An independent method for determining the age of the universe

The observed number of white dwarfs in a given volume of space increases monotonically with decreasing luminosity, as expected from cooling rate considerations. However, their number drops abruptly at a luminosity of log (L/L_sun;) ≈ -4.5, due to the finite age of our Galaxy. Comparing this sudden drop in the observed luminosity distribution with the best theoretical evolutionary white dwarf models, the authors derive an age for the Galactic disk of 9.3±2.0 Gyr. To obtain the age of the universe, one must add the time between the big bang and the first appearance of stars in the Galactic disk. The authors choose a value (and stated error) that can include all of the currently reasonable models describing this early era. They estimate the age of the universe to be 10.3±2.2 Gyr.