Evolution & finished work

[RickD]

How is time dependent on the universe?

Here Hana. Maybe this will help:
http://www.reasons.org/articles/histori ... ng-of-time

[Byblos]

Why outside spacetime? There could be spacetime with not expanding space, therefore balanced. And inside it solar system as we have it.

Not according to Borde, Vilenkin, and Guth (I should say and still be anthropic).

How is time dependent on the universe?

Time is a measure of expansion (change). No expansion, no time.

But regardless of any and all of that, if you're postulating life without space-time in a static universe then please explain how this life began without alluding to time.

[PaulSacramento]

Great link Rick.

[1over137]

Why outside spacetime? There could be spacetime with not expanding space, therefore balanced. And inside it solar system as we have it.

Not according to Borde, Vilenkin, and Guth (I should say and still be anthropic).

Please, quote here what BVG theorem is. I so far only know that positive expansion rate leads to beginning.

How is time dependent on the universe?

Time is a measure of expansion (change). No expansion, no time.

No expansion, no time? Would in unexpanding universe be everything frozen? I do not think so.

But regardless of any and all of that, if you're postulating life without space-time in a static universe then please explain how this life began without alluding to time.

I am not postulating life without space-time.

[Byblos]

Why outside spacetime? There could be spacetime with not expanding space, therefore balanced. And inside it solar system as we have it.

Not according to Borde, Vilenkin, and Guth (I should say and still be anthropic).

Please, quote here what BVG theorem is. I so far only know that positive expansion rate leads to beginning.

Expansion not only leads to the conclusion that there was a beginning but also indirectly to the basic requirement for life. A universe cannot be said to be anthropic unless it is expanding at an average Hubble rate greater than zero. In addition to expansion, there are 2 more requirements for a universe to have the possibility of being anthropic, and those are 1) low entropy (which is extremely improbable), and 2) the constant anthropic values of our universe. Now we may even drop the 2nd one if we were to postulate a different universe than ours, with different laws of physics and entirely different forms of life. But even with 2) dropped, the high improbability of low entropy is enough to drive the point across. Roger Penrose calculated the probability of a low entropy universe happening by pure chance at 10^10^123 to 1 (that's a 10 with an exponent of 1 followed by 123 zeroes).

For much more details on this (BVG theorem and the anthropic values) I would suggest Robert Spitzer's "Contemporary Contributions of Physics and Philosophy for the Existence of God" or listen to his lectures on the anthropic principle and contemporary physics and God.

How is time dependent on the universe?

Time is a measure of expansion (change). No expansion, no time.

No expansion, no time? Would in unexpanding universe be everything frozen? I do not think so.

Of course it would be frozen, it's static.

But regardless of any and all of that, if you're postulating life without space-time in a static universe then please explain how this life began without alluding to time.

I am not postulating life without space-time.

Indirectly you are because space-time is created plank time after a singularity. If there's no singularity there is no expansion and therefore there is no space-time.

[RickD]

Great link Rick.

Reasons.org FTW!!!!!!

[1over137]

Here is what BVG theorem is about: (http://rfforum.websitetoolbox.com/file?id=1176639)

"IV Discussion.
Our argument shows that null and time-like geodesics are, in general, past-incomplete in inflationary models, whehether or not energy conditions hold, provided only that the averaged expansion condition H > 0 holds along these past-directed geodesics. This is a stronger conclusion than the one arrived it in previous work in that we have shown under reasonable assumptions that almost all casual geodesics, when extended to the past of an arbitrary point, reach the boundary of the inflating region of spacetime in a finite proper time (finite affine length, in the null case).
What can lie beyond this boundary? Several possibilities have been discussed, one being that the boundary of the inflating region corresponds to the beginning of the Universe in a quantum nucleation event. The boundary is then a closed spacelike hypersurface which can be determined from the appropriate instanton.
Whatever the possibilities for the boundary, it is clear that unless the averaged expansion condition can somehow be avoided for all past-directed geodesics, inflation alone is not sufficient to provide a complete description of the Universe, and some new physics is neccesary in order to determine the correct conditions at the boundary. This is the chief result of our paper. The result depends on just one assumption: the Hubble parameter H has positive value when averaged over the affine parameter of a past-directed null or noncomoving timelike geodesic.
The class of cosmologies satisfying this assumption is not limited to inflating universes. Of particular interest is the recycling scenario."

And so on. They also mention Steindhart-Turok cyclic model. I see that those two groups have disagreement. Hmmm.

Byblos, there can be time in the static universe. Here is what static universe is: http://en.wikipedia.org/wiki/Static_universe
There is time in physical equations (see http://arxiv.org/pdf/1203.4513v2.pdf). There are planets moving around the sun for example. Things are not static.

Indirectly you are because space-time is created plank time after a singularity. If there's no singularity there is expansion and therefore there is no space-time.

