Suppose scientists decided to send a message to an extra-solar civilization (like the message we’re listening for, with SETI), and you were put in charge of what to say. The brainiacs say your message will reach them in about a billion years, give or take a few hundred million. You can send them anything you want: music, karaoke, classic literature, porn, a personal message, anything you want.
Wikipedia would be a poor choice, I think, especially if they got to see any of the comments pages. They’d invent time travel just to come back in time and kill us.