def definition def or abbrev

`obs_age_Gyr`

No prose has been written for this declaration yet. The Lean source and graph data below render without it.

formal statement (Lean)

 109def obs_age_Gyr : ℝ := 13.787

Definition body.

 110
 111/-- Early-universe Hubble measurement (km/s/Mpc).
 112    Planck 2018: 67.36 ± 0.54. -/