Dark Matter as Aether
Posted 8:30 AM
Maybe dark matter is aether, the as-yet undetected matter than light travels through. The principle objection to the "aether" models was simply that it was "very complex" and "you didn't need it" to model all known phenomena. Then again, this was also the principle scientific objection to the earth being round. We don't "need" lots of things - but it's not scientific to discard them unless disproven. Only stumbling block to real scientific inquiry is that a lot of real wackos "believe" in aether.
To transmit high-frequency waves, and yet only make up 50% or so of the matter in our sparse universe, it would have to be packed and massless. Darn near undetectable.