Wednesday, June 20, 2012 7:29:21 AM
It's called elastic force, which in this case is stronger than the force of gravity. Like Altaru said, basic physics. Now if you want to see a really cool application of physics, specifically angular momentum, watch this.
Wednesday, June 20, 2012 5:54:42 AM
That's awesome ... in the most simple terms, the bottom is being pulled *UP* by the spring at the same rate the slinky is falling as a whole, thus making the bottom remain in the same place.