No worry, I did not intend any criticism of 'dark matter'. I understand it as a placeholder concept for 'something we know amazingly little about, except that it appears to be in conflict with the naive version of our observations'. It reminds me of the very complex ways humans calculated the planetary motions, when they believed the sun revolved around the earth - once the proper relation was understood, a comparatively simpler model sufficed. As I understand it, we have plenty of guesses at what dark matter could be, including quantum particles that emit no energy we (currently) can observe. I believe the original theory of ether also sufficed in its time, until we had enough observations that contradicted that model. I'm not saying dark matter is wrong in any way, but it appears to me, it's a place-holder concept for until knowing what is _really_ going on, like 'planet X'.