Ask Ethan: How Does A Photon Experience The Universe?
“Relativity says all inertial frames of reference are equally valid and true. From a photon's point of view the entire cosmos is flattened into a two-dimensional timeless plane. Imagine I place an apple on my desk, then a while later replace it with a banana. How does the photon perceive my desk to be, when it's all flattened into a plane without any sense of time?”
At rest, everything looks like you expect: clocks run at the same rate everywhere you look, distances are exactly as they appear, and material objects possess the color you know them to intrinsically possess. Close to the speed of light, however, all of that changes. Clocks run slower as objects move closer to the speed of light relative to you. Distances appear contracted along the direction of relative motion, including for physical objects and the fields they generate. And colors appear either redshifted or blueshifted, depending on how quickly an object moves either away from your or towards you, respectively. These effects get more and more severe the closer objects move, relative to you, to the speed of light.
But what if you reached the speed of light? What would the Universe look like from a photon’s (or any massless particle’s) point of view? The answer is most definitely not what you expect! Find out on this edition of Ask Ethan.
