"Mysterious will-o’-the-wisps ignited by microlightning"
"Electrical discharge from microscopic bubbles offers a new explanation for fleeting flames of folklore"
(Hermann Hendrich’s 1901 mural shows will-o’-the-wisps dancing with an eerie blue light. Picture Art Collection via Alamy)
"The eerie phenomenon has been said to be dancing bones, the hovering souls of dead children, and ghost lights meant to confuse travelers. For hundreds of years, folklore has sought to explain the will-o’-the-wisp, the fleeting flames occasionally seen above swamps and graveyards in the dark of night. Scientists have long suspected the flickers arise from flammable methane gas produced by decaying organic matter. But it’s been unclear how this gas could catch fire. Now, new research suggests that tiny lightning bursts jumping between microscopic bubbles can spark the phenomena, sometimes also called a jack-o’-lantern.
“This is really an interesting step forward,” says James Anderson, a chemist at Harvard University. “It reveals a mechanism by which chemical reactions can be initiated.” Anderson says the power of microbubbles to trigger reactions could also help explain how essential biomolecules formed prior to the dawn of life. The work is published today in the Proceedings of the National Academy of Sciences.
(In an experimental setup, high-speed cameras captured microlightning flashes (lower middle) occurring between microscopic air and methane bubbles in water. Richard N. Zare)
In recent years, Richard Zare, a chemist at Stanford University, and his colleagues have studied how tiny bubbles, just nanometers to micrometers in size, can generate strong electric fields, sparking reactions. When bubbles of different sizes form at the interface between water and air, charges on their surfaces separate, with negative charges accumulating on smaller bubbles, leaving larger ones more positively charged. This creates electric fields across small distances that trigger what amounts to bursts of microlightning as the charges attempt to equalize.
Zare wondered whether these electrical outbursts could explain the will-o’-the-wisp of lore. To find out, Zare’s team designed a machine with a submerged nozzle that blew microbubbles of methane and air into water. High-speed cameras then caught tiny light flashes as bubbles collided."
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