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The Almighty Buck Youtube

YouTuber Won $10,000 Bet With a Physicist Over Wind-Powered Vehicle (businessinsider.com) 200

Derek Muller, creator of the science-themed YouTube channel Veritasium, won a $10,000 bet with UCLA physics professor Alexander Kusenko, who claimed that Muller's wind-driven land yacht couldn't travel faster than the wind without any additional power sources. After recruiting science stars Neil deGrasse Tyson and Bill Nye to help settle the debate, the professor eventually conceded that it was in fact possible. Insider reports: Created by Rick Cavallaro, a former aerospace engineer, Blackbird is unique because it can move directly downwind faster than the wind itself for a sustained period. Any sailor worth their salt can tell you that a boat can travel faster than the wind by cutting zigzag patterns; that's called tacking. But the idea that a vehicle can beat the breeze traveling straight downwind, no tacking involved, is controversial. "I knew this was a counterintuitive problem. To be perfectly honest with you, when I went out to pilot the craft, I didn't understand how it worked," Muller told Insider.

Blackbird is so counterintuitive, in fact, that less than a week after Muller released his video (below), Alexander Kusenko, a professor of physics at UCLA, emailed to inform him that it had to be wrong. A vehicle like that would break the laws of physics, Kusenko said. "I said, 'Look, if you don't believe this, let's put some money on this,'" Muller said. He suggested a wager of $10,000, never imagining Kusenko would take it. But Kusenko agreed, and in the weeks that followed, they exchanged data and argued about Blackbird. They even brought in several of science's biggest names, including Bill Nye and Neil deGrasse Tyson, to help decide who was right. In the end, Muller emerged victorious.

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YouTuber Won $10,000 Bet With a Physicist Over Wind-Powered Vehicle

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  • Fresh news? (Score:4, Funny)

    by sTERNKERN ( 1290626 ) on Friday July 30, 2021 @03:08AM (#61637077)
    I remember this happening a couple of weeks back.. or has he won an additional 10000$?
    • Yeah, old news. Why is this suddenly on science alert and here as though it's news.
    • Re:Fresh news? (Score:4, Insightful)

      by thegarbz ( 1787294 ) on Friday July 30, 2021 @05:25AM (#61637285)

      I remember this happening a couple of weeks back.. or has he won an additional 10000$?

      Very fresh, only a couple of weeks behind is batting above the average here in Slashdot.

      • In general I think the Slashdot editors should be defended for their work, but this is a story that makes it hard... Maybe there was a reason that it languished in the submission queue for so long? Something about the actual definition of "tacking" that might have been more familiar to the other editors of Slashdot?

        Disclaimer: I am NOT a sailor, but my fuzzy recollection is that you can't go faster than the wind running before it, but I believe there are conditions when you are running at certain angles to

    • Re: (Score:2, Funny)

      by Anonymous Coward

      He actually won $10,000, not '10000$'. I'm %100 sure of that.

      • In Quebec the french form for ten thousand dollars is 10 000 $
        and for a dollar fifty it's 1,50 $
        Yeah, confusing

  • Back to the future (Score:5, Informative)

    by bug1 ( 96678 ) on Friday July 30, 2021 @03:20AM (#61637091)

    This was a thing last decade, that guy should get some Venture capital, for betting !!!

    From Discovery channel in 2010,
    https://www.youtube.com/watch?... [youtube.com]

    • by The_Noid ( 28819 ) on Friday July 30, 2021 @04:22AM (#61637177) Journal

      It was also on Slashdot on the 6th of November, 2010: https://hardware.slashdot.org/... [slashdot.org]
      One of the few Slashdot stories I still clearly remember :)

      • If you watch the video, the physicist had a bunch of good arguments why it shouldn't work. The most compelling probably being that transitioning to faster than the wind leads to a division-by-zero error in the equations which describe the motion. So he probably felt he was on solid ground making the bet. The division-by-zero actually turns out to be due to a simplification made in the equations to make it easier to solve. If you remove that simplification and solve the long version the hard way, there turns
  • My explanation:

    We all agree that a windmill can extract power from the wind-- we see that every day!

    Separately, we agree that, with sufficient power, a vehicle can be propelled at speeds faster than the wind-- we see this every day as well!

    If we hooked up the windmill to the vehicle (for example, using electricity), we could easily power a vehicle faster than the wind using that same wind. For instance, if we had a 1KW wind turbine, and that was powering an electric bicycle, you could easily get up to 30mph

    • I'm not denying it works but consider the counter example, the windmill is mounted on a truck that is driving downwind at exactly the same speed as the wind is going. How can the windmill generate any power at all?

