What do you believe is the fate of the universe?

[HedonismBot]

Our universe has two options (correct me if I'm wrong), either it will reach a point where it's expansion comes to a hault and will crash in on itself in a reverse big bang, or it will continue expanding. If it does continue to expand, there will be a time when life will be impossible (at least as we know it) when all matter has decayed, i.e. protons and the like. This means no more life, ever. If the former option is correct perhaps there will be endless cycles of universes. However I think that all current data is pointing towards the dead universe option. I remember one article saying that the universe is expanding at an accelerating rate, and this rate is also accelerating. If the universes expansion continues at this pace it will end in a "big rip" as they called it, where galaxies will be ripped apart due to one end moving so much faster than the other. This process will eventually extend down to stars, planet, and eventually even neutrons wll be broken down into the most basic building blocks of matter. I don't like this idea very much as it leaves this universe unihabitable, it would seem. I believe that there will always be life, forever and ever, either because we live in a "multiverse" full of universes, where some die and some new ones are born, or that the universe will one day collapse on itself to give birth to future generations who will have no clue that we ever existed. Anyways sorry that this is rambling, I am just curious as to what others believe the ultimate fate of life in the universe is.

[flatline]

This (http://www.pbs.org/deepspace/timeline/) is science's best guess currently. I think its kinda sad, but we'll still have a few trillion years of good times.

The Stellar Era Ends
100 Trillion Years in the Future

Astronomers assume that the universe will gradually wither away, provided it keeps on expanding and does not recollapse under the pull of its own gravity. During the Stelliferous Era, from 10,000 years to 100 trillion years after the Big Bang, most of the energy generated by the universe is in the form of stars burning hydrogen and other elements in their cores.

The Degenerate Era
100 Trillion to 10^37 Years in the Future

This era extends to Ten Trillion Trillion Trillion years after the Big Bang. Most of the mass that we can currently see in the universe is locked up in degenerate stars, those that have blown up and collapsed into black holes and neutron stars, or have withered into white dwarfs. Energy in this era is generated through proton decay and particle annihilation.

The Black Hole Era
10^38 to 10^100 Years in the Future

This era extends to Ten Thousand Trillion Trillion Trillion Trillion Trillion Trillion Trillion Trillion years after the Big Bang. After the epoch of proton decay, the only stellar-like objects remaining are black holes of widely disparate masses, which are actively evaporating during this era.

The Dark Era
Times Later than 10^100 Years in the Future

At this late time, protons have decayed and black holes have evaporated.Only the waste products from these processes remain: mostly photons of colossal wavelength, neutrinos, electrons, and positrons. For all intents and purposes, the universe as we know it has dissipated.

[MatthewRyan]

The main theories are:

1 Big Freeze or Heat Death
2 Big Rip: infinite time, finite lifespan
3 Big Crunch: finite time and lifespan
4 Multiverse: no complete end
5 False vacuum

You can check them out at wikipedia. Heat death seems to be the most probable IMO.

-Matt

[mostsmooth]

the reason the universe expansion acceleration is increasing is because it is being sucked by adjacent universes that are collapsing. when they finally crunch and explode again, our universe will stop expanding and begin to crunch. its really weird

[Metric]

My favorite exposition article on this question is here (written by John Baez, a quantum gravity researcher):

http://math.ucr.edu/home/baez/end.html

To get you started, the first paragraph is this: "It's interesting to ponder the end of the universe. And I'm not talking the short run, like how the Earth's continents will collide in 250 million years, or how the Andromeda galaxy will collide with the Milky Way in 3 billion years, shaking loose many planets in many solar systems, or how the Sun will become a white dwarf in 7.8 billion years. I'm talking about the long term future! "

[billygrippo]

for some reason the pulsating universe type death seems the most logical to me. at least in a very broad sense.

[Nielsio]

[ QUOTE ]
This era extends to Ten Thousand Trillion Trillion Trillion Trillion Trillion Trillion Trillion Trillion years after the Big Bang.

[/ QUOTE ]

At least it's not a slow death..

[yukoncpa]

Hi Metric,
This was an awesome essay,

“Then what? Well, in about 10^23 years the dead stars will actually boil off from the galactic clusters, not just the galaxies, so the clusters will disintegrate. At this point the cosmic background radiation will have cooled to about 10-13 Kelvin, and most things will be at about that temperature unless proton decay or some other such process keeps them warmer. “

Metric, will any of this occur if there is no sentient being to observe it? What’s your take on the eventual death of the universe and consciousness?

[Metric]

[ QUOTE ]
Metric, will any of this occur if there is no sentient being to observe it? What’s your take on the eventual death of the universe and consciousness?

[/ QUOTE ]
If there is no life around to observe it, then it seems fairly certain that the universe is bound for thermodynamic death of one sort or another.

However, the second question you ask is quite profound -- if I could say something great about it, I'd publish it. From the article, Baez makes the following quote:

"Freeman Dyson has discussed the fate of intelligent life in the far future assuming a perpetually expanding universe, but assuming the cosmological constant is zero. In this situation the temperature of the universe decreases ever closer to absolute zero, and Dyson figured out that in principle, intelligent life could last forever and think an infinite number of thoughts, although slower and slower. This idea seems to be ruined by the presence of a nonzero cosmological constant and the resulting nonzero lower bound on the temperature."

Statistical physics is extremely difficult to sidestep. One can construct all sorts of neat ideas for preserving intelligence forever, but I have a hunch that in the end they are all somehow equivalent to "Maxwell's demon."

So basically, although I very much want to hold out hope for the future of intelligence, it's extremely difficult to think of any way to do it -- in fact, it would probably be equivalent to finding a systematic way to violate the 2nd law of thermodynamics. So if you find a way to preserve intelligent life forever, you may have simultaneously solved all of our energy problems.

[tcleberg]

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