swansont

I’ve seen that attitude elsewhere, and have no reason to think it’s smaller in a profession where it can be exercised as part of the job. I think what’s more damaging is the enabling attitude that gives us the thin blue line. That behavior I have seen, when I was in the military. Covering for a comrade’s bad behaviors instead of doing your duty. So when someone behaves badly, the system fails to expose the culprit, and people fail as well. Can you clarify who are the out of control, hostile ones in this? Aggressive policing is one of the systemic problems.

We’re not talking about a process. We’re talking about the possible configurations that make up one state. Statistical mechanics, not classical thermodynamics. Do you understand why he says “of course” here? To separate this from the previous sentence, where he talks about spontaneous change. Because they aren’t the same thing.

There’s no compression. You keep trying to recast this in terms of some other (probably familiar) problem, which is why you don’t end up at the answer in the book. (which is what my earlier explanation was trying to highlight - no compression needed for the one-ball case.) But I was responding to your claim that work is required for the gas CoM to change, and that’s not the case (the container has mass), which is something one is expected to learn in first-semester physics. Your objection has no basis in physics. But that’s not all he said. He invoked it if you were preparing that state, as opposed to a spontaneous fluctuation. He made a clear (IMO) distinction.

You need to go back and study first-semester physics. No work is necessary.

I'm not convinced you can effectively do the former, but I agree with the latter. As I said above, accountability is one of the main parts of the reform that is needed.

I disagree with this. There are too many people who want power over others, and don't wield it responsibility. The police are a magnet for such people. Your experience is likely with people who joined that culture willingly. Getting martial arts training foisted upon you does not mean you have joined that culture. Just like training in other aspects of society — workplace training on e.g. sexual harassment and sexual assault hasn't won everyone over to a culture that respects women, for similar reasons. (feel free to substitute other culture subsets for that) This is one reason the focus has been on attempts at fixing systemic problems and holding people accountable. You might not prevent one instance of excessive force by an individual, but if you don't tolerate such behavior, you might be able to prevent the next 20 instances the individual might have perpetrated, because they will no longer be on the police force.

That wasn't the premise. The premise was that there are people on the police force predisposed to use violence/excessive force. On what do you base this?

You added a partition, where there was none. You added a piston earlier, and talked about changing variables that were fixed, and doing work. You’ve done little but change the conditions.

No, you don’t get to change the conditions of the example. It’s an ideal system. You keep ignoring that. Even if it isn’t, fine. If we’re at STP and have one mole of gas, so the volume of the container is 22.4L. The ideal gas has a mass of, say, 10 grams. The container is just under 30 cm a side and has a mass of, say, a kg. You have your momentum transfer, so the container can shift a small amount if needed. How are those violated? Action/reaction arises from force. Arrival, departure, etc. are not force. Nothing external. It’s all internal. That’s not how gases behave. It’s not a 1-for-1 matchup. You could have 10 moving right with 1 unit of momentum and 1 moving left with 10 units, and momentum is zero. So you agree you don’t need the atoms to have their momentum cancel Why are small fluctuations OK, but larger ones require work?

There is no change in P, V or T ? This was never part of what I had been discussing. I wasn’t aware you were waiting for me to address it. With one ball it’s not a problem, though. So the number of particles is equal in each octant? What if there are an odd number of particles? You said 42 before I brought this argument up. I hope causality isn’t under attack here, too. 42 isn’t divisible by 8. Let’s make it 48 - 6 particles per octant. Why can’t that number change? Why can’t there be 7 in one octant, and 5 in another? What prevents that? It’s not momentum. They travel at different speeds, and there’s a finite transit time.

Yes. I didn’t introduce “single observer bias” “agenda” is offensive? You’re the one who stated a plan, not included in the OP. But there is no compression, and no heat flow. The entropy hasn’t fallen. AFAIK they’re wrong about that. Will you now, finally, address the outstanding questions: What is the mechanism that prevents more balls being on one side of the box*? At what value of N does the mechanism manifest itself? *This is a big issue, because if we have symmetry, I can draw this line along any axis. If it can’t happen, then doesn’t the number in each octant have to be constant? If it’s not, then some half has more than the other

It seems the answer is “no” Apparently it’s a slogan and not an obligation.

These are two separate issues. One does not follow from the other (emphasis added) The courts have ruled that this is not the case in the US https://mises.org/power-market/police-have-no-duty-protect-you-federal-court-affirms-yet-again They can back off and let you be attacked, and they are not being derelict in their duty. According to the law/courts. If someone is predisposed to using violence, giving them more tools to do violence won’t result in more violence? Interesting take.

