Manipulating the paths of electrons is no small task, but the researchers were able to drastically simplify the process by using high pressure gas. The pressure makes the electrons act erratically as atoms collide with one another, slightly bending their paths. Once off their normal paths, electrons can be pushed into higher orbit with far less energy than would be needed at low pressure. As collisions subside, the electrons try to go back to their usual paths, albeit at their new higher orbits. In order to remain in that higher orbit, they must absorb energy around them, and that process slows the gas particles tremendously, causing a rapid, precipitous drop in temperature.