Conceptual image of microlightning in a water droplet. (Image generated by StudyFinds)
In a nutshell
- Water droplets create “microlightning” when they split, producing electrical discharges without any external power source
- These tiny electrical sparks can transform simple gases into complex organic molecules—including amino acids and RNA components—in just microseconds
- Since water sprays are far more common than lightning strikes, this phenomenon may have been a major contributor to creating life’s building blocks on early Earth
STANFORD, Calif. — Every splash of water on Earth might be creating microscopic lightning bolts—and this electrical phenomenon could have sparked the chemistry of life itself. Stanford University researchers have discovered that when ordinary water droplets split, they generate “microlightning” powerful enough to transform simple gases into complex organic molecules, potentially solving a longstanding mystery about how life’s building blocks first formed on our planet.
The study, published in Science Advances, reveals that sprayed water forms droplets with opposite electrical charges. When these droplets come near each other, they create electrical sparks capable of transforming surrounding gases
From Water Spray to Life’s Building Blocks
Knowing this, the research demonstrated something extraordinary: when water droplets were sprayed into a mixture of gases similar to Earth’s early atmosphere (nitrogen, methane, carbon dioxide, and ammonia), the resulting microlightning produced organic molecules with carbon-nitrogen bonds. These included hydrogen cyanide, the amino acid glycine, and even uracil—one of the four key components of RNA.
This natural phenomenon happens constantly in ocean waves, waterfalls, and rainfall. Unlike lightning strikes, which are rare and random, water sprays are everywhere on our planet. This ubiquity points to microlightning as a potentially major contributor to creating life’s ingredients on early Earth.
The path to this discovery began with a 19th-century paradox. Pure water is typically a poor electricity conductor, yet in 1867, Lord Kelvin built a device that generated sparks between metal buckets collecting water droplets. The explanation? When water droplets split, smaller ones carry negative charges while larger ones retain positive charges.
The Power of Microlightning
To investigate this phenomenon, researchers created a sophisticated setup that could suspend and then split individual water droplets while recording the results with high-speed cameras and light detectors.
The electrical field between these charged water microdroplets proved remarkably powerful—exceeding 8 billion volts per meter. Through careful experiments, the team determined that microlightning produces energy between 12.13 and 12.5 electron volts—enough to ionize elements like xenon.
In the prebiotic chemistry experiments, water droplet microlightning achieved in microseconds what the famous Miller-Urey experiment demonstrated decades ago about lightning’s potential role in creating life’s precursors. The reactions began with nitrogen and methane molecules breaking apart, forming reactive fragments that combined to create increasingly complex organic compounds.
Conducted in 1952, the Miller-Urey experiment was a landmark study in origin-of-life research where scientists Stanley Miller and Harold Urey simulated early Earth conditions to see if organic compounds could form spontaneously. They created a sealed apparatus containing water (representing the primordial ocean), methane, ammonia, and hydrogen (representing the early atmosphere), and subjected this mixture to continuous electrical discharges (simulating lightning) for about a week. When they analyzed the resulting solution, they discovered it contained various amino acids—the building blocks of proteins—as well as other organic compounds essential for life. The experiment demonstrated that complex organic molecules could be synthesized from simple inorganic precursors under conditions thought to resemble early Earth, suggesting a possible mechanism for how the chemical precursors to life might have formed naturally before biological processes existed.
To verify the findings of this new study, researchers ran control experiments with single water droplets that didn’t split. These produced no hydrogen cyanide, confirming that the creation of organic compounds required the microlightning between oppositely charged droplets.
“Microelectric discharges between oppositely charged water microdroplets make all the organic molecules observed previously in the Miller-Urey experiment, and we propose that this is a new mechanism for the prebiotic synthesis of molecules that constitute the building blocks of life,” says senior author Richard Zare, a professor of chemistry in Stanford’s School of Humanities and Sciences, in a statement.
A New Chapter in Life’s Origin Story
This discovery extends beyond explaining how life might have begun on Earth. With water covering over 70% of our planet’s surface, microlightning would have provided a continuous, widespread mechanism for creating organic compounds across Earth’s early oceans and shorelines.
“On early Earth, there were water sprays all over the place – into crevices or against rocks, and they can accumulate and create this chemical reaction,” notes Zare. “I think this overcomes many of the problems people have with the Miller-Urey hypothesis.”
The research doesn’t overturn existing theories about life’s origins but adds another compelling pathway. Multiple mechanisms—traditional lightning, hydrothermal vents, meteorite impacts, and now microdroplet microlightning—likely contributed to the prebiotic chemistry that eventually led to life.
“We usually think of water as so benign, but when it’s divided in the form of little droplets, water is highly reactive,” says Zare.
