The light fantastic

Physicists in China and elsewhere are vying to build lasers so powerful theycould rip apart empty space. Physicist Ruxin Li and colleagues in Shanghai, China, are breaking records with the most powerful pulses of light the world has ever seen. At the heart of their laser, called the Shanghai Superintense Ultrafast Laser Facility (SULF), is a single cylinder of titanium-doped sapphire about the width of a Frisbee. After kindling light in the crystal and shunting it through a system of lenses and mirrors, the SULF distills it into pulses of mind-boggling power. In 2016, it achieved an unprecedented 5.3 million billion watts, or petawatts (PW). But the team has larger ambitions. It will soon begin building a 100-PW laser at the Station of Extreme Light, which would open up myriad scientific applications. Some even think the machine could “break the vacuum”—conjuring up particles from empty space.