In November 1915, Albert Einstein published his theory of general relativity. A key point in his theory is that massive objects distort the fabric of space-time, the way a bowling ball on a trampoline would stretch and warp the fabric around it. In order to prove Einstein’s theory right, scientists traveled the globe to be under the solar eclipse of 1919. There they witnessed the sun bending the light of background stars by the amount Einstein predicted. Nowadays, scientists use the same concept – gravitational lensing – to learn more about galaxies and quasars in the early universe.