Two physicists have been developing a theory of superfluid dark matter, an idea that I explore at length in the article “Dark Matter Recipe Calls for One Part Superfluid.” Perhaps most intriguing is that the new theory reproduces in many ways the predictions of a model called Modified Newtonian Dynamics, or MOND, which was first proposed in 1983. MOND abandons dark matter particles entirely. Instead, it posits that there should be a way to tweak the laws of gravity to explain key astronomical observations.
MOND is something of a mirror image to the dominant view of dark matter — that it’s made of weakly interacting massive particles, or WIMPs. MOND accurately describes the rotation curves of galaxies — precisely the regime where WIMP models fall short — but doesn’t work well for galaxy clusters.
Few physicists believe that the laws of nature change at different scales; for this reason and others MOND has been largely abandoned by the mainstream research community. But physicists must still grapple with reconciling their preferred dark matter models with the predictions that MOND gets right.
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