Is the Universe Analogous to Water with Entropy and Symmetry?

[closet mathemetician]

Could the universe have been at one time near the time of the big bang, in a highly symmetrical state, like liquid water? Consider that water has maximal entropy, AND maximal symmetry. Then, the maybe the universe underwent a phase change and "froze". When water freezes it acquires rigid structure and loses symmetry and its entropy decreases.

Suppose that mass is "frozen" spacetime "water" that has acquired rigid, non-symmetrical structure (broken symmetry) through undergoing a phase change. Then, suppose the universe starts to melt. As it melts, entropy increases. You eventually get "chunks" of "ice/mass" floating in "spacetime/water". The mass will eventually "melt" away as its entropy increases (and the symmetry of surrounding spacetime).

Maybe, like water, on a macro scale spacetime looks like a "continuous" and "smooth" medium on which we can do differential geometry. But when you "zoom in" on a molecular level, dg doesn't work and you need statistical mechanics to describe what's going on.

In phase changes, in between homogeneous regions, there are regions of chaotic behavior and fractal patterns and complexity emerge. Sort of what we see all around us. Maybe eventually the universe will "evaporate" and become a "gas".

I know all this is naive, and I hope this is the right forum for this. If not, sorry, feel free to move or delete.

Thanks for reading.

 

[twofish-quant]

Could the universe have been at one time near the time of the big bang, in a highly symmetrical state, like liquid water? Consider that water has maximal entropy, AND maximal symmetry. Then, the maybe the universe underwent a phase change and "froze". When water freezes it acquires rigid structure and loses symmetry and its entropy decreases.

That's sort of the standard model of cosmology says happened. The only difference is that in the universe entropy is increasing while temperature is decreasing and this is possible because the universe is expanding.

The way that things work is that the universe starts out as a hot low entropy gas, and as it cools, things start freezing. The process be which the elements form is something akin to freezing.

Suppose that mass is "frozen" spacetime "water" that has acquired rigid, non-symmetrical structure (broken symmetry) through undergoing a phase change. Then, suppose the universe starts to melt. As it melts, entropy increases. You eventually get "chunks" of "ice/mass" floating in "spacetime/water". The mass will eventually "melt" away as its entropy increases (and the symmetry of surrounding spacetime).

You can have entropy increase as temperature decreases in an expanding universe. Whether something freezes or not depends on temperature and not entropy. What is interesting about cosmology is that things freeze at different temperatures and that fact makes the universe what it is.

Maybe, like water, on a macro scale spacetime looks like a "continuous" and "smooth" medium on which we can do differential geometry. But when you "zoom in" on a molecular level, dg doesn't work and you need statistical mechanics to describe what's going on.

It works the other way. You start with the working assumption that the universe is smooth just like you can get very far by assuming the Earth is a perfect sphere. You think apply statistical mechanics to the smooth gas, and then you calculate the non-smoothness as a "small correction." Compare with observations and see what happen.

Something to remember is that the universe in general is a lot colder than temperatures we are used to, so that a lot of cosmology is done involving temperatures and pressures that we are used to. I'm always amazed why people find t=0 to the interesting, whereas I really find understanding the universe at t=450,000 years to be a lot more interesting because you can try to figure out t=450,000 years at temperatures at which water is a liquid.

I know all this is naive, and I hope this is the right forum for this. If not, sorry, feel free to move or delete.

It's not naive. The problem is that it's not original, and most of the ideas have been worked out before. If you have or can get your math level to the point that you can do differential equations, then you should pick up a book on physical cosmology.

Also people often understand why scientists have to read up on what people have done before. In a lot of fields you read up on what has been done before since this is dogma, that you are expected to believe. In physics, you read up on what people have done before so that you can not repeat what people have already thought about.

 

[Chalnoth]

Also people often understand why scientists have to read up on what people have done before. In a lot of fields you read up on what has been done before since this is dogma, that you are expected to believe. In physics, you read up on what people have done before so that you can not repeat what people have already thought about.

I don't think this is a distinction between physics and any other field of scholarly study. Having an understanding of what people thought of in the past is just a necessary prerequisite to having something intelligent to add to the discussion.

The real danger isn't learning too much about what people have thought of in the past, but instead learning too little. If a group of people becomes insular and stops paying attention to others outside of their small group, they're less likely to have the flaws in their arguments pointed out, and thus are more likely to be wrong.

 

[closet mathemetician]

Twofish-quant, yes I know that my post is along the basic lines of cosmological thought. The thing that just occurred to me was the connection between symmetry and entropy. I hadn't put those two together before. Even though, based on the responses, I haven't got it exactly right, I believe there is a deep connection there. Symmetry and entropy seem to be two of the most important concepts in modern physics.

And, yes, I'm working on my math. Lot's of math to learn, and its just a hobby, but little-by-little I'm getting there.

Thanks for your, and everyone's responses.

 

[Chalnoth]

Twofish-quant, yes I know that my post is along the basic lines of cosmological thought. The thing that just occurred to me was the connection between symmetry and entropy. I hadn't put those two together before. Even though, based on the responses, I haven't got it exactly right, I believe there is a deep connection there. Symmetry and entropy seem to be two of the most important concepts in modern physics.

It is most definitely the case that symmetry and entropy are two of the most important concepts in physics. However, I'm not so sure that there is a deep connection between the two, as they're pretty different.

Entropy is essentially a measure of probability. A higher-entropy configuration is a more probable one. The way we figure this out is we ask the question of exactly how many possible configurations of the underlying matter (e.g. specific positions and velocities of the individual atoms) can mimic the macroscopic observables (pressure, temperature, volume). Some sorts of configurations have many, many times more the possible configurations, and thus are higher in entropy.

Systems tend to move from low-entropy configurations to high-entropy configurations because the higher-entropy configuration is a vastly more probable configuration.

Symmetry, by contrast, is just a statement that if you make some specific sort of change to the system, the system's behavior is left unchanged. The interesting thing about this is that every time there exists such a symmetry, there is a conserved quantity that goes along with that symmetry. For instance, if you have a system that doesn't change when it is rotated by some amount, then that is a system that conserves angular momentum. If you have a system that behaves the same at one time as it does at a later time, then that is a system that conserves energy.

This is known as Noether's theorem, and it is especially interesting in quantum mechanics where we find that things like the conservation of electric charge come down to underlying symmetries in quantum mechanical wavefunctions. In fact, in quantum mechanics, you can describe all of the behavior of the three quantum mechanical forces just by describing the symmetries they obey and adding in a few free parameters that pop up (e.g. the masses of the particles).

Symmetry and entropy are interrelated, of course, like everything is. But it seems to me that they're rather different concepts.

 

[closet mathemetician]

Symmetry and entropy are interrelated, of course, like everything is. But it seems to me that they're rather different concepts.

Yes, I understand that, but they seem to both increase in the same direction. More entropy, more symmetry, less entropy, less symmetry. And the idea of the 2nd law of thermodynamics, that entropy increases over time seems to line up with the idea that the universe's symmetry has broken, but is gradually moving back toward a more symmetrical state. That was the main thing that I was focusing on.

 

[Chalnoth]

Yes, I understand that, but they seem to both increase in the same direction. More entropy, more symmetry, less entropy, less symmetry.

Yes and no.

This is true if you don't take gravity into account. But for self-gravitating systems, the opposite holds: gravitational collapse involves an increase in entropy, meaning that a highly symmetric cloud of gas has much lower entropy than a bunch of stars, while the bunch of stars has significantly less symmetry.