By now you've probably seen the latest video of Lexus' hoverboard technology, a two-minute spot produced as part of their "Amazing in Motion" advertising campaign. The board itself is incredibly cool—literally—the technology relies on superconductors, cooled using liquid nitrogen to somewhere below -200°C, and as a result it emits a trail of futuristic-looking fog (actually condensing water vapor) wherever it goes. Unfortunately, the video, which shows a number of skateboarders trying out their favorite sport sans wheels, is more than a little misleading.
When the clip made the rounds at our office, it sparked a good deal of discussion; Halfstache, one of two experienced skateboarders in our midst, maintains that a good portion of the video looks like digital trickery, while the other, Buzz Skyline, insists that it could be done for real with a large enough budget. But you don't even have to go as far as the VFX studio to find the video's disingenuity: the board is on a track.
They've gone to great lengths to disguise it by burying a magnetic rail just below the surface of the concrete in their custom skatepark, but unfortunately the hoverboard as it currently exists is little more than a maglev train for one. The guy who takes a ramp into the bowl at 1:21 looks like he's guiding his own motion, but that's the only path possible on such a board; the rider has no control beyond how fast he goes.
The principle that allows the board to float is known as flux pinning, and it relies on the magnetic induction of currents in superconductors. To help explain how, a more transparent version of the underlying mechanism might be useful, so to that end we've included the following video from Tel Aviv University:
If you've taken first-year physics (or ever used a shake-powered flashlight) you know that a changing magnetic field will create a current in a conductor, and we can think of what's happening here in terms of that. When the demonstrator changes the position or orientation of the superconducting wafer with respect to the magnet, he's changing the magnetic field experienced by the wafer, which creates a persistent current within it. Thanks to this, the magnetic field through the wafer can't change without also altering this current, so the wafer remains "locked" in place by the inertia of the charge-carriers which comprise that current.
Later in the video, the demonstrator sends the wafer around a track, where they've constructed what's known as an equipotential surface; the superconductor can move freely along the track without experiencing a change in magnetic field. Lexus' hoverboard is traveling along a similar track; anywhere besides on that one rail, in that one specially-constructed skatepark, it's infinitely less useful than its wheeled counterpart. (As an interesting aside, that skatepark is a potential NIGHTMARE for any real boarders who are tempted to put it to use, given that they're likely to be unaware of the high-strength magnets buried in the bowls and ramps. This wouldn't be a problem if all the metal components of a board were aluminum, but the wheel bearings and axles are often made of stainless steel, so skating over a line of buried magnets would be a lot like hitting an invisible trip-wire; the board would slow down significantly, but the rider very likely would not.)
While it's still awesome that Lexus has managed to scale the technology up to the point where it can support a person's weight, the way it's presented is thoroughly disappointing; I feel like Lexus is trying to sell us a slot car as an "RC car". Yes, technically the slot car is remote-controlled, but having control over acceleration in one dimension isn't what comes to mind when I hear that phrase. They know that this is a hoverboard only in the strictest sense of the word, but they're willing to come as close as legally possible to outright lying about its capabilities...all in the name of cold, hard clicks.