How to Teach the Science of Manipulative Gravity

Gravity in Action

• 1

  Place trash bag flat and have it lifted into the air slightly by four students, one on each corner. Make sure to kept the bag tight enough to remain flat.

• 2

  Place the first marble in the center of the bag. The marble should sit in the center of the flat bag; allowing a little slack is helpful. This is how gravity behaves, by bending the space around the massive object.

• 3

  Throw the second marble onto the bent bag and observe how gravity works. The center marble "pulls" the other marble off of its original course curving the second marble toward the center. Manipulative gravity is displayed by allowing more or less lack in the bag.

• 4

  Pull slightly harder on the bag allowing a marble to settle in the center again. Roll the second marble, and note the differences. The marble can easily roll in the intended direction and has little curve to its path caused by the center marble's effect on the bag. This is similar to a less-massive object residing at the center. Allow more slack; the marble's representation of gravity is manipulated and more powerful.

Playdough Black Hole

• 5

  Form playdough into a solid cube. This represents a field of space with no mass in it.

• 6

  Place small fingernail marks on each side of the cube somewhere away from the center.

• 7

  Press into each side uniformly with your fingers. This represents manipulative gravity in three dimensions. The first experiment literally happens on all sides of an object in real space-time.

• 8

  Pressing harder will slowly change the positions of the initial marks. This change should be as uniform as possible on all sides.

• 9

  Patting the sides of the bent cube will help keep the object stable as manipulative gravity increases. This is similar to a star's core as it becomes a black hole. It is impossible to achieve a paper-thin center, but in nature that is how a black hole affects space-time as the ultimate source of manipulative gravity.