SOME say the world will end in fire,
Some say in ice.
From what I've tasted of desire
I hold with those who favor fire.
But if it had to perish twice,
I think I know enough of hate
To know that for destruction ice
Is also great
And would suffice.
Eschatology.
We may contemplate, but probably not know, how the universe will end.
Not the "world" - that we know - although we do not know how humanity will end.
Rather we can consider how the observable universe may end.
- Heat death - it is conceivable the universe ends in high thermal state; this could come during collapse in a cyclic universe, or through something like inter-universe collisions in the ekpyrotic scenario.
A cyclic hot collapse could lead to rebirth through a bounce.
- Annihilation through phase transition: it is possible, if not likely, that our vacuum is not a "true vacuum" and the universe could suddenly transition to a lower energy vacuum state. In the process a lot of energy would be released, everywhere, and possbly the laws of physics would effectively change. Good neis that this would happen pretty much instantaneously, if it did.
Note that this scenario may closely parallel formation scenarios for the universe and so could be considered a part of cyclic rebirth.
- Universe could expand and cool to a cold, empty vacuum, with only the little bit of matter bound gravitationally near us left observable. This would eventually all go into black holes which would then evaporate, leaving a cold empty vacuum.
- The vacuum could accelerate to a "big rip". Every atom and particle of your and everyones body would be ripped apart and sent flying off. Unlikely, but not ruled out.
- It is conceivable, but not consistent with observations, that the universe would "fill in" as it expands with new stuff, and just go on much the same (per the perfect cosmological principle).
All scenarios predict a very long probably lifetime for the universe, although some could lead to annihilation of time scales as short as billions of years (or shorter with but with very low probability).
All variations of these scenarios could take place embedded in a larger "multiverse" setting.
Our local observable universe might be annihilated, but the rest go on much longer, possibly forever.
Anthropic Principle
- Weak anthropic principle: universe must be such that (intelligent) life like us may exist.
- Strong anthropic principle: universe is such that (intelligent) life like us must exist.
- Final anthropic principle: (intelligent) life like us once it exists must persist in the universe.
The weak anthropic principle is severely skewed by observer bias.
It may simply be a statement of possibility, that life can exist in some circumstances, and that the universe is large and diverse enough that this occurs. This may imply a very large universe, much larger than the observable universe, and possibly diverse in the physical properties and state of the different patches of the universe.
The strong anthropic principle is contentious. Possibly untestable.
The final anthropic principle is gross wishful thinking, or naive theology.
The interesting question is whether it is true anyway.
Last updated 01/08
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