That makes sense. Now it’s coming back to me: you zoom your microscope into one tiny nm^3 cube of air. In a right-to-left temperature gradient you’ll see systematically faster air molecules moving rightward and slower molecules moving leftward, because they’re carrying the temperature from their last collision. Whereas in uniform temperature, there’s “detailed balance” (just as many molecules going along a path vs going along the time-reversed version of that same path, and with the same speed distribution).
Thinking about the diode-resistor thing more, I suspect it would be a waste-of-time nerd-sniping rabbit hole, especially because of the time-domain aspects (the fluctuations are faster on one side vs the other I think) which don’t have any analogue in SGD. Sorry to have brought it up.
That makes sense. Now it’s coming back to me: you zoom your microscope into one tiny nm^3 cube of air. In a right-to-left temperature gradient you’ll see systematically faster air molecules moving rightward and slower molecules moving leftward, because they’re carrying the temperature from their last collision. Whereas in uniform temperature, there’s “detailed balance” (just as many molecules going along a path vs going along the time-reversed version of that same path, and with the same speed distribution).
Thinking about the diode-resistor thing more, I suspect it would be a waste-of-time nerd-sniping rabbit hole, especially because of the time-domain aspects (the fluctuations are faster on one side vs the other I think) which don’t have any analogue in SGD. Sorry to have brought it up.