More than a quarter consists of dark matter, while the rest is dark energy, a mysterious force driving the accelerated expansion of the cosmos. Dark matter cannot be observed directly because it neither emits nor absorbs light. The gravity of dark matter bends and distorts the light coming from distant galaxies, a phenomenon known as gravitational lensing. “And when we observe thin bridges of normal matter between clusters, we see matching bridges of dark matter as well.”According to astrophysicist Rutuparna Das of the Harvard–Smithsonian Center for Astrophysics, understanding dark matter is essential to understanding our own origins. Without dark matter, galaxies would not have enough gravity to stay intact — they would slowly drift apart, leaving the universe a much emptier place.