      The only way I can see that you can cross this barrier is for you to accelerate to the wind speed, the wind to slow down slightly so you're now going faster than the wind (and can start to extract energy again) and then the wind picks up again and you can accelerate some more.

      ISTR it was demonstra

      • Re:Why this works (Score:5, Informative)

        by The_Noid ( 28819 ) on Friday July 30, 2021 @04:30AM (#61637195) Journal

        You should not think of this thing as a windmill. It is not. It's a propeller like in an airplane. The wheels power the propeller.

        Then why does it move at all, if the windmill is not what is extracting the power? Simple. Anything you put in the wind will start moving. With an ideal 0-friction, anything you put in the wind will accelerate until it moves at the same speed as the wind. Now blow backwards into the wind, and you'll move faster than the wind!

        • Thanks. That makes sense.

        • by grmoc ( 57943 )

          This isn't correct.

          The windmill, if coupled directly to the ground, *is* generating power, even when the truck or whatever is going the speed of the wind downwind because the wind is still moving relative to the ground.

          There is a lot less efficiency, because the windmill is having lots of drag, etc. but that doesn't change the fact that the difference between the windspeed relative to the ground is generating power which is then being used to move the vehicle (in this case mechanically).

          • This isn't correct.

            The windmill, if coupled directly to the ground, *is* generating power, even when the truck or whatever is going the speed of the wind downwind because the wind is still moving relative to the ground.

            There is a lot less efficiency, because the windmill is having lots of drag, etc. but that doesn't change the fact that the difference between the windspeed relative to the ground is generating power which is then being used to move the vehicle (in this case mechanically).

            You are right, but that isn't how this works; it's an explanation for a different vehicle. The power is transferred from the wheels to the fan and the fan is pushing the vehicle along. I know it's a sin here on Slashdot, but you need to actually watch the video to the end.

            A key thought, that might help, is that if you turned this vehicle back to front and tried to go upwind, it would go backwards and would still (in principle, if you could control it right) go faster than the wind downwind. Another key t

            • Re:Why this works (Score:5, Insightful)

              by grmoc ( 57943 ) on Friday July 30, 2021 @05:03AM (#61637263)

              There are a bunch of other videos, by the way-- Rick has talked about this since at least 2000, if not before.

              This is definitely how it works, but if if the explanation isn't making sense then *shrug*. The great thing about physics is that you can explain the thing different ways or in different reference frames and it is still the same thing.

              Here is another example for you:
              A sailboat without a keel can only go windspeed because the energy captured is based on the difference in the speed of the boat vs the wind. When the boat is at windspeed, no more energy can be captured.

              A sailboat with a keel can go faster than the wind because it can react the wind against the water under the boat.

              A windmill in a pickup truck where the windmill isn't directly coupled to the ground via gears will act like a sailboat without a keel.
              A windmill in a pickup trick where the windmill is coupled directly to the ground via gears will act like a sailboat with a keel.

              • by The_Noid ( 28819 )

                You may know about it, but you are doing a terrible job of explaining it :)

                The keel of a boat has nothing to do with it. The keel has no effect when going straight in the direction of the wind. No "ordinary" boat can go faster than the wind, going straight in the direction of the wind. (One could, in theory, make a Blackbird-like boat that can do it, though I think the friction/drag of the water would be too much of a problem to make it work)

                The wheels of Blackbird power the fan, not the other way around.
                Th

                • Here is a related example. Consider one of those horizontal escalators that you see at airports to help you walk quickly. Remove the guard rails. Say it moves at 1m/s.

                  Now can you build a cart that has a wheel on the conveyor, another on the ground next to it, no power source, yet travels forward faster than 1m/s?

                • ...(One could, in theory, make a Blackbird-like boat that can do it, though I think the friction/drag of the water would be too much of a problem to make it work)...

                  A hydrofoil with waterwheels. Call it the Flying Blackfish.

            • by grmoc ( 57943 )

              And yes, Blackbird has also done the same thing of going upwind faster than the wind.

              BTW, I may actually know about this and the people involved, shocking as it is on Slashdot!

        • by etash ( 1907284 )
          yes but if you extract power from the wheels to blow back into the wind, you'll slow the car. and there is friction. so how can you remove energy from the car and then use that energy to make the car run faster? at best case scenario (=100% efficiency you'd still have the same final speed)
          • by The_Noid ( 28819 )

            Because the car is extracting more energy from the wind than the wheels put into the fan. In the end, moving air is being slowed down. That releases energy.

