Gravity Visualized: A demo by a physics teacher

Although gravity may be intuitive to some, this demonstration may help others see in a different light how gravity works. In the demonstration the professor uses a large sheet of Lycra, stretchy material often used for clothing or book covers, to represent spacetime. He uses different objects of different masses and diameters to show how each object affects spacetime and other objects.
http://www.youtube.com/watch?v=MTY1Kje0yLg