My latest Mind and Matter column for the Wall Street Journal is on how the future turns out:
Last month a crash dummy flew to 5,000 feet above ground level in a personal jet pack. The inventor, New Zealander Glenn Martin, has spent decades on the project and is ready to start selling the device for $100,000 each next year. The gasoline-driven machine can stay aloft for 30 minutes, thanks to what is, in effect, a pair of large leaf-blowers. A parachute provides partial reassurance if something should go wrong.
Mr. Martin's achievement is a reminder that, though we often underestimate the progress of a technology, sometimes we overestimate it. Back in the 1950s it seemed almost obvious that by the 21st century jet packs would be ubiquitous and routine aids to travel. They featured in sci-fi novels and comics and television series like "Lost in Space." A time-traveler who arrived from that era might be impressed by our Internet and mobile phones but amazed at our lack of working jet packs.
But the Bell Rocket Belt now gathers dust in the Smithsonian's Air and Space Museum. Its exceedingly short flight time, 20 seconds, was both impractical and unsafe. Unlike airplanes, jet packs cannot land gracefully when the power fails. Soon even the comic-book heroes of the future had begun to do without jet packs.Several jet packs were indeed under development by the late 1950s. One of them, called the Jump Belt, used compressed nitrogen. Another, the Aerojet, used compressed hydrogen peroxide. A few years later, Bell Aerospace's Rocket Belt, also using hydrogen peroxide, seemed the most promising and briefly took James Bond off the ground in "Thunderball."
Just who will buy Mr. Martin's version is still unclear. He is pinning his hopes on emergency workers who need to get somewhere in a hurry. Good luck with that.
There's a general point here. Though communication has advanced beyond the wildest dreams of futurologists of the 1950s, transportation has underperformed. Our time-traveling visitor would be shocked at the absence of routine space travel and the general scarcity of helicopters in civilian life. He would be surprised to find that our cars aren't really that different in mechanism or speed from the things with fins that he drove. In vain would you boast of electric windows and catalytic converters.
The reason for transportation's relative technological stagnation, compared with communication, is diminishing returns, which have blunted our ability to squeeze more out of technology. The fuel needed to fly at supersonic speeds is prohibitively expensive, as the Concorde proved. It has been said that if the car had experienced the sort of cost reductions that computing has found through Moore's Law-which says that the density of transistors on a chip doubles every two years-it would travel to the moon and back on a teaspoon of gasoline.
By contrast, the telephone and telegraph had barely changed since he was born; radio and talkies had been around since his youth; only television and (yawn) telex were true novelties. (That the satellite would do more for communication than for transportation in the years ahead was emblematic of what was to come.)An elderly person alive in 1950 would have witnessed extraordinary changes in the mode, speed and availability of transport: cars, motorcycles, powered flight, jet engines, rockets, outboard motors, electric trains, hovercraft, helicopters and supersonic speed.
Which technologies today are about to hit the brick wall of diminishing returns, and which are poised for sudden price collapses?
The big question is over health care. In recent times it has tended to invent effective but expensive new procedures-medical jet packs, though more useful-such as surgery, scanning and radiotherapy. But some think it might be on the brink of finding cheaper therapies through regenerative medicine and genome sequencing. The latter's cost is down by 99% in about a decade, far faster than Moore's Law.