In the Futurama episode "A Clone Of My Own", Professor Farnsworth creates a clone of himself, Cubert, to carry on his research after his death. Cubert doesn't share all the Professor's knowledge - it takes a blow to the head before he realises how the ship's engines work - but there's one gap in his knowledge that confuses me.
When the Professor boasts that the Planet Express ship can travel between galaxies in "mere hours", Cubert retorts that that's impossible because "you can't go faster than the speed of light". Prof. Farnsworth retorts that scientists increased the speed of light centuries ago, allowing the ship to move as fast as it does without violating relativity.
This was obviously exposition for the benefit of the audience, but in-universe, it suggests that Cubert understands the concept of light-speed, but only knows its 21st-century value, not the 31st-century value. How could this be the case? How come his knowledge of physics is centuries out-of-date?