In this artistic rendering, a blazar is accelerating protons that produce pions, which produce neutrinos and gamma rays. Photons are also produced. While you might not think much of the difference between particles moving at the speed of light and those moving at 99.99999% the speed of light, the particles themselves have two vastly different experiences of the Universe under those two disparate conditions.(ICECUBE/NASA)

Ask Ethan: How Does A Photon Experience The Universe?

If you think you have problems today, be glad you’re not moving at the speed of light.

Special relativity, even though it’s over 100 years old, is still one of the most puzzling and perplexing discoveries about the nature of the Universe itself. The (Newtonian) laws of physics that we’re used to here on Earth remain valid under almost all conditions, but not if you’re moving close to the speed of light. Clocks run at different rates, distances appear altered, and objects themselves change color dependent on their speed relative to you. Yet, at the same time, relativity declares that the laws of physics are the same and invariant for all observers, regardless of their motion. So what does this mean for a photon, which itself moves at the speed of light? Patreon supporter Rob Hansen wants to know, asking:

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?

Let’s imagine what happens in three cases: for someone at rest, for someone moving…