Are we close to sustainable energy?
A major breakthrough has been announced by US scientists in the race to recreate nuclear fusion.
Physicists have pursued the technology for decades as it promises a potential source of near-limitless clean energy.
On Tuesday researchers confirmed they have overcome a major barrier - producing more energy from a fusion experiment than was put in.
But experts say there is still some way to go before fusion powers homes.
"Today's success rests upon the work done by many scientists in the US, UK and around the world. With ignition now achieved, not only fusion energy is unlocked, but also a door is opening to new science."