      • by grmoc ( 57943 )

        If the windmill is on the truck and it isn't coupled to the ground via gears or the like, then it will generate no power when the truck is going windspeed-- in that case the windmill is coupled to the truck, not the ground, and the difference in speed between the wind and the truck is zero.

        The windmill has to be coupled to the ground.
        Only then can the difference between the ground and the wind matter.

    • Re:Why this works (Score:5, Informative)

      by tlhIngan ( 30335 ) <slashdot.worf@net> on Friday July 30, 2021 @05:06AM (#61637271)

      It's NOT a windmill! It's a propeller!

      The wind does not turn the propeller that then turns the wheels. Instead, the vehicle moves forward which turns the wheels, which then turns the propeller that provides thrust that moves the vehicle faster.

      To prove this, they created a 3D printed model you can print out, assemble and put it on a treadmill. The vehicle will stay put on the treadmill - proving that it's a propeller - the treadmill spins the wheels which spins the propeller. The propeller provides thrust allowing the vehicle to stay put on the treadmill.

      No violation of physics - the treadmill supplies energy into the system which spins the wheels and powers the propeller In the real life case, the wind supplies the forward movement to spin the wheels that powers the propeller.

      How they built a 3D model - https://www.youtube.com/watch?... [youtube.com]

      In the explanation video - https://www.youtube.com/watch?... [youtube.com] - they show a little model propelled by a 2x4 that shows the principle clearly.

      Basically, the reason it's hard to understand is the same reason Plane on a Conveyor Belt is a thing. It's not intuitive. But you have to realize a car on a conveyor belt is because the car tires are referenced to the ground, but a plane's tires freewheel and the plane flies based on the airspeed. Basically the ground speed of an aircraft is independent of the airspeed. In fact, a plane can take off backwards given a sufficiently strong wind.

      In the same way, this vehicle is traveling through two mediums at the same time - it's using movement over the ground to power a propeller, which is working through air.

      • by Viol8 ( 599362 )

        "In the real life case, the wind supplies the forward movement to spin the wheels that powers the propeller."

        How? I'm still not seeing how the wind provides drive to the wheels.

        • Re:Why this works (Score:4, Informative)

          by fazig ( 2909523 ) on Friday July 30, 2021 @06:35AM (#61637399)
          If you really care to understand, you can build your own and perform experiments with it:
          The CAD files that were used for the small scale tests: https://www.thingiverse.com/th... [thingiverse.com]
          Source: https://www.youtube.com/watch?... [youtube.com]
          • by Viol8 ( 599362 )

            Well thanks for that really useful reply. Its all clear now.

            • by fazig ( 2909523 )
              I see, that video was already posted. So well, I'll try something.

              I suppose your question is where the initial momentum comes from that turns the wheels?
              With the treadmill it's rather obvious. The rest is inertial mass + gravity + friction on the wheels, which some gear transmission turns into thrust caused by the propeller.

              With the large scale version it's a bit less obvious.
              All I can point out is that the effect does not start right away.
              The initial momentum, if not provided by an internal motor has
        • you should have seen the original design. It had a circular rail along which 3 small land yachts drove. Now land yachts can not only drive faster than the wind , they can even - by zigzagging - achieve downwind speeds which are higher than the wind speed. So instead of zigzag the land yachts drove around a vertical axis. that worked but it was kind of unwieldy . Then they said hey let's just remove the wheels, fix the yachts on the circular rail and have the rail rotate. Then they remove the bodies of the

      • It's NOT a windmill! It's a propeller! The wind does not turn the propeller that then turns the wheels. Instead, the vehicle moves forward which turns the wheels, which then turns the propeller that provides thrust that moves the vehicle faster.

        This explanation is confusing because it doesn't explain how the free-stream wind energy is captured. It doesn't make it clear what is "slowing down" the free-stream wind, which is necessary for energy extraction. That is, the wheels aren't driving the propeller

      • It's NOT a windmill! It's a propeller!

        The wind does not turn the propeller that then turns the wheels. Instead, the vehicle moves forward which turns the wheels, which then turns the propeller that provides thrust that moves the vehicle faster.

        I think you're right, despite what I wrote earlier. It's just confusing because energy still always flows from airstream to blades, and not blades to airstream. It's just not extracted rotationally.

      • Basically, the reason it's hard to understand is the same reason Plane on a Conveyor Belt is a thing. It's not intuitive. But you have to realize a car on a conveyor belt is because the car tires are referenced to the ground, but a plane's tires freewheel and the plane flies based on the airspeed. Basically the ground speed of an aircraft is independent of the airspeed. In fact, a plane can take off backwards given a sufficiently strong wind.

