That part is known as "God".
Not exactly. Assuming Big-bang, there wasn't even an empty vacuum before creation. No "space," no "time." I'd say too, no mass, and no energy. The universe just "sprang to." Time zero, no such thing as "before" that, only after.
My observation pertains after the big bang, in a universe that has space, mass, energy and so forth. That "empty" vacuum of space has more happening than an extreme mass density situated somewhere in space is counterintuitive.
Note too, my remark puts those "objects" in isolation. Taken in context, a black hole has profound effect on surrounding masses and energies. Just that inside the event horizon, time and space cease to exist. "Black hole inside a black hole" is a meaningless construct.