Thermodynamics and Cosmology

[coldcreation]

You describe an infinite universe then point to posts talking about the de Sitter model which is closed.

 

Without going into great detail, the de Sitter models (one of which is empty and the other with matter) are NOT closed. They are open, hyperbolic geometrically.

 

 

There is a static de Sitter model - but it looks nothing like your model. At the bottom of this page you can see a comparison between some different models including de Sitter's.

 

The models shown in your link are all expanding models, if I am not mistaken. Indeed the is an expanding model called the Einstein de Sitter model but ironically it is neither Einstein's of de Sitter's. Recall, in 1917, when the infamous static models by Einstein and de Sitter emerged, the universe was not yet expanding. The expanding version came much later.

 

 

Are you suggesting that as the mass of your universe changes there is no corresponding global curvature because de Sitter found a static solution to the field equations.

 

No. You introduce an important point that I did not elaborate on in my previous post. How does a change in global mass density affect the global curvature. The simple answer is that is does, but the deviation from an isotropic curved spacetime is small, as evolution is very slow in the look-back time. The deviation will only manifest itself at great distances, compatible with distant supernovae type Ia observed in the deep universe.

 

 

In fact de Sitter's static solution depends on the universe being about twice the size of the observable universe because the temporal component is variable and vanishes at the "equator" of an arbitrary coordinate.

 

Where did you get this from?

 

 

Also, there is a difference between a GR cosmological model that has static coordinates and one that is static in terms of expansion. Oddly enough de Sitter had them all. In terms of expansion he had a static model and an expanding model, and in terms of coordinates his "static expansion" model he wrote in static Euclidean space coordinates (like einstein) and with non-static hyper-hyperboloid Minkowski space-time coordinates. But, the only reason his static-static model was static was because of a cosmological constant - just like Einstein's.

 

 

What do you mean by "static in terms of expansion," by "static expansion"?

 

True, the cosmological constant was present (and nonzero) in at least one de Sitter model.

 

 

The interesting point is that there are static solutions to the field equations: three of them to be precise. One has a spherical geometry, one has a Minkowski metric, and the other, de Sitter's, a hyperbolic geometry. The latter is the only one that is tenable; based on observational evidence

 

 

 

In any case, I see your model as having nothing substantial in common with any of these.

 

It does actually. There is only a minor difference between the CC interpretation and the hyperbolic de Sitter model, with respect to the value of lambda.

 

 

 

I believe the combination of increasing mass + GR + no expansion would lead to a gravity well where all the matter has settled. Given enough time this is the solution gravity finds because it is only attractive and all matter responds to it. Everything (eventually) would swirl down the gravity drain.

 

Absolutely not. That happens only when gravity is considered an attractive force, not when gravity is correctly taken as a curved spacetime phenomenon (not to mention the physical role of lambda). In the case of global curvature there is no central gravitational well. There is very little observable difference between a cosmological Doppler redshift (a change in the scale factor to the metric), and redshift due to propagation through a curved spacetime continuum: a general relativistic redshift. This is not a gravitational redshift of a photon departing from a compact source, it is a global effect due to the nonzero mass-energy density of the manifold.

 

Whether one chooses to describe a redshifts as curved spacetime phenomenon (global gravitational shifts, if you will) or as a Doppler effect depends on which coordinate system is chosen: a non-Euclidean metric?a hyperbolic spacetime in accord with GR preferably?or a flat, Euclidean, special relativistic space with a changing scale factor to the metric, respectively.

 

All all spectral shifts can be understood as gravitational or Doppler. As far as I know, these are the only interpretations possible for cosmological redshift z since they are both wavelength independent over the entire range of the spectrum (over 19 octaves). Any other result would not be allowed by observation.

 

 

 

 

CC

[modest]

The interesting point is that there are static solutions to the field equations: three of them to be precise. One has a spherical geometry, one has a Minkowski metric, and the other, de Sitter's, a hyperbolic geometry. The latter is the only one that is tenable; based on observational evidence

CC

De Sitter's model IS a minkowski metric. I think you should research de Sitter's model before you compare it to your own. Firstly - de Sitter had one model that continued to evolve but kept the same basic structure. Secondly - his model cannot be said to be Euclidean or Minkowski as he worked it out both ways. Do you know what this means? Different coordinate systems describing the same model. One description has static coordinates and the other is more cartesian-like. His first description is thus:

 

a hypersphere of 4 dimensions embedded in 5 dimension Euclidean space with imaginary time coordinates. This would be called the static solution as the coordinates are "static". This is not called "the static solution" because it "does not expand". Rather, it does expand. In fact Einstein's main objection to this model was that it is not globally static. This same model was originally described like this:

 

a 4-hyper-hyperboloid embedded in a 4+1 Minkowski spacetime with a space-time like time coordinate. This is the non-static coordinate system. It has the Cartesian-like coordinate system. And yes - it is a Minkowski metric.

