For the uninitiated, Coinbase — a cryptocurrency exchange — ran a 60 second spot that featured a QR code bouncing around in a way reminiscent of old DVD screensavers. It was a roaring success.

Suppose you are trying to transmit a message. Convert each character into bits, and each bit into a signal. Then send it, over copper or fiber or air. Try as you might to be as careful as possible, ...