Invisible Glass Rube Goldberg Machine

A thick piece of glass sits next to a mixture of two clear, colorless oils. The mixture is adjusted to match the glass’ refractive index or index of refraction—”a dimensionless number that describes how fast light travels through the material.” When the glass is submerged into the oil, it seems to disappear.

One in their “To the Scientists of the Future” series, EUPHRATES and Masahiko Sato team up with Japan’s National Institute for Materials Science (NIMS) to create an Invisible Glass Rube Goldberg demonstration. When the oil mixture is added to the aquarium, the glass ramps, stairs, and dominoes disappear. What kind of movement does it show?

Try this experiment at home or in class with a simplified setup. In this We The Curious video, Ross Exton demonstrates how a trick of light can make things disappear.

There are more visual examples of refraction at Kiddle.

Watch more from the To the Scientists of the Future series . Plus:
• Pattern distortions seen through a glass of water
• The Reversing Arrow Illusion
• LENSES, an interactive light & sound installation

h/t Tinkering Studio and Exploratorium. Thanks, Linda Carson!