Why, if there is no singularity, there is expansion? And why "therefore there is no spacetime"? I do not understand.

[PaulSacramento]

In a parallel universe or a different dimensions, where the laws of physics are NOT like ours, would time be as we know it?

[Byblos]

Here is what BVG theorem is about: (http://rfforum.websitetoolbox.com/file?id=1176639)

And so on. They also mention Steindhart-Turok cyclic model. I see that those two groups have disagreement. Hmmm.

Of course they have disagreements but they haven't presented anything that would nullify the BVG theorem.

Byblos, there can be time in the static universe. Here is what static universe is: http://en.wikipedia.org/wiki/Static_universe
There is time in physical equations (see http://arxiv.org/pdf/1203.4513v2.pdf). There are planets moving around the sun for example. Things are not static.

As a physicist you understand this stuff infinitely more than I do so then I go back to my initial request, please describe how the anthropic principles (low entropy, units of complexity, constant laws of interaction, finite amount of mass) necessary to give rise to life, any kind of life, can be preserved in a static universe to have the possibility to give rise to any type of repeatable life form.

Indirectly you are because space-time is created plank time after a singularity. If there's no singularity there is expansion and therefore there is no space-time.

Why, if there is no singularity, there is expansion? And why "therefore there is no spacetime"? I do not understand.

Apologies, sometimes I think much faster than I type and I end up missing little key words that are significant to the meaning I am trying to convey (I did that in another thread and caused major confusion). The sentence should read as follows:

Indirectly you are because space-time is created plank time after a singularity. If there's no singularity there is NO expansion and therefore there is no space-time.

which I corrected where I initially posted but evidently not fast enough as you quoted the version with missing word. Sorry about that.

[1over137]

As a physicist you understand this stuff infinitely more than I do so then I go back to my initial request, please describe how the anthropic principles (low entropy, units of complexity, constant laws of interaction, finite amount of mass) necessary to give rise to life, any kind of life, can be preserved in a static universe to have the possibility to give rise to any type of repeatable life form.

I have to look first at the principles you mentioned. Maybe you can help me.

Indirectly you are because space-time is created plank time after a singularity. If there's no singularity there is NO expansion and therefore there is no space-time.

I do not agree with "therefore there is no space-time". Look at the static universe. The equations are similar to the nonstatic, just there is one constant more. There is space as well as time in the equations and are intertwined.

[PaulSacramento]

No such thing as a "Static universe" and while it can be postulated, there is no evidence for the possibility of it's existence.
Our is most definitely NOT static of course.
Of course there is no reason to believe that in a "static universe" time would behave the same way as in ours and the only reason it is theorized that it WOULD is because to theorize that it wouldn't would make the static universe "timeless" or "independant of time" and that is just not conceivable to physics as we know it.
Even though a static universe in of itself is would not be dependent on our laws of physics.

[Byblos]

As a physicist you understand this stuff infinitely more than I do so then I go back to my initial request, please describe how the anthropic principles (low entropy, units of complexity, constant laws of interaction, finite amount of mass) necessary to give rise to life, any kind of life, can be preserved in a static universe to have the possibility to give rise to any type of repeatable life form.

I have to look first at the principles you mentioned. Maybe you can help me.

I will give a brief description. For more details listen to the lectures on the subject I posted earlier (starting here).

Anthropic principles needed for any type of universe to have the possibility of producing any kind of life form:

1) Low entropy: Order is highly, highly improbable and disorder is highly, highly probable. Low entropy is an absolute requirement for any chance of a life form.

2) Units of complexity: Without units of complexity that tend to go from less complex forms to more complex forms there can be no life. From star formation we get carbon (and other basic elements), carbon has a specific way of coalescing and bonding that would allow for carbon-based life form. Robert Spitzer calles this "Complexification toward higher order activity", which basically means if we have a bunch of green goo and it turns into a bunch of red goo, so what? It's still goo. For life form to be so called it must be complex and it must be go from lower order activity to higher order (complex) activity.

3) Constant laws of complexity: There must be laws of complexity and they must be constant, otherwise we get no uniformity, no repeatability, and no life form.

4) Universal constants within an extremely narrow range that will give rise to life

There are more of course but those are the basic anthropic requirements that potentially can give rise to life (to go ahead and actually give rise to life such as in our universe, the universal constants will have to be narrowed down considerably more, making low entropy highly, highly, highly improbable, on the order of virtual infinity to 1 that it came by pure chance).

Here's the point though, you know what all these anthropic principles have in common? You guessed it, they all require an expanding universe.

Indirectly you are because space-time is created plank time after a singularity. If there's no singularity there is NO expansion and therefore there is no space-time.

I do not agree with "therefore there is no space-time". Look at the static universe. The equations are similar to the nonstatic, just there is one constant more. There is space as well as time in the equations and are intertwined.

