A soap bubble is a very thin film of soap water that forms a spherical shape when blown. Soap bubbles are fragile and easily burst. They have been used in art, science, and entertainment for centuries.
The first recorded use of soap bubbles was by the ancient Greek scientist Aristotle in the 4th century BCE. He observed that when you blew on a piece of soapy water it would form a round shape. Aristotle believed that the gods used soap bubbles as shields to protect themselves from human beings.
Soap bubbles were popularized in the 18th century by English scientist Joseph Priestley. He discovered that if you added salt to soapy water it would make the bubbles last longer before bursting. Priestley’s discovery led to people using soap bubbles for entertainment at fairs and circuses.
Today, soap bubbles are still used for entertainment and art. But they also have scientific value. For example, scientists study how soap films behave to learn about surface tension—the force that makes water beads up on a clean surface like glass or metal. Surface tension is caused by the attraction of water molecules to each other and to the surfaces they touch. When you blow a bubble, surface tension pulls the walls of the bubble together so it doesn’t collapse right away. If you add color to your soapy solution, you can see different colors interact at the boundary between two layers of air in the bubble—this is called interference patterns! You can also experiment with blowing different shapes of bubbles by using wire frames dipped in soapy solution—hexagons, spheres, cylinders…the possibilities are endless!