Top 10 Most Debated Dark Matter Theories

Israeli physicist Mordehai Milgrom proposed in 1983 that Newton's laws break down at very low accelerations, eliminating the need for dark matter entirely. MOND successfully predicts galaxy rotation curves but struggles with galaxy cluster observations and the cosmic microwave background, leaving the physics community deeply divided.

Originally proposed to solve the strong CP problem in quantum chromodynamics, axions are ultra-light hypothetical particles that could form a cold dark matter background. The Axion Dark Matter Experiment (ADMX) at the University of Washington and CERN's IAXO project are actively hunting for them using powerful magnetic fields and microwave cavities.

A hypothetical heavier cousin of known neutrinos that interacts only via gravity, sterile neutrinos could explain dark matter and the matter-antimatter asymmetry simultaneously. Anomalous X-ray signals from galaxy clusters detected by ESA's XMM-Newton telescope tantalyzed researchers, but subsequent analyses have cast doubt on the detection.

Stephen Hawking and Bernard Carr proposed in the 1970s that black holes formed in the early universe's density fluctuations could constitute dark matter. LIGO's detection of unexpectedly massive black hole mergers revived interest, though microlensing surveys by Japan's Subaru telescope have placed tight constraints on their abundance.

Standard cold dark matter models predict dense cores in galaxy centers, but observations show flatter profiles. SIDM proposes that dark matter particles scatter off each other, redistributing mass. Simulations by teams at UC Irvine and the Max Planck Institute match observations better than collisionless models, but the required interaction strength remains debated.

Particles with masses around 10⁻²² eV would have de Broglie wavelengths spanning entire galaxies, suppressing small-scale structure formation. This "fuzzy" behavior could explain why fewer dwarf galaxies exist than cold dark matter predicts, but Lyman-alpha forest observations from the Keck Observatory in Hawaii have placed increasingly tight constraints.

These theories propose an entire parallel "dark sector" with its own forces and particles, mediated by a dark photon that couples feebly to ordinary matter. Experiments at Jefferson Lab in Virginia and at CERN's NA62 are searching for dark photons, but no evidence has emerged — leading some physicists to question whether the hidden sector is hiding or simply nonexistent.

Dutch theoretical physicist Erik Verlinde proposed in 2010 that gravity is an emergent entropic force and that dark matter effects arise from the entanglement structure of spacetime itself. The radical idea generated enormous attention at the University of Amsterdam, but concrete predictions have been difficult to reconcile with galaxy cluster dynamics and gravitational lensing data.

Justin Khoury at the University of Pennsylvania proposed that dark matter forms a superfluid in galaxy cores, where it behaves like MOND and reproduces its empirical successes, while reverting to standard particle-like dark matter on larger scales. This hybrid approach is elegant but introduces additional parameters, and critics question whether it merely papers over two unsolved problems.

Israeli physicist Mordehai Milgrom proposed in 1983 that Newton's laws break down at very low accelerations, eliminating the need for dark matter entirely. MOND successfully predicts galaxy rotation curves but struggles with galaxy cluster observations and the cosmic microwave background, leaving the physics community deeply divided.

Originally proposed to solve the strong CP problem in quantum chromodynamics, axions are ultra-light hypothetical particles that could form a cold dark matter background. The Axion Dark Matter Experiment (ADMX) at the University of Washington and CERN's IAXO project are actively hunting for them using powerful magnetic fields and microwave cavities.

A hypothetical heavier cousin of known neutrinos that interacts only via gravity, sterile neutrinos could explain dark matter and the matter-antimatter asymmetry simultaneously. Anomalous X-ray signals from galaxy clusters detected by ESA's XMM-Newton telescope tantalyzed researchers, but subsequent analyses have cast doubt on the detection.

Stephen Hawking and Bernard Carr proposed in the 1970s that black holes formed in the early universe's density fluctuations could constitute dark matter. LIGO's detection of unexpectedly massive black hole mergers revived interest, though microlensing surveys by Japan's Subaru telescope have placed tight constraints on their abundance.

Standard cold dark matter models predict dense cores in galaxy centers, but observations show flatter profiles. SIDM proposes that dark matter particles scatter off each other, redistributing mass. Simulations by teams at UC Irvine and the Max Planck Institute match observations better than collisionless models, but the required interaction strength remains debated.

Particles with masses around 10⁻²² eV would have de Broglie wavelengths spanning entire galaxies, suppressing small-scale structure formation. This "fuzzy" behavior could explain why fewer dwarf galaxies exist than cold dark matter predicts, but Lyman-alpha forest observations from the Keck Observatory in Hawaii have placed increasingly tight constraints.

These theories propose an entire parallel "dark sector" with its own forces and particles, mediated by a dark photon that couples feebly to ordinary matter. Experiments at Jefferson Lab in Virginia and at CERN's NA62 are searching for dark photons, but no evidence has emerged — leading some physicists to question whether the hidden sector is hiding or simply nonexistent.

Dutch theoretical physicist Erik Verlinde proposed in 2010 that gravity is an emergent entropic force and that dark matter effects arise from the entanglement structure of spacetime itself. The radical idea generated enormous attention at the University of Amsterdam, but concrete predictions have been difficult to reconcile with galaxy cluster dynamics and gravitational lensing data.

Justin Khoury at the University of Pennsylvania proposed that dark matter forms a superfluid in galaxy cores, where it behaves like MOND and reproduces its empirical successes, while reverting to standard particle-like dark matter on larger scales. This hybrid approach is elegant but introduces additional parameters, and critics question whether it merely papers over two unsolved problems.