Exploding black holes could explain an antimatter mystery

Car-sized black holes exploding in the first tenth of a billionth of a second after the Big Bang might solve one of cosmology's greatest puzzles: why matter dominates our universe instead of antimatter.

Scientists have long wondered how matter gained its advantage, since the cosmos should have started with equal amounts of both. When matter and antimatter meet, they annihilate each other, which should have left behind a featureless universe of pure energy.

But physicist Alexandra Klipfel and her team propose that tiny primordial black holes, each weighing about a thousand kilograms, formed from density fluctuations in the early universe's quark-gluon plasma. These black holes would have rapidly evaporated through Hawking radiation before exploding dramatically.

Those explosions would have launched shock waves through the plasma, creating sharp boundaries where conditions differed drastically on either side. Inside the shock wave's thin shell, temperatures would be so extreme that particles couldn't have mass because the Higgs mechanism wouldn't function. Outside, particles would gain mass normally.

This mass-changing border, combined with other early-universe physics, could have caused matter to accumulate at the shock wave boundaries, giving it the edge it needed to dominate our cosmos and eventually form stars, planets, and galaxies.