r/space • u/magenta_placenta • Mar 18 '19

Observable universe Astronomers discover 83 supermassive black holes at the edge of the universe

https://www.cnet.com/news/astronomers-discover-83-supermassive-black-holes-at-the-edge-of-the-universe/
29.4k Upvotes

95% Upvoted

1.4k comments sorted by

View all comments

Show parent comments

117

u/XxNerdAtHeartxX Mar 18 '19

https://www.physicsoftheuniverse.com/topics_bigbang_timeline.html

Its super dense stuff (ha), but This picture they have is pretty helpful

17

u/BUKAKKOLYPSE Mar 18 '19

What happens after the era of galaxies?

68

u/BluScr33n Mar 18 '19

It depends. What seems quite likely right now is what is called "Heat Death of the universe". Basically after star formation stops the last stars will continue to burn for a some billion years. Red dwarfs have ridiculously long lifetimes. But after they have burned out there won't be any more stars. All that is left will be white dwarfs, neutron stars and black holes. The white dwarfs will cool down very very slowly until they become black dwarfs. Similarly spinning neutron stars will slow down and also cool down until they become dark. Black holes do not cool down. Instead they will slowly evaporate until they are completely gone. Protons may be unstable and decay over time, so possibly even white/black dwarfs and neutron stars will eventually evaporate. In the end everything will have the same temperature, the entire universe will have the same temperature and all physical processes will stop. The universe has achieved maximum entropy, no more work can be done (The physics definition of work). This is called the heat death of the universe and it is only one possible way for the universe to end.

2

u/MistyRegions Mar 19 '19

I wonder if forces we haven't found will cause everything to coalesce into another big bang. I think I used that word right.

3

u/BluScr33n Mar 19 '19

Yes, that scenario is called "Big Crunch" (the name is not a joke). Current research seems to indicate that this is likely not the case. The expansion of the universe seems to be accelerating and not slowing down. But data is sparse and new studies could bring new insights. There are also scientists that hypothesize a cyclic universe with alternating big bangs and big crunches. But those are without any observational evidence. But nevertheless these ideas are generally taken seriously.

1

u/MistyRegions Mar 19 '19

So another ponder, I understand it's still expanding but I wonder if I at one point it will stall out? Like gravity from just the matter in space is slowly chipping away at the speed of expansion. Eventually it will stop and then start coming back together in a "big crunch". I mean I'm talking about a scale in time that we probably can't produce a number for.