Big Bang Theory executive producer Bill Prady took to the show's Facebook page to comment on the casting of Dr. Hawking. "When people would ask us who a ‘dream guest star’ for the show would be, we would always joke and say Stephen Hawking – knowing that it was a long shot of astronomical proportions,” he said. “In fact, we’re not exactly sure how we got him. It’s the kind of mystery that could only be understood by, say, a Stephen Hawking.”
Keep an eye on StarTrek.com for additional details about both appearances.