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Well, you can add temperatures. Temperature is defined to be average kinetic energy of particles, and addition of kinetic energies is well defined. The way Go
by shasta 16y ago
Well, you can add temperatures. Temperature is defined to be average kinetic energy of particles, and addition of kinetic energies is well defined. The way Google does the addition is in this sense correct - there's a reason it's called absolute zero.
The thing is that you usually don't want to add temperatures, for the same reason that you generally don't want to add other averages: they're usually not particularly interesting quantities. For this reason, you might encapsulate the definition of temperature and not expose the addition operation, but the dimensional analysis is fine the way Google does it.
- kd5bjo 16y agoAdding kinetic energies is well defined, but adding averages is not.
- aphyr 16y agoWhat the what? Averages over kinetic energies are summations. Adding them is well-defined and has a straightforward interpretation as the average energy per particle. Formally, temperature is defined as T = 1/(\partial(S)/\partial(E)) with fixed external parameters volume, particle count, etc. where S is the entropy of the system and E is its total energy. Playing fast and loose with words, as you pump energy into a system, if it becomes chaotic slowly, you're at high temperature. If it becomes chaotic quickly, you're at low temperature. Much of the difficulty involved with calculating temperatures comes from the fact that we chose the inverse of that partial to be "temperature"--which means that you cannot add temperatures for most systems together and negative absolute temperatures are "hotter" than positive ones, (yes, Cindy, you can experimentally obtain systems below absolute 0 :)). However, it is usually possible to calculate the thermal equilibrium of the system, which would be an excellent "average" temperature.