Jim Austin

I mention this because the HomePod's "smart" features—its integration with Siri and the Apple Music streaming service—is a big part of its appeal. In its natural element, the HomePod provides a way of accessing music that, although as old as our century, to me is still new and unfamiliar: Forget your hoary music collection, your Rolling Stones and Beethoven. Decide what kind of music you want to hear—a genre or a mood—then leave the choice to Siri and her algorithmic minions.

The sampling theory formulated by Claude Shannon in the late 1940s had a key requirement: The signal to be sampled must be band-limited—that is, it must have an absolute upper-frequency limit. With that single constraint, Shannon's work yields a remarkable result: If you sample at twice that rate—two samples per period for the highest frequency the signal contains—you can reproduce that signal perfectly. Perfectly. That result set the foundation for digital audio, right up to the present. Cue the music.

Over one busy week in 1986, Karlheinz Brandenburg laid the foundation of a technology that a few years later would upend the record business. Brandenburg, a PhD student in electrical engineering at the Friedrich-Alexander University Erlangen-Nuremberg, was figuring out how to code digital music efficiently enough that it could be delivered over digital telephone lines. A patent examiner had concluded that what the application proposed was impossible, so over a week of late nights, Brandenburg produced the proof of concept and more. It was another decade before the technology—MPEG-2 level III, more commonly known as MP3—would find its true home, the Internet.