Dark Matter

When we look up at the night sky, everything we see—stars, planets, galaxies—makes up only a tiny fraction of the universe. Astonishingly, scientists estimate that all visible matter accounts for less than 5% of the cosmos. The rest? It’s mostly made of something we can’t see or touch: dark matter.

Dark matter doesn’t emit, absorb, or reflect light, making it invisible to telescopes. Yet, its presence is undeniable. Astronomers first suspected its existence in the 1930s when they noticed galaxies spinning faster than they should. According to the laws of physics, these galaxies should have flown apart if only visible matter were holding them together. Something unseen—an invisible mass—was providing the extra gravity needed to keep them intact.

Since then, evidence has piled up. We can “see” dark matter indirectly through its gravitational effects, like how it bends light from distant galaxies in a phenomenon called gravitational lensing. Computer simulations also show that dark matter acts as the cosmic scaffolding that allows galaxies to form and cluster together. Without it, the universe as we know it might not exist.

But what exactly is dark matter? That remains one of the biggest mysteries in physics. Scientists have proposed several candidates, from WIMPs (Weakly Interacting Massive Particles) to axions, and some even claim that are mathematical models are themselves flawed, but no answer has been confirmed.