Earlier quoted context omitted.
Entropy is more accurately defined as hidden information, or the number of possible microstates that a system in a certain macrostate could have. Here's a great lecture by Leonard Susskind on the topic: https://www.youtube.com/watch?v=n7eW-xPEvoQ
What distinguished macrostates from each other? What distinguishes a macrostate from a microstate?
Battling Entropy
51–60 of 62 posts
Re: Battling Entropy
#52Earlier quoted context omitted.
Wait, what happens if we look into the collapsing of the galaxy from an informational-theoretic view of entropy? As far as I know, thermodynamic and informational-theoretic entropy are the same except for the Boltzmann constant. It certainly seems to me that the informational entropy of the galaxy is lower than the original gas cloud. That is, if I wanted to describe the state of a single atom in the gas cloud (lets…
I'm less familiar with the information perspective of this topic. Why would you need more bits to describe a single atom in a galaxy vs a single atom in a gas cloud? If a set amount of bits are required to describe an atom then that amount will not change whether or not the atom is in a galaxy or a gas cloud.
If we have a lot of similar locations, we can use compression to reduce the amount of bits required.
A basic example of this compression would be to take the current location and represent it with two parts. The first gives the location accurate to the nearest light-second, and the second gives the location within that cubic light-second.
Now, we can do huffman-coding [1] on the first part. In a gas cloud, the atoms are distributed over all possible cubes of light seconds. In a planetary system, they are concentrated in a much smaller set of planetary light seconds. This would make the huffman-coding a lot more efficient.
There are almost certainly smarter compression methods than what I just described, but the above serves as an illustration. The information-theoretic entropy of a distribution can be seen as a lower bound on the average amount of bits needed when applying compression to the distribution. I believe (am not sure) that this is a tight lower bound (i.e. there exists a compression method that gets as close to the lower limit as you want)
Re: Battling Entropy
#53Earlier quoted context omitted.
Interestingly, biological beings seems to defy the second law by working to reduce disorder, or surprises, in the sensory system. This is the meat of Karl Friston's Bayesian hypothesis of the brain.
You forgot to include the sun in your analysis.
And the rest of the sky. ;-)
Re: Battling Entropy
#54Earlier quoted context omitted.
The thermodynamic point of view is a description of the system as a macroscopic state.
And properties of macroscopic states are 'unphysical'?
Macroscopic states are not a complete description of physical systems and the same microstate could be part of different macroscopic states.
The thermodynamic variables are not properties of the microstate (the "physical reality"). They are properties of the macrostate, which is a model of the unknown "physical reality".
If you don't like the original phrasing, let's say that "Thermodynamical entropy is not a fundamental property of a system. It’s a property of our description of the system as a macroscopic state."
Re: Battling Entropy
#55Earlier quoted context omitted.
>> a perfectly uniformly distributed of zero temperature mass ... is the perfect order At max entropy, things would not be uniformly distributed: equal distance between each atom. Rather they would be randomly distributed. There'd be some clumping but without much pattern. If such a system were of near infinte size, the number of variations of its alignments would far exceed the much smaller near-infinity of slightly…
This is entirely incorrect. Our solar system started out as a gas cloud of randomly distributed atoms which then proceeded to become atoms organized into spheres called planets. This happened spontaneously and is not the result of energy entering or exiting the system. Almost all atoms started out in a state of random distribution before transforming themselves into almost perfect spheres orbiting in an almost perfec…
> This happened spontaneously and is not the result of energy entering or exiting the system.
This is not true: gravitational collapse usually produces energy in the form of heat that radiates away, making the surrounding universe more entropic.
Re: Battling Entropy
#56People think that entropy increasing is basically atoms going from a state of organization to a state of random distribution. All you need to do is look at the universe to see how off this definition is. The universe started as a big bang: a soup of randomly distributed particles. Then the atoms proceeded to self organize into perfect spheres called planets and stars which in turn organized themselves into flat order…
There are two things wrong with your analysis: one, the universe will not remain in the state of perfect spheres of stars and planets, it will eventually end up in a radiation and fundamental particle soup as all complex particles decay and the universe’s expansion overrides gravity. Plus, you’re not looking at the whole picture: a random gas cloud has potential energy, while the spherical object it collapses into has much less-the increase in order means that heat and other disorder is produced in the process, which leaves the system.
