3 ms·

I wouldn't call all of it "non-traditional" (though some of it is). Either way, the author is being very sloppy with his "proofs", so it's hard to learn anythin

I wouldn't call all of it "non-traditional" (though some of it is). Either way, the author is being very sloppy with his "proofs", so it's hard to learn anything from the article unless you already know the details.

amluto 3y ago
(5) (the minimum value of entropy) seems to come from an extremely hand-wavy argument on page 5 here: https://arxiv.org/abs/2307.09914 https://arxiv.org/abs/2307.09914 It appears to be an example of argument by italics. I’m not convinced that it has any real content — it seems to be trying to say that the author thinks all systems are either being observed or they aren’t, and that there are therefore at least two microstates. I think this is entirely missing the point and is mostly wrong. Even in the highly classical case of a gas, you have a box full of gas, with n particles and some volume V, etc. Those parameters form the macro state. Now you count microstates, take the log, and get the entropy. But nowhere in the count is a set of states where the gas is observed and a set where it isn’t. If you have a box of gas with n particle, etc, it’s implied that the gas exists! So I don’t buy it. I’ll stick with S >= 0.
- pdonis 3y ago
  > (the minimum value of entropy) seems to come from an extremely hand-wavy argument So does the "maximum force" argument, which is given in this paper: https://arxiv.org/abs/physics/0309118 https://arxiv.org/abs/physics/0309118 It is, to say the least, not generally accepted as a valid argument.
  - amluto 3y ago
    Wow, there’s not a whole lot argument at all in there. Maximum power seems especially odd — power is extensive. If you have two maximum power systems, don’t you end up with double the power?
    - pdonis 3y ago
      > power is extensive So is force. Two maximum force systems should also end up with double the force.
      - amluto 3y ago
        True, but “force” as used in that paper is so vague I gave up. Force is applied somewhere, and it makes very little sense to add up forces in different places. Although if you ignore GR and add up forces everywhere, you get F=0 (Newton’s third law), which is well below the supposed maximum. And trying to decide whether the net internal force of a system (0) is an extensive property is a bit silly :) Admittedly, power has much the the same problem. Saying that P <= P_max is some sort of physical law requires a lot more explanation of what it would mean than the paper even tries to give it.
- codethief 3y ago
  You're right, I was only looking at line (5) briefly and thought he was talking about the minimum change of entropy. S ≥ k ln2 is incorrect, as you say. A system whose state is fully known has no entropy. One can either see this through counting the number of microstates (which is 1) or by applying Shannon's definition of entropy to the trivial probability distribution which is 1 for precisely one state.

amluto 3y ago

(5) (the minimum value of entropy) seems to come from an extremely hand-wavy argument on page 5 here: https://arxiv.org/abs/2307.09914 https://arxiv.org/abs/2307.09914 It appears to be an example of argument by italics. I’m not convinced that it has any real content — it seems to be trying to say that the author thinks all systems are either being observed or they aren’t, and that there are therefore at least two microstates. I think this is entirely missing the point and is mostly wrong. Even in the highly classical case of a gas, you have a box full of gas, with n particles and some volume V, etc. Those parameters form the macro state. Now you count microstates, take the log, and get the entropy. But nowhere in the count is a set of states where the gas is observed and a set where it isn’t. If you have a box of gas with n particle, etc, it’s implied that the gas exists! So I don’t buy it. I’ll stick with S >= 0.

pdonis 3y ago
> (the minimum value of entropy) seems to come from an extremely hand-wavy argument So does the "maximum force" argument, which is given in this paper: https://arxiv.org/abs/physics/0309118 https://arxiv.org/abs/physics/0309118 It is, to say the least, not generally accepted as a valid argument.
- amluto 3y ago
  Wow, there’s not a whole lot argument at all in there. Maximum power seems especially odd — power is extensive. If you have two maximum power systems, don’t you end up with double the power?
  - pdonis 3y ago
    > power is extensive So is force. Two maximum force systems should also end up with double the force.
    - amluto 3y ago
      True, but “force” as used in that paper is so vague I gave up. Force is applied somewhere, and it makes very little sense to add up forces in different places. Although if you ignore GR and add up forces everywhere, you get F=0 (Newton’s third law), which is well below the supposed maximum. And trying to decide whether the net internal force of a system (0) is an extensive property is a bit silly :) Admittedly, power has much the the same problem. Saying that P <= P_max is some sort of physical law requires a lot more explanation of what it would mean than the paper even tries to give it.
codethief 3y ago
You're right, I was only looking at line (5) briefly and thought he was talking about the minimum change of entropy. S ≥ k ln2 is incorrect, as you say. A system whose state is fully known has no entropy. One can either see this through counting the number of microstates (which is 1) or by applying Shannon's definition of entropy to the trivial probability distribution which is 1 for precisely one state.