Time has a beginning?

[Frankenstyle]

I was asking why, at that instant when a singularity appears out of "nowhere," "nothing" and "timelessness" the laws of thermodynamics are not violated? I don't believe anyone has explained that -- if there is an explanation.

First let's take "time" out of the thermodynamics question. Expansion was the expansion of spacetime blah, blah, blah, you don't violate cause and effect until time becomes enough of a separate entity from space for it to be in effect...blah, blah. I don't mean to sound dismissive, but that's a dead horse that won't take any more beatings.

As for "something coming from nothing", the vacuum of space is boiling with "something coming from nothing". Look up vacuum fluctuations, and the Casimir effect, or Hawing radiation. Something from nothing is a non issue. As far as entropy, well the extremely early universe was highly ordered, and it's all been winding down from there. If fact, if anything, invoking a Big crunch comes a lot closer to violating thermodynamics. Which is why, if the universe did oscillate, the numbers don't support it bouncing forever.

That said, I admit I'm skimming over some of the kinks in the fine details. Mostly because the big picture holds up, and the rest is spit and polish.

You seem very defensive about the work of Steinhardt and Turok, but no one is attacking them personally. They're a couple of guys with an idea that they're throwing against the wall to see what sticks. Personally, I think it'd be neat-o if they're work adds to our understanding of how thing work.

Realistically, I don't think that's too likely a scenario, but I sincerely wish them better luck with their next hypothesis.

Also, I just want to add that I'm confused by your insistence that the scientific community is led by tradition to some common comfort zone. Certainly people are often creatures of habit, but do you really think there is such a concentrated effort to "stick to the old ways"?

It reminds me of the spiritualists who insist that science refuses to accept the existence of ghosts because it'd "Blow their minds". I've always found that such a funny mindset, because who wouldn't want to be the guy who discovered proof of an afterlife? Your name would be better known than Einstein. As long as your evidence held up under scrutiny.

I guess my point is that you may want to consider that Steinhardt and Turok's ideas aren't being dismissed because no one is looking into them. It may be that they are being dismissed because you don't have to look that far into them, before it all starts to fall apart.

 

[Ragnarok]

That would be true for a real rubber sheet, where stretching it in one direction affects how hard it is to stretch it in another. For the analogy you have to assume an infinitely stretchable rubber sheet, so that stretching it doesn't alter how much force is needed to stretch it further.

Although in all fairness I should point out that there are far more than just one problem with this kind of analogy.

One 'fer instance' being that the universe is not 2-dimensional like a rubber sheet, and has area above and below it. It sounds more like a slab of see-through rubber, with billions of rice krispies and their crumbs scattered within it.

 

[Perpetual Student]

Steinhardt and Turok present an interesting alternative to the consensus model of cosmic history. Unfortunately, I don't have any special knowledge that would enable me to claim that their model is superior to or inferior to mainstream thinking. In fact, I lack the expertise in physics and cosmology to ever decide that question on my own, which is why I come here for input.
As I have already stated, I am particularly unhappy about concepts like time having a beginning, so that I am drawn to the S & T cyclic model.
I find it discouraging that so many here, who appear to have a good knowledge of cosmology, are quite negative about the cyclic model -- it certainly does make me doubtful of S & T's theories. However, I remain encouraged by the fact that these two men are first rate theoretical physicists, who have made serious contributions to physics and cosmology -- so, they are not to be dismissed like a couple of plasma cosmologists or electric universe head-cases.
The fact that no one here appears to give S & T even a shred of credibility makes me wonder whether there might not be an unwillingness to speculate out of the box. As I indicated, Steinhardt and Turok are not a couple of cranks!

 

[Reality Check]

Steinhardt and Turok present an interesting alternative to the consensus model of cosmic history. Unfortunately, I don't have any special knowledge that would enable me to claim that their model is superior to or inferior to mainstream thinking. In fact, I lack the expertise in physics and cosmology to ever decide that question on my own, which is why I come here for input.
As I have already stated, I am particularly unhappy about concepts like time having a beginning, so that I am drawn to the S & T cyclic model.
I find it discouraging that so many here, who appear to have a good knowledge of cosmology, are quite negative about the cyclic model -- it certainly does make me doubtful of S & T's theories. However, I remain encouraged by the fact that these two men are first rate theoretical physicists, who have made serious contributions to physics and cosmology -- so, they are not to be dismissed like a couple of plasma cosmologists or electric universe head-cases.
The fact that no one here appears to give S & T even a shred of credibility makes me wonder whether there might not be an unwillingness to speculate out of the box. As I indicated, Steinhardt and Turok are not a couple of cranks!

IMHO, everyone here has given S & T more than a "shred of credibility".
The earlier cyclic models had problems with the laws of thermodynamics. The S & T model seems to have got around this. But there other problems such as its basis in the (so far incomplete and not fully understood) string theory and uncertainty as to what actually happens when two branes collide.

