gravitational-lensing

A complete primer on dark matter — Vera Rubin's galaxy rotation curves, gravitational lensing, CMB, WIMP and axion candidates, what experiments have ruled out, the MOND debate, primordial black holes, and where the science stands in 2026.

What is dark matter and dark energy? Discover the invisible forces shaping 95% of the universe — from galaxy rotation curves to the accelerating cosmos.

Gravitational lensing, the deflection of light by mass, was predicted by general relativity and first measured during the 1919 solar eclipse. Strong lensing produces Einstein rings and multiple images, weak lensing maps dark matter statistically, and microlensing reveals planets through brief brightenings of background stars.

Galaxy clusters are the largest structures held together by their own gravity: hundreds to thousands of galaxies, a vast reservoir of X-ray-bright gas, and a dark matter halo that outweighs everything else. They also work as natural telescopes, bending and magnifying light from the early universe.