Traditional cosmology begins with the Big Bang — the idea of Georges Lemaître. However, a new approach, inspired by the work of Stephen Hawking, bypasses the mystery of the initial moment. Instead of a point of infinite density, we have a smooth boundary where spacetime is born from a timeless ocean, like a bubble in the depths of water. A key role is played by a chronometer field: it sets time in motion inside the newborn universe. There, rapid inflation takes place, smoothing everything out to the familiar flatness.
The hypothesis can be tested: collisions between bubbles should leave circles in the microwave background — traces of contact with other worlds.
The term 'Big Bang' was coined by astronomer Fred Hoyle in 1949 — he used it as a mockery of a competing theory, but the name stuck.
The image of 'bubble' universes floating in a primordial ocean is reminiscent of fictional multiverses, for example in the movie 'Everything Everywhere All at Once' or the Discworld novels.