In a new episode of the educational television show Star Talk, theoretical physicist Stephen Hawking explained why nothing existed before the Big Bang. A fragment of the transfer, see below.
In a conversation with the host - astronomer and popularizer of science Neil Degrass Tyson - Hawking answered the question of what happened before the Big Bang. His answer - "nothing" - he explained by the Euclidean approach to quantum gravity, within which the usual time characteristic of our Universe is replaced by an imaginary one and is considered as the fourth spatial dimension. Thus, the universe looks like a curved four-dimensional surface, similar to the surface of the Earth.
Such a Euclidean universe, according to Hawking and his colleague James Hartle (James Hartle), has no boundaries, while it is closed. The Big Bang, therefore, can be viewed as an analogue of the South Pole, to the south of which there is nothing. Likewise, there was no time and space before the universe.