Physics – 6.2.3 The Universe | e-Consult

The Hubble constant (H₀) measures the rate of expansion of the universe. Specifically, it indicates how quickly the recession velocity of a galaxy increases with its distance from us.

Its significance lies in providing a crucial parameter for cosmological models. H₀ allows us to estimate the age of the universe (by extrapolating backwards from the present expansion rate), the size of the observable universe, and the universe's ultimate fate (whether it will continue expanding forever, eventually slow down, or recollapse). A higher value of H₀ implies a faster expansion rate and a younger universe. The current estimate of 2.2 × 10^-18 s^-1 is a key value used in many cosmological calculations and models, although there is ongoing debate about its precise value due to various measurement techniques and systematic errors.