What's the (dark) matter

These posts have been very sparse, as I expected, formal study of the subject stifles free thinking.  I tackled my tutors on my 2015 cosmology module on how a 3-d shape (a sphere) can be used to explain that 2-d space (its surface) can have curvature without invoking the third dimension, is fair to show that 3-d space can still have curvature without a 4th dimension, but hit a brick wall.  Unless time is sufficient alone to be that 4th dimension.

But as time goes on I am more confident to gloat, with gravitational waves now being clearly found in LIGO (Sept 2015), the seekers of dark matter particles must be getting increasingly desperate. With all their candidates, and all the possibilities of sensitive measurements, there must come a point soon where they admit that if dark matter is real, it must have been discovered by now.

I find it incredible that a phenomenon discovered by measurements of gravitational effects, and with no physical evidence, is taken as something with a physical explanation and not a gravitational one!  Just as Newton's relativity was upgraded by Einstein's, so can Einstein's relativity be upgraded to account for dark matter.  It seems to be apparent independence of DM that is holding us back, especially in cases like the bullet cluster where colliding gas slows down but the non-self-interacting DM does not, and separates out.  Well I would be more inclined to question these measurements or inferences than to search for the elusive lumps of non-interacting stuff.