On the first day of the first course as a CS major, the prof said something like "in this course you'll learn how computers work from the bottom up", turned to the blackboard, and wrote Maxwell's equations. We laughed, and he said, "You're laughing because I got it wrong, no? You need quantum mechanics for transistors".

We actually ended up starting at logic gates, flip-flops, and latches. But the joke was a great reminder that your floor is someone else's ceiling.