How to produce black holes during inflation: with a ball, a hill and a speed bump.
Two binary black hole mergers were detected within 20 minutes of each other. But does this mean that there were four black holes… or just two?
All of the black hole mergers we’ve seen so far with LIGO/Virgo have surprised us with their mass-spin relationship. Are we misunderstanding stellar collapse? Or is there something even more exotic going on?
Gravitational waves are distorted by the objects that lie in their wake – how can we learn more about their journey through the cosmos?
As the Hubble tension continues to bubble, can an extra phase of expansion set right our understanding of the Universe’s history?