Dark Matter Could Originate From Other Dimensions, Study Suggests
Dark matter accounts for the majority of the universe's mass, but scientists still struggle to say what it actually is and where it originated from.
Dark matter could consist of particles called gravitons that appeared right after the Big Bang - possibly from other dimensions, according to a new study published in the journal Physical Review Letters
"Massive gravitons are produced by collisions of ordinary particles in the early universe. This process was believed to be too rare for the massive gravitons to be dark matter candidates", physicist at the University of Lyon in France Giacomo Cacciapaglia, who is a co-author of the study, told Live Science.
Having teamed up with colleagues from the Korea University - Haiying Cai and Seung J. Lee - Cacciapaglia found that the number of particles created after the Big Bang was just enough to account for all the dark matter that humans are capable of detecting in the universe.
Should these gravitons exist, the study says, they would have a mass of less than 1 megaelectronvolt (MeV) - which is about twice the mass of an electron. According to a new theory now being explored by the scientists, there could be more than four known dimensions (three dimensions of space, along with time). When gravity propagates through extra dimensions, it results in the creation of gravitons in our universe.
"The main advantage of massive gravitons as dark matter particles is that they only interact gravitationally, hence they can escape attempts to detect their presence", Cacciapaglia said. "Due to their very weak interactions, they decay so slowly that they remain stable over the lifetime of the universe".
For the same reason, according to him, they are slowly produced during the expansion of the universe and accumulate there to the present day.
Scientists earlier believed that too little gravitons were created after the Big Bang to account for all dark matter, but the new theory suggests that there could actually be more of them.
"The enhancement did come as a shock", Cacciapaglia said. "We had to perform many checks to make sure that the result was correct, as it results in a paradigm shift in the way we consider massive gravitons as potential dark matter candidates".
Now, the only way to explore this theory and find more evidence would be to rely on powerful particle accelerators like the Future Circular Collider at CERN, which should begin operating in 2035.
According to Cacciapaglia, this instrument is "the best shot we have at future high-precision particle colliders", and the team is "currently investigating" future possibilities to continue their research.