Shaking the dark matter paradigm

A theory about gravity challenges our understanding of the universe. For millennia, humans held a beautiful belief. Our planet, Earth, was at the center of a vast universe, and all of the planets and stars and celestial bodies revolved around us. This geocentric model, though it had floated around since 6th century BCE, was written in its most elegant form by Claudius Ptolemy in 140 AD. When this model encountered problems, such as the retrograde motions of planets, scientists reworked the data ...