The mysterious substance of dark matter, accounting for 80% of the universe’s mass, has puzzled scientists for decades. Despite overwhelming evidence, its particle nature remains unknown. Two recent studies by Professor Stefano Profumo at the University of California, Santa Cruz, propose theories that attempt to answer this fundamental question.
One study explores whether dark matter emerged naturally from conditions in the early universe, forming a “mirror world” with its own particles and forces. This shadow sector would obey many of the same physical laws as our known universe. Profumo’s work draws inspiration from quantum chromodynamics (QCD), which describes how quarks are bound together inside protons and neutrons.
In this scenario, dark matter could be created through a process involving dark quarks and gluons, binding together to form heavy composite particles called dark baryons. Under certain conditions, these dark baryons could collapse into extremely small, stable black holes that would account for all the observed dark matter. This theory offers a new, testable framework grounded in well-established physics.
Profumo’s other study explores whether dark matter might be produced by the universe’s expanding “cosmic horizon” – essentially, the point of no return beyond which nothing can escape. This paper suggests that a brief period of accelerated expansion could have “radiated” particles into existence, resulting in a wide range of dark matter masses.
These mechanisms are highly speculative but offer self-contained and calculable scenarios that don’t rely on conventional particle dark matter models. Profumo’s work builds upon his 2017 textbook “An Introduction to Particle Dark Matter,” which presents lessons on the nature of dark matter and its connections to cosmology and elementary particle physics.
Source: https://phys.org/news/2025-08-theories-dark-mirror-world-universe.html