In the movie “Contact,” Jodie Foster plays an astronomer who discovers a signal that, when decoded, proves to be instructions to build an interdimensional spacecraft. Great story — great movie — but the book had a far more stunning premise. In that, Foster’s character takes up mathematics, and discovers that, at about a sextillion digits into it, π contains a binary-encoded message. I found that to be a pretty mind-blowing concept. Michael Specter’s article in last week’s New Yorker elicited a similar reaction in me, only stronger, what with being true. It turns out that 8% of our DNA consists of retroviruses, the remnants of long-ended genetic battles between humans and viruses that infect our RNA and use it to launch an attack on our DNA. This battle goes back 100 million years, and the “infections” are found exactly as would be expected along the evolutionary tree. In fact, placental birth is a result of an infection shared by all mammals. Mind expanding, eh?