Shape of the Universe

Comparison of an anapole field with common electric and magnetic dipoles. The anapole field, top, is generated by a toroidal electrical current. As a result, the field is confined within the torus, instead of spreading out like the fields generated by conventional electric and magnetic dipoles.
Date:8 September 2013 Tags:, ,

Simple theory may explain mysterious dark matter

Doughnuts are all around us, according to a new dark matter theory. Before you fire up the coffee machine, though, be advised that no confectionery is involved. A new theory proposes that dark matter, an invisible form of matter that makes up 85 per cent of all the matter in the universe, may be made out of particles that possess an unusual, doughnut shaped electromagnetic field called an anapole.

Two theoretical physicists at Vanderbilt University – Professor Robert Scherrer and post-doctoral fellow Chiu Man Ho – have published their theory in the journal Physics Letters B.

“What I like about this theory is its simplicity, uniqueness and the fact that it can be tested,” said Scherrer. The pair propose that dark matter may be made out of a type of basic particle called the Majorana fermion. (Although the particle’s existence was predicted in the 1930s, it has not yet been detected.) That view is shared by others, but unlike them Scherrer and Ho have performed detailed calculations that demonstrate that these particles are uniquely suited to possess a rare, doughnut- shaped type of electromagnetic field called an anapole. This field gives them properties that differ from those of particles that possess the more common fields possessing two poles (north and south, positive and negative) and explains why they are so difficult to detect.

“Most models for dark matter assume that it interacts through exotic forces that we do not encounter in everyday life. Anapole dark matter makes use of ordinary electromagnetism,” said Scherrer. “Further, the model makes very specific predictions about the rate at which it should show up in the vast dark matter detectors that are buried underground all over the world. These predictions show that soon the existence of anapole dark matter should either be discovered or ruled out by these experiments.”

Source: Vanderbilt University


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