I understand but Einstein's static universe theory has largely been discredited, has it not?

[PaulSacramento]

Yeah, based on Hubbles discoveries and a few other things.
I think it might have been one of Einstein's'/Sciences attempts to solve the issue of origin of life.
While one can appreciate science not wanting to fall into a "God of the gaps thing" and always look for an explanation but imagination can only get you so far.

[1over137]

I am not saying that we live in static universe. I was correcting your statements like there is no space-time in static universe and so on.

And by the way. There could be the same physical laws in static universe as in our universe up to the law concering the expansion of the universe. There would be the same Newton equations describing our every day experiences, Maxwell equations describing electromagnetism, quantum mechanical laws describing the world of the tiny, and so on.

[1over137]

I first will focus on the first mentioned principle.
I have found some intresting things concerning the low entropy state of early universe.

First, what low enetropy state of early universe means:
http://en.wikipedia.org/wiki/Entropy_(arrow_of_time):

"The thermodynamic arrow is often linked to the cosmological arrow of time, because it is ultimately about the boundary conditions of the early universe. According to the Big Bang theory, the Universe was initially very hot with energy distributed uniformly. For a system in which gravity is important, such as the universe, this is a low-entropy state (compared to a high-entropy state of having all matter collapsed into black holes, a state to which the system may eventually evolve)."

Our real world is quite orderly plus mystery of low entropy state of early universe:
http://www.edge.org/3rd_culture/carroll ... index.html:

"If you didn't know any better, if you asked what the universe should be like, what configuration it should be in, you would say it should be in a high entropy configuration. There are a lot more ways to be high entropy — there are a lot more ways to be disorderly and chaotic than there are to be orderly and uniform and well arranged. However, the real world is quite orderly. The entropy is much, much lower than it could be. The reason for this is that the early universe, near the Big Bang, 14 billion years ago, had incredibly low entropy compared to what is could have been. This is an absolute mystery in cosmology. This is something that modern cosmologists do not know the answer to, why our observable universe started out in a state of such pristine regularity and order — such low entropy. We know that if it does, it makes sense. We can tell a story that starts in the low entropy early universe, trace it through the present day and into the future. It's not going to go back to being low entropy. It's going to be compliant entropy. It's going to stay there forever. Our best model of the universe right now is one that began 14 billion years ago in a state of low entropy but will go on forever into the future in a state of high entropy.

Why do we find ourselves so close to the aftermath of this very strange event, this Big Bang, that has such low entropy? The answer is, we just don't know. The anthropic principle is just not enough to explain this. We really need to think deeply about what could have happened both at the Big Bang and even before the Big Bang. My favorite guess at the answer is that the reason why the universe started out at such a low entropy is the same reason that an egg starts out at low entropy. The classic example of entropy is that you can take an egg and make an omelette. You cannot take an omlette and turn it into an egg. That is because the entropy increases when you mix up the egg to make it into an omelette. Why did the egg start with such a low entropy in the first place? The answer is that it is not alone in the universe. The universe consists of more than just an egg. The egg came from a chicken. It was created by something that had a very low entropy that was part of a bigger system. The point is that our universe is part of a bigger system. Then you can start to try to understand why it had such a low entropy to begin with. I actually think that the fact that we can observe the early universe having such a low entropy is the best evidence we currently have that we live in a multiverse, that the universe we observe is not all that there is, that we are actually embedded in some much larger structure."

law entropy and inflation:
http://preposterousuniverse.com/eternitytohere/faq.html

"Does inflation explain the low entropy of the early universe?
Not by itself, no. To get inflation to start requires even lower-entropy initial conditions than those implied by the conventional Big Bang model. Inflation just makes the problem harder."

1) Low entropy: Order is highly, highly improbable and disorder is highly, highly probable. Low entropy is an absolute requirement for any chance of a life form.

I see.

Now to the expansion of the universe:
http://en.allexperts.com/q/Astrophysics ... sion.htm#b:

"the expansion of the universe results in a cooler universe, and therefore one with increased entropy (as required by the second law). It's almost as if an expanding universe is required, if the second law is to be obeyed.

The exception would be a contracting universe. What would happen if the universe contracted to a large black hole, or even if multiple small black holes were formed? Well, the entropy would also increase! When matter falls into a black hole, its ordered information is lost to the universe, so the universe becomes more disordered (increases entropy). This was proven by Kip Thorne and by Hawking. So it doesn't matter if the universe is expanding (cooling) or collapsing into black holes, it's entropy is always increasing!"

So, how does the law entropy principle leads to an expanding universe? It can lead also to a contracting universe. At the beginning there was a low entropy state of the universe. Second law of thermodynamics leads to increasing entropy, but increasing entropy does not lead to only expanding universe.