Popular science communicator and creator of the Veritasium YouTube channel Derek Muller and UCLA professor of physics Alexander Kusenko have a $10,000 bet on a wind-powered vehicle that has been at the center of a heated debate for over a decade. The vehicle in question is the Blackbird, an experimental land yacht that was built to prove a physics debate: can it move faster than the winds that propel it if wind is its only source of acceleration?

At first, this appears to be a huge violation of the laws of conservation of energy, one of the cardinal tenets of our universe. Physics says wind-powered vehicles can exceed wind speeds when they are oriented at an angle to the wind direction, but not when they are exactly parallel to the downwind force. Rick Cavallaro, who designed Blackbird in 2010, never claimed to have found a way around this law but instead believes they built a machine that can get much more out of the wind than is conventionally expected.

The Blackbird has a large propeller at the back connected to the wheels, When the vehicle moves thanks to the action of the wind, the propeller pushes air behind the land yacht, making it go faster. Eventually even faster than the wind, apparently proving the debate. It works not just with a downwind but also with an upwind. However, many people remained extremely skeptical of the results.

That’s where Muller comes in. He made a video on the controversial vehicle, titled “Risking My Life To Settle A Physics Debate,” and put himself in the driver’s seat to test it.

Muller found that the vehicle did indeed exceeded the speed of the downwind measured. He also provided an explanation for how the whole system worked. But the explanation did not sit well with Prof. Kusenko.

Kusenko had previously collaborated with Muller so got in contact with him, reports Vice, and after a friendly back-and-forth decided to settle this with the hefty $10,000 wager. Kusenko’s main argument against the explanation and the vehicle is not that it’s impossible but that it did not prove what it was set up to prove.

In a series of slides he has shared, Kusenko argues that the Blackbird can only get faster than the wind if the wind speed changes throughout the traveling. According to the physicist’s formula, with a constant wind speed, the vehicle won’t be able to outrun the wind. Not only that, but if it were to outrun the wind, the vehicle would experience a deceleration.

And that brings us to the wager. The text clearly states that the wind in the test needs to be constant in time and not change the height between the vehicle and the propeller. The two have planned to work this out with a model version of the Blackbird that can be more easily tested under laboratory conditions. Everything pertaining to this experiment will be shared publicly.

Witnessed to this wager included Neil DeGrasse-Tyson, Bill Nye, and Sean Carroll. If Kusenko is vindicated, Muller’s going to donate the money to Kudu an online learning platform that Kusenko co-founded. Muller has asked Twitter for help to find the right charity to donate the sum if it turns out he's right.

[H/T: Vice]