 

So, do you see how strange it sounds for you to say there are three solutions to the field equations that can be static:

• spherical geometry

• Minkowski Metric and

• hyperbolic geometry

and your model best fits the hyperbolic one which is de Sitter's? Because de Sitter's single model can be any and is all of these? The Friedman-Robertson-Walker Model can certainly be hyperbolic geometry :( and I know how much you hate that model! So - is that really the basis that you're building your model on? :lol:

 

If you do not understand the difference between de Sitter's static model and Einstein's globally static model or even the difference between spherical or hyperbolic space-time then you need to go back to the CC model-o-universe drawing board.

 

I don't know what turned you on to de Sitter's model (I personally find it very insightful) but I think you have been misled about the basics. The very best mathematicians have a hard time extrapolating GR into a cosmological model. I don't think Einstein really understood de Sitter's model - at least not until Klein explained it to him. So, I don't understand why it works the way it does. But, I would suggest studying the basics behind these geometries and metrics before trying to equate them to your model.

 

-modest

[Little Bang]

CC, I claim the BB was not from a black hole as you know, therefore the BB would not be an artifact.

[coldcreation]

...snip...I don't know what turned you on to de Sitter's model (I personally find it very insightful) ...snip...

-modest

 

 

Since this discussion has deviated way off-topic, I have moved it to this thread, Redshift z, where the discussion is on-topic.

 

 

CC

[Pluto]

Hello All

 

I posted a post.

 

No response.

 

Does this mean this link is closed.

[modest]

Hello All

 

I posted a post.

 

No response.

 

Does this mean this link is closed.

You were talking about galaxies, jets, and black holes. I didn't understand how this was being related to thermodynamics as part of the discussion here. Do you believe, perhaps, that black holes cannot exist because they violate thermodynamics? If so, how so?

 

-modest

[coldcreation]

Hello CC

 

The compacted ultra dense plasma matter(UDPM) that some people call Black holes is the subject of Thermodynamics and Cosmology.

 

The neucelon (UDPM) similar to any compacted cores have properties of plasma. One interesting property is the Z-Pinch process that is responsible for the creation of jets.

 

We see this in the evolution of galaxy formation and the relationship with the size and activity of the neucleon.

...

z-pinch dynamics

 

While the Z-pinch sounds compelling, it has little if anything to do directly with thermodynamics, or cosmology. Correct me if I'm wrong.

 

The link you provide, does not mention thermodynamics, entropy, conservation, energy, cosmology.

 

It's a great way to generate high-temperature/high-density plasmas though.

 

Why not start a new thread on it? I'll participate.

 

 

CC

[Pluto]

Hello All

 

Thank you CC

 

I will.

 

Be back later,,,,,,,,visitors at the door.

[Brinnie]

“The test of extrapolation to the most distant future does not, I think, disclose any definite weakness in the present system of science—in particular, in the second law of thermodynamics on which physical science so largely relies. It is true that the extrapolation foretells that the material universe will some day arrive at a state of dead sameness and so virtually come to an end; to my mind that is a rather happy avoidance of a nightmare of eternal repetition. It is the opposite extrapolation towards the past which gives real cause to suspect a weakness in the present conceptions of science. The beginning seems to present insurmountable difficulties unless we agree to look on it as frankly supernatural. We may have to let it go at that…Instead of honestly facing the intricacies of our problem, we may be led to think that its difficulties have been solved when they have only been swept over the boundary. Sweeping them back and back, the pile increases until it forms an unclimbable barrier. Perhaps it is this barrier that we call “the beginning.” (Eddington, A. 1958, The Expanding Universe, pp. 124-125)

 

Nothing valid is created without nature.

 

Coldcreation

 

i dont underrrstand the 1st paragragh, only the last sentance. can u put it into simple engrish 4 me?

 

[Moontanman]

There is another option to the big crunch and heat death for the universe. see it here.

 

When Branes Collide: Science News Online, Sept. 22, 2001

 

Michael

Mistral wind

[Little Bang]

Brinnie, in his first paragraph he is saying that he does not have a problem with the universe expanding forever only with it having a beginning. I don't really understand his logic since he is a steady state guy.

[modest]

 

i dont underrrstand the 1st paragragh, only the last sentance. can u put it into simple engrish 4 me?

 

 

Yeah CC, prove broken thermodynamic symmetry at t=0 to a scientologist, would ya?

 

Little Bang, I think CC was looking more toward the problem at the singularity than the lack of a problem with the heat death in that quote - but I'll let the guy speak for himself.

 

-modest