely dense and infinitelysmall singularities are described as retaining and event horizons, then the question is, now that YOU mention it, whether this one would also. Please note that this singularity involves not only the collapse of matter but of space time itself leaving nowhere to extend an event horizon into. If indeed we imagine that an event horizon remains, then we would be forced to explain just where such a horizon would be extending into since space has disappeared into the singularity. This is totally unlike the regular singularities where the surrounding universe remains intact leaving a place where an event horizon can indeed manifest itself. So since the question is whether a fed black hole can ever reach a point where it rebounds or regurgitates, and a black hole harbors a singularity, then this Big Crunch or Oscillating universe theory seems to indicate that it might. That is unless the qualitative difference between it and a regular infinitely small singularity makes the conclusion untenable which very well might be the case. 



#22
May812, 01:44 AM

Sci Advisor
PF Gold
P: 9,174

When you attempt to apply the laws of thermodynamics to a cyclical universe model, you are immediately confronted with serious issues.




#23
May812, 03:36 AM

P: 334





#24
May812, 05:40 AM

Sci Advisor
PF Gold
P: 9,174

When you propose a cyclical universe, you inherit the burden of explaining how it conforms to the laws of thermodynamics.




#25
May812, 09:52 AM

P: 334





#26
May812, 01:55 PM

P: 334

Here a couple of videos relevant to the thread.
Journey Into a Black Hole http://www.youtube.com/watch?v=eI9Cv...feature=fvwrel Black Holes and Galaxies http://www.youtube.com/watch?v=gib2i...feature=relmfu 



#27
May812, 07:39 PM

P: 1,781

You don't need to have a big crunch in principle do you?
If all the matter (dark and light) and energy (dark and light) in the universe (best guess of course as to the quantity) were dropped into one black hole, what would be the radius of the event horizon? I estimate (without having done the math) about 1 galactic radius. 



#28
May812, 09:17 PM

P: 334

Cyclic models such as the Big Crunch demand that the cycles be infinite. But that in turn requires that we deal with the problem of heat death caused by entropy. In fact, that original cyclic model was discarded exactly because of it since heat death would bring the oscillations to a halt. But other cyclic models such as the Steinhardt–Turok model and The Baum–Frampton model are considered more feasible by some because they evade the heat death scenario in various ways. However, they too create problems that elude a theoretical solution. In any case, at present evidence indicates that expansion is accelerating while deceleration and reversal have no such observational support. Cyclic Models http://en.wikipedia.org/wiki/Cyclic_model 


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