An Etymological Dictionary of Astronomy and Astrophysics

The proposal whereby the → Universe would not have begun with a → singularity. Instead, the → Big Bang would be an ordinary point of → space-time. The proposal, advanced by James Hartle and Stephen Hawking (1983) results from an attempt to combine aspects of → general relativity and → quantum mechanics. Based on an imaginary time assumption, it predicts a closed Universe that would start at a single point, that can be compared to the North Pole of the Earth on a two-dimensional space.
Before the → Planck era there was space, but
the real time began with the Big Bang event. → Hartle-Hawking initial state.

See also: → boundary; → hypothesis.