The US has finished constructing a huge physics experiment aimed at recreating conditions at the heart of our Sun. The US National Ignition Facility is designed to demonstrate the feasibility of nuclear fusion, a process that could offer abundant clean energy. The lab will kick-start the reaction by focusing 192 giant laser beams on a tiny pellet of hydrogen fuel. To work, it must show that more energy can be extracted from the process than is required to initiate it.
physics laser nuclear fusion energy