And there may be additional payoff for this research. Those itsy-bitsy zaps might offer chemists a green trigger to drive useful chemical reactions.<\/p>\n
Looking for the spark<\/p>\n
Most folk tales describe will-o\u2019-the wisps as something to be feared.<\/p>\n
Folklore tends to attribute the eerie lights \u2014 also known as fool\u2019s flame, ignis fatuus or jack o\u2019 lanterns (yes, that\u2019s where carved Halloween pumpkins get their name) \u2014 to a spirit or fairy that\u2019s trying to mislead a traveler. Their light can flicker, hover and glide. Those brave enough to touch one have would have found it cool to the touch.\u00a0<\/p>\n
Science has offered other explanations. The most common is swamp gas released by rotting plants (or decaying flesh). Swamp gas is mostly methane, a flammable hydrocarbon.\u00a0 And under certain conditions, methane can burn slowly with a cool blue flame.<\/p>\n
Unable to capture a will-o\u2019-the-wisp, Garlaschelli went back to his lab in Italy. There, he experimented with compounds given off by rotting plants or creatures. With the right combo, he got a mix of gases to ignite on its own. But it still wasn\u2019t quite right. It burned with a green flame, not a blue one.<\/p>\n Back in 1776, another chemist at the same university studied ghost lights. This Alessandro Volta proposed that some spark ignited the swamp gas<\/a>. Now, a California team has found data to support Volta\u2019s idea.<\/p>\n Micro-lightning from methane bubbles<\/p>\n Earlier this year, chemist Richard Zare\u2019s team at Stanford University showed that tiny water droplets can create even tinier electrical sparks<\/a>. Could tiny bubbles do the same? And if so, might these zaps create will-o\u2019-the-wisps by igniting the methane gas seeping out of swamps?<\/p>\n Zare proposed this to Yu Xia, a researcher in his lab. Xia, now at Jianghan University in Wuhan, China, put together a team to test that. First, they designed and 3-D printed a nozzle. It would make tiny bubbles in water, mimicking gas seeping from a swamp.<\/p>\n Any zaps between bubbles would probably not be visible to the unaided eye. So they set up two instruments to help. The most sensitive one was a photon<\/a> counter. It would alert them to any reaction that emitted light, even dim light. A high-speed camera would capture sparks strong enough to make visible flashes.<\/p>\n As the chemists began bubbling air into the water, the photon counter gave a signal. This meant micro-lightning was happening. But the camera didn\u2019t pick up any flashes.<\/p>\n Next, they bubbled a mix of methane gas and air through the water. Now, more photons emerged than before and the water heated up. But still, no flashes.<\/p>\n So the team adjusted their nozzle to make bubbles of a different size. To see a spark, the bubbles had to be very tiny and crowded together. Over and over they did this, hundreds of times \u2014 until finally, zap! The camera caught micro-sparks of lightning.<\/p>\n The team described that success Sept. 29 in Proceedings of the National Academy of Sciences.<\/p>\n Where are the wisps now?<\/p>\n This clearly shows micro bubbles can discharge electrical zaps, says chemist Antonio Pav\u00e3o. He works at the Federal University of Pernambuco in Recife, Brazil. Yet he\u2019s not convinced the experiment explains ignis fatuus. A swamp is quite different from this lab setup, he points out.<\/p>\n Pav\u00e3o has done his own research on will-o\u2019-the-wisps. He has focused on a lack of modern-day sightings. Why don\u2019t people see swamp lights anymore, he wonders? If the new theory is correct, he thinks people should still be reporting them.<\/p>\n Long ago, travelers carried lanterns at night. Maybe, Pav\u00e3o says, those lanterns sparked swamp gas to ignite.\u00a0<\/p>\n Garlaschelli, now retired, also finds bubble-zaps igniting swamp gas an intriguing idea. But it doesn\u2019t fully answer the mystery of will-o\u2019-the-wisps for him, either. The new experiments were done in the water, he notes. Will-o\u2019-the-wisps, in contrast, are flames that hover in air.<\/p>\n Do you have a science question? We can help!<\/p>\n![\"a](\"https:\/\/www.newsbeep.com\/nz\/wp-content\/uploads\/2025\/09\/1440_swamp_lights_willow_wisp_feat.jpg\")
A painting of will-o\u2019-the-wisps shows the light dancing like fairies.Hermann Hendrick\/Wikimedia Commons (Public Domain<\/a>)<\/p>\n![\"two](\"https:\/\/www.newsbeep.com\/nz\/wp-content\/uploads\/2025\/09\/1440_swamp_lights_willow_wisp_exp_setup.png\")
Diagram (A) shows the experimental setup. Methane gas bubbles into a tank of water. A camera is set to capture any micro-lightning between bubbles. As two bubbles approach each other (B), an electric charge builds. When they get close enough, electrons jump between them, causing a zap of micro-lightning.Y. Xia et al.\/PNAS 2025 (CC 4.0 BY-NC-ND<\/a>)<\/p>\n