4 ms·

I would envision two chambers A and B connected by two vents X and Y, like Maxwell's demon but with two vents instead of one and both vents permanently open. Wh

I would envision two chambers A and B connected by two vents X and Y, like Maxwell's demon but with two vents instead of one and both vents permanently open. Whereas X is an ordinary vent, Y has the property that any particle passing from A to B through it reaches B shortly before it leaves A. Any particle passing from B to A through Y disappears for a short time before reappearing in A. It seems to me that this setup would induce a current of air blowing from A to B through Y and from B to A through X, but I'm only an amateur and could be full of hot air myself.

jjk166 5y ago
Let's look at the two possible timelines here: At some point a particle pops up into existence in B, increasing B's pressure. Some time later, a particle from A disappears, decreasing A's pressure. This pressure differential would cause flow from B to A through X. Alternatively, a particle randomly disappears from B, decreasing B's pressure. Some time later, a particle appears in A, increasing A's pressure. This would cause flow from A to B through X. The more particles that cross from A to B via Y, increasing B's pressure, the more likely it is for particles to pass from B to A via Y, keeping these two effects equal. These two pressure differentials would cancel out for large numbers of particles. You've essentially just hooked up the system to itself, but at a future point in time. Unless the overall pressure of the system is changing, there is nothing to induce the flow. If you are increasing the pressure, valve Y is essentially just a standard one-way valve.