Light speeds along at 300,000 km/s—yet it never tires. Photons, having no mass, blaze through the near-empty vacuum of space without losing energy. When they dodge dust, gravity wells, or magnetic fields, they may scatter or dim, but those hurdles are rare in the vast cosmos.
Light is tireless: how does it maintain its energy through infinity? © coffeekai, iStock
The Relativity Paradox and Time Perception
Einstein’s relativity gives us time dilation: for humans, light journeys take ages; for photons, time stands still. If you could ride a beam of light, your departure from a distant galaxy and landing at Earth would seem simultaneous. Space itself squeezes along your route, compressing light-years into a blink.
Astronomical Observation as a Time Machine
Staring through a telescope is like watching history unfold. Sunlight takes eight minutes to arrive; Alpha Centauri’s light takes more than four years. Photons from Orion’s Nebula set out 1,500 years ago, and Andromeda’s glow left 2.5 million years back. Every photon is a tiny time capsule, carrying secrets of distant stars and galaxies right into our eyes.
