In this video we explore the colorful science of fluorescence.

A really cool way to play with fluorescence at home is get a blue or violet laser pointer and shine it into a dish or jar of water where you have added a drop of fluorescent highlighter fluid. You’ll clearly see the beam as the solution fluoresces in its path.

Now the common definition of fluorescent is something that glows a visible color when exposed to ultraviolet light. Fluorescence is actually much broader than that and you don’t need ultraviolet light in particular. For example in the yellow fluorescent dye “rubrene” both violet and green lasers will activate it and glow yellow. This proves you don’t always need ultraviolet light. But a red laser will not activate a yellow dye. Why is that?