The Origin of Dark Matter and the Cosmological Constant

The concept of exotic charged dust is introduced here to represent dark matter. The term "exotic" means that the dust is not composed of normal matter, and the charge--for lack of a better term--is not an electric charge. It is also shown that the often-used approximate expression for dark matter density corresponds to an exact solution of the coupled Einstein-Maxwell equations for charged dust. The Einstein field equations tells us is that for a flat universe the cosmological constant acts as a gravitating negative energy distribution that is gravitationally repulsive; following Schwinger, it is shown that the vacuum must have a negative energy spectrum if QFT is to be gauge invariant.