We hear a lot about the approaching end of the fossil fuel era. But as various companies work on wind and solar, there's a group of scientists quietly working on another method of generating electricity, in the lab that once created the atomic bomb. This week, Bloomberg Technology's Jing Cao visits the researchers who are smashing hydrogen atoms together in a process called nuclear fusion. They say they're on the brink of a major milestone, but they face an age-old problem: not enough funding.