Main Question or Discussion Point
What force is responsible for the phenomenon of heat transfer?
What seems to move? And what do you mean by 'automatically'?Because it just seems to move automatically - so don't you need a force when something happens automatically?
It is a statistical effect. A system in a closed volume with some fixed total energy E, has equal chance to be in any of the possible physical states with energy E. Suppose you have two systems, one has energy E1 and the other has energy E2. Then system 1 can be in Omega(E1) possible states, system 2 can be in Omega1(E2) possible states. So, the comboined system can be in Omega1(E1)*Omega(E2) possible states.I mean that the average translational kinetic energy of a hot space seems to get less when next to a colder space. And this seems to happen spontaneously or without any external interference.
For example, I am in my apartment and it's all warm in here. Then I open the door to the hallway where it's cold. The hot air just rushes out the door. I am assuming this is heat transfer - am I wrong? If I am right, what I am asking is, what force if any is responsible for this behavior? And if there is no force responsible for this behavior, then why not?
There is no conductive (or convective - thanks timmay) heat transfer in vacuum for precisely the reason you state.Slightly linked to this follows the questions, why does heat not dissipate to an equlibric state across all space time, and how does heat transfer through vacuum in the lack of kinetic energy??