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Sewanee Student Presents at Physics Seminar Series

William Traill Jackson Jenkins

Will Jenkins, a Physics major from Greenville, AL, presented at the latest Physics Seminar Series in the Advent semester. This event, coordinated by Dr. Randolph S. Peterson, focused on how Earth's magnetic field allows us to observe Larmor precession of protons in water using a nuclear magnetic resonance (NMR), a device very similar to the more commonly known magnetic resonance imaging (MRI). Jenkins specifically discussed the theory behind Larmor precession, which mainly consists of relationships between the magnetic moments of the protons, frequency of their precession, and the external magnetic field. 

This was followed by a discussion of the fascinating phenomenon of "spin flip," which has the spooky attribute of appearing to transcend the limitations of time. This works by observing the precession of protons decaying with time (see image below). However, mix in a tiny burst of magnetic field from the spin flip coils (indicated by the three lines in the graph), and the decay can be reversed again and again with the initial starting phase being the only dominant limiting factor. In a small way, it actually breaks the barriers of time. 

Magnetic field graph 

For more information on the Physics Seminar Series, contact Dr. Peterson at rpeterso@sewanee.edu