>>40554063 (OP)> Before dying, Stephen Hawking had proposed a fascinating idea: to describe time not with real numbers ®, but with complex numbers ©, that is, a two-dimensional set.> And then the question becomes no longer “How do we go back in time?” but “Back in which direction?” It’s like wanting to go south, but having to choose: southeast or southwest? And in Hawking’s complex time model, there are also things like “south-north,” but let’s not complicate things any further for now.Hartle–Hawking State
J. B. Hartle and S. W. Hawking, “Wave function of the Universe,”
Physical Review D, Vol. 28, No. 12, pp. 2960–2975 (15 December 1983)