We are never, ever, ever going to have flying cars. But it will be a long time before we stop wanting them.

Last month, I had a brief period of rage-blindness after yet another flying car was unveiled at some auto show or tech conference.

The body of the prototype should be smashed apart with sledgehammers and the engine flung into an active volcano. It would be a better use of the resources than building another useless flying car.

Flying cars are impossible. Not because you can鈥檛 build one! No, we can definitely build compact flying machines. But because our physical and social infrastructure cannot handle them.

The physical part is obvious. We鈥檇 have to build innumerable control towers, landing strips, and radar systems.

The social part is where we run into an even bigger problem.

We鈥檇 need hundreds, thousands more air traffic controllers, not to mention a vast army of flight instructors, ground crew, and newly trained maintenance personnel. Building up the infrastructure for flying cars would be akin to building up an army to fight a world war.

Would you be happy if your taxes were doubled so that people making $250,000 a year or more could fly to work?

One of the most famous stories in technology is that of the QWERTY keyboard. This is the fable of technological lock in: old typewriters were built with the top row of letters starting with QWERTY, because the keys were less likely to jam. Then we taught everyone how to type using this layout. Now jammed keys aren鈥檛 an issue, but if you changed it鈥�

That鈥檚 lock in, the place where hard technology (we can make better keyboards!) meets practical social reality (I am not bloody learning to type again!).

But we will continue to see inventors crank out flying cars, and we鈥檒l still see people who will want them.

That鈥檚 also part of our social infrastructure. The 20th century trained those of us in the industrialized west to want and expect certain things: personal transport, 鈥渓abour saving鈥� gadgets, and steady progress. We have cars, so we want cars that are faster or better or shinier. Or that can fly, sure.

We expect progress along lines we can easily imagine. That鈥檚 why we鈥檝e been waiting for flying cars for 80 years, but no one expected the smart phone.

The next big thing? You don鈥檛 want it, because you haven鈥檛 imagined it yet.