Space and Physics

New Dark Matter Theory Says It's A Type Of Particle We've Known About For 80 Years


Jonathan O'Callaghan

Senior Staff Writer

clockJul 25 2015, 18:31 UTC
1322 New Dark Matter Theory Says It's A Type Of Particle We've Known About For 80 Years
Other theories suggest dark matter would be compact, shown in white on the left, while this latest theory allows it to spread out, right. NASA/STScl/Kavli IPMU.

Ah, dark matter. Creator of the universe, sculptor of galaxies, great brewer of coffee (probably). There seems to be nothing it can’t do, or isn’t responsible for, but there’s just one problem: Where the hell is it?


The hunt for dark matter may seem at times like searching for an invisible needle in an infinite haystack, but researchers now think they may have a vital clue in its discovery. We know, you’ve heard that countless times before. Bear with us.

A team of scientists has theorized that dark matter is not the exotic particle everyone thought it would be, but is instead nothing more than a different version of the humble pion, known to science since 1935. Pions, for those who don’t know, are the particles that bind atomic nuclei together. Dark matter, the team suggests, would be similar but not exactly the same to regular pions.

“When people talk about dark matter, they assume it is really exotic stuff, like in an extra dimension, or involved in super-symmetry,” Hitoshi Murayama of the University of California, Berkeley, and University of Toyko, and a co-author on the study published in Physical Review Letters, told IFLScience.

“Of course, this idea is very sexy, but at the same time there’s no evidence for these ideas. So we think it could be something more mundane and maybe more familiar to us.”


Dark matter, as a type of pion, would have very few differences to regular pions. It would have a simlar mass, for example, but Murayama describes it as a “carbon copy,” and not identical. Indeed, other research has suggested dark matter particles only interact with themselves, and not regular matter or photons, which the pion theory would allow.

“Dark matter is our mother. Without it, no stars, galaxies or even us would have been born,” said Murayama. It’s thought that, just 380,000 years after the Big Bang, it was dark matter that was responsible for breaking the uniformity – or “smoothness” – of the universe. Tiny variations in dark matter upset the balance of the homogenous cosmos, allowing matter to lump together and form the stars, galaxies and planets we see today.

The significance of this theory is that it could indicate a discovery of dark matter is imminent via experiments running around the world. For example, the Large Hadron Collider (LHC) at CERN, the new SuperKEK-B and the upcoming SHiP could all potentially make a discovery in the near-future – and prove if this pion theory is correct. “The minute we proposed it, people wrote a bunch of papers to test how to prove it, so there’s quite a bit of excitement there,” said Murayama.


Ultimately, it will take a direct detection to confirm this research and it is, after all, only a theory. “Science is always like that,” said Murayama, “no matter how beautiful it is.”

So, we're close. Sort of. Coffee, please.

Space and Physics
  • dark matter,

  • Universe,

  • big bang,

  • particle,

  • pion