This demonstration allows for a visual depiction of the effect of a large mass on the fabric of spacetime. In particular, what effect a black hole does or does not have on the other stars around it and how that effect depends on the mass of the black hole.

Materials:

* large latex balloon cut open and pulled flat, or sheet of latex

* round bowl, 4"- 5" in diameter

* tape

* package of small round beads

* 1" solid ball bearing (the eraser end of a pencil can be used as a replacement)

Procedure:

1. Tape the sheet of latex (this represents space-time) tightly across the top of some round object...such as a bowl. The sheet should not be so tight that it will tear if stretched further, but should be taut enough that there are not any wrinkles!

2. Scatter a few beads on the sheet of latex (this represents matter that is near the black hole).

Make sure they are spread out to all parts of the sheet.

3. Gently drop the ball bearing onto the sheet of latex (this represents the black hole). Try not to let it bounce! If you donÆt have a ball bearing, gently push down on the center of the sheet with the eraser end of a pencil.

4. Explain what happened to the matter when the black hole was put into place. Why did this occur?

5. What would happen if the ball bearing was heavier (or if you push harder on the pencil)? What physical analogy to the black hole may be made?

Annie Jump Cannon (1863 - 1941) was known as the worldÆs expert in the classification of stars. Her work laid the foundation for modern stellar spectroscopy.