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>The more I think about your reply the less sense it makes to me. I think the issue is more with your understanding then my explanation. >What do you think is

>The more I think about your reply the less sense it makes to me. I think the issue is more with your understanding then my explanation. >What do you think is the definition of macrostate? We first introduce the very fundamental statistical ideas of microstates and macrostates. Given a system (e.g., a gas), we view it as built from some elementary constituents, (e.g., molecules). Each constituent has a set of possible states it can be in. The thermodynamic state of the system (which characterizes the values of macroscopic observables such as energy, pressure, volume, etc. ) corresponds to many possible states of the constituents (the molecules). The collection of states of all the constituents is the microstate. To keep things clear, we refer to the macroscopic, thermodynamic state as the macrostate. The vast disparity between the number of possible macrostates versus microstates is at the heart of thermodynamic behavior! The number of distinct microstates giving the same macrostate is called the multiplicity of the macrostate. The multiplicity is a sort of micro-scopic observable which can be assigned to a macrostate. >The standard notion in statistical mechanics is that if we have, for example, a volume of gas in equilibrium at (constant) ambient temperature and we measure the pressure it doesn’t change. The macrostate doesn’t change. That’s what being in equilibrium means. The macrostate is in that case defined by the variables P,T,V. If all you knew was the value of these three variables and they didn’t change how could the macrostate - or the entropy - change? This notion is wrong. It CAN change. It just has an extreme low probability of changing from equilibrium to some low entropy state. The probability is low enough that you practically don't need to consider it, but you must consider it from a technical standpoint. If by sheer luck all gas particles moved to the exact left side of the container. My measurement tool (thermometer) for macrostate was on the right side of the container then it registers zero. There is nothing in the laws of physics that prevents this from happening. Only probability makes this situation unlikely to happen. >You tell me that if you know the precise position of the particles of that gas then the macrostate and the entropy change all the time. No. I'm saying that the temperature reading on the thermometer a macroscopic measurement is INDEPENDENT of knowledge. Your mind doesn't control microstates and thus the macrostate of the system. >But you also tell me that “Knowing more or less about a system does not change it's entropy.” Which is in flagrant contradiction with the two previous paragraphs. Flagrant? You're offended? Well you can leave if you're offended. Using words like this also Offends me so we can end the conversation.

kgwgk 4y ago
> I think the issue is more with your understanding then my explanation. That's what I said, that it doesn't make sense to me... hopefully it does make some sense to you! > This notion is wrong. It CAN change. It just has an extreme low probability of changing from equilibrium to some low entropy state. You also said before that the macrostate "changes with time; even at equilibrium". There is no point in discussing fluctuations if we can't agree on the notion of equilibrium and the corresponding macrostate defined by its (average) macroscopic properties. It's fine that you have your very own notion of things. Unfortunately it makes the discussion difficult. BTW, no need to be offended: https://www.classicthesaurus.com/flagrant_contradiction/synonyms https://www.classicthesaurus.com/flagrant_contradiction/syno...
- deltasevennine 4y ago
  >There is no point in discussing fluctuations if we can't agree on the notion of equilibrium and the corresponding macrostate defined by its (average) macroscopic properties. You mean microscopic. Equilibrium would then be the temperature that the thermometer is most likely to read at any point in time given infinite time. Do you agree or disagree. If you agree it's fine. So with time eventually the particles will configure itself into a macrostate that reads 0 on the thermometer.
  - kgwgk 4y ago
    What I’m trying to say is this: https://books.google.ch/books?id=vsU2DwAAQBAJ&lpg=PA45&dq=equilibrium%20macrostate&pg=PA51#v=twopage&q&f=false https://books.google.ch/books?id=vsU2DwAAQBAJ&lpg=PA45&dq=eq... “An isolated system is in equilibrium if the sharp constraints and expectation values which define its macrostate pertain to constants of the motion only.” “Whenever the macroscopic data include an expectation value, a measurement of the pertinent observable may yield a wide range of outcomes.” I’m not making up the idea of an equilibrium state being associated with a macrostate.
    - deltasevennine 4y ago
      This is my definition: https://www.sciencedirect.com/topics/mathematics/equilibrium-macrostate https://www.sciencedirect.com/topics/mathematics/equilibrium... "The equilibrium macrostate is that with the most microstates, and this is the state of greatest entropy. A macroscopic flux is most likely in the direction of increasing entropy." >I’m not making up the idea of an equilibrium state being associated with a macrostate. I know you aren't. TBH not even sure why equilibrium needs to be brought up. The topic "is entropy is independent of knowledge?" You disagree with that statement. Macrostate is defined in terms of microstates and is independent of your knowledge of the exact configuration of the microstates. You have some blunt tool like the thermometer that gives you macroscopic data and that hides the microstates from you. But if I had some precision tool that reads the position of every particle I can still identify how that configuration of microstates will influence the blunt tool. The blunt tool hides knowledge, but your knowledge of the microstate does not change the reading on that blunt tool. Because entropy is defined in termms of macrostate it stays the same regardless of which tool you used to do the measurement.

