For centuries, humanity has written its understanding of gravity in the language of Newton and Einstein — laws born on Earth and tested, until now, only at modest cosmic distances. A team of researchers using the Atacama Cosmology Telescope has extended that test to the grandest scales ever attempted, measuring how gravity behaves across hundreds of millions of light-years, and found the ancient equations still hold. The universe, it seems, is not governed by different rules at its edges — but it is hiding something vast and invisible at its heart.