The Hartle-Hawking State

The Hartle-Hawking State is a concept in quantum cosmology proposing that the universe began in a "smooth", finite state with no distinct beginning or boundary. It suggests that, at the earliest moments, time behaves more like space, allowing the universe to originate without a traditional “initial” moment. Think of it as the universe arising from a quantum "nothing" that’s more like a smooth, rounded shape rather than a sharp start. This idea helps scientists understand the conditions of the universe at its inception, blending quantum mechanics with cosmology to explore how the universe could have spontaneously emerged.