Setting new constraints on the age of the Universe

There are three independent techniques for determining the age of the Unive rse: via cosmochronology of long-lived radioactive nuclei, via stellar mode lling and population synthesis of the oldest stellar populations, and, most recently, via the precision cosmology that has become feasible with the ma pping of the acoustic peaks in the cosmic microwave background. We demonstr ate that all three methods give completely consistent results, and enable u s to set rigorous bounds on the maximum and minimum ages that are allowed f or the Universe. We present new constraints on the age of the Universe by p erforming a multiband colour analysis of bright cluster ellipticals over a large redshift range (0.3<z<0.9), which allows us to infer the ages of thei r stellar populations over a wide range of possible formation redshifts and metallicities. Applying a prior to Hubble's constant of H-0 = 72 +/-8 km s (-1) Mpc(-1) we find the age of the Universe to be 13.0(-2.0)(+3.0) Gyr (1 sigma), in agreement with the estimates from Type Ia supernovae, as well as with the latest uranium decay estimates, which yield an age for the Milky Way of 12.5 +/-3 Gyr. If we combine the results from cluster ellipticals wi th the analysis of the angular power spectrum of the cosmic microwave backg round and with the observations of Type Ia supernovae at high redshift, we find a similar age: 13.2(-0.8)(+1.2) Gyr. Without the assumption of any pri ors, universes older than 18 Gyr are ruled out by the data at the 90 per ce nt confidence level.