The most profound aspect may be the simplicity of this discovery: the process that potentially helped create life’s building blocks happens in every raindrop, waterfall, and wave. In the common splashing of water lies a possible secret to life’s beginnings.
Paper Summary
Methodology
The researchers employed several innovative experimental setups to investigate the microlightning phenomenon. First, they created an acoustic levitation system that could suspend a single water droplet in air between a transmitter and a reflector. By controlling the distance between these components, they could squash the droplet and eventually cause it to split into smaller droplets. High-speed cameras operating at 20,000 frames per second captured the motion of the droplets, while sensitive photon detectors measured light emission during the splitting process. To determine the ionization capability of the microlightning, the researchers built a sealed chamber connected to a mass spectrometer. They sprayed water microdroplets into this chamber containing various gas molecules with known ionization potentials, including benzene, octane, bromine, and xenon. For the prebiotic chemistry experiments, they used a similar setup but with a gas mixture of nitrogen, methane, carbon dioxide, and ammonia (similar to that used in the Miller-Urey experiment). The products formed were directly monitored using high-resolution mass spectrometry, allowing the researchers to identify the organic molecules created during the process.
Results Breakdown
The researchers observed several key results. First, they confirmed that when water droplets split, luminescence occurs due to electrical discharge between oppositely charged droplets. This was verified through photon detection showing increased light emission during droplet splitting. They demonstrated that the electric field between oppositely charged water microdroplets exceeds 8 × 10^9 V/m, and by testing various molecules with different ionization potentials, they determined that the energy of the microlightning falls between 12.13 and 12.5 electron volts. This energy is sufficient to ionize many gas molecules, including benzene (9.24 eV), octane (10.25 eV), bromine (10.55 eV), and xenon (12.13 eV). In their prebiotic chemistry experiments, they detected several important organic compounds forming through the microlightning process, including cyanoacetylene, cyanoacetaldehyde, cyanoacetic acid, glycine, urea, and uracil. These reactions occurred in less than 120 microseconds. A control experiment showed that the formation of hydrogen cyanide from nitrogen and methane was specifically due to the microlightning between oppositely charged droplets, not from the interaction of gas with a single microdroplet.
Limitations of the Study
Though groundbreaking, this study has several limitations. The researchers note that their ability to detect certain compounds was limited by the sensitivity of their mass spectrometer, meaning that additional products might have formed but remained undetected. The experiments were conducted under controlled laboratory conditions that may not perfectly replicate the conditions of early Earth. Additionally, while the researchers were able to detect several important prebiotic molecules, they acknowledge that other products were likely formed but not detected due to instrument limitations. The study also doesn’t thoroughly explore how variations in droplet size, temperature, pressure, or gas composition might affect the microlightning phenomenon and subsequent chemical reactions. The experiments were conducted over short timeframes (microseconds), so the study doesn’t address how these reactions might proceed over longer periods that would be relevant to geological timescales.
Discussion and Takeaways
The primary significance of this research is that it identifies a previously unrecognized natural energy source that could have contributed to prebiotic chemistry. The researchers suggest that microlightning from water droplets could have been an important complement to traditional lightning in synthesizing organic compounds on early Earth. This is particularly notable because water sprays are much more common and continuous than lightning strikes. The parallel with the Miller-Urey experiment results suggests that microlightning could produce similar chemistry but potentially on a more widespread scale. The researchers also highlight that this phenomenon explains unique reactivity at the gas-water interface that had been observed in previous studies. Beyond origin-of-life implications, this discovery contributes to our understanding of charge separation in water droplets and electrical discharges in nature. The researchers named this phenomenon “microlightning” because it exhibits properties similar to lightning, including the ability to excite, dissociate, and ionize molecules.
Funding and Disclosures
The study was supported by the Air Force Office of Scientific Research through the Multidisciplinary University Research Initiative (MURI) program (grant number AFOSR FA9550-21-1-0170) and the National Natural Science Foundation of China (grant number 22306073). The authors declared no competing interests that might have influenced the research or its interpretation. The researchers acknowledged assistance from X. Zhang from the College of Chemistry at Nankai University in building the droplet levitation setup. Richard Zare is also a member of Stanford Bio-X, the Cardiovascular Institute, Stanford Cancer Institute, and the Wu Tsai Neurosciences Institute as well as an affiliate of the Stanford Woods Institute for the Environment.
Publication Information
This research, titled “Spraying of water microdroplets forms luminescence and causes chemical reactions in surrounding gas,” was published in Science Advances (Volume 11, article eadt8979) on March 14, 2025. The authors are Yifan Meng, Yu Xia, Jinheng Xu, and Richard N. Zare, affiliated with the Department of Chemistry at Stanford University, with Yu Xia also affiliated with the School of Environment and Health at Jianghan University in China. The paper was submitted on October 15, 2024, accepted on February 6, 2025, and published on March 14, 2025..
