Order and harmony vs disorder and chaos.

[revo74]

The word 'cosmos' is defined as an orderly harmonious systematic universe. There are some people who actually think that disorder, randomness and chaos is a better description of the Universe, but I disagree. For the most part the Universe exhibits a very high degree of order, harmony and regularity.

A poster said: ""Highly ordered"? More like "hardly ordered"! You see real order only on very specific scales. Once you get larger than galaxies, any semblance of "order" vanishes. Going down, you get intermittent order but mostly jumbled messes. You get pockets of order that are indistinguishable from the spontaneous order that are predicted by chaotic laws."

What do you think about this comment? Additionally, would you agree that the Universe exhibits a high degree of order, harmony and regularity? If so why? If not why?

Alfred Wegener said:
"Chaos is but misunderstood order"

 

[zaybu]

It depends how you look at the problem If you take the 2nd law of thermodynamics, entropy is always increasing with time. So the universe started with low entropy (high order) and since the Big Bang, disorder has been increasing. If you look at certain patches of the universe, galaxies are forming, but on the whole, disorder is winning over order.

 

[marcus]

Roger Penrose has some video lectures online where he discusses the entropy of the universe. I'll get a link if anyone wants to watch. One version of the talk is just slides+audio but to me it is easier to understand than the full video version.

 

[Smusko]

This is image is representative on how we think the universe looks on the largest scales.

[PLAIN]http://upload.wikimedia.org/wikipedia/en/c/c0/Local_galaxy_filaments_2.gif
from http://en.wikipedia.org/wiki/Galaxy_filament

Looks pretty chaotic.

 

[marcus]

Beautiful picture! Thanks Smusko.

One point Penrose explains is that the overall entropy has a big component which is the gravitational field entropy.

Normally we picture entropy neglecting gravity and using some conventional picture like gas molecules in a box.
If they start concentrated over in one corner that is low entropy and in time they spread out uniformaly to fill the box---uniform is high entropy. That is not the scientific definition but it is an intuitive way we have of thinking.

With the attractive gravitational field it is so to speak the opposite. Uniform field with all the matter spread out evenly is low entropy---like a huge uniform dust cloud.
Then over time stuff will tend to CLUMP--fall together in cobwebby clots, coagulate and curdle into wisps and lumps. Clumpy is high entropy.

That is different from the gas molecules in a box picture. If the gas happened to start out in clumps (regions of overdensity and regions of underdensity) it would spread out.

So as long as gravity is universally ATTRACTIVE then the way gravity-entropy goes is visually opposite from the way gas-entropy goes.

That's why I'd add something to what Zaybu said. The formation of a galaxy is not an isolated local exception to the rule. It is clumping. It is an increase in entropy.

However you should keep in mind that gravity might not always be attractive, under all conditions. If gravity should change sign (say at very high density) and become universally repellent, then the Second Law would favor uniformity and everything would want to be evenly spread out! So UNclumping would happen and UNclumpy would be the high entropy or equilibrium state----just like it is with gas in a box.

 

[zaybu]

Yes, Marcus is right. With gravity in the picture, the reverse for the case of gas diffusion is true. Here is a thumbnail that shows with gravity, a decrease in temperature will yield an increase in entropy. And this is what's happening since the Big Bang.

 

[Tanelorn]

Looking at Smusko's picture, which is great by the way, it appears that the universe is going to look pretty different when much older. It seems that whole Clusters of Galaxies are going to merge producing monster sized galaxies. Perhaps the only thing preventing an end to the present order in our universe, may be the accelerating expansion of the universe, by limiting the maximum size of such future super sized galaxies? Apparently, BCG galaxies are already 100 times the mass of the milky way and growing!

http://upload.wikimedia.org/wikipedia/commons/f/f5/Abell_S740.jpg