kgwgk 4y ago

> I think the issue is more with your understanding then my explanation. That's what I said, that it doesn't make sense to me... hopefully it does make some sense to you! > This notion is wrong. It CAN change. It just has an extreme low probability of changing from equilibrium to some low entropy state. You also said before that the macrostate "changes with time; even at equilibrium". There is no point in discussing fluctuations if we can't agree on the notion of equilibrium and the corresponding macrostate defined by its (average) macroscopic properties. It's fine that you have your very own notion of things. Unfortunately it makes the discussion difficult. BTW, no need to be offended: https://www.classicthesaurus.com/flagrant_contradiction/synonyms https://www.classicthesaurus.com/flagrant_contradiction/syno...

deltasevennine 4y ago
>There is no point in discussing fluctuations if we can't agree on the notion of equilibrium and the corresponding macrostate defined by its (average) macroscopic properties. You mean microscopic. Equilibrium would then be the temperature that the thermometer is most likely to read at any point in time given infinite time. Do you agree or disagree. If you agree it's fine. So with time eventually the particles will configure itself into a macrostate that reads 0 on the thermometer.
- kgwgk 4y ago
  What I’m trying to say is this: https://books.google.ch/books?id=vsU2DwAAQBAJ&lpg=PA45&dq=equilibrium%20macrostate&pg=PA51#v=twopage&q&f=false https://books.google.ch/books?id=vsU2DwAAQBAJ&lpg=PA45&dq=eq... “An isolated system is in equilibrium if the sharp constraints and expectation values which define its macrostate pertain to constants of the motion only.” “Whenever the macroscopic data include an expectation value, a measurement of the pertinent observable may yield a wide range of outcomes.” I’m not making up the idea of an equilibrium state being associated with a macrostate.
  - deltasevennine 4y ago
    This is my definition: https://www.sciencedirect.com/topics/mathematics/equilibrium-macrostate https://www.sciencedirect.com/topics/mathematics/equilibrium... "The equilibrium macrostate is that with the most microstates, and this is the state of greatest entropy. A macroscopic flux is most likely in the direction of increasing entropy." >I’m not making up the idea of an equilibrium state being associated with a macrostate. I know you aren't. TBH not even sure why equilibrium needs to be brought up. The topic "is entropy is independent of knowledge?" You disagree with that statement. Macrostate is defined in terms of microstates and is independent of your knowledge of the exact configuration of the microstates. You have some blunt tool like the thermometer that gives you macroscopic data and that hides the microstates from you. But if I had some precision tool that reads the position of every particle I can still identify how that configuration of microstates will influence the blunt tool. The blunt tool hides knowledge, but your knowledge of the microstate does not change the reading on that blunt tool. Because entropy is defined in termms of macrostate it stays the same regardless of which tool you used to do the measurement.