Dark Matter Theory Takes a Big Hit
Widely accepted theories of dark matter, a mysterious invisible substance that can only be detected indirectly by the gravitational force it exerts, expect the solar neighborhood to be filled with the stuff – but it isn’t, at least as far as can be detected.
This extra ingredient in the cosmos was originally suggested to explain why the outer parts of galaxies, including our own Milky Way, rotated so quickly, but dark matter now also forms an essential component of theories of how galaxies formed and evolved. Today it is widely accepted that dark matter constitutes about 83% of the mass in the Universe, though it has resisted efforts to clarify its obscure nature. All attempts so far to detect dark matter in laboratories on – Earth – have failed.