A New Way to Measure the Expansion Rate of the Universe: Redshift Drift

Almost all the galaxies in the Universe are speeding away from us because of the Big Bang and the acceleration of dark energy. One technique to measure this expansion is redshift, seeing how light is reddened over time as its wavelength stretches out. But every observation astronomers can make is a snapshot, measuring the redshift now. But an intriguing idea is to measure how the redshift changes over time as a galaxy's movement accelerates. It's called "redshift drift" and requires an exact ser...