Why do grapes sparkle in the microwave?

Whether experienced physicists or experienced experimenters, many researchers have faced a question: why do grapes sparkle when you put them in the microwave? More than a few microwaves have been destroyed to answer this fundamental question of physics.

A team of researchers has decided to test this question in a rigorous way so that you do not have to do it. They discovered that grapes – either a cut in two or two touches – are able to focus the energy of microwaves into two "hot spots". When hot spots touch, they create a plasma or ionized gas that emits light and heat. It turns out that the size of the grapes is the key to this quirk in the science of cooking. The results were published this week in the journal Proceedings of the National Academy of Sciences.

The physicist Aaron Slepkov, author of this study, tells us how grapes can harness the energy of the waves of this family kitchen and what that can tell us about the field of photonics.

Further reading

• Read the study in Proceedings of the National Academy of Sciences.
• Learn more about the psychology of wine in this Science Friday video.
• It may not be prudent to create a hot spot in your microwave, but you can do other science at home! Try a Science Friday Educate activity.