“I mean,” Hockney continued, “I’ve observed his progress, though at times that was by no means easy, and for the longest time I felt that his position on the photographing of his work”—a flat prohibition, as it happens (which is one of the principal reasons he was so much less well known among the public at large)—“was pretty preposterous, and somewhat fetishistic.” Irwin for his part accounted for that absolutist injunction by arguing that a photograph could capture everything that the work was not about (which is to say its image) and nothing that it was about (which is to say its presence), so why bother?

Hockney paused and took a drag on a cigarette before going on to confound me entirely: “The thing is,” he now said, “with time I’ve come to see that Irwin was right about that ban on photographing his work; I wish I’d imposed a similar ban regarding my own from the outset.” (This from an artist whose work was more photographed and more ubiquitously visible in the world than that of just about anybody else, with the possible exception of Andy Warhol!) “I mean, no one can come upon one of my paintings in a museum, say, and simply see it; instead they see the poster in their college dorm or the dentist’s office or the jacket on the book they are reading, all sorts of second-rate mediations getting in the way of experiencing the work as if from scratch.”

One billion people live in slums. Their numbers are supposed to double over the next quarter-century. So: Who are those people — and what must their lives be like?

The Norwegian photojournalist Jonas Bendiksen has spent a good deal of time in Indian, Kenyan, Indonesian, and Venezuelan slums, and his website, The Places We Live, features dazzling 360-degree photos of homes and shanties, navigable and altogether immersive, along with audio recordings made by the inhabitants. Prepare yourself to gape, gasp, laugh, cry, and experience every emotion in between: In Mumbai, you’ll meet the Shilpiri family (15 people crammed into a tiny space through which floodwater and garbage regularly stream). In Nairobi, the head of the Dirango household takes great pride in his cramped abode, giving a tour that takes just seconds. “You have to visit somewhere before you judge,” he explains. Thanks, Mr. Bendiksen, for starting us on the journey.

Lest your inner libertarian objects to such interventions, Champ is quick to correct the idea that the community would ultimately find its own balance.

“The amount of time it would take for the community to self-regulate—I don’t think it could sustain itself in the meantime,” she says. “Anyway, I can’t think of any successful online community where the nice, quiet, reasonable voices defeat the loud, angry ones on their own.”

In this sense, Champ doesn’t just shepherd along the Flickr ethos; she’s a larger advocate of intelligent growth in an often chaotic zone.

“People become disassociated from one another online. The computer somehow nullifies the social contract,” she says. In other words, people sometimes go nuts amid the anonymity of the Internet.