James Martin/CNET

You know that saying, "Don't reinvent the wheel"?

Greg Henderson never got the memo because that's how he spends his time -- and his money -- these days.

Henderson is the guy who shocked "Back to the Future" fans everywhere in 2014 when his startup, Arx Pax, unveiled the seemingly impossible: the Hendo -- a hoverboard that actually hovers above the ground.

Since then, Arx Pax has built a second-generation device, the Hendo 2.0. The meter-long board, which sits above four hover engines, still needs to glide over a conductive surface like copper, so you can't fly it outside like Marty McFly. But the newer, lighter and quieter board, which was built with input from professional skater Tony Hawk, is a major step toward creating a device that, until recently, was pure science fiction.

Building the hoverboard, though, is only the tip of Henderson's ambitions. In a few thousand square feet in an understated, one-story office park in Los Gatos, Calif., Henderson oversees a team of 16 employees working on some of the most far-reaching technological projects of any startup in Silicon Valley. That's saying something in a place known for its moonshots.

The same core technology that Arx Pax is using to power its aluminum-framed hoverboard -- what it calls its Magnetic Field Architecture -- could also reinvent the wheel and rail, shield buildings from earthquakes, pull a satellite through space (aka a tractor beam) and even fight infectious diseases.

That makes Arx Pax the most ambitious startup you've probably never heard of.

"As an architect, I learned early that the greatest obstacle is overcoming the resistance to human change," says the 50-year-old Henderson, who co-founded Arx Pax (Latin for "citadel of peace") with his wife, Jill, in 2012. "But where there's a will there's a way and there's a lot of that around here."

First thing's first. The hoverboard is the reason we're talking about Arx Pax, even though it's not a hoverboard company. In fact, it never intends to mass produce a hoverboard. Instead, Arx Pax is really a magnetic-levitation motor company trying to find ways to license its technology, including its hoverboard patents, to everyone it can.

A longtime US Army officer turned architect, Henderson began thinking about magnetic forces after seeing the devastation wrought by California's Loma Prieta earthquake in 1989. His idea: If magnetic forces could be used to lift a building before a quake struck, it could spare it the costly damage.

That might sound crazy, but Henderson never dropped the idea. However, it's the public's obsession with the hoverboard that helped put his company on the map.

Beyond earning Arx Pax international media attention, his 2014 crowdfunding campaign raised more than $500,000 from some 3,100 people. Henderson pledged to send 10 hoverboards to backers who donated at least $10,000. (Last fall, Arx Pax says it gave those backers the choice of taking a Hendo 2.0 or waiting for the next generation device. The majority chose to wait, according to the company, which says its goal is to deliver that in "coming months.")

Since that campaign, Arx Pax has been running on funds from friends and family. And it's been applying the same electromagnetic technology underlying its hoverboard to, well, pretty much every sector of the economy -- transportation, entertainment, health care, aeronautics and manufacturing.

"We have some really exciting projects going on," says Henderson.

But for all its promise, Arx Pax hasn't had a lot of scrutiny, and it's hard to find experts who can even evaluate Henderson's claims or its ambitions.

"We do believe Arx Pax has promise for magnetic levitation and induction powered propulsion, but we have not looked into their 'Magnetic Field Architecture' concept too closely," wrote UC Berkeley engineering professor David Dornfeld and mechanical engineer Caleb Boyd, co-founder of Hyperloop Initiative Program, a Berkeley student group working to develop technologies related to the next-gen transportation system.

Great expectations

If the Hyperloop is ever a thing, there's a good chance Arx Pax will power it. The high-speed rail conceived by SpaceX and Tesla founder Elon Musk imagines whisking people in pods between San Francisco and Los Angeles at 760 miles per hour. That means covering the distance between the northern and southern California cities in about 30 minutes, versus the six or more hours it takes by car. But it's still just a concept. To make the Hyperloop real, Musk's SpaceX has been holding design contests.

Of 22 teams advancing to the next round of SpaceX's competition to design the pods, 10 are using Arx Pax tech, which ditches the wheels, axles and a track entirely.

Creating propulsion without wheels or rails could have serious ramifications for cars. Though Arx Pax's propulsion system requires that anything it powers be on a conductive surface like aluminum or copper, car makers are interested.

Representatives from 11 auto companies have visited Arx Pax, according to Henderson. Some are thinking about "long-term development of a hover car," he said. "Others are interested in things like hovering cars in showrooms, being able to move a brand new car around with a fingertip."

Last June, Arx Pax nabbed headlines when Henderson said it had developed a way of protecting buildings from earthquakes -- by making them hover, of course. His method relies on using his magnetic engines to effectively lift a building right before a quake. It's tied into a government program called ShakeAlert that can send early warning signs.

Now playing: Watch this: We got to ride the improved Hendo 2.0 hoverboard

Arx Pax also thinks its tech can create a whole new entertainment venue: hoverparks, as in amusement parks built on conductive surfaces allowing hover-skateboarding, hover-go-karting and even hover-luging.

Then there's its partnership with NASA. Arx Pax announced last year that it would begin working with the space agency to create devices that could pull satellites through space. In layman's terms, it's called a tractor beam, like the thing you remember seeing in "Star Trek."

Manipulating magnetic forces could also be a valuable tool to fight disease, according to Henderson. Animals like mosquitoes use the earth's magnetic pull to navigate, allowing Arx Pax tech to be used like an insect tractor beam to fight mosquito-borne viruses such as West Nile or Zika.

That's Henderson's hope anyway.

The problem, though, is no one really knows if Arx Pax can pull it all off. Henderson acknowledges that Arx Pax may have "offended" the scientific community because it hasn't published any white papers about its technology. "We haven't gone through peer review yet," he concedes. "That's coming."

Pressed for a more concrete timeline, Henderson said, "Publishing papers or articles suitable for peer review is still an important goal. Though we can't commit to an exact time frame, we anticipate submitting our research sometime in the year."