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 ...

Nearly 400,000 years after the Big Bang, the primordial plasma of the infant universe cooled enough for the first atoms to coalesce, making space for the embedded radiation to soar free. That ...

With CMB-S4, scientists hope to connect a sandy desert with a polar desert—and revolutionize our understanding of the early universe. In the 1960s, an anomalous, faint electromagnetic glow was ...

Scientists are reeling from an unexpected blow after news that a much anticipated future observatory—designed to decipher the earliest moments of cosmic history—won’t be able to proceed with its ...

The cosmic microwave background, shown at left in this illustration, is a flash of light that occurred when the young universe cooled enough for electrons and protons to form the first atoms. It ...