Right after the Big Bang, unusual luminaries could be born — dark stars. Unlike the Sun, they didn’t burn nuclear fuel but fed on collisions of dark matter particles, which release energy. Like a snowball rolling downhill, such a star rapidly sucked in gas, gaining up to millions of solar masses. Its own gravity created enormous spacetime curvature, and the star collapsed into a black hole. This scenario was predicted by Subrahmanyan Chandrasekhar and Richard Feynman: no internal pressure can stop such a collapse. This is likely how the seeds of supermassive black holes, which we see in the centers of galaxies, formed. Without dark stars, ordinary stars wouldn’t have had enough time to grow these giants in the young Universe. Amazing fact: a million-solar-mass dark star would stretch out to Pluto’s orbit, yet its surface would be colder than an incandescent light bulb.