Galaxies on Instagram: "In Interstellar, Miller’s planet orbits close to the black hole Gargantua, where gravity is so strong that time runs much slower. This is gravitational time dilation, a prediction of Einstein’s relativity. On the planet, one hour equals about seven years outside. So when Cooper and Brand return after only a few hours, Romilly has aged 23 years waiting in orbit. Einstein’s theory explains this: gravity warps spacetime itself, slowing time near massive objects. For the crew