Fun with Slinkies!

Most of you have probably played with a slinky before, but I bet you never noticed this:

This is a real thing, not an optical illusion

So what's going on here? How does the bottom of the slinky hold up? Basically, the bottom of the spring is experiencing an upward force from the top of the spring, and that upward force doesn't go away until the top has met the bottom. With normal objects, the whole thing drops at once, but springs' elasticity changes things. Check out this video for a more complete answer:

Physics!!