The future of the Universe? Not such an easy prediction...
If the Universe consists only of matter and radiation, and as far as we think we know, it started by expanding, then we would think that we could assume its future as follows:
The 1st hypothetical end of the Universe
If, as we think, the rate of expansion is too great for matter and radiation in the Universe to overcome, then, although gravity may slow down this expansion, the Universe will continue to expand forever. So, if the above thermal death prescenario is correct, or what is known as the Great Freeze.
The 2nd hypothetical end of the Universe
However, the opposite could also happen. That is, if there is enough matter and radiation to overcome the gravity of the initial expansion, the Universe would expand, but gravity would slow it down and eventually stop it. Then the expansion will reverse and become a contraction. This approach leads, obviously, to another inversion: the reversal of the Big Bang into a Big Crunch.
The 3rd hypothetical end of the Universe
Could the above two approaches finally be combined? Well, the Universe would continue to move at a "limiting" speed, as the expansion rate asymptotically (that's what I mean by "limiting") drops to 0. This is the case known as the Critical Universe.
Once again, it is confirmed that in science we know what we think we know...
The 1st hypothetical end of the Universe
If, as we think, the rate of expansion is too great for matter and radiation in the Universe to overcome, then, although gravity may slow down this expansion, the Universe will continue to expand forever. So, if the above thermal death prescenario is correct, or what is known as the Great Freeze.
The 2nd hypothetical end of the Universe
However, the opposite could also happen. That is, if there is enough matter and radiation to overcome the gravity of the initial expansion, the Universe would expand, but gravity would slow it down and eventually stop it. Then the expansion will reverse and become a contraction. This approach leads, obviously, to another inversion: the reversal of the Big Bang into a Big Crunch.
The 3rd hypothetical end of the Universe
Could the above two approaches finally be combined? Well, the Universe would continue to move at a "limiting" speed, as the expansion rate asymptotically (that's what I mean by "limiting") drops to 0. This is the case known as the Critical Universe.
Once again, it is confirmed that in science we know what we think we know...
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