Early Universe: A Quark-Gluon Soup

The early universe, mere seconds after the Big Bang, was a vastly different place than it is today. Instead of stars and galaxies, it was a boiling soup of quarks and gluons, punctuated by microscopic black holes. These aren’t the stellar-mass black holes we observe now, but primordial black holes (PBHs) – hypothetical objects formed in the universe’s first moments.

Hawking Radiation and PBH Evaporation

While black holes are known for absorbing everything, they also emit energy through Hawking radiation, a phenomenon predicted by physicist Stephen Hawking. Smaller black holes radiate faster and eventually evaporate completely. PBHs weighing under 500 trillion grams would have vanished by now, but not without a dramatic finale.

Violent Demise: Relativistic Fireballs

Researchers at Vrije Universiteit Brussel and MIT have challenged the conventional understanding of PBH death. A new paper, available on arXiv, suggests that the energy released by these dying microscopic black holes wasn’t simply diffused, but unleashed in incredibly violent relativistic fireballs. This occurred due to extreme pressure gradients created as the black holes evaporated.

The Four Phases of PBH Evaporation

  • Phase 1: Slow evaporation creating an expanding plasma bubble.
  • Phase 2: Instantaneous energy release modeled by the Blandford-McKee regime.
  • Phase 3: Shockwave slows down, modeled by the Sedov-Taylor regime.
  • Phase 4: Energy dissipation into surrounding plasma.

Solving the Mystery of Baryogenesis

This violent PBH evaporation process may explain baryogenesis – the existence of matter over antimatter. According to Big Bang theory, equal amounts of both should have been created, leading to complete annihilation. The researchers propose that PBH shockwaves could have temporarily disrupted the Electroweak symmetry, creating pockets where matter prevailed.

Electroweak Symmetry and Matter Creation

If the early universe’s temperature dropped below 162GeV, Electroweak symmetry would have broken. The shockwaves from PBH explosions could have briefly raised temperatures above this threshold, creating the necessary out-of-equilibrium conditions for matter to dominate. This is the focus of a companion paper by the same research team.

From Black Hole Shockwaves to Everything We See

The findings suggest that the universe’s structure, and indeed all matter – including ourselves – may originate from the shockwaves created by exploding primordial black holes. This offers a new perspective on our cosmic origins, potentially replacing the notion of being “made of star-stuff” with being “made of black hole shockwaves.”