Here’s a question for you. What’s something that’s fundamentally important to how we perceive the world, yet we can’t reach out and touch it, and we can’t hear it? Light! You — right now! — are awash in a sea of billions and trillions of particles of light. Besides rainbows, sunbeams, computer screens, incandescent bulbs, candles, fireflies, and countless more ordinary and extraordinary objects reflecting, refracting, shimmering, glowing, radiating, and emitting the familiar type of light our eyes can see, there are other types of light that our eyes don’t see. Ever heard of ultra violet or infrared light? What about x-rays, gamma rays, micro waves, or radio waves? You can’t see these types of light with your eyes, but there are other ways of perceiving them: anybody who has felt the warmth of a a fire, the heat of a sunburn, or seen x-rays at a doctor’s office has experienced infrared, ultra violet, and x-ray light, respectively.
An astronomer can collect light with her telescope to learn about planets, stars, and galaxies too far to ever visit. But what is light anyway? If you want to know, UW astronomy grad student Nicholas Hunt-Walker has the answer!