I love this story because as Feynman puts it, there's a difference between knowing the name of something and really knowing it.
Since we're on the topic of light -- despite going to a great school and taking several physics courses, I suffered from a severe misconception until about a month ago. Maybe you have it too.
Think about a light wave. You might imagine a diagram like this:
http://betterexplained.com/wp-content/uploads/graphs/Wave.pn...
Yep, you've seen it a million times. Light is a wave and wiggles up and down... right?
Oh really? Do you think the fastest thing the universe travels in a zigzag pattern? Hey, why don't we beat the speed of light by moving on a straight line! Nobel prize time!
No, the y-axis is amplitude of the field. The graph is not a Family-circus dotted line following the particle's motion! A better diagram may be this:
http://betterexplained.com/wp-content/uploads/graphs/wave_am...
It's the intensity of the wave which is varying. But we memorize the "light is a wiggling wave" diagram and wind up with a severe misconception.
(Shameless plug: I blog at http://betterexplained.com and try to hammer away at the insights that have befuddled me.)