So much happened in the earliest moments of the universe. Elementary particles appeared, the first nuclei of hydrogen and helium, and fluctuations of energy and matter set into motion the formation of ...

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 ...

For decades, astronomers were certain that half of the ordinary matter in the universe — protons and neutrons, the building blocks of everything we see — had simply gone unaccounted for. The cosmic ...