The show has an official science advisor.

When you have a show that frequently references scientific terms, theories and experiments, you’ll definitely need the script to be verified by someone who actually knows these things. Of course, The Big Bang Theory has that person and his name is David Saltzberg. As a science advisor, he helps the writers with the scripts and is also present at every taping session so he can help edit or answer last minute questions that the cast or director may have.