That's very clever, but there is also a clear phallic reference indicated by the picture which seems to say that getting a PhD makes you even a bigger **** than you already were.
But, the really big picture is that the sum total of all people pushing out that boundary (whether those people have Ph.D.s or not) is much more than a little blip on the surface. That total of all human effort makes the surface expand like a supernova.