The holographic principle is arguably the most tangible and tantalizing clue to a quantum theory of gravity, but for years physicists didn’t know what to make of it. That changed in 1997 when Juan Maldacena, now at the Institute for Advanced Study, came up with the first concrete example of what the principle means and how it works. Here Maldacena gives us a summary. The filmmaker is Gary Smaby, who was an artist-in-residence at the Kavli Institute for Theoretical Physics in Santa Barbara in 2012, at the same time I was the writer-in-residence there.