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Uploaded:2014-03-14
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Hank gives it to you straight about "anti-gravity technology" -- basically, it doesn't exist. But if you really want to hover, you have options!

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Sources:
http://www.amasci.com/amateur/hovercft.html
http://science.howstuffworks.com/hoverboard1.htm
http://magnetbahnforum.de/index.php?en_what-is-maglev
http://shanghaichina.ca/video/maglevtrain.html
http://science.howstuffworks.com/transport/engines-equipment/maglev-train.htm
http://inhabitat.com/japans-new-310-mph-floating-maglev-bullet-train-hits-the-tracks-for-testing/
http://www.instructables.com/id/Asymmetrical-Capacitor-Thrusters-the-Biefeld-Brow/
http://www.gizmag.com/mit-ionocraft/26908/

 HUVrTech hoax


[intro music]

So in the last couple of weeks you may have been exposed to the internet contagion that was the HUVrTech hoax, a phony commercial in which Tony Hawk appeared to be hawking a Back to the Future style hover board. If you fell for it, I mean, I guess that's what hoaxes are for, but you probably need to hone your BS detector a little better. And if you managed to miss it I'm sure that you want a hoverboard as much as anyone else. Unfortunately it's my job to break it to you: 'anti-gravity technology' is not a thing. If you spend any amount of time on or near an object that has mass, you're going to experience gravity. But the good news is, if you really do want to levitate: you have options.

 Personal hovercraft


For example, there are personal hovercraft. They look like a jet ski that had a baby with a lawn mower, and they are about as low-tech as both of them. They work by lifting the vehicle over a cushion of air created by a gasoline-powered fan, which lets you glide around a few inches above the ground, so long as you don't go over sand or water. They don't look very cool, and they only go about twenty five kilometers per hour, and if you want one, it'll run you about fifteen thousand US dollars. What they do have going for them is that they exist.

 Magnetic levitation


If you want something a little higher tech, might I suggest magnetic levitation? That technology exists already. In fact, the fastest trains in the world use it, with magnets under the train floating inches above electromagnetic coils along the tracks. Because they never touch the ground once they start moving, these kinds of vehicles aren't slowed down by friction. Air resistance is their biggest source of drag.

The high-speed Shanghai Maglev moves at four hundred and thirty five kilometers per hour, and the new Maglev bullet train developed for Japan will operate at five hundred kilometers per hour. Of course for this technology to work on a Marty McFly scale, a personal magnetic vehicle would only work on some special infrastructure, like a system of magnetic rails or ground panels. This would be a lot more limiting, and it also doesn't exist.

 Ionocraft


So okay. You wanna really levitate. No magnets, no special panels - you wanna float silently on a craft with no moving parts and you wanna be able to fly over anything you want - sand, water, a Sarlacc pit, ... ? Okay, you want an ionocraft.

So far they only exist on the really small scale, like something you could fly around on your desk, but they do work. They lift themselves by ionizing the air around them, and creating a powerful flow of that ionized air from positive electrodes on the top of the craft to negative ones on the bottom. Since the 1920s, when it was first discovered, this kind of air flow has been known, rather enchantingly, as 'ionic wind'.

The fun begins at the top of the ionocraft, where lots of sharp, spiky electrodes are charged with massive amounts of electricity. Thanks to something called 'the Biefeld-Brown effect', air ionizes when it encounters electrified sharp edges, so these electrodes quickly start tearing electrons off all the nearby molecules in the air. This creates a cloud of positively charged ions, which are immediately drawn down to the powerful negative electrode at the bottom of the craft. As the ions rush along the sides of the craft, those ions collide with all of the neutral air molecules around it, pushing them down. At the same time that stampede of ions creates a vacuum on top of the ionocraft. So with vacuum on top and a strong push below, you get a lift and the craft silently floats into the air. There is a name for it: it's called 'electro-hydrodynamic thrust', and it's more efficient than a jet engine.

While a jet produces two Newtons of thrust for every kilowatt of electricity, ionocraft produce a hundred and ten Newtons of thrust per kilowatt. Jets, it turns out, waste a lot of kinetic energy, but ionocraft waste almost nothing.

So what's the problem? Energy. Ionocraft need lots and lots of electricity to operate. It takes about one watt of electricity to lift one gram of weight, so creating even a small craft using electro-hydrodynamic thrust would require megavolts to operate. That's millions of volts. To give you a sense of perspective: the batteries on most electric cars provide somewhere between three hundred to four hundred volts.

 Conclusion


So maybe the reason the HUVrTech hoax was so tempting it's because it's a technology we all want so bad. And there are technologies that are working toward that eventual goal. Maybe by the time the internet comes up with an automatic hoax debunking app, we'll all have our hover boards.

 Closing notes


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