3 ms·

I would have thought that the laws of entropy would continue to exist, even once this thought experiment plays out. Sure, once the particles have been divided,

by lwhi 6y ago

I would have thought that the laws of entropy would continue to exist, even once this thought experiment plays out. Sure, once the particles have been divided, the difference between the hottest and coldest particles in each room would be reduced; but why wouldn't the scale of temperatures not subdivide to infinity? The bounds of each universe have changed - but why _wouldn't_ the same laws continue?

lwhi 6y ago
Thank you whoever chose to downvote. Nothing like punishing genuine curiosity, ay!
- engineer_22 6y ago
  It violates entropy because work is being done to the combined system. The subdivided systems, if looked at in their own reference frame, would exchange entropy and mass which is work. After that time, If all else is held equal, your intuition is correct that entropy would be conserved in each subdivided system.
FabHK 6y ago
You could take a homogeneous gas, use the demon to separate it in hot and cold (using no energy), then use the temperature difference to perform useful work (with any number of engines, such as Sterling's), then use the demon again, and hey presto, you got yourself a perpetual motion machine. (BTW, one can buy Sterling engines, some of which work with body temperature, ie holding it will create enough temperature difference to turn the engine: https://thestirlingengine.com https://thestirlingengine.com https://www.stirlingengine.co.uk/default.asp https://www.stirlingengine.co.uk/default.asp https://en.wikipedia.org/wiki/Stirling_engine https://en.wikipedia.org/wiki/Stirling_engine )
kgwgk 6y ago
The "laws of entropy" are about the observer's uncertainty about the physical state which is then described as a thermodynamical system (in equilibrium in the classical formulation). And they can be “violated”, even though it’s unlikely it’s not impossible. For a demon who knew the position and velocity of every particle there is no entropy (or it doesn't change if we define one). Maxwell: “One of the best established facts in thermodynamics is that it is impossible in a system enclosed in an envelope which permits neither change of volume nor passage of heat, and in which both the temperature and the pressure are everywhere the same, to produce any inequality of temperature or pressure without the expenditure of work. This is the second law of thermodynamics, and it is undoubtedly true as long as we can deal with bodies only in mass, and have no power of perceiving the separate molecules of which they are made up. But if we conceive of a being whose faculties are so sharpened that he can follow every molecule in its course, such a being, whose attributes are still as essentially as finite as our own, would be able to do what is at present impossible to us.”

by lwhi 6y ago

lwhi 6y ago

Thank you whoever chose to downvote. Nothing like punishing genuine curiosity, ay!

engineer_22 6y ago
It violates entropy because work is being done to the combined system. The subdivided systems, if looked at in their own reference frame, would exchange entropy and mass which is work. After that time, If all else is held equal, your intuition is correct that entropy would be conserved in each subdivided system.

FabHK 6y ago

You could take a homogeneous gas, use the demon to separate it in hot and cold (using no energy), then use the temperature difference to perform useful work (with any number of engines, such as Sterling's), then use the demon again, and hey presto, you got yourself a perpetual motion machine. (BTW, one can buy Sterling engines, some of which work with body temperature, ie holding it will create enough temperature difference to turn the engine: https://thestirlingengine.com https://thestirlingengine.com https://www.stirlingengine.co.uk/default.asp https://www.stirlingengine.co.uk/default.asp https://en.wikipedia.org/wiki/Stirling_engine https://en.wikipedia.org/wiki/Stirling_engine )

kgwgk 6y ago

The "laws of entropy" are about the observer's uncertainty about the physical state which is then described as a thermodynamical system (in equilibrium in the classical formulation). And they can be “violated”, even though it’s unlikely it’s not impossible. For a demon who knew the position and velocity of every particle there is no entropy (or it doesn't change if we define one). Maxwell: “One of the best established facts in thermodynamics is that it is impossible in a system enclosed in an envelope which permits neither change of volume nor passage of heat, and in which both the temperature and the pressure are everywhere the same, to produce any inequality of temperature or pressure without the expenditure of work. This is the second law of thermodynamics, and it is undoubtedly true as long as we can deal with bodies only in mass, and have no power of perceiving the separate molecules of which they are made up. But if we conceive of a being whose faculties are so sharpened that he can follow every molecule in its course, such a being, whose attributes are still as essentially as finite as our own, would be able to do what is at present impossible to us.”