I think the best answer is what Smolin- now of the Canadian Advanced Institute, but formerly at UPENN and educated at Harvard- hypothesized some time ago, but has distancing himself from it since then.
You see he is the principal exponent of Loop Quantum Gravity wich is more fundamental than string theory in that LQG does not assume space and time exist. Instead they can derive it from what they call loops, whatever that means.
I do not pretend to understand it. But recently they have been able to derive the big bang along with space and time. So Smolin is very successful right now and his early hypothesis is beneath him.
But I can understand jis early hypothesis and it makes sense to me.
He claims that universes beget universes. That is mother universes produce baby universes in the wombs of each universe. The womb of a universe is each of its black holes. Now perhaps it only works for supermassive black holes. So perhaps not all black holes qualify.
So Smolin hypothesized that if every black hole above some critical size spawns baby universes, then after countless generations, the most prevalent univere would be ones that produce the greatest number of black holes above critical size. So almost every universe in existence must be similar, in its fundamental constants.
So if our universe is such a one, and it is known that the fundamental constants in our univere are such as to result in intelligent life, then that is testable theoretically. I never saw any results of that.
Anyway, look in the book of Brian Greene called the Elegant Universe and he shows pictures of how the singularity inside a black hole, which is really not a singularity but a cosmic egg containing the unified field (which is massless- so massive black holes destroy mass)----these pictures show how new universes decouple from old ones producing new space and time in the process. He also verbalizes (Greene) about the process, but no math or real physics is presented.
So black hole singularities may be the womb of our universe. The unified field is of course quite intense and would provide the initial energy you are looking for. By my calculations, if it is a 26-D field, in 26 dimensions like the original non-super symmetric string theory, it contains enough phase space to spawn a new universe, but not if it is only 10 dimensions.
So that is a possibility that may some day be either proved or disproved by either string theory or Loop Theory or both.
In addition, I want to believe it for religious reasons. In the Sri Bagavatum which is one of the books of scripture of Hinduism, the God Vishnu is characterized as being inside a cosmic egg, sitting on a coiled snake with new universes coming out of his nose. Since this same book predicts the form of quark physics, I am willing to interpret that picture as saying that universes beget baby universes. As Smolin pointed out, it is a possibility based on the understanding of current physics.
I bet this begets more questions,