What Is Light?

Light is a guide, a signal, a whisper from the cosmos. It is the lighthouse standing against the storm, offering safe passage to weary travelers. It is the flicker of fireflies in the night, tiny beacons searching for one another across the void. It is a distant star, pouring warmth into a rainforest, calling life to awaken.

But what is light, really?

The ancients saw it as divine, something woven into the fabric of existence. To the Egyptians, light was the power of Ra, the Sun God, who sailed across the sky each day, bringing life, order, and renewal. The Greeks, too, were captivated by light. Empedocles, a philosopher of the fifth century BCE, believed that light streamed out from our eyes, touching objects and allowing us to see them—a theory both poetic and deeply human, as if vision itself was an act of reaching out to the world. Yet even then, questions remained. Was light a substance? A force? An essence of the gods?

Centuries passed, and light continued to reveal and conceal itself in turn.

Newton, with his prisms and precision, bent light to his will, breaking it apart into colors, revealing its hidden structure. He saw it as particles, small and obedient, marching forward in perfect, predictable lines. But light, like truth, rarely stays within the lines.

Then came Young, with his double-slit experiment, and the world took a breath. He sent light through two narrow slits, expecting to see two neat bands on the other side. Instead, he saw an interference pattern—waves colliding, merging, canceling each other out. Light was not just a particle; it was a wave.

But the real strangeness appeared when scientists looked more closely. Later experiments found that if they observed the light—if they placed a measuring device to watch which slit it passed through—the interference pattern disappeared. The very act of observation forced light to behave as a particle, as if it knew it was being watched.

What did this mean? That reality shifts depending on whether we are looking? That consciousness itself plays a role in shaping what is real?

Einstein followed, unraveling more mysteries. He showed that light was energy in its purest form, carried by particles with no mass, moving so fast that time itself could not catch them. Photons, he called them—quanta of light, messengers of the universe. He discovered that light does not simply travel through space; it bends with gravity, curves with the shape of reality itself. It is both constant and relative, unchanging yet shaped by its surroundings.

And still, the mystery deepened.

If light is information—if it carries the very code of existence itself—then what does that make us? Are we not also pockets of energy, waves and particles entangled in time, flickering briefly before vanishing? Are we not, in some strange way, like light itself?

A massless, timeless expression of something greater.

Perhaps the real question isn’t just what light is, but whether we are, in some way, made of the same thing. And if light changes when observed, could it be that reality itself is waiting to see what we decide to be?