To me it is conceivable that to two photons that pre-existed the Big Bang were of such high energy, and such short wavelength, that they could easily fit into the extra 6 dimensions of superstring space in addition to the regular 4 dimensions we're familiar with. All 10-dimensions of superstring space were available to them. When they finally interfered, resulting in the Big Bang, the shower of low-energy particles bled out into 4-dimensional spacetime, and the tiny spaces of the extra 6 dimensions became forever inaccessible to them, too small to fit into.

I wonder if anything is still bumping around in those extra 6 dimensions. They would have to be especially energetic and sub-pico-scopic in size.