September 13, 2012 8:30 am
Every kid knows that Slinkys are magical, but here’s evidence that might even give physicists a pause.
Australia science video maker Derek Muller proves that Slinkys can float in the air – at least for a second. In a new video on Veritasium, Muller hold a Slinky suspended from a second story window until it reaches its full length and comes to rest. He then releases the Slinky, and here the magic ensues. NPR explains:
If you keep your eye on the bottom of the Slinky, on the last curl at the very end, you will notice that as the top of the Slinky starts to fall, the bottom doesn’t drop. It just hangs in the air, levitating, as if it had its own magic carpet. It will stay there, hovering quietly, until a wave, or signal, passing through the Slinky finally reaches it. Apparently, the bottom doesn’t know it’s supposed to fall, so it sits there, seeming to defy gravity, until the very end.
Watch Muller’s video to see this craziness for yourself:
But child-like magic and wonder can only last for so long. Physicists explain that the Slinky is, indeed, abiding by the rules of the universe. The idea that information has to pass through a whole object before the entire object “knows” what to do applies not just to Slinkys but to tables, chairs, cats, cakes, our own bodies – everything, really. Slinkys just demonstrate this principle exceptionally well.
Radiolab guest and Cornell mathematician Steve Strogatz describes the physics behind the Slinky’s floatation as “beautiful, profound, even tragic.”
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