I'm having a problem with understanding how energy flows from one body to the other. So gases at high pressure travel towards low pressured areas. So there is a reason behind this. Since molecules of gases have the tendancy to move away from each other, they travel towards low pressured areas. So molecules are the paticles that comprise all the matter. So what is heat energy comprised of? Are there any particles in it? Why does it travel from a hotter body to a colder body??