The dimensionless age of the Universe: a riddle for our time
Abstract
We present the interesting coincidence of cosmology and astrophysics that points toward a dimensionless age of the universe H0*t0 that is close to one. Despite cosmic deceleration for 9 Gyr and acceleration since then, we find H0t*0 = 0.96 +/- 0.01 for the LCDM model that fits SN Ia data from Pan-STARRS, CMB power spectra, and baryon acoustic oscillations. Similarly, astrophysical measures of stellar ages and the Hubble constant derived from redshifts and distances point to H0*t ~ 1.0 +/- 0.1$. The wide range of possible values for H0*t0 realized during comic evolution means that we live at what appears to be a special time. This "synchronicity problem" is not precisely the same as the usual Coincidence problem because there are combinations of OmegaMatter and OmegaLambda for which the usual coincidence problem holds but for which H0*t0 is not close to 1.
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