Lensing effects in galactic retarded gravity: Why “Dark Matter” is the same for both gravitational lensing and rotation curves

Abstract

Galaxies are huge physical systems having a generic size of tens of thousands of parsecs. Thus, any modification at the center of the galaxy will affect the outskirts only tens of millennia afterwards. Those retardation considerations seem to be neglected in present day analysis used to estimated rotational velocities of matter in the rim of the galaxy and its surrounding gas. The significant differences between the velocities predicted by Newtonian action at a distance theory and observations are usually dealt with by either assuming an unobservable type of matter usually referred to as “dark matter” or by modifying the laws of gravity (MOND as a typical example). Here we demonstrate that considering general relativistic effects one can explain the apparent excess matter leading to gravitational lensing in both galaxies and galaxy clusters. We also explain why the amount of “dark matter” must be the same for both rotational curves and gravitational lensing.