        Yep.

        In the same way, this vehicle is traveling through two mediums at the same time - it's using movement over the ground to power a propeller, which is working through air.

        Close, not quite. The force input is the ground to wind speed difference, the propeller gently reduces this difference for power like a stationary windmill does. However, the faster the vehicle goes, due to the gearing it’s functionally equivalent to fixing the propeller base to the ground and running weightless frictionless power lines to power a motor on the vehicle. The propeller still gently feels the ground to wind speed and the vehicle speed isn’t important like the wheels on an

    • If you are going directly downwind, then once the vehicle reaches wind-speed, the air is not moving relative to the vehicle, so there is nothing to turn the turbine blades.

      There is, apparently, a way to overcome that, but I guess it is not immediately obvious to many people.

    • by jythie ( 914043 )
      I think what makes this particular device so difficult to wrap one's head around is that there isn't really anything else like it. It combines a number of components in a novel way that seems to produce thrust, so figuring out why this works and all the other 'if we just add the right combination of transformers and gearing, we get more energy than we put in' devices.
  • Genuine question: when vehicle speed exceeds wind, how is the net drag force not pointing backwards, slowing the vehicle down?

    For drag to be zero or directed forwards, the coefficient of drag would have to be zero or negative, wouldnâ(TM)t it?

    • If you rely on drag, that is true. With lift, it's an entirely different situation.

      A sailing boat sailing downwind uses only drag, So downwind, you can never sail faster than the wind in a steady situation (meaning that you actually can if the wind varies in strength)

      But a sailing boat sailing half-wind speeds up and gets powered all the time, until it creates so much head wind that the drag gets too large. You can compare it to skating: you can get really high speeds with only slow movements of the skater

    • You have to watch the second video for a better explanation. TL;DW: the wind push the car, the moving forward respect the ground make the wheel spin, the wheel spin make the propeller push air behind, ??, profit :)

      Seriusly, it's a sort of lever, that multiply the push of the wind.

      Take a look at this: https://youtu.be/yCsgoLc_fzI?t... [youtu.be]

      And I also recommend this video: https://www.youtube.com/watch?... [youtube.com] for another explaination

      • The problem with that explanation is that you don't need any wind at all to achieve this. If there is no wind at all, you automatically go faster that the wind, your wheels push the propeller and the propeller pushes the wheels. It's a perpetuum mobile

        • Not at all. It's a lever that multiply the current drag. With no wind, no drag, and 0 multiply by any number is still zero.

          And like in any mechanical lever (like also in a gearbox) you can multiply the drag, but you decrease the force and so the acceleration. And I haven't take in account friction in account yet.

          If you consider the friction at certain point increasing the multiply factor, you also reduce the force below the friction force and you get no increased drag anymore.

          Like in the first video linked,

      • I can't grasp the "lever" part, but I can imagine that the wind is not actually pushing a "static" propeller, but pushing against a propeller that is blowing back. The wind is then blowing against a "cushion" of air, which in turn pushes the propeller forward (and thereby the wheels).

        No lever would help you if both the propeller and the wheels are working to slow you down.

        • I can only suggest to watch the first video I linked again. You can see the cart is going forward faster than the bar hold by Derek.

          I think the analogy is correct, but in the case of the wind is a bit more complicated. When the vehicle is still, the wind push it forward. Now the wheels are connected to the propeller through a gear box, with a right ratio so the propeller rotate fast enough to push the vehicle further and not too much because the force will be too weak to go against the inevitable resistance

    • by grmoc ( 57943 )

      Yes.
      The drag will work in opposition to any energy gained by the prop.. and once the energy gain of the prop is the same as the drag, it stops accelerating.

    • When the vehicle moves faster than the wind, the drag force *is* pointing backwards and it *does* try to slow down the vehicle.
      The coefficient of drag is not a vector, it's just a scalar coefficient that's always positive. The sign of the drag *force* results from the sign of the *relative* speed (U_fluid - U_body), which will point backwards when the craft is moving faster than the air around it. You can choose the positive and the negative direction arbitrarily, but be *consistent*.

      The fact that the vehic

  • Would there be a way to make this work (theoretically) with flying objects that are not connected to the ground, using wind speed differentials in the air?
  • Cool video, but I was surprised to not have found it earlier, or even heard of it (the video is a month old).

