A fascinating new paper released today suggest that both dark matter and dark energy can be explained by a single phenomenon – particles of matter with negative mass. I give a link to the paper below, but I will attempt a quick layman’s explanation.
Fundamentally, orthodox positive-mass attracts other positive-mass, and negative-mass would repel other negative-mass. The interesting part is the interaction between positive-mass and negative-mass particles. The positive-mass particle is repelled, but the negative-mass particle is attracted i.e. the positive-mass ‘runs away’ but the negative-mass ‘follows’.
The scientist behind this new theory, has run computer simulations which show that a galaxy would indeed become surrounded by a halo of negative mass particles, and that this halo would exert a kind of pressure on the orthodox matter galaxy, maintaining, for example, its spiral shape in rotation. This is important because it is understood that without some kind of dark matter influence, the spiral arms of a galaxy would not rotate fast enough to maintain their shape, indeed not fast enough to be consistent with observations. This is one of the reasons dark matter is theorised in the first place.
The other aspect of this theory is that because the negative mass particles, outside of the halos, are repelling each other, they exert an outward pressure, like a gas, which can be interpreted as the cause of the expansion of the universe. However this would require continual creation of such particles to keep up the expansive pressure. My gut feeling is that this is the weakest proposal in the theory, particularly since the author points out the beauty of having negative mass particles to balance the orthodox positive mass particles – everything else of course has balance – positive and negative electrical charges, magnetic poles…