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Endless Universe - Beyond The Big Bang - P.J Steinhardt & N Turok

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The Vulcan
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« on: November 24, 2012, 21:32:00 PM »

So normally this should go under the book review section, but I'm just starting this book and unqualified to deliver a decent review in any way. This book really puts forward the Cyclical model as opposed to the big bang theory that I feel at least comfortable swallowing. The book is geared to the general reader and goes through all the stuff that I'm at least aware of - basically giving quickies on the big bang, the normal inflation model explaining it dark matter etc.

But this Cyclic Model is so exciting and refreshing it gives me goosebumps, it's something I really have never heard before - which is why I'm posting it here.

I do realise this isn't a scientiffic forum per se, but I'm just putting this out there. I have just a quick question:  Are there any peer reviewed articles on this - has this gained any acceptance?

 Are there any good criticisms on it and why should people oppose this model?

This book sounds very convincing and if anyone knows something about this cyclic model I'd love to hear it, but as this is such a new concept to me I'd really appreciate  some opinions and maybe a scientiffic article or two.

This really is a difficult one to wrap my head around and it seems to answer some difficult questions, but most of it fills me with a sense of wonder that I haven't really had from popular science books for quite some time
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Rigil Kent
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« Reply #1 on: November 25, 2012, 08:34:32 AM »

AFAIK the major problem for the cyclical model is that it hinges on the idea that the universe is dense enough to stop it from expanding indefinitely, and ultimately crunch. Observations seems to indicate the opposite: the universe appears to be flying apart ever faster, maybe due to that mysterious "dark energy". 

Even so, because of it's parallels with biological birth and mortality, I also very much like the idea of a cyclical universe. It somehow seems a more amicable place.

Rigil
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brianvds
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« Reply #2 on: November 25, 2012, 11:28:29 AM »

Even so, because of it's parallels with biological birth and mortality, I also very much like the idea of a cyclical universe. It somehow seems a more amicable place.

Rigil

As long as you don't happen to live at the time of the crunch. :-)
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Rigil Kent
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« Reply #3 on: November 25, 2012, 12:59:39 PM »

Laat my terugdink aan wat my peetpa altyd gesê het: "Die wêreld is wyd, maar hy druk my dat ek sk*t."
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Mefiante
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« Reply #4 on: November 26, 2012, 10:51:33 AM »

Observations seems to indicate the opposite: the universe appears to be flying apart ever faster, maybe due to that mysterious "dark energy".
That’s exactly right:  Current consensus among cosmologists and astrophysicists is that our universe is not heading for a Big Crunch in any finite future and that it will expand forever, eventually dying a heat death (when its entropy reaches an absolute maximum) after many trillions of years.

There is also a conceptual difficulty with the “bouncing” universe.  It assumes an absolute spacetime frame that somehow exists outside the universe which would allow an observer to place the expansion-contraction cycles into a temporal succession.  However, this is counter to current thinking in two ways.  First, as a matter of definition, the universe has no “outside” — at least none that is or ever could be physically accessible to us.  Second, said current thinking holds that spacetime is the very stuff created by the universe’s expansion and so an “external” spacetime reference frame is an odd thing to posit, perhaps even a contradictory one.  Moreover, any Big Crunch (which amounts to a complete resetting of everything) would, as far as we presently understand, comprehensively destroy all information about any “prior” state of the universe and so there cannot be any detectable traces of any possible pre-Big Bang state.

In conclusion, the “bouncing” universe must, for now at least, remain in the realm of speculative metaphysics.  By contemporary standards, it’s not a scientific hypothesis because there is no known way it could be tested.  Should new observations and/or thinking produce different models and/or better knowledge, it is of course possible that all of the preceding will change.

'Luthon64
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The Vulcan
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« Reply #5 on: November 26, 2012, 18:18:12 PM »

The book states that Dark Matter shaped the past and that Dark Energy will shape the future, I was always under the impression that both were one and the same thing and understood it as the repulsive force of Dark energy, okay so this is REALLY telling of the level ofmy ignorance  They explain how the dark matter was the dominant force at the birth of the universe and how dark energy is the dominant force now, the bit where the cyclic model differs from the inflationary model is that the CM disagree that this state of DE being dominant is permanent. Turok/Steinhardt points out that the initial singularity in Friedman’s equation, which we understand as the beginning of space-time is an assumption and not a proven fact.

I’m really impressed in the way this book is written, it feels like I’m watching Derren Brown doing those subliminal perception tricks of his, I mean this book reads like a well oiled machine  They have lots of really nice analogies and it has certain nuances that make it feel like their argument is the right one, kinda like a romance novel on science.

But although this may be a hypothesis, they actually claim it’s  theory stating that it fits all the scientific facts just as well as the inflation model, I always  assumed the inflation model to be THE theory although it doesn’t explain what happened before, you know how those arguments go with almost any theist! 

As you say Rigil this theory makes the world seem a more amicable place. However how do you wrap your head around the picture that our universe is not the only universe, that all 13,7 billion light years of the observable universe moves in some other dimension with lots of other bouncy bubbles if our universe alone is unimaginably huge? I hear what you say Mefiante, but it does make you think that maybe the big bang inflation model really isn’t the final answer yet (not that I ever said/though it was). I’m certainly no mathematician and I really am very ignorant about much in life and the more I learn, the more I realise that I cannot escape ignorance. Whatever the case may be - I love it when accepted thought is challenged and new ideas are explored, whether this will hold any water I’m unable to tell, that’s why I put this thread out there.

