3 ms·

I haven't taken beyond high school physics, so this question is probably obvious, but I haven't been able to find the answer (probably don't know the right term

I haven't taken beyond high school physics, so this question is probably obvious, but I haven't been able to find the answer (probably don't know the right terms to search). When I increased the slider that allows you to change the flow of time for the gas in the cube, it really looked like visualizations I've seen of increasing the temperature of a gas. Is there a deeper relationship here? Could an observer tell the difference between a cube $A$ of gas in which the flow rate of time were doubled and a cube $B$ of gas with normal time passage, but a correspondingly increased temperature? If so, what would give it away?

keonix 4y ago
IIRC temperature is proportional to velocity squared so increase in simulation speed will result in squared increase in temperature. But even if we account for that we are not dealing with ideal gas in real world, there bound to be collisions that break molecules apart or even start nuclear fusion at certain speeds
TremendousJudge 4y ago
The thing is, temperature is just motion at very small scales. On a solid, particles are attached to one another via the atomic forces, and a "temperature increase" means that the particles are jiggling more. With high enough jiggling, the particles start to break apart and the substance undergoes a phase transition. Now, when it's a gas, the particles are jiggling so much they aren't attached to one another, they are flying around at very high speeds as shown in the visualization. So, your intuition is correct: increasing the speed of the particles then is in fact the same as "increasing the temperature" of the gas.
xani__ 4y ago
Yup, and that is how ultrasonic heat pumps work! JWST has one https://webb.nasa.gov/content/about/innovations/cryocooler.html https://webb.nasa.gov/content/about/innovations/cryocooler.h... basically, make a standing wave of gas in a pipe and the peak of pressure will be hotter than the valley. Put the thing you want to cool in the valley, radiator in the peak, and voila, a heat pump.

keonix 4y ago

IIRC temperature is proportional to velocity squared so increase in simulation speed will result in squared increase in temperature. But even if we account for that we are not dealing with ideal gas in real world, there bound to be collisions that break molecules apart or even start nuclear fusion at certain speeds

TremendousJudge 4y ago

The thing is, temperature is just motion at very small scales. On a solid, particles are attached to one another via the atomic forces, and a "temperature increase" means that the particles are jiggling more. With high enough jiggling, the particles start to break apart and the substance undergoes a phase transition. Now, when it's a gas, the particles are jiggling so much they aren't attached to one another, they are flying around at very high speeds as shown in the visualization. So, your intuition is correct: increasing the speed of the particles then is in fact the same as "increasing the temperature" of the gas.

xani__ 4y ago

Yup, and that is how ultrasonic heat pumps work! JWST has one https://webb.nasa.gov/content/about/innovations/cryocooler.html https://webb.nasa.gov/content/about/innovations/cryocooler.h... basically, make a standing wave of gas in a pipe and the peak of pressure will be hotter than the valley. Put the thing you want to cool in the valley, radiator in the peak, and voila, a heat pump.