Erase the image of a fireball erupting into empty space. The Big Bang was not an explosion inside space; it was the expansion of space itself, happening everywhere at once. Even the name was a historical accident, coined by steady state advocate Fred Hoyle on a 1949 BBC broadcast. This deep dive walks through the origins of the model, from Alexander Friedmann's 1922 equations and Georges Lemaître's primeval atom to Edwin Hubble's 1929 discovery that galaxies recede faster the farther away they are.

The hosts then run the clock back through cosmic inflation, when space doubled in size more than 80 times in a sliver of a second, through baryogenesis, where matter survived antimatter by one part in 30 million, through Big Bang nucleosynthesis and recombination at 380,000 years, and forward to the evidence: the cosmic microwave background, the  ...