Light: Classical and Quantum

Although light is all around us and we rely on it constantly to interact with the world, this experience gives us little intuition about what light actually is. In ancient Greece, philosophers thought we see objects by shooting invisible "probing" beams out of our eyes. In the 17th century, Newton thought light was like tiny cannon balls. Today, we are taught "light is both a particle and a wave," but what does that mean, and is it true? In this semilab we will study what light is from both a classical and quantum perspective. How does light move in highly confined spaces? How does the LASER work? How is the glowing incandescent lightbulb proof that light moves at a finite speed? These and other questions we will explore in this semilab.