It seems that the only two theories I typically see discussed are the following:
Big Crunch: The universal expansion stops, and goes backwards into a singularity again. Possibly winking out of existance at the time.
Heat Death: The universe expands forever, and someday the last proton decays, and we are left with an enormous expanse of total entropy. Effectively, no existance.
It also seems that Science favors one or the other scenario, depending on the latest data. First it was endless expansion, then crunch, now expansion…ugh.
Is there any in-between? That is, are there any scientific theories which are considered “possible” or at least “reasonable” which do not involve either of the two unimaginably frightening scenarios? And do they have a proper slang name? Such as, one where the universe neither ends up in heat death nor a crunch?
'Fraid not. Even if the universe manages to level out (i.e. stop expending, but never start contracting), the laws of thermodynamics would still dictate that the universe would suffer “heat death”.
The only way that the universe could last forever (in a state similiar to the one its currently in) would be for energy to somehow be injected into the universe from . . . somewhere else. And since nothing like this has ever been observed, or even predicted from current knowledge, it doesn’t seem very likely.
But all that is still very, very, very far off in the future. Closer at hand, our own sun will expand into a red giant and engulf the earth in another 5 billion years. So if humanity manages to survive that long, we’d have to find another planet to live on before we could worry about the end of the universe.
Well, this colliding brane theory does violence to the standard big crunch, or heat death scenarios, and still ends up with cyclic universe creation. Not being a physicist, mathematician or astronomer, I’d better leave things there. Perhaps JS Princeton will come along and enlighten us ?
Total and endless oblivion? Pretty frightening to me, even though it makes no sense. Somehow, thinking of all of existance wiped away, crunched away, or faded away to be unrecognizeable is just a Bad Thing. And I think it’s whistling by the graveyard to pretend otherwise.
I’m not saying there’s anything one can do about it, or that it helps to be upset, mind you. But I’m honest with myself about my irrationality.
Joe Random, I had read recently that a recalculation of how red giants form leads some to think it’s “inconclusive” as to whether or not the sun will go red giant, and if so to what amount it will expand.
The problem is entropy. There is no way to get around it. Unless we find out something really, really revolutionary about the way entropy works, I can’t see how our universe can avoid reaching equilibrium, not matter what it does. Perhaps there are other universes, chugging away elsewhere. It seems far to arbitrary for this to be all there is to existence. Those other universes may be eternal, but it likely would be hard to define what that means without a common timescale.
Well, you and I will both be long gone before that happens. And, quite frankly, I doubt humanity will survive anywhere near that long anyway. I find it difficult to get all worked up about a nebulous “end of the universe” that I can’t do anything about anyway, and neither I, nor any of my descendents are likely to be affected by.
Well, of course it seems bad from our point of view. We’re kind of dependant on existence to, well, exist.
I think that worrying about the end of the universe is kind of a projection of worrying about death in general. The one thing that tends to motivate people to accept death is the thought that the people they love, and the world they know will live on. To say that even the universe will die makes things look kind of futile if you think about it too much.
And I must admit, I like the idea of a Big Crunch better than heat death. At least then you can believe that there is some over-arching cycle of death a rebirth, and that existence, at least, will continue to exist.
Well, even if the sun doesn’t expand that much, it doesn’t matter in the long run. It will eventually run out of fuel, and life on the earth will be pretty much impossible.
I suppose humans could live in caves deep within the earth, and use nuclear fusion (which we surely would have mastered by then) to sustain ourselves for a loooong time. Unless we’ve managed to colonize other star systems by then. And that’s all assuming that humanity manages to survive that long.
Strangely enough, that type of thought doesn’t bother me.
Actually, thats not quite true. Assuming we create a theory of a COMPLETELY static sized universe, the theories of entrophy state that EVENTUALLY, anything can happen. Remember, entrophy is of a purely statistical nature. Given long enough time spans, scrambled eggs will unscramble and broken cups will fit itself back together. Personally, I find this alternative very interesting.
