Y Combinator’s universe is more vast than you might initially think.  There’s Y Combinator itself, consisting of at least 14 partners and advisors.  Paul Graham inherently means YC’s universe includes the Lisp programming language and Arc dialect.  The other partners are also all interesting characters, like Robert T. Morris and the Gmail creator, Paul “Don’t Be Evil” Buchheit.  YC funded companies total more than four hundred known startups, across at least thirty distinct markets.  YC’s alumni network is over a thousand people.  Twice a year, there’s also the process of applications and interviews.  Then between January-March and June-August there’s YC’s three month start-up program.  The program culminates in the semi-annual Demo Day.  YC’s universe also includes Hacker News, which now reaches 200,000 daily visitors.  Also the annual one-day Startup School, held at Stanford University.

And as always, the universe is expanding.