I am having trouble with the whole other “dimension”/space-time framework too, and I know cosmologists are more like science-philosopher, but they still are quite credible experts,

 I’m really battling forming an opinion on this one, about halfway through the book, but I’d be really love to know what scientific criticisms are out there challenging this one, for now I’m kind of a fence sitter on this one
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Rigil Kent
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« Reply #6 on: November 27, 2012, 07:36:28 AM »

... the CM disagree that this state of DE being dominant is permanent
For something to accelerate, it needs a force acting on it. Dark energy was suggested as the "force" behind the accelerating expansion. But the clue is in the name: the exact nature of dark energy is unknown. Does it push or pull? Is it a kind of reverse gravity? Dunno. So, if we know next to nothing about this force/energy, is it reasonable to assume that it will dissipate? Why shouldn't it get stronger?

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However how do you wrap your head around the picture that our universe is not the only universe
and
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I’m really battling forming an opinion on this one

I don't even try. I just enjoy it. Scientific speculation is infinitely more interesting than religious certainties handed down wholesale. It's both entertaining and awesome to read about the models that the brainy types come up with. You are quite right in wanting to delve a bit deeper before forming an opinion on the validity of the oscillating universe model.

Rigil
« Last Edit: November 27, 2012, 12:32:26 PM by Rigil Kent » Logged
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« Reply #7 on: November 27, 2012, 07:46:07 AM »

Neil Turok is a local okie.  He founded AIMS, where I go to get software upgrades (they only run Linux).  Therefore he must be right. The crunch phase will be interesting, as time runs backwards and we regain conciousness, grow younger and eventually get born in reverse, then dwindle into nothingness...
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« Reply #8 on: November 27, 2012, 09:35:38 AM »

However how do you wrap your head around the picture that our universe is not the only universe, that all 13,7 billion light years of the observable universe moves in some other dimension with lots of other bouncy bubbles if our universe alone is unimaginably huge?
I understand the universe to include everything that exists, not merely everything that can be observed.  It would therefore be contradictory to refer to more than one universe.  Perhaps we should rather talk of more than one cosmos to convey this idea.
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« Reply #9 on: November 27, 2012, 09:40:06 AM »

However how do you wrap your head around the picture that our universe is not the only universe, that all 13,7 billion light years of the observable universe moves in some other dimension with lots of other bouncy bubbles if our universe alone is unimaginably huge?
I understand the universe to include everything that exists, not merely everything that can be observed.  It would therefore be contradictory to refer to more than one universe.  Perhaps we should rather talk of more than one cosmos to convey this idea.
Quite so.  The 'uni' part of universe means one, so you can't have more than one universe.  It would be a multiverse, comprising two breasts.  Oh, sorry, that's a bosom.
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cr1t
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« Reply #10 on: November 27, 2012, 11:35:50 AM »

Neil Turok is a local okie.  He founded AIMS, where I go to get software upgrades (they only run Linux).  Therefore he must be right. The crunch phase will be interesting, as time runs backwards and we regain conciousness, grow younger and eventually get born in reverse, then dwindle into nothingness...


It's a interesting idea I'm not sure that time would reverse if the Universe shrank seems counter intuitive.

I've always liked the idea of cyclical universe but the Data points to it not being so.

What I think might happen is a big rip where space is pulled apart and all energy is returned to what makes up the outside.
Much like a soap bubble
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BoogieMonster
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« Reply #11 on: November 27, 2012, 11:57:23 AM »

I'm gonna ask a potshot in the dark question:

Some theory somewhere states our universe was created because quantum foam was doing it's thing, as that's what it does in absolute vacuum, and suddenly it did something novel and viola: Our universe.

Would it not follow that as our universe approaches absolute maximum entropy, such an event could occur again "inside" due to the extreme vacuum present?
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Mefiante
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« Reply #12 on: November 27, 2012, 12:03:57 PM »

It would be a multiverse, comprising two breasts.  Oh, sorry, that's a bosom.
Ja, the Higgs bosom.  It is thought to be the cause of certain mass commotions, especially when it is in a perked state of ample lift.  The Large Pelvis Collider is being prepped to test this hypothesis but the exact bump-n-grind frequency for establishing resonance is still uncertain.  Sweaty work continues on this vexing problem.

'Luthon64
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« Reply #13 on: November 27, 2012, 12:25:12 PM »

I'm gonna ask a potshot in the dark question:

Some theory somewhere states our universe was created because quantum foam was doing it's thing, as that's what it does in absolute vacuum, and suddenly it did something novel and viola: Our universe.

Would it not follow that as our universe approaches absolute maximum entropy, such an event could occur again "inside" due to the extreme vacuum present?

Well there is a thing called a white hole where it spits out stuff. Since it only exists in the math and nobody thinks we will see it, But the big bang looks a lot like a white hole so maybe space rips and new stuff comes pouring through.
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Mefiante
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« Reply #14 on: November 27, 2012, 12:31:06 PM »

Would it not follow that as our universe approaches absolute maximum entropy, such [a universe-producing] event could occur again "inside" due to the extreme vacuum present?
I’m not aware of any reason or principle preventing such a thing from happening.  However, the real question is whether it would be in any way detectable and/or have any consequences for our universe, as close to thermodynamic extinction as it may be.  The baby universe would produce its own spacetime manifold, separate from the parent universe’s, and so preclude, at least according to current theory, any information or mass/energy exchanges between the two.  There are large tracts of our universe that appear to be in state of near-static stable thermodynamic equilibrium (meaning the regional entropy there is asymptotically close to its maximum).  We haven’t detected any odd events (e.g. sudden disappearances of mass/energy or strong gravitational pulses, reflecting the mass/energy fraction “borrowed” for the production of the new universe) coming from such regions.

'Luthon64
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