A research paper that was published last year provides an interesting, simple and most importantly traditional answer to the mystery of dark matter. The pair of theoretical physicists Professor Robert Scherrer and post-doc fellow Chiu Man Ho, working at the Vanderbilt University of Nashville, Tennessee, US, published a detailed analysis on the subject of anapoles on the Physics Letters B online journal.
The article revolves around the elusive Majorana fermion, is a little like a common atom. However, it posses a unique electromagnetic field shape, described as an 'anapole'. As seen in the picture below, a Majorana fermion has magnetic field lines in a torus (donut) shape, as opposed to the standard north-south dipole of common atoms.
This 'unobservability' is exactly what the current issue is in regards to finding out the physical nature of dark matter; we cannot observe directly, we can only predict it. Hence, the Majorana fermion with its unique anapole, could be the solution. The most exciting aspect about the theory is that it does not rely on some new, unknown, exotic physical phenomena. In the past, scientist have observed atoms of CS-133 and Yb-174 exhibit magnetic anapoles.
As said by Dr. Scherrer:
“There are a great many different theories about the nature of dark matter. What I like about this theory is its simplicity, uniqueness and the fact that it can be tested."
[Reference: Vanderbuilt University]
Personally, I find the attractiveness of this theory lies in its simplicity and grounding in conventional physics. It is much more straightforward and realistic, and calls for far less imagination in comparison to other theories on dark matter. A analogy could be made with this theory to loop quantum gravity, where the far more exotic, fanciful and downright unscientific theories on gravity would be string theory.
Read the paper here.