If you simultaneously drop a feather and a bowling ball in a vacuum, they’ll hit the ground at the same time. In other words, despite their mass, they’re affected by a gravitational field in exactly the same way. The same goes for massive objects like stars, according to Einstein’s Theory of Relativity, and astrophysicists have confirmed his inference.

The scientists used radio telescopes to measure how a neutron star orbits two white dwarf stars in a similar system as how the Earth and moon orbit the sun. By comparing the speed, motion and masses of the bodies, they were able to perform a cosmic version of Galileo’s famous (though embellished) tests in the late 1500s. The results show that all three stars are affected in the same way by their gravity fields.