Karl Popper made a statements that should by engraved above the entrance to every proud physics department:
"A theory can never be proven, but it can be falsified, meaning that it can and should be scrutinized by decisive experiments. If the outcome of an experiment contradicts the theory, one should refrain from ad hoc manoeuvres that evade the contradiction merely by making it less falsifiable."
In 1915 Einstein finished general relativity and this theory has been successful in regimes where the acceleration is high (such is in the inner Solar system and close-orbiting binary stars. Then in 1933 (by Fritz Zwicky) and in 1980 (by Vera Rubin) it was found that galaxies were orbiting so fast at their low-acceleration edges that, if they had any decency at all, they should explode centrifugally. Yet they don't: they generally persist in sensible bound/round shapes.
This means that most of the observed cosmos, the bit with a low acceleration, does not agree with general relativity. The theory has been hugely falsified, but tell that to a mainstream physicist at a conference (I have done) and you'll be pigeon-holed in a category somewhere below holocaust denier and they'll walk away in disgust. Speaking objectively, given GR's failure with 90% of the data, you can either claim that general relativity is wrong, and invent a new theory (for example I have suggested MiHsC, which reduces the outward centrifugal force in galaxies) or you can claim that there is a huge amount of invisible matter holding the galaxy together by gravity: dark matter.
There are several reasons why it is obvious that the problem is a failure of theory and not due to dark matter:
1) The galactic problems always start at a radius where the acceleration goes below about 10^-10 m/s^2 which is also the cosmic acceleration, so it is obviously linked (in a way that MiHsC explains simply).
2) Globular clusters and wide binary stars, which are far too small to have any dark matter, also show the same anomaly, starting at the same critical acceleration.
3) Many other well known anomalies, eg: cosmic acceleration, the low-l CMB anomaly, the flyby anomaly, the Pioneer anomaly, Tajmar's spinning disc results, the emdrive and the proton radius puzzle are all consistent with the galactic rotation anomaly if you look within the framework of MiHsC.
4) Dark matter is just a mess. It needs huge amount of new matter to be added in an ad hoc way and it also needs new physics to keep it spread out in a galactic halo.
5) There is no evidence for dark matter even after 40 years of very expensive looking.
6) Philosophically: dark matter defends a theory (GR) that failed to predict galaxy rotation properly, by inventing an ad hoc manoeuvre that makes it less falsifiable (see Popper's warning above). If a theory uses an ad hoc fix that is, even worse: as vague as a bad politician's promises, then beware!
As a result of these points I'm amazed that the rest of physics is spending most of its money (each dark matter detector is on the order of $100 million dollars) to defend general relativity by looking for dark matter and almost no-one is challenging the theory. I agree the dark matter option should have been looked at, a null result, like Michelson and Morley's is useful, but it must be in proportion to other options. Instead dark matter is tacitly assumed in journal papers and magazines articles, and there are even dark matter conferences which are inherently unscientific, since they pre-assume the solution they're looking for!
As Popper suggested, instead of trying to defend the status quo, it has always been more effective to attack the prevailing theory. It is easy to attack general relativity since the counter-evidence is already plentiful (see above), so why don't they?
After ten tears of fighting it, I think the obsession with dark matter is like the age-old story of the Emperor's new clothes. People are told that only the cleverest can see the clothes (dark matter), so everyone of course says that they can see them when the Emperor goes on walkabout awarding post-doc positions, but eventually some idiot comes along and says 'Ho Ho The Emperor's Naked!' and the spell is broken. Well, I'm willing to be the idiot, and I have suggested MiHsC, and, although I say it myself, MiHsC is far more successful than GR, absolutely beautiful and simple in form, joins quantum mechanics and special relativity for the first time, and offers a new way to get energy and propulsion (by learning to put horizons in the zero point field). Since we're talking about invisible fashions, it seems appropriate to quote Coco Chanel:
The most courageous act is still to think for yourself. Aloud.
The most courageous act is still to think for yourself. Aloud.




