Look-back Time · t_L(z) = ∫dz/[(1+z)H(z)]
unseel.com · cosmic age of arriving light · Planck ΛCDM
z 0.0
t_L 0.0 Gyr
Stage photons in flight
Earth · receiver
Photons arriving
Source galaxies
CMB · last scattering
Unseel.com · Look-back Time