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Academic Minute

Dr. Robert Scherrer, Vanderbilt University – Magnetism and Dark Matter


In today’s Academic Minute, Dr. Robert Scherrer of Vanderbilt University lays out a hypothesis that could explain dark matters elusive nature. 

Robert Scherrer is Professor and Chair of the Department of Physics and Astronomy at Vanderbilt University. His broad research interest is cosmology, specifically including questions about dark energy, dark matter, big bang nucleosynthesis, and the large-scale structure of the universe.  He is also the author of a textbook on quantum mechanics, several popular science articles, and a number of science fiction short stories. He holds a Ph.D. from the University of Chicago.

About Dr. Scherrer

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Dr. Robert Scherrer – Magnetism and Dark Matter

The matter that surrounds us, that makes up our bodies, the earth, and the solar system, is just a fraction of the total matter in the universe.   The rest is dark matter, and scientists have been trying for the past four decades to understand it.  Most theories assume that dark matter interacts through very weak forces that do not have much of an effect on our everyday lives.  But what if it were simpler than that?   What if the dark matter felt the same electromagnetic force that causes a balloon to stick to the ceiling?  Our work suggests that this might be possible. 

My collaborator, Chiu Man Ho, and I have dusted off an old idea first proposed by a Russian scientist more than 50 years ago, called the anapole.  Think of it as an electromagnetic donut.  Imagine a hollow tube with a wire wrapped around it.  When a current flows through the wire, a magnetic field is generated in the center of the tube.  Now if you bend the two ends of the tube and connect them together, you get a donut.  And the magnetic field follows a ring around the inside of the donut:  the anapole.

The anapole field is special.  For one thing, it does not exert a force on electric charges at rest, only on moving charges.  If the dark matter particle behaved like an anapole, it would be harder to detect in underground experiments than other kinds of electromagnetic dark matter.  But our calculations suggest that dark matter detectors are very close to being able see these particles, so this idea should be confirmed or ruled out within the next few years.

Production support for the Academic Minute comes from Newman’s Own, giving all profits to charity and pursuing the common good for over 30 years, and from Mount Holyoke College.

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