This demonstration models the expansion of the Universe using a rubber band with dots or washers to represent galaxies. As the band is stretched, all the dots move apart, showing that galaxies recede from each other in proportion to their distance.

1. Take a long rubber band and mark several evenly spaced dots along its length to represent galaxies.
2. Hold one end fixed and slowly stretch the other end.
3. Observe how the dots move farther apart as the band is stretched.
4. Measure how far each dot moves compared to its original position.
5. Show that more distant dots move faster (they cover more distance in the same amount of stretch).

The Rubber Band Universe - Libke's Earth & Space Systems:

📄 Modelling the Expansion of the Universe - Cheryl Harper: https://www.cpepphysics.org/wp-content/uploads/2022/08/Student-worksheet-cosmological-redshift.pdf

• Try stretching the band from the center instead of one end to show expansion is the same from any galaxy’s viewpoint.
• Compare a slow stretch versus a quick stretch to represent different rates of expansion.

• Do not overstretch the rubber band—it may snap and cause minor injury.
• Keep the rubber band away from faces when stretching.

• What does each dot on the rubber band represent? (Galaxies.)
• Why do more distant “galaxies” appear to move away faster? (Because the stretch adds proportionally more distance between widely separated points, illustrating the Hubble–Lemaître Law.)
• How does this model illustrate the cosmological principle? (Expansion looks the same from any chosen reference galaxy.)
• How is this model limited compared to the real Universe? (The Universe expands in three dimensions, not just along a line; galaxies themselves do not expand.)