Professor Stephen Hawking is a world-renowned British theoretical physicist, known for his contributions to the fields of cosmology, general relativity and quantum gravity. He recently sat down with Neil Degrasse Tyson on his “Star Talk” show and it didn’t take long for the talk to get really deep, down to the very origin of the universe but also what came before it.

When asked “what was around before the Big Bang,” Hawking was very uncompromising, simply answering that there was “nothing.” The physicist goes on to explain that Einstein’s Theory of General Relativity states that time and space form a continuum, “which is not flat but curved by the matter and energy in it.

To answer what happened before the Big Bang, Hawking took a so-called Euclidian approach to quantum gravity to describe the beginning of the universe. What does that mean? According to Hawking, this means that ordinary time is replaced by imaginary time, and this imaginary time “behaves like a fourth direction of space.”

Hawking’s model claims that the history of the universe is a four-dimensional curved surface, just like the surface of the Earth but with two additional dimensions. What’s more, the boundary condition of the universe (the known and constraint value that must be true for the problem that you are working)… is that it has no boundary. In other words, there was no time before the beginning of the universe.

“One can regard imaginary and real time as beginning at the South Pole which is a smooth point of space-time where the normal laws of physics hold. There was nothing south of the South Pole so there was nothing around before the big bang,” Hawking explained.

That’s a pretty mind-blowing statement and although it comes from a foremost authority in cosmology like Hawking, the jury is still out on whether that was really the case or not.