The story of Superman; Superman, hundred of thousands of miles away Lois Lane is falling from a 100-foot building taking 3 seconds to hit the ground(an example). Sheldon says there's no way for Superman to catch her without Lois getting killed. Leonard says the opposite? Who is right? Just to be an arse, I'm going to give it away. If you watch the show, you would know that Sheldon is always right, and in this case, he is right. So, in the scenario above, lets say Superman would have to travel 30,000 miles in a second to catch her. Therefore, he would have to travel about 5*10^10 m/s to catch her, more than the speed of light. In the old comics, when traveling at that speed, time would actually reverse. In order to not reverse time, Superman would have to travel less than the speed of light, and therefore not catch Lois Lane. So, that's one reason of why Superman could not catch Lois Lane. Next time, more physics examples to enrich your life.