Physicists test the weak equivalence principle in an orbiting space station

The weak equivalence principle (WEP) is central to Einstein’s general relativity. It posits that gravity must accelerate everything equally, regardless of what it is made from. For the first time, a team led by Ming-Sheng Zhan at the Wuhan Institute of Physics and Mathematics has tested the principle using clouds of continuously free-falling atoms aboard an orbiting space station.