I am looking at this video about the timeline of the future. It says that the universe will stop expanding in about 1 googol years and become a cold bubble but I am not sure that will be true. There are several theories that can be true, so I am not sure which one. Anyone have some proof that one will be true? Thanks!
3$\begingroup$ You might be interested: en.wikipedia.org/wiki/Ultimate_fate_of_the_universe. $\endgroup$– AllureJul 14, 2019 at 22:16
There are several theories about the future of the universe, but I don't think we can be completely certain about any of them. The favourite at the moment, and probably the one with the most evidence to support it, is the dark energy universe which will go on expanding for ever, with the galaxies getting further and further apart and more isolated until they burn themselves out into total darkness. This raises problems about a unique, one-off beginning, with no cause, and vast quantities of matter and energy created magically out of nothing, thus violating the First Law of Thermodynamics.
My preferred option is the Big Bang-Big Crunch-Big Bounce universe in which the expanding universe is brought to a halt by gravity and collapses on itself to form a blue-shifted, shrinking universe which ends in a fireball and singularity similar to the one it was created from. Except it doesn't end. It erupts again (the Big Bounce) in a gigantic white hole which we call the Big Bang, and this cycle is repeated endlessly. It had no beginning, it will never end, and it doesn't violate the Fist Law of Thermodynamics.
3$\begingroup$ An infinitely repeating universe definitely violates the second law of thermodynamics, since it would require a decrease in entropy every time the cycle restarts. $\endgroup$ Jul 14, 2019 at 21:22