Drones ply the liminal space between the physical and the digital - pilots fly them, but aren't in them. They are versatile and fascinating objects - the things they can do range from the mundane (aerial photography) to the spectacular - killing people, for example.

Each year, thousands of UFOs are sighted and reported, which is an impressive tally of unidentified aerial phenomena. Surveys show that roughly one-third of the populace believes that at least some of this sky show is due to extraterrestrial spacecraft, here to probe our airspace and, when that proves boring, our bodies.

The fact that a cloud from a minor volcanic eruption in Iceland-a small disturbance in the complex mechanism of life on the Earth-can bring to a standstill the aerial traffic over an entire continent is a reminder of how, with all its power to transform nature, humankind remains just another species on the planet Earth.

My wife and I had decided not to let anybody take pictures of our home because it was just the last place on earth we had that was unscathed. But people have climbed over the fence they've taken aerial shots. They've gotten my address and put it on the Internet.