The amazing levitating Slinky
All the actions is in the first 140 seconds.The remaining four minutes of explanation, involving claims of “information transfer” and “signals,” strike me as, frankly, bulltwaddle. Much more plausible is the explanation furnished by Andrew Sullivan’s Daily Dish, which in turn came from an even more thorough explanation on Rhett Allain’s blog at Wired.com.
What you’re seeing:
If a slinky is hung by one end such that its own weight extends it, and that slinky is then released, the lower end of the slinky will not fall or rise, but will remain briefly suspended in air as though levitating.
[T]he best thing is to think of the slinky as a system. When it is let [go], the center of mass certainly accelerates downward (like any falling object). However, at the same time, the slinky (spring) is compressing to its relaxed length. This means that top and bottom are accelerating towards the center of mass of the slinky at the same time the center of mass is accelerating downward.