When a star goes supernova, unimaginable forces are at play. In some cases, these explosions can literally tear holes in the universe. So-called collapse supernovae represent the end of the life of massive stars. Once they have used up their main fuel, hydrogen, and fused it into helium, they swell into red giants and finally explode in a massive flash of energy. What remains is a super-compact neutron star or a black hole.