You had specifically focused on the CoM of the gas. You went out of your way to point this out. An observer traveling with the ball isn't really a viable approach, knowing full well we are going to move on to multiple balls, because we’ve already done this. Plus the view prior to this was an observer in the lab frame. You seem reticent to answer the question, which is quite obviously “no, the CoM of a single ball is not fixed” Indeed. One wonders what the point of introducing it was. Yes, of course, all if this posturing suggested an agenda. This “next stage” will be in a new topic, right? Can we get back to the discussion at hand? Belief is not a physics argument. It is obviously possible when N is small. What mechanism makes it impossible when N is large?

Explain the CoM problem for one ball in my example. Is the CoM fixed?

When m goes to infinity, the mass of the gas is irrelevant. The CoM will be the same, no matter what happens to the gas. It’s a non-issue for this explanation

The collisions are elastic and the box mass is infinite. Ideal system, remember? If there is no displacement, there is no work. These collisions would increase, not decrease, the volume of the box, so no.

When the ball is traveling, the CoM is moving, so this isn’t necessarily a constraint but it’s an idealized system (we start with an ideal gas) so the container has a mass >> the mass of the gas. Effectively infinite mass. edit: xpost with Ghideon

V doesn’t change. No, that does not follow Start with one ball, with some energy E, under the conditions of an ideal gas, in some box with rigid walls. Obviously, it can be anywhere in the box. Same thing for two. Wile they will occasionally collide and exchange energy and momentum, there is no mechanism that requires one ball be on each side. Two balls being on one side does not require a change in volume. Three balls, four balls - still no mechanism. Any conclusion about their average position is statistical. It’s like a coin toss of multiple coins - it becomes less likely to get all heads, or all tails, but nothing prevents it. Now increase it to an arbitrary number N. At what point does a mechanism manifest that prevents all the balls being on one side? What is that mechanism?

The piston was your introduction - which violates the conditions of the problem - so this clarifies nothing.

A piston means V isn’t constant. position ≠ momentum Why does it break these laws? It’s not a low entropy condition, as such. Did they say that, or is that your interpretation? Saying that doesn’t make it true. How does this allow a jump to absolute zero?

What does equilibrium mean in terms of a gas? So the parameters are not well-defined in that situation - they can show large deviations. Also note I responded to your question about the 2nd law being statistical, not the OP. The “small number” as applied to the OP is fabricated You did, though. Your gas became regularly-spaced, with no relative motion. It’s true there’s no path to get to that state, but AFAIK, nobody is claiming that state exists They are not “representative” if the videos you are decrying do not use them. You are trying to use a response to one very specific question and apply it to a broader question, which does not necessarily share the same assumptions. Do you want to discuss the issue you brought up in the OP, fine - do that. You want to discuss issues arising in stat mech, fine - open a new thread and do that. Don’t mix them.

Who said they were non-equilibrium? You didn’t indicate N=42 before, and regularly-spaced is a new addition, as well as zero relative motion. Where did these come from? You can’t go changing the parameters like that. Wikipedia articles like this are more like a textbook, but there’s more in the link. Not sure why you are thinking the system is low entropy.

It comes from statistical mechanics “Statistical mechanics postulates that, in equilibrium, each microstate that the system might be in is equally likely to occur, and when this assumption is made, it leads directly to the conclusion that the second law must hold in a statistical sense. That is, the second law will hold on average, with a statistical variation on the order of 1/√N where N is the number of particles in the system. For everyday (macroscopic) situations, the probability that the second law will be violated is practically zero. However, for systems with a small number of particles, thermodynamic parameters, including the entropy, may show significant statistical deviations from that predicted by the second law. Classical thermodynamic theory does not deal with these statistical variations.” https://en.wikipedia.org/wiki/Second_law_of_thermodynamics#Statistical_mechanics

Or, maybe we don’t compare police and the military - especially the highly-specialized, elite forces within the military. We do NOT expect a given police officer to manage violent confrontations on a daily basis. Over the scope of all police, a few will be faced with a violent situation on a given day, but there are ~800,000 police officers in almost 18,000 departments. Special forces in the military are less than 1/10 of that number. It’s unreasonable to expect to train that many people, especially absent the selection criteria we have for special forces that the police lack. If you want these to be closer to analogous, you need to select a subset of police for this training.