Tesla founder Elon Musk's Hyperloop is finally out in the open, and just as the billionaire tech entrepreneur said, it actually does look like what you get when you cross a Concorde with an air hockey table. But it's not the first far-out people-mover concept to ever capture our attention — and if Hyperloop falters, it's not the first that couldn't live up to the hype.
The original futuristic transport idea, flying cars were a part of myth and legend before they were part of science fiction. Greek heroes and gods took to the sky in style: Bellerophon rode Pegasus, a winged update to the most common vehicle of the time, the horse, while Helios drove a flying chariot drawn by "solar steeds." Later, Leonardo dreamed up the human-powered ornithopter, and some centuries after that, Hanna and Barbera gave "The Jetsons" retro-future flying vehicles.
Though many have been built in real life, they've never gotten close to crossing over into the mainstream. Why? The reasons are numerous: Even if the engineering made sense, the expertise required to pilot such a vehicle would be extensive, and the danger of a crash is massively increased.
That hasn't stopped companies like Terrafugia, however, which sells a strange-looking but unmistakably functional flying car. All you need is $279,000, plus a runway and a pilot's license. In the end, it's more of a street-legal plane than a flying car.
Much like flying cars, jetpacks have always been more fantasy than reality. Strapping a high-powered, brakeless and potentially very hot engine to one's back is inadvisable, even before takeoff! The things that could go wrong with one person wearing a jetpack — to say nothing of a whole city full — are innumerable.
That hasn't stopped people from making them, like the twin turbine "Martin" jetpack enthusiasts got to try a few years ago. And if you want the thrill without the combustion, you can ride a water-powered jetpack — although as this newscast-gone-wrong showed millions, that too is not without its risks.
Popularized in "Back to the Future Part II," the hoverboard just looked like a plain fun way to get around. Unfortunately, science hasn't quite caught up to Hollywood in this regard, and anti-gravity is as elusive today as it was in 1989. Before the Segway was revealed to be an electric scooter, it was rumored to be a hoverboard, leading to widespread disappointment when it arrived.
Of course, we have maglev trains and the occasional superconducting Moebius toy, but these don't scale very well: The high-tech tracks end up costing a fortune as they extend to hundreds of miles, and one short circuit could cause the rail-less version of a derailment. The Hyperloop uses a cushion of compressed air and other aerodynamic forces to stay afloat, which Elon Musk claims is far more realistic.
Pneumatic tube transit
Monday's Hyperloop announcement is perhaps the most advanced version of an idea that's been around for two centuries. The original "atmospheric railways" were proposed by English inventor George Medhurst in 1812, and experiments with tube-based transport of people and goods culminated in 1867, when Scientific American editor Alfred Beech demonstrated a working section of a pneumatic passenger railway at the American Institute Fair.
The fascinating history of these Victorian-era tube transit systems (and other early New York mass transit attempts) can be found in a comprehensive account by Joseph Brennan, hosted by Columbia University here — the old "Beach Pneumatic Transit" systems are highlighted in Chapter 2.
When you hear "car train," one of two things may come to mind. And as it turns out, both have been theorized! First, there's the actual car train, an oversized rail-rider that cars traveling long distances — say, between Los Angeles and San Francisco — would board like passengers. Since such huge numbers of cars travel between certain hubs, this could take hours off commutes and remove thousands of cars from clogged interstates. Inventor Anwar Farooq explains his vision in detail here, while Amtrak actually has a rudimentary version currently running between D.C. and Florida.
Those more familiar with intelligent vehicles or racing, however, may think of "car train" as a long line of vehicles driving extremely close together in an aerodynamically advantageous formation. Cruising at the speed limit while bumper to bumper, these "platooning" cars get great mileage and essentially drive themselves — except, of course, for the vehicle in front.
This is one sci-fi idea that is rapidly coming to fruition. The robo-cars of yore began taking shape in the real world with the Defense Department-funded "Grand Challenge," in which robotic vehicles worked their way over terrain using cameras, laser rangefinders and onboard computers. Now Google's autonomous vehicles have driven hundreds of thousands of miles with no mishaps, paving the way for a more mainstream roll-out.
Will you have a Google-powered self-driving car in the next five years? Existing laws and customs suggest the answer is no, but with ordinary cars getting smarter and more connected, don't be surprised if yours learns to park itself, avoid obstacles or alert the authorities if it's stolen.
Crazy? Maybe not
It seems doubtful that any of these technologies will hit our streets (or skies) exactly as envisioned. But even if things don't go quite the way sci-fi writers project, the ideas are still important.
Take the cars in "Minority Report," for instance, which go from manual to automatic as they fly up the side of a building. That's not going to happen any time soon — but you may be able to leave your car in a special zone and have a parking structure take control of the car, driving it to the nearest space. And hoverboards aren't likely to cruise into Toys R Us, but you can buy an electrically powered skateboard today that will let you carve your way to work — on the ground, admittedly, but it's still cool.
As for more advanced concepts, it's best to remember that many of the things we take for granted, from satellites to smartphones to digital cameras, were once science fiction themselves. Almost every world-changing technology starts as a crazy idea. First we laugh at it, then we want it, then we can't live without it.
Devin Coldewey is a contributing writer for NBC News Digital. His personal website is coldewey.cc.