Microwave grape plasma and the shape of water

The sparking of grapes in a household microwave oven has been a popular, if poorly explained online pop-sci phenomenon for decades. At first glance, simple explanations that treat wet grape skins as conductive antennas would seem to suffice. However, after years of playful investigation by a roster of undergraduate students, we now know that the explanation is far richer and more expansive. Using thermal imaging, ultrahigh-speed videography, and computer simulations we have been able to establish a photonic explanation for the phenomenon that reveals that grapes act as dielectric microwave resonators. In this talk I will discuss how viewing grapes as spherical water in a vacuum both provides a satisfying resolution to the “fruit plasma” mystery and provides new opportunities for research in nano-photonics and soft-matter technologies. Along the way, I’ll describe how this undergraduate-led and curiosity-based research went from “WTF?” to over 8 million Youtube views and a feature in the New York Times.

Aaron Slepkov is an Associate Professor of Physics & Astronomy and Canada Research Chair in the Physics of Biomaterials at Trent University. As a self-described lightsmith (Fr: lumifèvre), Dr. Slepkov is fascinated by light as a medium to be molded and shaped. His primary research involves development of nonlinear optical microscopy tools, and the application of those tools to a range of biomaterial systems. When he’s not accidentally misaligning his students’ experimental setups, Aaron is playing with fruit in the lab microwave oven or developing new forms of multiple-choice assessment techniques for physics education. Aaron completed a dual undergraduate degree in Physics and Chemistry at Brock University in 1999, followed by a masters (2001) and PhD (2006) in Physics at the University of Alberta. He then moved to Ithaca, NY, to conduct postdoctoral research in few-photon atom-waveguide interactions at Cornell. This was followed by second postdoc at the National Research Council of Canada in Ottawa, where he fell in love with nonlinear optical microscopy; a love he has since brought to Trent University in Peterborough, Ontario.