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 End of the universe?

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gbowskill



Posts : 12
Join date : 2011-08-27

PostSubject: End of the universe?    Sat Aug 27, 2011 2:27 am

I have not been studying the universe and the physics behind it for very long, only about one year.
it has been very interesting for me and has opened my eyes to what is really happening out there and how insignificant we in the going's on of the universe.
I hope with this website i can ask question's and get answer's to expand my knowledge.
this is my first question, I'm not sure how it work's, i hope i just post a new thread and it gets read, any help would be helpful Smile
My question is as follows.
I've been reading Stephen hawking's books and if i have picked it up right he believes time travel into the future is theoretically possible.
Now if this is true and we can travel into the future then surely we can reach the point in time when space and time (everything) ENDS! now the end of the universe means the end of past, present and future so if it is the end of the past it means if the end of the universe is in the future and will happen then we should not be here! So is there a theoretical end to the universe?
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astrolover

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Age : 30

PostSubject: Re: End of the universe?    Sat Aug 27, 2011 2:28 am

Travel into the future is easy. It is called aging. Not traveling into the future is a bit harder.

The "end of the universe" in the sense that Hawking is using it is not the end of the entire space-time manifold. So, no it does mean the end of the past, present and future.

Hawking is basically a relativist, and in the generall theory of relativity the spacetime manifold is the whole enchilada -- past, present and future. It does not change. If you could somewhow be aware of the entire manifold, you would literally know everything -- the past, the present, and the future. That manifold does not change, and there is no dynamics when taken as a whole. All that changes is the "slice" that we see of it. Hawking is talking about changes in that slice.
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TomK

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PostSubject: Re: End of the universe?    Sat Aug 27, 2011 2:29 am

I think you're perhaps misunderstand what it would mean if time had an end (for instance, if all worldlines terminated at some future Big Crunch singularity). That wouldn't prevent us existing in our present time span. It would just mean that we couldn't travel indefinitely into the future, even at the standard rate of one second per second.
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gbowskill



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PostSubject: Re: End of the universe?    Sat Aug 27, 2011 2:30 am

So have i got this right?

If i found some way of jumping forward into a future date a experienced the end of the universe not the end of the spacetime manifold(which does not change), i would perish along with everything else in my slice, and everyone i left behind in the past to come to this future time would experience no change in there slice of spacetime and would carry on as normal?
if this is wrong please please corret.

thank you.
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gbowskill



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PostSubject: Re: End of the universe?    Sat Aug 27, 2011 2:30 am

TomK wrote:
I think you're perhaps misunderstand what it would mean if time had an end (for instance, if all worldlines terminated at some future Big Crunch singularity). That wouldn't prevent us existing in our present time span. It would just mean that we couldn't travel indefinitely into the future, even at the standard rate of one second per second.

thank you for your reply, can i ask.
Do you believe the universe will experience a big crunch singularity or do you believe there will be a different end?

thanks for your reply.
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astrolover

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PostSubject: Re: End of the universe?    Sat Aug 27, 2011 2:31 am

gbowskill wrote:
So have i got this right?

If i found some way of jumping forward into a future date a experienced the end of the universe not the end of the spacetime manifold(which does not change), i would perish along with everything else in my slice, and everyone i left behind in the past to come to this future time would experience no change in there slice of spacetime and would carry on as normal?
if this is wrong please please corret.

thank you.

Yes if you were there you'd end up becoming part of that big crunch!

Its unknown how the universe will end, if at all. Presently it appears that space is expanding at an accelerated rate causing distant galaxies to become further apart. If the whole universe was to follow this continued expansion then eventually the observable universe will get smaller as the space in between gets larger, galaxies will become more distant apart except those that are gravity bound to each other. Maybe resulting in whats termed as the big freeze. But I shouldn't worry too much, by then the earth and our sun will have long since perished.
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astro_alan

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PostSubject: Re: End of the universe?    Sat Aug 27, 2011 2:32 am

You're assuming what the "end of the universe" is. This has been a major question throughout human history, I imagine. Only in the last 70 years or so have astronomers, et al., had the instruments to determine a rough outline of how the universe must end, or at least what current observations imply. Paul Davies wrote a pretty good book on this very topic - The Last Three Minutes. Obviously a not-so in-joke on Steven Weinberg's The First Three Minutes,
A Modern View of the Origin of the Universe [1977], which is pretty much a must read, despite its age.
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gbowskill



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PostSubject: Re: End of the universe?    Sat Aug 27, 2011 2:32 am

from what I'm picking up it seems no one really does know how everything will end, alot of people have different views about this, i have my own theory as well as to how this universe may end its time.
I'm not saying I'm correct but i don't think what i have in mind is impossible.
I'm going to have a look for the book you suggest in the library, failing that i will get it online I'm sure.
thank you for your reply.
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