A study conducted at Standford University, led by Professor Richard Zare, offered a new perspective on the debated Miller-Urey experiment, that life on Earth is originated from a lightning strike. The new research, published in March 2025, in the journal, Science Advances, suggests that water sprays alone are capable of producing organic compounds, eliminating the need for external electrical sources. It demonstrates that microlightning—the electrical charges occurring within water sprays—could trigger chemical reactions, leading to the formation of organic molecules from inorganic substances. The results support the idea that microlightning could have played a role in creating the essential building blocks for early life on Earth.
Microlightning refers to minuscule electrical sparks generated when microdroplets of water, carrying opposing electrical charges, come into close proximity. This phenomenon is particularly prevalent in environments where water is fragmented into fine sprays, such as crashing ocean waves, waterfall, mists, and aerosols.
This new study provides additional evidence and a fresh perspective on the controversial Miller-Urey experiment. This study was conducted by Richard Zare, the Marguerite Blake Wilbur Professor of Natural Science and professor of chemistry in Stanford’s School of Humanities and Sciences, along with postdoctoral scholars, Yifan Meng and Yu Xia, and a graduate student, Jinheng Xu.
Particle physicists wonder why matter exists, given that Big Bang should have produced equal amounts of self-annihilating antimatter. Neuroscientists seek to understand why animals display forms of subjective consciousness instead of merely a series of electrical impulses. Meanwhile, biologists tackle perhaps the most crucial question of ‘how did life originate on Earth?’.
Earth formed about 4.6 billion years ago, and for the next few billion years, it had a diverse mix of chemicals but lacked organic molecules with carbon-nitrogen bonds. These bonds are essential for proteins, enzymes, nucleic acids, chlorophyll, and other compounds that are vital to the structure and function of living organisms today.
Miller-Urey Experiment
In 1952, American chemist, Stanley Miller and physicist, Harold Urey, conducted an experiment in which they demonstrated that organic compounds, like amino acids, essential for life, could form when electricity was applied to a mixture of water and inorganic gases. It supported the scientific theory of Abiogenesis, which suggests that life can originate from non-living matter. In simple terms, the scientists showed that a lightning strike hitting the ocean could trigger chemical reactions with early atmospheric gases such as methane, ammonia, and hydrogen, resulting in the creation of organic molecules.
The experiment was seen as a groundbreaking moment, offering one possible explanation for how life could have first emerged on Earth. However, in the years that followed, many scientists began questioning the findings. They argued that ‘real lightning would have struck infrequently—and mostly in open ocean, where organic compounds would have quickly dispersed’ (a report by Scientific American).
The New Stanford Study
The new study from Stanford University revisits the concept of life’s electrifying origins, but in a different context—microlightning in water droplets. The theory proposes that droplets from crashing waterfalls or breaking waves could generate electricity between oppositely charged water droplets. This idea could potentially resolve one of the main criticisms of the original theory, as the ‘lightning’ would occur directly within the water droplets themselves.
Zare and his team first explored how water droplets developed different charges when separated by a spray or splash. They discovered that larger droplets typically carried positive charges, while smaller ones were negative. When the oppositely charged droplets came close together, sparks would jump between them. Zare refers to this phenomenon as ‘microlightning’, as it is similar to the way energy is built up and discharged as lightning in clouds. The researchers used high-speed cameras to capture the flashes of light, microlightning, between large and positively charged water droplets and smaller and negatively charged ones, which are difficult to detect with the naked eye.
Although the tiny flashes of microlightning are difficult to see, they still carry significant energy. The researchers showcased this by spraying room temperature water into a gas mixture containing nitrogen, methane, carbon dioxide, and ammonia—elements believed to have been present on Earth’s early atmosphere. This led to the formation of organic molecules with carbon-nitrogen bonds, including hydrogen cyanide (Precursor for various biomolecules), glycine (the simplest amino acid), and uracil (a building block of the ribonucleic acid or RNA).
The researchers suggest that these findings imply that it was not necessarily lightning strikes, but rather the tiny sparks created by crashing waves or waterfalls, that may have kickstarted life on Earth. Zare explained that on early Earth, water sprays were widespread, occurring in crevices or against rocks, where they could accumulate and trigger chemical reactions. He believes this approach addresses may of the issues associated with the Miller-Urey hypothesis. Zare’s research team focuses on exploring the potential of small amounts of water, including studying how water vapour might contribute to the production of ammonia—a key component in fertiliser—and how water droplets could spontaneously generate hydrogen peroxide. Zare noted that water is often seen as benign, but when it is divided into tiny droplets, it becomes highly reactive.
Beyond Earth, the principles underlying microlightning could extend to other planetary bodies with water in liquid form and dynamic atmospheres, such as Jupiter’s moon, Europa, or Saturn’s moon, Enceladus. This study introduces microlightning as a plausible factor in the origin of life, providing an alternative to traditional hypotheses and expanding the scope of environment considered conducive to life’s emergence.
Both biologists and astrobiologists have long recognised the crucial role of water in supporting habitable worlds, but if this new theory proves to be valid, its significance may have been greatly underestimated.
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