Every second for the last four-and-a-half billion years, trillions of hydrogen atoms have been converted into helium in the Sun's core and released an immense amount of energy in the process. This is a process known as nuclear fusion, and figuring out how to harness this source of virtually limitless clean energy on Earth has been a holy grail of physics for the last 80 years.

In the early days, most of the pioneering fusion research was done behind the closed doors of top secret government labs. At places like Sandia National Laboratory, physicists are still studying fusion energy using some of the most complex machines in the world in order to better understand the nuclear weapons fusion research helped create.