There are all kinds of theories having to do with the big bang and what caused it. It wouldn’t surprise me if Hawking had been among those who attempted to explain what caused it, but to my knowledge, or rather the only two of his theories that I know about, were more about the nature of the big bang than about what caused it.
One was that in the beginning, time was not real time but imaginary, which would have rounded off the tip of the bang and made it spacial rather than temporal, thus rendering questions about zero time rather like asking what is north of the north pole on our spherical earth. Time would have been sideways and space-like with no way to get to the initial point. At the earliest attainable point, things would have been very still, monotonously the same, and filled with an unimaginable density of potential energy. This of course, is not the cause of the big bang, but a description of it.
The other thing (that I know of and can understand, or at least think I understand) Hawking tried to do was to portray the initial instant of the big bang as a
regular singular point with a
removable singularity, a
weak singularity. I think he played with that for a while but that he eventually gave up on it. I don’t know the reasons why he gave up because I kind of like it.
I don’t actually put much stock in most of the theories purporting to describe things like the initial instant of the big bang or ‘times before the initial instant’, although I don’t rule out that maybe one out of the hundreds or thousands of mathematical/physical schema might be right. I enjoy reading about them, and if I’m able and have the time, trying to play with them, but I’m not hard and fast about them either way. Just as a matter of probability though, I think that most of them have to be wrong. Not very many of them could be right and still be compatible with each other, and maybe only one or even none of them are right.
I think the stuff after the big bang, and by that I mean the first millionth (or maybe the first billionth or the first trillionth or whatever . . .
) of a second or something like that, are on pretty solid ground. Before that I’m not particularly trusting that they actually know the physics.
PS: Upon further reflection, and after looking at the definitions, I’m probably all messed up on thinking that all of those singularities refer to the same thing. This is really what I was thinking of:
Euler differential equation
That’s the one I know how to handle with pencil and paper (and a big pink pearl eraser too of course
).