Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: Aidan on 05/01/2010 00:54:11
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When our Universe eventually succumbs to Entropy and all matter has decayed into a primordial soup of Elementary particles sometime in the next Trillion or so years would I be correct in surmising that The Universe would be Like a Quantum dot where Time and Space will become no more, there by allowing the Universe to go from being billions of light years in size to attaining a pre Big Bang state of Zero space Zero time = big bang. Maybe !?.
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Adrian - You wrote: "...would I be correct in surmising that The Universe would be Like a Quantum dot where Time and Space will become no more.." No, you would be wrong.
If the universe had a beginning it will always have an increasing age until such time as it might collapse in a Big Crunch. In addition, I believe you are referencing The Big Rip. Science had no evidence the increase in expansion will continue indefinitely any more then it had evidence it was always slowing down.
Specifically, science now accepts the early universe expanded faster then the speed of light. It is referred to as 'inflation'. But it stopped at some point. The name for this is 'a scalar field'. Its sort of a made up term that corresponds to a coil spring that is fully compressed, jumps out, but then stops jumping once it reaches its normal size.
I have seen no arguement the current accelerated expansion is not part of a similar scalar field and will come to similar abrupt end. No one knows.
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I thought a Big Crunch was an acceptable possibility for the end of the Universe, litespeed? If that is true, the matter should become very dense, small & hot, & spacetime would disappear momentarily while the singularity occurs, as the poster described..? Though describing a singularity as occurring is strange, since there is no time!
Adrian - You wrote: "...would I be correct in surmising that The Universe would be Like a Quantum dot where Time and Space will become no more.." No, you would be wrong.
So in the event of this Big Crunch, the OP would be right using what I've said above..
Is our understanding flawed? Can you clarify about exactly why?
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The 'Big Crunch' no longer really seems to be an option. In essence, it seems as though everything in the universe has effectively achieved escape velocity, so even if the 'force' that is causing the acceleration of the expansion of universe were to suddenly stop, gravity would not be strong enough to slow, stop and eventually draw everything back together again. The numbers are borderline, but it's generally accepted by the majority that they're beyond the margins of error.
Of course, this depends upon the acceleration of expansion of the universe being a real phenomenon in the first place, but that's a whole other kettle of fish to fry.
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What is Space & Time?
Why was there a Big Bang?
Why is our Universe going from a high energy state to a low energy state?
What will happen when the low energy state is reached?
Is space time the cause or an effect of High to Low, Hot to Cold matter state.
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What is Space & Time?
They are directions along which difference/change can occur. For example, you can't park two automobiles in exactly the same space. You could put one on top of the other, but then they'd still be in different spaces except that one 'space' is now on top of the other (which is probably now a little smaller than it was), instead of more normally for automobiles, to one side. Space then, is what allows many automobiles to exist at the same time without all being superimposed on each other. Space is also what allows you to get into your automobile and drive to a different space e.g. home (where you can then park in a different space, and walk to yet another space e.g. a pub/bar).
Time is what allows people who do shift work, and share a parking space at work, to both use the same parking space without their automobiles being superimposed upon each other. It's what also allows your automobile to rust, even when it's staying in the same place in space i.e. parked at home whilst you're at the pub/bar.
Space and Time are intimately related to each other and you can't really talk in any real depth about just one whilst ignoring the other. I think that one of the best illustrations of just how intimately space and time are linked is the phenomenon of relativistic time-dilation whereby the faster you travel through space, the slower you travel through time. The motoring analogy to this is to say that your automobile has a maximum speed of, let's say, 100 mph. If you drive at max speed on a North East heading of exactly 45°, you'll just think that you're moving at 100 mph. However, you could also say that you're travelling North at 70.7 mph and at the same time travelling East, also at 70.7 mph. Separating the North and East directions is what we do when we talk of space and time as separate things. If you now turn onto a more Northerly heading, let's say 30° East of North, whilst still driving at 100mph, you're now travelling North at 86.6 mph but only travelling East at 50 mph, even though you've maintained a steady speed of 100 mph all of the time.
Why was there a Big Bang?
Seems as good a way as any to start a party. Actually, are you really thinking about expanding universe vs. steady-state universe? The fact that the galaxies we observe seem to be moving away from each other suggests that they were closer in the past and the implication is that if you run time back far enough you'll reach a point where everything was in the same place. Given the amount of stuff that was squeezed into that same place, it seems likely that it all came out rather vigorously, rather than sedately, so a 'bang', and a 'big' one at that, seems an appropriate way to describe it. However, it wasn't an ordinary explosion in the conventional sense; it wasn't an explosion into space-time, but an explosion of space-time.
Why is our Universe going from a high energy state to a low energy state?
Entropy.
What will happen when the low energy state is reached?
Nothing. Literally. That is to say that there will be no energy gradient whereby energy may be allowed to run 'downhill' to do any work and change anything.
Is space time the cause or an effect of High to Low, Hot to Cold matter state.
Space-time doesn't seem to be a consequence of entropy but rather entropy describes the general behaviour of energy within space-time.
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What about Relativity!
How can you have Space Time relativity in an Entropic Universe, What is it that drives or limits the Universes fall into Entropy but space time, therefore is it not plausable that when Entropy is reached space time will cease.
Thereby rendering the Big Rip into what may in effect turn out to be a Big Crunch without any actuall crunching, just Zero Space Zero Time.
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What about Relativity!
How can you have Space Time relativity in an Entropic Universe, What is it that drives or limits the Universes fall into Entropy but space time, therefore is it not plausable that when Entropy is reached space time will cease.
Thereby rendering the Big Rip into what may in effect turn out to be a Big Crunch without any actuall crunching, just Zero Space Zero Time.
I'm not sure I followed that properly, but what do you mean by
What is it that drives or limits the Universes [sic] fall into Entropy
How is the universe falling into entropy? I'm afraid that means nothing to me.
What controls the rate of entropy is the gradient between two states, not space or time. Hence the statement:
therefore is it not plausable that when Entropy is reached space time will cease.
isn't true; there's no causality there.
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So when Entropy is reached & The Universe is filled with elementary particles all at the same energy level, Time shall continue as normal and space will keep expanding.
Unlikely.
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Until we can unify everything, and identify and explain the lowest level abstract fundamentals, we simply can't even make very educated guesses at what will happen. We can speculate, based upon our current understanding and knowledge but we need to remember that our current understanding and knowledge is dreadfully incomplete. This means that even our best speculations are almost guaranteed to be wrong, or at least incomplete in some respect.
However, it is through speculation that we devise new experiments to test and prove/disprove speculations, and when proved, turning the speculation into knowledge.
So whether it's likely, or unlikely, is just speculation until proved or disproved.
I'm not just trying to be disagreeable here, just that it's impossible to give a clear and definitive answer to some questions atm.
Although it was widely ridiculed at the time, Donald Rumsfeld's:
There are known knowns. These are things we know that we know. There are known unknowns. That is to say, there are things that we now know we don’t know. But there are also unknown unknowns. These are things we do not know we don’t know.
...statement is actually very profound (and probably one of the most profound things ever said by a politician in recent times) and applies most definitely to science.
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Very Good i Agree
Speculate Experiment Accumulate
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I don't know Aidan.
If we assume that all matter will erode, sort of? Into a gluon soup. Then the question might be if there still will be our arrow of time defining the universe.
Without that arrow there will be no distance, and no motion possible as seen from A to B.
And in such a place a quantum dot might be to big :)
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What is size without any means to measure it no time no space