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?
As the Hubble tension continues to bubble, can an extra phase of expansion set right our understanding of the Universe’s history?
A joint European and Japanese mission to Mercury sets off to answer questions about the planet’s geology, magnetosphere, and to try and prove Einstein wrong.
Is string theory compatible with observational data? Today’s paper looks at how avoiding the swampland of unsuccessful string theories can mean violating reliable constraints on cosmological quantities.