I use the subject query to typify a phenomenon that becomes noticeable with age in both directions - the surprise that someone is too young to know all about people I understood to be as iconic as Muhammad Ali (often cited as the most recognizable figure in the world), such as Paul Robeson (whose name got a blank response from my own son!) - and my own "who's Kurt Cobain?" (although I became fairly familiar with him when he blew his brains out).
This effect is really striking when one is in a foreign land where entire genres are noticeably blanked out "what's a 'double play' or a 'slam dunk'?"
The idea of there being only six months until some technology solves stuff (voice recognition, indexing pictures, communicating via brain waves) because "they used to say we'd never walk on the moon, so why can't we produce a time machine?"
I read that three paths not to get led up are time travel, anti-gravity, and teleportation. Of course perpetual motion has always been in there but the universe is in fact an example thereof - apparently quarks don't die.