Department of Physics & Astronomy

Fall 2008 Colloquia

 

Brandon Brown

Brandon Brown


Department of Physics,
University of San Francisco
How do organisms sense the Earth's magnetic field?
September 29, 2008 4PM, Thornton 411

Behavioral research has discovered a growing list of animals that can sense the Earth's magnetic filed. Organisms with significant migratory patterns or light-impaired environments are the most typical examples. In many cases, the sensitivity is exquisite enough to distinguish field variations of a microtesla in magnitude and a few degrees in vertical inclination. This talk will review examples of behavioral experiments from several systems, including crustaceans, reptiles, and mammals. It will also describe the two predominant theoretical mechanisms by which a creature could sense magnetic fields. One model relies on deposits of magnetic materials influencing neurons, while the other, the "radical pair" hypothesis, requires non-trivial quantum mechanical effects within an organism's visual system. At present, significant questions plague each model, and experiments suggest multiple mechanisms may be in play. This colloquium will present the first steps, and the remaining challenges, in developing a new option for the field.
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