A new study suggests that microscopic lightning bolts—called microlightning—within water droplets may have helped forge the very first amino acids on Earth.
The research revives and reimagines one of the most iconic experiments in science history, providing a fresh path toward understanding how life began.
How A 70-year-old Experiment Just Got A Powerful Update
The idea traces its roots back to 1953, when Stanley Miller and Harold Urey conducted a groundbreaking experiment. They recreated early Earth’s atmosphere—using ammonia, methane, hydrogen, and water vapor—inside a sealed glass chamber, and jolted it with electricity. The result? The spontaneous formation of amino acids, the fundamental components of proteins.
The new study published in Science Advances, led by Dr. Richard Zare, a professor of chemistry at Stanford University, took a microscopic detour. Instead of focusing on large-scale lightning, Zare’s team explored electrical interactions between charged water droplets as tiny as 1 micron in diameter.
“The big droplets are positively charged. The little droplets are negatively charged,” Zare explained to CNN. “When droplets that have opposite charges are close together, electrons can jump from the negatively charged droplet to the positively charged droplet.”
Mist In Motion: How Microlightning Works
The researchers reproduced Miller and Urey’s gas mixture, then sprayed it with a fine mist. Using high-speed cameras, they captured faint flashes—tiny sparks zipping between the droplets. These sparks, or microlightning discharges, triggered chemical reactions that generated amino acids like glycine and uracil, a nucleotide found in RNA.
While the physics and chemistry involved weren’t new, the scale was. “What we have done, for the first time, is we have seen that little droplets, when they’re formed from water, actually emit light and get this spark,” Zare said. “That’s new. And that spark causes all types of chemical transformations.”
Why This Matters More Than Lightning Bolts?
The appeal of microlightning lies in its frequency. Traditional lightning is dramatic, but rare—especially on primordial Earth. “Even on a volatile Earth billions of years ago, lightning may have been too infrequent to produce amino acids in quantities sufficient for life,” Zare told CNN. Mist, by contrast, would have been everywhere: oceans, volcanic spray, clouds. This opens the door to a much more plausible scenario for the constant production of life’s building blocks.
“Microdischarges between obviously charged water microdroplets make all the organic molecules observed previously in the Miller-Urey experiment,” Zare said. “We propose that this is a new mechanism for the prebiotic synthesis of molecules that constitute the building blocks of life.”
Experts Weigh In
Dr. Amy J. Williams, an astrobiologist and geobiologist at the University of Florida, emphasized the importance of such energetic catalysts.“Lightning, or in this case, microlightning, has the energy to break molecular bonds and therefore facilitate the generation of new molecules that are critical to the origin of life on Earth,” she explained.
She also pointed out the extreme energy required to free nitrogen atoms, which must bond with carbon to form amino acids. The team’s approach shows that microlightning has the energy necessary to initiate these bonds in a plausible setting.