That is the biggest, hardest,and possible never answered question in
cosmology. We can only theorize the cosmos always had intrinsic energy.
That this balanced energy eons ago was set out of balance by a quantum
fluctuation. Creating gravity,and other quantum dimensions, Fields
and the other forces. It was foam in the Planck size,but it grew faster
than Allan Guth could ever theorize. It was now rightly said to be
"Quantum geometry.(space on a ulramicroscopic scale.,where only QM
effects are reality. The beginning of a wave-particle duality. A time
just before radiation of photons. This Planck time would be the
time of the sub-micro universe. It was the beginning of the beginning.
It is still with us today but very well hidden. I can rightly say we
are the remnants of this scenario. Its left over garbage. I'm just one
of its waste products Bert, " Treb" wants to be included as well
Go figure