Until it is experimentally tested, DM is essentially equivalent to the ether. A useful unexplained tool which to date seems to work. Until another Michelson-Mo

Until it is experimentally tested, DM is essentially equivalent to the ether. A useful unexplained tool which to date seems to work. Until another Michelson-Morley experiment comes (and MOND might have something to say, or at least they seem to be testing DM experimentally), yes: as untestable as string theory is.