Originally Posted By: Marchimedes
Dark matter is uncounted for mass in the universe. We are pretty sure it's there because of gravitational lensing. That is, look at a distant galaxy and the light from stuff behind said galaxy gets bent around it by the gravitational mass of the galaxy and the amount estimated mass in the galaxy is insufficient to account for the stuff that we see.

When I first became interested in relativity it was scientifically accepted that the mass of distant galaxies was insufficient to cause the amount of redshift observed.

Part of my initial submission to academia suggested that we may be underestimating the mass of those galaxies.

My submission was ignored however seven years later I was delighted to read an article in New Scientist to the effect that astrophysicists had determined that the galaxies were 500 to a thousand times more massive than had previously been estimated.

Perhaps even that prediction may need to be revised.