Carly Simon's song "You're So Vain" doesn't identify its subject, yet actor Warren Beatty has asserted that it's about him.  Beatty's assertion begs a question: if anyone takes "You're So Vain" personally, is he or she technically correct?

The answer is Yes!  According to Hugh Everett's "many worlds" interpretation of quantum mechanics, every possible quantum vanity is realized.  In the many-branched tree of parallel universes, each and every vain human being is the true subject of Carly Simon's song.

This is very comforting! Imagine being vain enough to think YSV was about you, but finding out it wasn't. The very world might cease to revolve around one.

Technical question: Does Everett's theory still hold for values of "a" (a = age of vain individual) that are < Y (Y = years elapsed since song was written)? In other words, was Simon farsighted enough to build infinite references to unborn vain people into her song? 

Similarly, I note the problematics around individuals who were alive when the song was written but not yet vain, their vanity only to develop later on. In their case, I hypothesize a "critical vanity threshold," or CVT--the discrete moment at which someone's vanity has matured to the point where Simon's song begins to refer to him or her.