Distance scale of the universe and its implications for cosmology

Abstract

The cosmological distance scale is set by the Hubble's constant. Ever since the enunciation of the velocity distance relation by Edwin Hubble in 1929, observers have attempted the measurement of this constant. Naively speaking, the velocity of an external galaxy is determined by its redshift and its distance by its apparent faintness. In reality the measurements of these quantities are beset with many difficulties and uncertainties. This talk will begin with a review of the current status of these measurements against the backdrop of previous attempts. The Hubble constant is used for estimating the time elapsed since the big bang, i.e., the so-called age of the universe. The age depends on the specific model chosen. The second part of the talk will discuss this age-model relationship. How does this age compare with ages of some important components of the universe? Examples will be given from nuclear astrophysics to compare these ages with the age of the universe. The implications of such a comparison for the standard big bang cosmology will be discussed.