The current largely adopted view on dark matter implies that it's mostly made of Weakly Interacting Massive Particles (WIMPs). Although these are theoretical massive particles that scarcely interact with regular matter, making them very hard to detect, a huge effort has been made to discover them, on a global scale. Those of you who have read some of our articles may already know that we have written a lot on this topic, either extensively or tangentially. But, as a new study suggests, what if this effort was wrong from the beginning?

Two US scientists, Jonathan Feng, a physicist at the University of California, Irvine, and co-author Jason Kumar, from the University of Hawaii, published a paper named "Dark-Matter Particles without Weak-Scale Masses or Weak Interactions," which brought the issue of dark matter back on the table. What if, they say, it's not made (so much) of WIMPs? Since it's so hard to detect, it's also very difficult to study, and we have little evidence to what it really is. But there are many other theories related to its structural particles, equally valid, that don't imply WIMPs, which have not been taken into consideration.

 

The authors indicate that the phenomena generated by dark matter also apply if WIMPs are theoretically replaced with different, more weakly- or strongly-interacting particles. "WIMPs are a very specific example of dark matter, but there is a broader class of particles," explained Feng, cited by Universe Today. "We found that some of the models also predicted the right amount of dark matter for the universe, but with dark matter that was much more strongly or weakly interacting than WIMPs. We are wondering if almost-exclusive attention for WIMPs is really warranted."

 

There's evidence provided by studies that some types of strongly-interacting particles are constantly annihilated, releasing high-energy photons, largely observed across the universe, and Feng has a lot of confidence that further research in this direction could yield important clues on what dark matter is really formed of. Besides, WIMP-less dark matter opens doors to very interesting – and equally possible – theories.

 

"There are theories that there is a shadow world behind ours. It is a mirror world that is like ours, but doesn’t interact with ours," shared Feng. "With WIMP dark matter, that possibility is remote. WIMP-less dark matter requires new forces that we don’t really know much about. If you could have evidence of this type of dark matter, it might be a hint that this shadow world exists."