Actual scientists often visited the set of “The Big Bang Theory”. And the cast and crew are pretty lucky they did because one of them found radioactive material on the set!
A “famous physicist” once attended a taping and got a tour of the set afterward. He noticed an antique Geiger counter in Leonard and Sheldon‘s apartment. He informed them that in the old days before people knew better, Geiger counters used to have a piece of uranium in them for calibration.
So this guy went to his trunk and got his own Geiger counter and the old one did have radioactive material in it. So he took it with him to get rid of it.
Luckily, uranium isn’t as toxic as other radioactive materials and it’s most dangerous if inhaled in large quantities. So they probably weren’t in any real danger.
Source: Entertainment Weekly