Boring ol' heat death.
Eventually expansion will pull apart the galaxies far enough that they can no longer interact with each other. Perhaps gravity will lose to dark energy, and matter just falls apart. It's up in the air whether or not protons will decay or not, so we'll see.
When all of the matter has decayed, and there is nothing left but light/radiation, we're left with a universe of size 0. A random energy fluctuation/quantum tunneling event could kick-off another universe. Or so says conformal cyclic cosmology hypothesis/theory/guess/insane rambling of Roger Penrose or whoever the fuck said that shit.
I believe in the many worlds interpretation of quantum mechanics. It instinctively feels right to me. I also find the quantum immortality theory interesting. Furthermore I have another instinctual feeling that what we perceive to be distance doesn't exist in the way we experience it. What Einstein called spooky interaction at a distance is an interesting phenomenon which is yet understood.
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