The current cosmological model only works by postulating the existence of dark matter – a substance that has never been detected, but that is supposed to constitute approximately 25% of all the universe. But a simple test suggests that dark matter does not in fact exist. If it did, we would expect lighter galaxies orbiting heavier ones to be slowed down by dark matter particles, but we detect no such slow-down. A host of other observational tests support the conclusion: dark matter is not there. The implications of this are nothing short of a revision of Einstein’s theory of gravitation. Why the scientific community is in denial about the falsification of the dark matter model is a question that requires both a sociological and philosophical explanation, argues Pavel Kroupa.
Astronomers and physicists today understand the observed Universe in terms of a model universe in which the normal matter we see around us in the form of atoms makes up only 5% of all the energy in it. About 20% is made up of exotic dark matter particles and about 75% is made up of even more exotic dark energy. This dark-matter-based model (for each gram of normal matter there are 25 grams of the exotic dark matter) is about 20 years old, but the strong belief in the scientific community that dark matter exists goes back 30 years.
There is a simple test that these scientists are ignoring and which has already been applied and it tells us that dark matter does not exist.
The many searches worldwide for evidence of dark matter particles, going on since at least 30 years, have come up empty handed, and yet today the scientists are even more convinced that dark matter rules the Universe. This dark matter can be extremely light weight "fuzzy" particles that are extended over thousands of light years, or it may be made up of particles that are heavier, such as "weakly interacting massive particles" (WIMPS), or even primordial black holes that formed from exotic physical processes during the Big Bang. The theory of dark matter makes no predictions as to what the particles ought to be and what to look for, and so a very large number of scientists searching for it with laboratories and experiments deep under ground, in the polar regions or in space and in all countries try to prove the existence of dark matter particles and to get the Nobel Prize. Many tens of millions of tax-payer dollars are being used up each year on this search.
The most complex thing in the universe Read more But there is a simple test that these scientists are ignoring and which has already been applied and it tells us that dark matter does not exist. This test goes back to Subrahmanyan Chandrasekhar who, in 1943, showed that a massive body (e.g. a dwarf galaxy) that moves through a background of comparatively low mass particles (e.g. dark matter particles), will slow down. This process of "Chandrasekhar dynamical friction" is exceedingly well understood. It is the same physical mechanism by which our space craft are slingshot to the distant realms of the Solar System, by them first passing close-by a planet (e.g. Venus) in the inner Solar System, the planet slowing down a tiny little bit after the encounter, while the comparatively light-weight probe gets catapulted away, e.g. towards Pluto. A satellite galaxy slingshots myriads of dark matter particles to more distant regions around the major galaxy and so slows down and sinks towards the major galaxy to merge with it.
The galaxies behave as if they were naked, i.e., as if they did not possess the huge and massive haloes of dark matter particles which the theory predicts to be there.
With my collaborators and students, we have applied a number of observed galaxy systems to the calculations of Chandrasekhar dynamical friction we would expect to see if dark matter existed, and in all and every case it turns out that the slow-down is not in the data. We have studied the motions of the satellite galaxies around our own Milky Way at distances of a hundred thousand light years, the motions of galaxies a few million light years away relative to each other, and we also checked how quickly the bars of spiral galaxies rotate, and none of these systems show evidence for dark matter particles. The galaxies behave as if they were naked, i.e., as if they did not possess the huge and massive haloes of dark matter particles which the theory predicts to be there. Rather than observing the slow down of galaxies through Chandrasekhar dynamical friction, we observed a speed-up as the galaxies fall towards each other. This is the same as two stars that fall towards each other in a star cluster. They get faster until they pass each other and then they recede again from each other.
Escaping cosmology’s failing paradigm Read more We established this in a number of scientific research publications over the past decade [e.g. 1,2]. The implications of these findings are that the dark-matter-based models of the universe are not valid descriptions of the real Universe. Without dark matter, the current cosmological model breaks-down. Since the model rests on Einsteinian gravitation to be valid, it also means that we need to find a different theory of gravitation. But this would change the whole dynamics of the universe, its expansion rate and with dark matter having been rigorously falsified to exist, it also becomes senseless to consider dark energy as being relevant.
The implications for theoretical physics are immense, and it is therefore necessary to double, to triple, and even to quadruple check if the falsification of dark matter is truly correct. In fact, dark matter models of galaxy formation and evolution have already been falsified in 2012 . A particularly strong reason to reject the dark-matter models is through the observation that satellite galaxies are typically orbiting their host galaxies in vast disks of satellites, much like the planets orbit the Sun in one plane, while according to the dark matter models, they should be orbiting in all possible directions [4,5].
Without dark matter, the current cosmological model breaks-down. Since the model rests on Einsteinian gravitation to be valid, it also means that we need to find a different theory of gravitation.
So the above mentioned newer tests merely confirm the rejection of the dark matter models, with overwhelming confidence. Still, to be completely and totally sure that dark-matter-based models do not account for the real Universe, further tests have been made. This is necessary, also because the research community has largely ignored these falsifications, has been awarding itself many important research prizes on work on dark matter, and has even been quite actively trying to discourage young researchers to follow-up on the implications, while at the same time proposals for research money to study the most successful alternative, Milgromian gravitation (MOND), are being largely turned down.
