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Plat
2010-Dec-25, 03:01 PM
I need to get up to date on the current consensus on the likely fate of the universe? Is it heat death, big crunch, big freeze, big bounce (didn't this get disproved a couple of years ago?)

cosmocrazy
2010-Dec-25, 03:44 PM
Maybe the big rip? if the universe continues its accelerated expansion?

StupendousMan
2010-Dec-25, 03:48 PM
The current evidence suggests that the universe will expand indefinitely.

forrest noble
2010-Dec-25, 06:40 PM
I need to get up to date on the current consensus on the likely fate of the universe? Is it heat death, big crunch, big freeze, big bounce (didn't this get disproved a couple of years ago?)

The presently favored BB model involves dark energy; the expansion of the universe would accordingly be accelerating until its ultimate heat demise. There are however dozens of other BB versions including the big rip, and models that propose multiverses and cyclical universes in almost countless different versions. You may not wish to bet the farm on the possibility of any/all of these present models, concerning what will be the prevailing model in the next 25 years. Your same question asked 25 years from now might contain few or none of the models which are considered possible today.

Cougar
2010-Dec-25, 08:16 PM
The presently favored BB model involves dark energy...

You make it sound like it's a hot fudge sundae. As Stupendous Man said, "The current evidence suggests that the universe will expand indefinitely." Notice the inclusion of the word "evidence."


There are however dozens of other BB versions including the big rip, and models that propose multiverses and cyclical universes in almost countless different versions.

Many of which have no evidence to their account.


Your same question asked 25 years from now might contain few or none of the models which are considered possible today.

On the other hand, it was only some years ago that Nobelist Steven Weinberg (http://en.wikipedia.org/wiki/Steven_Weinberg) pointed out:

"One can imagine a category of experiments that refute well-accepted theories, theories that have become part of the standard consensus of physics. Under this category I can find no examples whatever in the past one hundred years."

forrest noble
2010-Dec-25, 09:29 PM
You make it sound like it's a hot fudge sundae. As Stupendous Man said, "The current evidence suggests that the universe will expand indefinitely." Notice the inclusion of the word "evidence."
You are right, there is only one primary cosmological model. If the universe accordingly expands "forever" it will eventually freeze to death :( The Big Freeze, although the Big Rip is also thought to be "very appealing" :razz:



Many of which have no evidence to their account. True, most I think attempt to explain one facet or another of the standard model that they do not believe is very appealing :)


On the other hand, it was only some years ago that Nobelist Steven Weinberg (http://en.wikipedia.org/wiki/Steven_Weinberg) pointed out:

"One can imagine a category of experiments that refute well-accepted theories, theories that have become part of the standard consensus of physics. Under this category I can find no examples whatever in the past one hundred years." I agree but maybe within the next 100 years however, I think with few exceptions, that much of the slate written in the 20th century might be replaced by simpler and better supported theories.

astromark
2010-Dec-26, 07:15 PM
We have zero evidence of the universe slowing or not continuing to expand at a eccelorating rate so, a colder more sparse environment is assured...
But that not in our lifetimes will any signs of this be obvious...

neilzero
2010-Dec-26, 08:41 PM
The recent consensus on this forum and www.space.com seems to be that our galaxy and our local group of galaxies is not expanding, so in a million times a million years = one trillion years, our galaxy will be about the same size and mass about 20% of the present mass, but very cold and dark as scarcely any stars will be main sequence. Galaxies outside our present local group will be much farther away than at present, with rare exceptions. Our local group will loose mass mostly due to collisions and gravity assist maneuvers that occur the next trillion years. If star birth has decreased .001% in our galaxy, the last 100,000 years, it will be near zero in 10 billion years. Neil

BigDon
2010-Dec-27, 09:56 PM
And the deep time papers I've been linked to from here seem to think the Universe can make it at least three times Neil's time line (3 trillion) before their calculations get too murky. And everything becomes iron. :)

Cougar
2010-Dec-28, 02:35 AM
The recent consensus on this forum and www.space.com seems to be that our galaxy and our local group of galaxies is not expanding, so in a million times a million years = one trillion years, our galaxy will be about the same size and mass about 20% of the present mass, but very cold and dark as scarcely any stars will be main sequence.

In other words, roughly 100 times the current age of the universe. Imagine how much time that is!


Galaxies outside our present local group will be much farther away than at present, with rare exceptions. Our local group will lose mass mostly due to collisions and gravity assist maneuvers that occur the next trillion years. If star birth has decreased .001% in our galaxy, the last 100,000 years, it will be near zero in 10 billion years.

I'm not checking your figures, but that sounds about right, particularly since, IIRC, universe-wide star birth peaked some number of billion years ago. Of course, in 10 billion more years, there would still be a whole lot of warm red dwarfs, wouldn't there? That's where I'd go. :cool: