[KholdStunner]

so far there are only 2 theories of how the universe will 'end'

1- The big crunch: the gravity in the universe is so powerful that over-powers the expanding universe and it all comes back to one place and eventually we have a reverse-big-bang

2- The Big Freeze: the universe will continue to expand and all stars will eventually burn out and the universe will become dark, frozen, and time will have practically stopped.



do i have this info right? wrong? close? Please add-on or correct this.

[J.C.MacSwell]

Quote

so far there are only 2 theories of how the universe will 'end'

1- The big crunch: the gravity in the universe is so powerful that over-powers the expanding universe and it all comes back to one place and eventually we have a reverse-big-bang

2- The Big Freeze: the universe will continue to expand and all stars will eventually burn out and the universe will become dark, frozen, and time will have practically stopped.



do i have this info right? wrong? close? Please add-on or correct this.

Why will time practically stop?

[Ophiolite]

I think it's a poetic way of saying little will happen.

[KholdStunner]

well, actually, there will be massive black holes (the size of 10-100 billions stars) scattered through the universe almost everywhere you look. And some of them will continue to grow. And basically everything will be locked inside a blackhole. Atleast thats what i believe a subtheory of the big freeze is.

and yes i did not mean time will completely stop literally, like opiolite said

[Syd]

I like the idea of everything locked inside black holes. But i think it will be just another phase of the Big Freeze, couse after some time black hole will also disappear. Universe will be full of radiation, entrophy will be the highest/ or lowest, i cant remember how it goes/ Anyway, life will be impossible

[Bettina]

Life will be impossible for any species, but time per se will not stop. Although if nobody is left then what exactly is time good for.

Eventually even the black holes will evaporate though it will be many trillions of years after the last fire goes out before they do. I don't know how long it will take after that before matter itself breaks down too.

Not to worry.....

I expect another big bang will happen somewhere at sometime, and start this whole discussion over again :-)

Bettina

[star dust]

this discussion could be be happening all over the universe by loads of humanoid type creatures... weird.

[Severian]

The Big Freeze is more commonly known as 'The Heat Death of The Universe'.

[Martin]

Quote

Life will be impossible for any species, but time per se will not stop. Although if nobody is left then what exactly is time good for.

Eventually even the black holes will evaporate though it will be many trillions of years after the last fire goes out before they do. I don't know how long it will take after that before matter itself breaks down too.

Not to worry.....

I expect another big bang will happen somewhere at sometime, and start this whole discussion over again :-)

Bettina

For some reason I like the sentence
"Eventually even the black holes will evaporate though it will be many trillions of years after the last fire goes out before they do."

maybe it just a lucky way the words fell together i.e.style

I wish you would read a sample from Lee Smolin about cosmic natural selection

based on LQG one can argue that what are classically viewed as singularities at bigbang and blackhole are not singularities (LQG does not break down there but continues) and that one can merge into the other.

the collapse non-singularity at the pit of a BH can continue on to form the expanding non-singularity of a new BB
inflation (which occurs naturally in LQG without a lot of extra paraphernalia or fine tuning) can supply the necessary energy and matter for the new universe.

so while the mother U gets emptier and colder, other ones bud off from it at its blackhole branchpoints (these create new futures, time is not a single line)

well it is an interesting idea and Smolin is one of the best theoretical physicists around and the hypothesis is testable. he offers suggestions as to observational ways it might be shot down, if wrong.

he has a book about this called Lives of the Cosmos, or Life of the Cosmos
and there is stuff on the web under the heading "cosmic natural selection"
or CNS, but the only thing I have read is a technical paper that came out last year and is due to be published in a collection by IIRC Cambridge U press.
the technical paper is called "Scientific Alternatives to the Anthropic Principle"
http://arxiv.org/abs/hep-th/0407213
there is a link to a PDF of the full article if anyone wants. it has some
non-mathematical parts that are intuitive, you just have to look for them interspersed amongst the harder pieces

[Martin]

Quote

so far there are only 2 theories of how the universe will 'end'

1- The big crunch: the gravity in the universe is so powerful that over-powers the expanding universe and it all comes back to one place and eventually we have a reverse-big-bang

2- The Big Freeze: the universe will continue to expand and all stars will eventually burn out and the universe will become dark, frozen, and time will have practically stopped.



do i have this info right? wrong? close? Please add-on or correct this.

I think wrong.
I am glad you asked people to add-on. that was nice because it leaves open for a third or fourth possible picture. I will give a third possible picture.

first of all some people talk about the universe ending in a singularity. But singularities do not exist in nature, they exist in theories and they occur where theories break down, having reached the limits of their applicability
the way to fix a singularity is to improve the theory

the idea of "universe ends" is not clear
even if the universe gets too cold or hot or disorderly for any conceivable life, IT still goes on

it merely goes on in a condition which we living beings do not find interesting and which we dont want to think about.

so I think you might productively reword the question about the Extreme Future(s) of the universe, beyond where we can picture life surviving---I dont know how to word this

A third picture besides your Too Hot collapse and your Too Cold thinning out
is the picture that time branches where there is a black hole

so time if very FORKED

In this picture, our universe has already given rise to millions of new universes---since it makes a new one whenever a black hole forms

(because in LQG collapse leads to a bounce along which spacetime continues and in LQG inflation is generic: it happens without a lot of extra paraphernalia and finetunig, Ganashyam Date wrote a paper about this recently, and the universe exits from inflation automatically after a certain condition is reached---the so called 'graceful exit')

In LQG the bigbang non-singularity looks rather much like the blackhole non-singularity except viewed from the other side. Whatever matter collapses in the BH is amplified by inflation as space re-expands

so this Forked Time picture is one possible picture and it would not be very interesting unless it were possible to TEST it by experiment/observation. A scientific theory should make predictions that would allow it to be refuted or falsified if we then observe stuff that is contrary to the predictions.
If a picture doesnt make predictions it is just a daydream and doesnt explain anything.

So this picture has some predictions connected with it which are discussed in the Smolin paper
"Scientific Alternatives to the Anthropic Principle"
http://arxiv.org/abs/hep-th/0407213
maybe it will be tested and proven wrong, but it hasnt been proven wrong yet

[Auburngirl05]

Stephen Hawking was a major proponent of the "big crunch" theory, but not long ago he issued a statement saying that he had been wrong about many things in the postulation, basically "recanting". Astronomy and cosmology isn't a strong subject for me so I don't know the details of what he was mistaken on, just felt like it was worth mentioning.

[mustang292]

Pssssst! I know how the Universe will end! http://www.time.com/...0625/index.html <---It is explained right here. If the cosmos is moving at escape velocity, no Big Crunch.

[Bettina]

Quote

For some reason I like the sentence
"Eventually even the black holes will evaporate though it will be many trillions of years after the last fire goes out before they do."

maybe it just a lucky way the words fell together i.e.style

I wish you would read a sample from Lee Smolin about cosmic natural selection

based on LQG one can argue that what are classically viewed as singularities at bigbang and blackhole are not singularities (LQG does not break down there but continues) and that one can merge into the other.

the collapse non-singularity at the pit of a BH can continue on to form the expanding non-singularity of a new BB
inflation (which occurs naturally in LQG without a lot of extra paraphernalia or fine tuning) can supply the necessary energy and matter for the new universe.

so while the mother U gets emptier and colder, other ones bud off from it at its blackhole branchpoints (these create new futures, time is not a single line)

well it is an interesting idea and Smolin is one of the best theoretical physicists around and the hypothesis is testable. he offers suggestions as to observational ways it might be shot down, if wrong.

he has a book about this called Lives of the Cosmos, or Life of the Cosmos
and there is stuff on the web under the heading "cosmic natural selection"
or CNS, but the only thing I have read is a technical paper that came out last year and is due to be published in a collection by IIRC Cambridge U press.
the technical paper is called "Scientific Alternatives to the Anthropic Principle"
http://arxiv.org/abs/hep-th/0407213
there is a link to a PDF of the full article if anyone wants. it has some
non-mathematical parts that are intuitive, you just have to look for them interspersed amongst the harder pieces

Thanks for the links. Loop quantum gravity is new to me. I like it. :-)

From what I've read, and in plain english, the reverse big bang isn't going to happen and that leaves the universe ending in a singularity out the door. At least for now. This is "good" anyway, because life will be around longer in an open universe than a closed one since life can adapt to a cold environment more readily than a hot one. So, life will keep adapting and who knows, maybe whats left of us will end up frozen and preserved in stone for whatever miracle takes place next.

If the miracle doesn't occur at that stage, then matter itself, including black holes, will break down into photons and neutrinos and from what I'm told "Mother U" will end up as just pure radiation. Either way, it will be cold, dark, unpleasant and very unknowing if any intellegence can survive as radiation.

But like I said, another big bang can occur. If one did, why can't another.
I kind of wonder if there are more universes out there, but thats another story.


Bettina

[5614]

Bettina said:

the reverse big bang isn't going to happen and that leaves the universe ending in a singularity out the door.

These are all theories, none are certain... it is effectively impossible to currently rule out the main theories (1. we keep expanding or 2. universe stops expanding and all comes back in on itself aka 'reverse big bang') because we simply do not know and we personally probably never will, our great great etc grandchildren may.

[Bettina]

5614 said:

These are all theories, none are certain... it is effectively impossible to currently rule out the main theories (1. we keep expanding or 2. universe stops expanding and all comes back in on itself aka 'reverse big bang') because we simply do not know and we personally probably never will, our great great etc grandchildren may.

I agree. When we make statements like I did, it is based on the current thoughts. Consider a scale which tips both ways. If the evidence is strong to tip the scale much farther to one side, then that model is considered the accepted one. It doesn't mean its set in concrete.

Right now, the model is for a non collapsing universe and thats what I believe now unless the scale changes. In fact, I found some old cosmology books that had the scale tipped the other way, but they were old.

Bettina

[5614]

Bettina said:

Right now, the model is for a non collapsing universe and thats what I believe now unless the scale changes. In fact, I found some old cosmology books that had the scale tipped the other way, but they were old.

Sure the scales will tip with time, a quote from Einstein (when he was a professor was):
Student: "Einstein, this year's exam paper had the same questions as last year"
Einstein: "Yes, but this year all the answers are different"
(or something along those lines)

Is there a conclusive non-biased source that says that the scales are tipped? As far as I was aware it was not particuarly tipped either way, but then that's because I see/know an equally strong argument both for and against each of the two theories, so to me it's quite even.

[Bettina]

Quote

Sure the scales will tip with time, a quote from Einstein (when he was a professor was):
Student: "Einstein, this year's exam paper had the same questions as last year"
Einstein: "Yes, but this year all the answers are different"
(or something along those lines)

Is there a conclusive non-biased source that says that the scales are tipped? As far as I was aware it was not particuarly tipped either way, but then that's because I see/know an equally strong argument both for and against each of the two theories, so to me it's quite even.

Its here....
http://map.gsfc.nasa.../mr_limits.html

[5614]

OK, fair enough... in that case I'll settle saying:

Bettina said:

then that model is considered the accepted one. It doesn't mean its set in concrete.

NASA website in Bettina said:

The nature of the dark energy is still a mystery. If it changes with time, or if other unknown and unexpected things happen in the universe, this conclusion could change

[Ophiolite]

The most elegant solution would be that we live in an oscillating Universe. That would match the oscillating character of our theories: metaphysics reflecting cosmology.

[Bettina]

5614 said:

OK, fair enough... in that case I'll settle saying:

Quote

Originally Posted by Bettina
then that model is considered the accepted one. It doesn't mean its set in concrete.

Quote

Originally Posted by NASA website in Bettina's post
The nature of the dark energy is still a mystery. If it changes with time, or if other unknown and unexpected things happen in the universe, this conclusion could change

Not quite.....it really says this :-)

For the theory that fits our data, the Universe will expand forever. (The nature of the dark energy is still a mystery. If it changes with time, or if other unknown and unexpected things happen in the universe, this conclusion could change.)



__________________
Jonathan aka 5614
---
The funny thing about common sense is that it's not very common