Three other very major tests of the dark-matter based models have been published recently:
(A) One test relies on how rapidly a dark-matter-filled universe can form extremely massive clusters of galaxies that also penetrate each other. The El Gordo galaxy cluster is immensely heavy, weighing a thousand times the mass of the Milky Way and Andromeda together. This cluster is actually composed of two such clusters which have formed and transgressed through each other at a time when the Universe was only half its present age. It turns out that the dark-matter-based models cannot, under any circumstances, grow such massive clusters and also have them falling through each other by that time, falsifying the dark-matter based models rigorously .
(B) Astronomers have also discovered that the local Universe expands more rapidly than the distant Universe. This problem, known as the "Hubble Tension", has triggered many concurrent conferences and hugely long texts written by hundreds of scientists in which all possible solutions are being discussed and explained. Very exotic dark-matter-based models are being developed, with additional processes being speculated to act on dark matter (e.g. dark matter could be decaying, there could be dark photons) or that dark energy has some complex time behaviour or multiple dark forms. Impressive is that this vast expert community, that includes or is driven by major-prize-winning scientists, is entirely ignoring the obvious solution to the Hubble Tension: we are in a region spanning more than a billion lightyears across which contains fewer galaxies by about a factor of two than should be there. Galaxies in this void fall towards its sides (like apples falling to the ground) which is why we witness an apparently faster expanding Local Universe. While this "KBC Void" naturally accounts for the Hubble Tension, the KBC Void is entirely incompatible with the dark-matter-based models because these constitute a model universe which is homogeneous and isotropic on scales larger than a few dozen million lightyears .
(C) Another test of the dark matter models is to compare the thickness of galaxies with those observed in the real Universe in which more than 90 per cent of all galaxies are very thin spiral, or disk, galaxies. In the dark matter models galaxies grow over time mostly by merging with other galaxies. These galaxy-crashes typically destroy the thin disks. Our sophisticated analysis of thousands of observed galaxies show the dark matter based models to be totally incompatible with the real Universe, as the model produces galaxies that are typically too roundish compared to the profusive thin disk galaxies in the real Universe . Other problems between the real Universe and the dark-matter models include massive galaxies to have been observed at an early time at which they should not yet exist , that modern observations tell us there to be dust between galaxies which challenges the interpretation of the cosmic microwave back ground as being the photosphere of the Hot Big Bang  and that the cosmic microwave background has features in it that are incompatible with an inflationary origin, suggest that the Universe is structured on all scales  (like a fractal perhaps) such that it may be understandable in terms of dust emission rather than a Hot Big Bang.
We need to scientifically understand why the dark-matter based model, being the most falsified physical theory in the history of humankind, continues to be religiously believed to be true by the vast majority of the modern, highly-educated scientists.
Three implications arise from the above:
(a) Modern cosmological theory is totally wrong and we need to develop a new theory based on MOND. MOND is a modern non-relativistic theory of gravitation which extends that of Newton by incorporating data from galaxies which were neither available to Newton nor to Einstein, both of whom had to base their deductions on data limited to the Solar System only. All predictions made 40 years ago by Mordehai Milgrom in the foundation papers [12,13,14] have been verified, and in Prague and Bonn we (with Nils Wittenburg and Nick Samaras) are now performing the first ever full cosmological calculations with star formation of a MOND universe. MOND comes from a simple space-time scale symmetry  and may be a consequence of the quantum vacuum , opening a possible path towards unifying gravitation with standard-model particle physics. A major recent review for further in-depth reading has just been published .
(b) We need to scientifically understand why the dark-matter based model, being the most falsified physical theory in the history of humankind, continues to be religiously believed to be true by the vast majority of the modern, highly-educated scientists. This is a problem for the sociological and philosophical sciences and suggests a breakdown of the scientific method .
(c) What role does the modern fixation on prize-money, awards and rewards play in the unparalleled stagnation of physics? Does the modern homo-cosmologicus only want prizes and awards, rather than to advance our understanding of the physical cosmos?
 "Galaxies as simple dynamical systems: observational data disfavor dark matter and stochastic star formation" Kroupa, P., 2015CaJPh..93..169K
 "Fast galaxy bars continue to challenge standard cosmology" Roshan, M. et al., 2021MNRAS.508..926R
 "The Dark Matter Crisis: Falsification of the Current Standard Model of Cosmology" Kroupa, P., 2012PASA...29..395K
 "Phase-Space Correlations among Systems of Satellite Galaxies" Pawlowski, M., 2021Galax...9...66P
 "Are Disks of Satellites Comprised of Tidal Dwarf Galaxies?" Bilek, M., et al., 2021Galax...9..100B
 "A massive blow for ΛCDM - the high redshift, mass, and collision velocity of the interacting galaxy cluster El Gordo contradicts concordance cosmology" Asencio, E. et al., 2021MNRAS.500.5249A
 "The KBC void and Hubble tension contradict ΛCDM on a Gpc scale - Milgromian dynamics as a possible solution" Haslbauer, M. et al., 2020MNRAS.499.2845H
 "The High Fraction of Thin Disk Galaxies Continues to Challenge ΛCDM Cosmology" Haslbauer, M., et al., 2022ApJ...925..183H
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 "From Galactic Bars to the Hubble Tension: Weighing Up the Astrophysical Evidence for Milgromian Gravity" Banik, I. and Zhao, H.S., 2022Symm...14.1331B
 "A Philosophical Approach to MOND: Assessing the Milgromian Research Program in Cosmology" Merritt, D., 2020, Cambridge University Press, ISBN: 9781108492690, 2020