In 1929, Edwin Hubble discovered that galaxies are receding — the universe is expanding, like rising dough. Today we know it's growing faster and faster, and usually the accelerator is called dark energy. But physicists have shown that it's not some unknown force doing the pushing, but tiny black holes born right after the Big Bang.
In the new model, these primordial black holes have a repulsive core instead of a destructive singularity. The ultra-light ones acted like yeast, inflating the universe in its first moments. Black holes with the mass of an asteroid but squeezed to the size of a proton still work today, mimicking dark energy. This way, they resolve the famous dispute over the rate of expansion, as revealed by observations from Adam Riess and others.
A black hole weighing as much as an asteroid, squeezed to the size of a proton. It evaporates faster than light flashes, yet can inflate the entire universe.