Does light lose energy as it crosses the universe? The answer involves time dilation.

The Pinwheel galaxy, 25 million light-years away, illustrates light's journey through space. Light, as massless electromagnetic radiation, travels at the universe's speed limit of 186,000 miles per second, maintaining this speed in the mostly empty space. From a photon's perspective, time stops and space compresses, making the journey instant. However, from Earth's view, the light took 25 million years to reach us, demonstrating the relativity of time and space in the cosmos.