Re: Battling Entropy
#57People think that entropy increasing is basically atoms going from a state of organization to a state of random distribution. All you need to do is look at the universe to see how off this definition is. The universe started as a big bang: a soup of randomly distributed particles. Then the atoms proceeded to self organize into perfect spheres called planets and stars which in turn organized themselves into flat order…
There are two things wrong with your analysis: one, the universe will not remain in the state of perfect spheres of stars and planets, it will eventually end up in a radiation and fundamental particle soup as all complex particles decay and the universe’s expansion overrides gravity. Plus, you’re not looking at the whole picture: a random gas cloud has potential energy, while the spherical object it collapses into ha…
>one, the universe will not remain in the state of perfect spheres of stars and planets, it will eventually end up in a radiation and fundamental particle soup as all complex particles decay and the universe’s expansion overrides gravity.
Right, that's a technicality. Before that happens my statements about entropy apply.
>Plus, you’re not looking at the whole picture: a random gas cloud has potential energy, while the spherical object it collapses into has much less-the increase in order means that heat and other disorder is produced in the process, which leaves the system.
So the universe automatically divides itself into solid spheres and excess heat radiation? Sounds like a type of organization to me. Keep in mind, according to the definition of Entropy, as the universe transforms itself into this state, it is STILL transforming into a state of higher entropy. I am not talking about energy exiting or entering the system.
I am saying in a closed system, particles condensing into spherical planets is a transformation from a low entropy state to a high entropy state. Spherical planets are a high entropy form of disorder according to the definition of entropy. You'd know this if you truly understood entropy.
This is very different from something like life on a closed system like earth, where energy is continuously fed into the system then dissipated... overall lowering the entropy of earth but increasing entropy of the universe overall...
Re: Battling Entropy
#58Earlier quoted context omitted.
This is entirely incorrect. Our solar system started out as a gas cloud of randomly distributed atoms which then proceeded to become atoms organized into spheres called planets. This happened spontaneously and is not the result of energy entering or exiting the system. Almost all atoms started out in a state of random distribution before transforming themselves into almost perfect spheres orbiting in an almost perfec…
> This happened spontaneously and is not the result of energy entering or exiting the system. This is not true: gravitational collapse usually produces energy in the form of heat that radiates away, making the surrounding universe more entropic.
When you look at the universe as a whole as a closed system this is happening to every particle in general. The system is organizing atoms into perfect spheres while making heat radiation randomly distributed. There is still a division here, still a form of order and organization happening spontaneously.
However this system is still ascending into higher entropy. What is wrong here is your notion of what entropy is. You think that high entropy as something similar to very random but uniformly distributed noise. This is not what entropy is. The definition is more complex and can encompass very organized structures as well.
Re: Battling Entropy
#59Earlier quoted context omitted.
And properties of macroscopic states are 'unphysical'?
Macroscopic states are not a complete description of physical systems and the same microstate could be part of different macroscopic states. The thermodynamic variables are not properties of the microstate (the "physical reality"). They are properties of the macrostate, which is a model of the unknown "physical reality". If you don't like the original phrasing, let's say that "Thermodynamical entropy is not a fundame…
How could the same microstate be part of different macrostate? Like, if I described the microstate of a drop of water, wouldn't it have, as a whole, one temperature? I thought that a macrostate could have many different microstates, but not vice versa
Re: Battling Entropy
#60Entropy has been increasing since the big bang, when it was at minimum value. While the total energy didn't change since then, there has been a vast increase in the potential locations of that energy and a vast increase in the number of different interactions possible within that energy. This increases entropy because the possibility space has increased. Boltzman entropy is defined as the number of potential microsco…
Thermodynamical entropy is not a physical property of a system. It’s a property of our description of the system as a macroscopic state. Quantum (von Neumann) entropy is a related but different concept. It’s worth noting that it is constant for a closed system. Cosmological entropy can be defined in different ways. In summary, entropy means many things and not all “entropies” behave in the same way.
What are example physical properties of a system that can be separated from the properties of "our description of the system as a macroscopic state"?