# The Expanding Universe

**Topics:**General relativity, Universe, Physical cosmology

**Pages:**2 (588 words)

**Published:**January 19, 2013

Objective: To interpret a model demonstrating the theories of our expanding universe. Hypothesis: I believe the two marked points on the balloon will be farther apart each time the balloon is blown up. Materials:

* 1 un-inflated balloon (when inflated, the balloon should have a round shape and be approximately the size of a soccer ball) * Markers

* About 30 cm (12 inches) of string or yarn

* Ruler or tape measure

Procedures:

1. Place an un-inflated balloon on a table. The balloon represents the universe. Use a marker to make small, filled-in circles on the balloon. The circles represent galaxies. 2. Pick four of the circles around the balloon and label these A, B, C, and D. 3. Hypothesize what will happen to the distances between the labeled circles when you blow up the balloon ¼ full, ½ full, and ¾ full. 4. Measure the starting distances, in inches or centimeters, between each of the labeled galaxies. Record the measurements in a data chart. 5. Blow up the balloon about ¼ of the way. Use a piece of string to temporarily tie the balloon. (Do not tie the balloon itself into a knot.) 6. Untie the string. Repeat the same procedures by blowing up the balloon to ½ and ¾ of its full size.

Data:

Data Chart |

Galaxies| Distance:

Un-Inflated balloon (inches or centimeters)| Distance:

¼ full (inches or centimeters)| Distance:

½ full (inches or centimeters)| Distance:

¾ full (inches or centimeters)|

A to B| 3 ½ cm| 5 cm| 9 cm| 13 cm|

A to C| 4 cm| 4 cm| 9 cm| 13 ½ cm|

A to D| 3 ½ cm| 5 ½ cm| 12 cm| 17 ½ cm|

B to C| 4 cm| 4 cm| 8 ½ cm| 13 cm|

B to D| 2 cm| 2 ½ cm| 5 cm| 7 ½ cm|

C to D| 3 cm| 3 ½ cm| 5 ½ cm| 10 ½ cm|

Analysis:

After reviewing your data and graph, how do the density and distribution of your “stars” change as the balloon expands? -The density and the distribution of the “stars” change as the balloon expands by...

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