Do photons wear out? An astrophysicist explains light's ability to travel vast cosmic distances without losing energy

Do photons wear out? An astrophysicist explains light,’s ability to travel vast cosmic distances without losing energy

The speed of light is the fastest anything can travel. What happens to a photon from a galaxy 25 million light years away on its journey toward Earth?

Do photons wear out? An astrophysicist explains light's ability to travel vast cosmic distances without losing energy

San Diego CA (SPX) May 21, 2025 My telescope, set up for astrophotography in my light-polluted San Diego backyard, was pointed at a galaxy unfathomably far from Earth. My wife, Cristina, walked up just as the first space photo streamed to my tablet. It sparkled on the screen in front of us. "That's the Pinwheel galaxy," I said. The name is derived from its shape - albeit this pinwheel contains about a trillion stars.