    Sadly this kind of awesome content, isn't what YouTube feels needs to be propelled faster than all the other monetized turds that dump out of the average recommended feed.

    The theory? They wouldn't want their audience getting smart enough to snap out of that YT addiction.

    Perhaps that is the key to understanding the mysteries of the YouTube algorith...Oooh, another rug cleaning video! BRB.

  • by bradley13 ( 1118935 ) on Friday July 30, 2021 @07:07AM (#61637465) Homepage

    Debating in the comments how this is possible isn't very useful. Watch the explanatory video. [youtube.com] It's fascinating. Near the end is a model they set on a treadmill - and it runs faster than the treadmill. In a nutshell:

    • The wheels drive the propeller
    • The propeller pushes air to the back, driving the vehicle forward
    • The wheels are moving faster relative to the ground, than the propeller relative to the air
    • From this difference comes the energy gain - the video presents the equations
    • The only limit is the energy loss of the system

    The video also provides references - it turns out that this is nothing new, just relatively unknown. And apparently lacking any sort of practical applications, but it seems like there must be one!

  • This is what's wrong with today's scientists. When they're faced with facts, they just roll over and give in instead of doubling-down and never admitting they're wrong.
  • Old news for old nerds
  • The best explanations are in Rick Cavallaro's 2017 lecture [youtube.com]. It's an hour long, but as he says in the lecture,

    "There's a dozen ways to explain how this can be done. Eleven of them sound like complete nonsense to most people, but it's always a different eleven. When I get to the one that clicks for somebody, they say, 'Why didn't you start with that one?'"

    The one that made it click for me was to consider the mechanics of the system, not the aerodynamics. As a result of the counterintuitive nature of lift,

  • Taking a bet is not evidence and as the saying goes extraordinary claims require extraordinary evidence and we hadn't been shown any really strong evidence with the initial claims. I was very sceptical, it would've been trivially easy to fake the videos.

    Now it has been proven to Neil Degrasse Tyson and Bill Nye, I have to concede. I still don't think that video provides a good explanation about what is going on here. It still looks like free energy.

    • The law of conservation of energy does impose itself, but it imposes itself in the normal way that it does with gearing: The faster you try to go, the less torque you get. Eventually, the available torque isn't enough to overcome friction, and that puts a limit on your top speed. With zero friction and prop-travel-to-wheel-travel ratio approaching 1, your speed multiplier will head toward infinity. In my experiments [slashdot.org] with an idealized mechanical version of the system, I've been able to get up to about 3x
    • I've also been thinking about the psychology of this: We have an intuitive sense that the law of conservation of energy implies a law of conservation of velocity. Things shouldn't be able to go faster than what's driving them. But there's no such thing as a law of conservation of velocity. It simply doesn't exist, and it's a way that our brains fool us into getting the wrong answer when we encounter clever use of gearing as we do with directly downwind faster than the wind.

      If you want an extreme exampl

  • I think the easiest way to explain it is the reference point that is the most “fixed”.

    In a circuit, it’s typical to only compare voltage differences and it’s often assumed the 0V reference is for all practical purposes zero. Likewise, it makes sense in a car to say the ground speed is zero and to put everything in reference to that because it simplifies a lot of the thinking. But you can do really cool things like making capacitors charge in parallel and discharge in series usin
  • Maybe the EM Drive works after all!

    • I think the mistake we make when trying to understand this is that we intuitively sense that the law of conservation of energy implies a law of conservation of velocity. It doesn't, of course. There's no such thing as a law of conservation of velocity.
  • People look at this thing and think the wind pushes the fan, which spins the wheels. That never happens.

    It is a very light weight, low friction device. The wind pushes it, the way the wind pushes YOU when you walk down the street.

    Because the thing moves forward, the wheels spin. The axle transfers the spin up to the fan, which spins like a PROPELLER, pushing it just a tiny bit faster than the wind. This in effect pushes more air back against the wind. It is literally blowing air INTO the wind. Not a lot, just a little. So instead of having a max speed equal to the wind, it has a max speed equal to the wind + the tiny bit extra it pushes back.

    Counters to "energy being conserved". The energy is always being conserved, but speed is not energy. No rule about speed being conserved. Energy is conserved as follows - the wind is being collected from an area that is larger than the vehicle itself - the propeller, by pushing air backwards, makes the collection area equal to the shape of the vehicle PLUS the disk of spinning air created by the propeller. Net net, it collects more energy from the wind than a normal sail would.

    Also note, this effect is so slight that increasing friction, say by putting this in water on a boat, would negate the effect.

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