Everything in the universe has gravity — and feels it too. Yet this most common of all fundamental forces is also the one that presents the biggest challenges to physicists. Albert Einstein’s theory ...

Every fundamental force in nature that acts on astronomical scales must decrease with distance. Otherwise, for example, a distant planet or star would exert a stronger pull on us than Earth does. Life ...

Repulsive gravity at the quantum scale would have flattened out inhomogeneities in the early universe First light The cosmic microwave background, as imaged by the European Space Agency’s Planck ...