Possibilities of the end of the universe: Ice.
The universe had a beginning and it will have an ending.
Time may go on forever, but the universe will end as far as we are concerned.
Even if time approaches infinity if no atoms are left we will die. Many of them can happen at different points.
The most popular, the big rip.
The big rip means an end to spacetime itself. This one is definitely the end. Dark energy drives the expansion of the universe. This expansion is accelerating rapidly, so fast in fact, that it will reach an infinite space in a finite time. First it will rip the galaxies apart. After a few hours planets will be ripped apart, last comes stars an instant before the end.
This fate however, is based on W, or the ratio of the pressure of dark matter to its energy density. If it is above negative one the universe will collapse on itself, if it is -1 it will expand forever but slow down and if it is less than -1 this will happen.
The big freeze.
This one is the most painful as it would last the longest. As the universe expands the average energy density and temperature would reach 0. Stars have enough dust to form for the next trillion- one hundred trillion years. Which is not yet infinity. Black holes will then rule the universe as all light fades away. Once black holes evaporate nothing will be left but a few stray particles.
The death of the atom.
Eventually even atoms themselves will die. Protons (if unstable) most likely have a half of 10^34 years. Which means eventually they will all disintegrate, which means eventually we will run out of atoms. At 10^37 years one thousand half-lives would have gone through and that is enough to statistically destroy every single proton in the observable universe. This is a sure end to humanity as we know it.
We have so much to learn.
This above is assuming that we keep expanding. This is based on the state of dark matter. We know nearly nothing on the state of dark matter which may have changed in the past. During the inflationary part of the big bang a form of dark matter simply called the inflation field may have been present but then degraded. Eventually we may be able to figure it out.
More on the big bang here
picture source: www.nasa.gov/images/content/386911main_Swift_M31_large_226.jpg
more reading https://en.wikipedia.org/wiki/Future_of_an_expanding_universe
https://en.wikipedia.org/wiki/Ultimate_fate_of_the_universe
I'm liking this post - A LOT!!
Well maybe or maybe not...
http://mathworld.wolfram.com/HamiltonianCycle.html
Any ending of the universe would actually imply information loss and would require the AMPS paradox to be correct. Science is telling us the AMPS paradox is just wrong. So it's very probable that we will undergo Quaternary return. The only real question is how large is the Hamiltonian of the universe and is Lambda aka Dark Energy an actual constant, or does it vary over time?
Since Lambda was high enough at one time to fuel the inflationary epoch, then the universe wound down for a bit and now it's picking up speed. I would not be surprised at all to find that it's evolving in a sigmoid fashion. That also means it might reverse.
Also there are topologies which do not require either a beginning or an end, but could bend / twist or warp in such a way that they might look to us like they do. A mobius strip would be one, a toroid would be another and of course the lemniscate.
Finally, if the universe is the result of a collection of fields at certain energy levels, there is always the possibility of tunneling to a different state. That would mean there was no big bang, but that when we drop in, we did so right before the CMB event. It also means we might spontaneously tunnel again. ;)
As always great post!
nice post ~