If you grew up in the 80s or was a business executive during that time, then you probably remember playing with a device that had steel ball bearings suspended from thin wires (otherwise known as a Newton's Cradle). They were fun to play with, and were great when you were really, really bored. The only problem is that because the color remained the same, this executive toy could become boring as well. But now there is a variation on this "blast from the past" with the Kinetic Light Newton's Cradle
On this variation, the balls actually light up, and change color as they transfer energy from one ball to the other. The basic premise of this device is that as one ball hits a ball at the far end, its energy is transferred all through the other balls until it reaches the ball at the other end. In theory, if you didn't have such a thing as friction, and air resistance, the balls would continue to hit each other indefinitely (essentially a perpetual motion device).
With the Kinetic Light Newton's Cradle, you can watch as the balls change color while striking each other. This is MUCH more fun than the original, and will keep you much more entertained.