We don't know how He did it. Perhaps he converted a vast energy supply into matter. However He did it, I believe that He did it.
“I think that we can convert many things, and we can change many things, and we can assemble many things...but creation belongs uniquely to God.”
Yes. Phsyics can neither prove G-d or disprove G-d.
G-d is NOT the universe. G-d is the creator of the universe.