Will two rare supernovas finally tell us how fast the universe is expanding? Perhaps, but we'll have to wait for it for them ...

The mystery of dark matter—unseen, pervasive, and essential in standard cosmology—has loomed over physics for decades. In new ...

The clearest pictures yet of the newborn cosmos strengthen the prevailing model of the universe but deepen a mystery about its expansion rate. Measurements of this rate, known as the Hubble constant, ...