Perpetual motion is physically impossible because friction bleeds energy away as heat with every single movement, and nothing can stop that leak. But viral videos of "forever" marble machines rack up millions of views every year. We built one ourselves to show you the trick: there's a hidden motor inside. Pull it out, and the loop dies in seconds. Hiding the thing that's actually doing the work? That's its own kind of engineering. If you want to learn more, check out ‪@KiwiCo at kiwico.com/YTShorts. #science #kiwico #engineering #perpetualmotion