Abstract

High quality photometry and spectroscopy of disk galaxies has shown that the mass of a galaxy is the only parameter that determines the dark matter attributed to a galaxy. Together with other results on elliptical galaxies we look carefully at the fundamentals that led to the idea that Dark Matter was needed to account for the motions of stars and gas in galaxies. It turns out that the problem is with the use of Newtonian dynamics to explain motions in galaxies. Einstein showed that the field of the gravitating object must not be neglected and that assumptions of homogeneity, isotropy and spherical symmetry are the root cause. Gravitational field lines are affected by other masses in the same way that light is affected. This changes the way that gravitational forces act upon material orbiting in the disk of a galaxy and are proportional to ~1/r as observed rather than ~1/r^2 predicted by Newton. This error led to the invention of Dark Matter. Gravitational field interaction also reduces gravitational forces outside an object, reducing the forces between galaxies and giving effects that could be mistaken for Dark Energy. Dark Matter and Dark Energy were each introduced as concepts in order to make specific astronomical observations fit in with the then understanding of the physics involved. We demonstrate that by replacing Newtonian dynamics which essentially forces symmetries on objects with Einstein's general relativistic dynamics is very likely to make the need for either Dark Matter or Dark Energy to go away.

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