No where near being an astrophysicist, so my comments here have less than no consequence, but I can't help but wonder that most of the discrepancies calculated are due to the immense distances that the light we observe here and now has traveled to get here, and what may or may not have happened to it during that journey. To say that the photons that ultimately arrive in our instruments remained pristine & untouched by *any* force during their billion(s)-plus-year journey across space seems incredibly naive to me. I suppose the fact that what we observe in the heavens doesn't look like old analog "noise" that used to show up on our CRT TVs between UHF/VHF channels tells us there is some coherency, but still... That's a lot of time and a lot of distance to cover, right?
Dark matter fills 'empty' space, strongly interacts with visible matter and is displaced by visible matter.
The reason for the 'missing dark matter' is that the galaxy is so diffuse that it doesn't displace the dark matter outward and away from the galaxy to the degree that the dark matter is able to push back and cause the stars far away from the galactic center to speed up.
It's not that there is no dark matter connected to and neighboring the visible matter. It's that the galaxy is not well defined enough to displace the dark matter to such an extent that it forms a 'halo' around the galaxy.
A galaxy's halo is not a clump of dark matter traveling with the galaxy. A galaxy's halo is the state of displacement of the dark matter.
So, is our sun's evil twin dark matter? Is the missing tenth planet in our solar system dark matter? Is dark matter really just cold ordinary matter? If they can't find it in our immediate area of the universe it would seem that several theories including the big bang need to be reconsidered.
The exception that proves the rule. When that saying came about it meant the exception that tests the current rule, potentially changing it. 'Dark' is scientist speak for 'we have no information whatsoever'. That applies to approximately 80% of the universe. Huge respect to Stephen Hawking who was spot on when he said, "We are just an advanced breed of monkey on a minor planet of a very average star. But we can understand the universe and that makes us very special indeed." With one minor exception. We can contemplate the universe. Still incredibly special but we are far from understanding it.
Jerry May
I am not surprised since much guesswork as it turns out is askew, beginning with the notion the the universe suddenly materialized via the big bang or creation. Come on geniuses. If you explode something, the far flung fragments aren't older than the ones that fell nearby. They are the same age. Back to the calculator.
Gene Preston
Martin Lo at JPL and I have been studying the need for an extra 1/r force term which when added eliminates the need to have the CDM. My notes on this are posted here describes our work. The odd galaxy seems to lack a black hole or has a very low mass one. Galaxies with super massive black holes are controlled by the black hole through the 1/r term and gives them their shape as well as the spiral arms. We are working on simulation models to prove this.
Douglas E Knapp
Jerry May not be right. The age of a thing has to do with how much time has passed for it. Time does not run at the same speed everywhere, it is related to the amount of mass at that spot. So you idea about an explosion and everything being the same age is wrong and shows a fundamental high school level lack of info about how time, mass and space work.
"the find may just turn out to be the exception that proves the rule" Based on proper English this would mean Dark Matter doesn't exist! Probably correct.
I'm a believer in the KISS principle (of science). Dark Matter is an old idea and too complicated to be in the overall scheme of things. All one has to do is tweak gravity a touch and Dark Matter is no longer required!
Douglas Bennett Rogers
This bears the same relation to dark matter as supernova 1987a bears to neutrinos. In the case of the supernova, the neutrino pulse came at precisely the right time and in the right amount to be a neutrino pulse from the nuclear reaction required by the theory.
Could the missing mass be either orbiting neutron stars, small black holes or, less likely, multitudes of planets, or a combination of these non-emitting bodies?