Scientists have observed many distant objects with instruments like Hubble and the upcoming James Webb Space Telescope, but everything we’ve seen represents all those stars, nebulae, and galaxies are just the tip of an unfathomable iceberg. Only about 15 percent of the universe is made up of the matter we can see, with the rest being mysterious dark matter and energy. Scientists still don’t know what dark matter is, but two theoretical physicists at the University of California Davis have a new hypothesis and a way to test it.
Researchers John Terning and Christopher Verhaaren presented their work at the recent Planck 2019 conference, and a pre-print version of the paper is available for download. The pair started this work to find an alternative to the increasingly unlikely WIMP hypothesis of dark matter. For years, scientists suspected that dark matter would turn out to be the Weakly Interacting Massive Particle (WIMP). However, experiments have failed to prove that, so scientists are back to the drawing board to explain what particle or particles make up the quarter of the universe attributed to dark matter.
According to Terning and Verhaaren, the answer could be a form of “dark magnetism” involving a variety of theoretical particles. In macroscopic applications, magnets always have two poles, but quantum theory predicts monopoles also exist. These particles have just one “end” of a magnet, and Terning and Verhaaren have suggested that dark monopoles may exist and interact with dark photos and dark electrons.
The pair lay out a potential method for detecting dark monopoles with an electron beam. Electrons moving in a circle near a monopole would develop altered wave functions (electrons are both particles and waves in quantum theory). The phase differences when the electron is on different sides of the monopole should create an interference pattern called the Aharonov-Bohm effect. Terning and Verhaaren say it should be possible to infer the presence of dark monopoles by the way it shifts electron phases as they pass by.
Dark matter is most likely around us all the time, but it may be a while longer before we can detect it. The expected phase shift is extremely small, and the technology to detect it doesn’t yet exist. The researchers believe we’ll get there, though. Terning points to the LIGO gravity wave experiment as an example of technology catching up with theory.
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