age of the universe

age of the universe A time determined by the reciprocal of the value of the Hubble constant to be between 10 and 20 billion years. The calculation of the Hubble constant, and hence the age of the universe, depends on which theory of cosmology is used. Usually, the age of the universe is calculated by assuming that the expansion of the universe can be described by the big-bang theory. Some estimates for the age of the universe suggest a figure that is less than the age of some stars in the universe, which would constitute a major paradox for cosmology.