And once again you are appealing to argument by authority. Steinhardt and Turok are definitely first rate theoretical physicists. This does not say anything about the correctness or not of their theory.

I would definitely not characterize their theory as "speculating out of the box". It is good theory looking for more theoretical work and experimental verification (not a speculation).

 

[Jiddu]

“You campaign in poetry. You govern in prose.”

---Mario Cuomo

"Always be a poet, even in prose"

-Baudelaire

 

[Perpetual Student]

IMHO, everyone here has given S & T more than a "shred of credibility".

I don't see the basis for that comment. Virtually all responses here have been quite negative.

The earlier cyclic models had problems with the laws of thermodynamics. The S & T model seems to have got around this. But there other problems such as its basis in the (so far incomplete and not fully understood) string theory and uncertainty as to what actually happens when two branes collide.

It appears there are problems with all cosmological models. Analogous to the question of what happens when two branes collide, in the consensus model we have the question of what happens at t = 0.

And once again you are appealing to argument by authority. Steinhardt and Turok are definitely first rate theoretical physicists. This does not say anything about the correctness or not of their theory.

All I am saying here is that their credentials provide them with a basis for considering their ideas -- not that they are correct. As a layman, I must consider credentials to determine credibility. You may have the expertise to decide on your own; I do not.

I would definitely not characterize their theory as "speculating out of the box". It is good theory looking for more theoretical work and experimental verification (not a speculation).

OK

 

[sol invictus]

I don't see the basis for that comment. Virtually all responses here have been quite negative.

Negative responses to a theory do not mean the authors aren't granted a even a "shred of credibility". The whole point of science is to evaluate ideas on their own merits, and not on the merits of their creators or proponents.

Steinhardt is one of the inventors of inflation (did you know that?). He's an extremely good physicist that has made major contributions to several fields. Same goes for Turok, although he's perhaps not quite on the same level. But that has nothing at all to do with whether or not the cyclic universe is a good theory.

Theories are theories, people are people - you need to learn to separate them.

It appears there are problems with all cosmological models. Analogous to the question of what happens when two branes collide, in the consensus model we have the question of what happens at t = 0.

We may have a question - since the model simply doesn't include a prediction about t=0 - but we do not have a problem. The model doesn't depend on what happened at t=0. Cyclic models do depend on that, and moreover they have a serious inconsistency if they're eternal, or precisely the same issue (about origins) if they're not, like the ST model.

The ST cyclic models do not avoid the issue of the beginning of time (see the quote Skwinty posted by Steinhardt, in case you missed it - even he agrees). So if that's what you are looking for, their models don't do it.

 

[ponderingturtle]

Fundamental physics can actually be quite important. The current universe is a direct result of whatever happened before, so understanding what happened before leads to better understanding of what is happening now. And what is happening now is important because, aside from knowledge for its own sake, it leads to things like nuclear fission, hopefully fusion soon and who knows what else after that.

If we can produce testable theories about it then it will be very useful and important. Arguing over untestable hypothosises, is the provenance of religion after all.

Anyway, everyone knows that angles don't dance. They're not acute enough.

Bad spellers of the world Untie!

 

[Reality Check]

The ST cyclic models do not avoid the issue of the beginning of time (see the quote Skwinty posted by Steinhardt, in case you missed it - even he agrees). So if that's what you are looking for, their models don't do it.

The quote from Steinhardt posted by Skwinty is about the end of the cycles. Whether there is a beginning to the cycles is addressed further down the web page - http://www.physics.princeton.edu/~steinh/cyclicFAQS/index.html

Has the cyclic model been cycling forever?
It is possible that the universe has been cycling forever into the past and will cycle forever into the future without violating any known laws of physics. On the other hand, it is also conceivable that the universe did have a beginning and settled into regular cycling behavior. In the latter case, there would only be a finite number of cycles in our past. Both ideas are currently being explored. The issue is more of a theoretical issue than a practical one because the basic predictions of the cyclic model are insensitive to whether there was a beginning or not. In either case, every observer today has undergone an enormous number of cycles of acceleration and dilution of matter since that earlier era. Particles or radiation emitted in a hypothetical pre-cyclic phase would be annihilated or thermalized by the present epoch. Hence, there would be no imprint to inform the observer whether the number of previous cycles has been few or infinite. (Some argue that, as a matter of principle, even if there were an infinite number of cycles in the past, there must have been something that preceded the cycling. The argument is based on analogy with inflation, for which it is known that the expansion phase is "geodesically incomplete," a technical way of saying space-time must include something in the past other than inflationary expansion: there must be some beginning or pre-inflation phase or cosmic singularity. However, because of the bounces, it is not clear whether the same arguments apply to cycling.)

 

[sol invictus]

The quote from Steinhardt posted by Skwinty is about the end of the cycles. Whether there is a beginning to the cycles is addressed further down the web page - http://www.physics.princeton.edu/~steinh/cyclicFAQS/index.html

If there is always an end after a finite number of cycles, then there was also a beginning (because if not, an infinite number of cycles have already taken place, contradicting the assumption).