Huh? Yeah, maybe once every 10^1000000 years one half of the universe will get 0.000001% denser in energy, but reassemble into planets and galaxies? I can’t even think of that long of a time.
The thing is, it doesnt matter if it is 10^10 or 10^10^10^10, we have an INFINITE time to work with. That is something that most people have a very hard time wrapping their heads around the first time through.
Anything that IS possible WILL eventually happen. Given a long enough time span, you will have bizzare things happen like the entire SMDB crew forming out of thin air and then all simultaneously choking to death due to lack of oxygen to pluck one from the top of my head. That is why I find it so exciting.
There are a number of different theories around - and until Special Relativty and Quantum Dynamics are assimilated into a single theory then it’s open season on guessing which is the right one. Different theries each have their strengths and weaknesses, and each has the ultimate flaw of not being able to wholly match observation.
Speaking of which, entropy is not a statistical construct, but an observational one.
Actually, this post reveals what is wrong with most people’s understanding of infinity. 10 coins can be in 1024 states. A million coins in 2[sup]1000000[/sup] states. You are talking about a number that is “fora all practical purposes” infinite. But it gets worse. A countably infinite number of coins can be in an uncountably infinite number of states. No matter how much time you have, you can’t have all the states of the coins appear. Never, ever. Period.
(What is really amazing is that exactly this flaw in logic appears in the new cover story of Scientific American. Big hint for editors of SA: next time someone writes a story about infinity, run it by someone who knows about Cantor’s set theory.)
There is a model which is exactly the half way house between Big Crunch and Heat Death in which the universe contiunes to expand, but the rate of expansion slows down over time, giving the universe a finite size at t=infinity. Their is no theoritcial problem with this model, the only problem is observational, in that it requires the universes total mass to be within a very narrow band.
Yes, just because t is infinte dopes certainly not mean that everything will happen.
For example imagine a decaying probabilty (for exampe the chance that two particles collide in an expanding universe)
A simple dice probabilty: imagine your trying to throw a ‘1’ on a dice of x sides, if you fail to throw a 1 on the dice on an attempt, then x is increased by a factor of 2. If x=4 at n(attempt)=1, then the total probabilty you have thrown a 1 after n= infinty is equal to 0.5.
The problem with considering an infinite universe in infinite time (or even MC MC’s finite but huge espansion) is that we are in an expanding universe. Once objects are so far away from one another that they are apparently receding faster than the speed of light, no communication between them is possible. You can’t have the SDMB crew appearing if the distance between their particles precludes their ever coming together.
Anthracite, thank you for answering my question. I don’t have this fear myself, and I see it merely as another interesting manifestation of physics rather than a Bad Thing.
Frank Tipler has suggested that if there is a Big Crunch, then processes will speed up as the universe approaches the singularity, so a sufficiently advanced intelligence could co-opt the speeded up processes to “live” at faster and faster rates. Thus the intelligence could live for an infinite amount of subjective time, all crammed into the last microseconds of the Universe. I think his book was called “God and the New Physics”. (Disclaimer: I haven’t read it, only reviews of it.)
Most physicists don’t get too excited about this scenario, tho.
Tipler’s speculations - in The Physics of Immortality; God and the New Physics was by Paul Davies - are part of a tradition arguing about another resolution to Anthracite’s existential crisis. Realise that heat death is a process rather than a single event and try to ride it out. The classic set of speculations along these lines was in a 1979 set of lectures entitled “Time Without End” by Freeman Dyson. Now you have to warm to a vision in which one of the more pessimistic passages runs:
Terraforming ? Pah! Get cracking on re-engineering the entire universe …
Dyson argued that in an open universe, although it would get eternally colder, some processes would always continue and these could be exploited by intellegent life to survive, albeit with everything running slower and slower.
Many of the details of how we think the universe will age have changed in the intervening quarter century; John Baez gives an up-to-date summary. The differences are such that in an article for the November 1997 issue of Scientific American, Lawrence Krauss and Glenn D. Starkman concluded that Dyson-like schemes can’t work. But if oblivion does bother you, it may still be worth trying to find a loophole.
