The galaxies had much smaller redshifts than the quasars. Instead, Arp supported the redshift quantization theory as an explanation of the redshifts of galaxies. These distances are often estimated using photometric redshifts when spectroscopic redshifts are unavailable. Other science topics include simulations, calibration, photometric redshifts, quasars, and Milky Way science. Some astrophysicists were unconvinced that the cosmological redshifts are caused by universal cosmological expansion. The NICMOS measurements may have discovered galaxies at redshifts up to 12. Controversy existed over whether Seyfert redshifts were of cosmological origin. Euclid will measure spectroscopic redshifts for 50 million objects. This will be important for signals originating at cosmological redshifts greater than 1. Here, this distinction is indicated by a "p" subscript for photometric redshifts. These redshifts are uniformly isotropic, distributed evenly among the observed objects in all directions. The most distant objects exhibit larger redshifts corresponding to the Hubble flow of the universe. But as the Universe expands, the curvature redshifts away more slowly than matter and radiation. He was also the first to relate these redshifts to velocity.