The way he is trying to escape that is to use inflation... since inflation produces a lot of volume, it's possible (in a special kind of global picture) for new regions to keep appearing. Each region lasts only a finite number of cycles, but several new ones are produced during that period.

That same logic (or lack of it) applies to some models of ordinary inflation too. There are many problems with it - but regardless of that, my point stands: you gain nothing from cyclic models that wasn't there in inflation, and you pay a high price in new unwarranted assumptions.

 

[Perpetual Student]

Negative responses to a theory do not mean the authors aren't granted a even a "shred of credibility". The whole point of science is to evaluate ideas on their own merits, and not on the merits of their creators or proponents.

How much credibility do you give the authors?

Steinhardt is one of the inventors of inflation (did you know that?). He's an extremely good physicist that has made major contributions to several fields. Same goes for Turok, although he's perhaps not quite on the same level. But that has nothing at all to do with whether or not the cyclic universe is a good theory.

Yes, Steinhardt discusses his role with inflation in the book.
When did I say that their credentials makes their theory good? From my layman's perspective, it gives them credibility. But obviously there are many cosmologists with equal or even superior credentials that do not agree with them. So, I come here for additional input and discussion.

Theories are theories, people are people - you need to learn to separate them.

More arrogance!

We may have a question - since the model simply doesn't include a prediction about t=0 - but we do not have a problem. The model doesn't depend on what happened at t=0. Cyclic models do depend on that, and moreover they have a serious inconsistency if they're eternal, or precisely the same issue (about origins) if they're not, like the ST model.

Looks like a problem to me, if you have no clue about t=0!

The ST cyclic models do not avoid the issue of the beginning of time (see the quote Skwinty posted by Steinhardt, in case you missed it - even he agrees). So if that's what you are looking for, their models don't do it.

RC has already provided more of Steinhardt's comments, specifically, "It is possible that the universe has been cycling forever into the past and will cycle forever into the future without violating any known laws of physics."

 

[Reality Check]

RC has already provided more of Steinhardt's comments, specifically, "It is possible that the universe has been cycling forever into the past and will cycle forever into the future without violating any known laws of physics."

And the next sentence is: " On the other hand, it is also conceivable that the universe did have a beginning and settled into regular cycling behavior."
In other words: Steinhardt is stating that the universe may or may not have have had a beginning and that further research is needed ("Both ideas are currently being explored.").

 

[Perpetual Student]

And the next sentence is: " On the other hand, it is also conceivable that the universe did have a beginning and settled into regular cycling behavior."
In other words: Steinhardt is stating that the universe may or may not have have had a beginning and that further research is needed ("Both ideas are currently being explored.").

That alone is an improvement over the "beginning of time" scenario of some theories.

 

[sol invictus]

How much credibility do you give the authors?

Beyond what I already said about them? I'm not sure what you're asking.

Looks like a problem to me, if you have no clue about t=0!

No clue? No, that's not accurate. There are many guesses; the cyclic model is one.

RC has already provided more of Steinhardt's comments, specifically, "It is possible that the universe has been cycling forever into the past and will cycle forever into the future without violating any known laws of physics."

Anything which cycles forever violates the laws of thermodynamics.

 

[Reality Check]

That alone is an improvement over the "beginning of time" scenario of some theories.

What he is saying is that the ST theory may or may not be infinitely cycling. It may or may not have a beginning of time. It is not an "improvement' - it is an issue to be resolved.

 

[Perpetual Student]

Originally Posted by Perpetual Student
How much credibility do you give the authors?
s.i.:Beyond what I already said about them? I'm not sure what you're asking.

It was a rhetorical question. In the context above, I am not asking about the authors outside of the theories they present in their book. You clearly give their theories no credibility.

 

[Perpetual Student]

What he is saying is that the ST theory may or may not be infinitely cycling. It may or may not have a beginning of time. It is not an "improvement' - it is an issue to be resolved.

It certainly is.

 

[Tubbythin]

Looks like a problem to me, if you have no clue about t=0!

That strikes me as somewhat analogous to the creationist not accepting evolution because it doesn't explain abiogenesis.

RC has already provided more of Steinhardt's comments, specifically, "It is possible that the universe has been cycling forever into the past and will cycle forever into the future without violating any known laws of physics."

How do they get around the 2nd law of thermodynamics (without violating the first)?

 

[Mikeuk]

Many many years ago I recall a theory that invoked 'Time Dilation' with the stae of the early universe i.e. because all the matter in the universe was moving so fast and inflation was increasing way beyond the speed of light, then any way of describing time would have been virtually meaningless.

Unfortunatly my maths/understanding is not up to working this out. Is there any evidence that time would be inconsistent in the very first instants after BB ?

 

[Reality Check]

How do they get around the 2nd law of thermodynamics (without violating the first)?

Paul Steinhardt's CYCLIC MODEL FAQs page gives the answer.