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The Heat Death is accepted by most as the end of the Universe, but how can that be? Wouldn't the Big Crunch make a lot more sense? I mean, even if everything in the Universe is spread out uniformly and still expands (which is the Heat Death as far as I know), wouldn't gravity, even if extremely slowly, pull everything back together, so that the Big Crunch happens? Even if gravity gets a lot smaller the further something is away, there is still a minimal force left, which over time should lead to the Big Crunch, or not?

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  • $\begingroup$ You seem to be starting from a false premise. Heat death and a big crunch are not a binary choice for the ultimate fate of the universe. We don't even really have a good way of describing the total entropy of the universe in cosmological models, so we don't have a way of formulating what heat death would even mean. Heat death is more of a Victorian way of looking at the issue. $\endgroup$ – Ben Crowell Jan 12 at 21:14
  • $\begingroup$ I might be wrong, but i think i didn‘t Start with a binary choice, as my assumption was that even if the Heat Death would happen, then there could be a Big Crunch afterwards (unlike in binary, where one couldn‘t happen after the other, because that would be a new possibility, so trinary). Though now i got an answer why that shouldn‘t be possible as far as we understand the acceleration of expansion. $\endgroup$ – Lexyth Jan 12 at 21:20
  • $\begingroup$ the big rip seems to be the way right now $\endgroup$ – Wolphram jonny Jan 12 at 22:54
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Observational evidence indicates that the expansion of the universe is accelerating, not decelerating. In fact, according to the best cosmological model, it has been accelerating for the last five billion years.

The theoretical reason for the acceleration is believed to be dark energy uniformly filling the universe and providing a repulsive effect that exceeds the attractive effect of the matter and radiation in the universe.

There is no evidence to support a Big Crunch in our future.

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  • $\begingroup$ Right, i think i read something about that (and that it has to do with Dark Matter/Energy or so)... that makes it impossible to overcome the velocity of expansion, since gravity gets weaker... totally forgot about that. Thanks^^ $\endgroup$ – Lexyth Jan 12 at 20:36
  • $\begingroup$ If you don’t get a better answer, please click the check mark to accept this one. Thanks. $\endgroup$ – G. Smith Jan 12 at 20:38
  • $\begingroup$ I will, but it has a 10 minute cooldown before you can accept an answer (was still 6 minutes when i tried(2mins ago)(still 3 mins))^^ $\endgroup$ – Lexyth Jan 12 at 20:39
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    $\begingroup$ BTW, dark matter does not contribute to the acceleration. Dark matter is attractive, just like ordinary matter. The main difference is that it doesn’t have electromagnetic interactions so we can’t see it. $\endgroup$ – G. Smith Jan 12 at 20:42
  • $\begingroup$ Yeah, just checked and apparently it‘s caused by Dark Matter (one of the possible causes). $\endgroup$ – Lexyth Jan 12 at 20:46

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