The behavior of molecules in different phases of matter represents a balance between the kinetic energies of the molecules and the attractive forces between them. All molecules are attracted to each other. The molecules are in the solid-state. At higher temperatures, the kinetic energy of the molecules is higher.
The experimenter observed this experiment in a lab rather than natural world because it might be dangerous to the atmosphere if he does the experiment in the natural world and it was still an hypothesis so that's why he did it in the lab.
