“We usually think of water as so benign, but when it’s divided in the form of little droplets, water is highly reactive,” said Richard Zare, describing a line of laboratory work that moves electricity’s role in life’s origin from rare, sky-splitting bolts to something more ordinary: spray.
The Miller-Urey apparatus, consisting of gases contained within a glass enclosure, zapped with an electric discharge, producing amino acids, has been one of the most long-lasting pictures used in the history of the study of the origin of life. The basis of that experiment, and the discussions it has provoked, is as follows: early Earth must have used a means of forming carbon-nitrogen bonds, the chemical framework in which proteins and nucleic acids are synthesized. Dissociation of the strong bonds of nitrogen requires a strong force of energy. It can be provided by lightning, and lightning is sporadic; seas are large; and the water is insidious.
The more recent work retains the traditional chemistry in perspective and alters the physical phase. In experiments at Stanford led by researchers published in Science Advances, the experimenters sprayed water mist in a gas mixture that was intended to simulate a portion of the atmosphere of the early Earth- nitrogen, methane, carbon dioxide, and ammonia and observed the results when droplets were repeatedly sprayed, collided, and separated. The imaging revealed using high-speed shots small flashes: microelectric discharges between oppositely charged droplets. The charge pattern matters. In the study by Zare et al., larger droplets were observed to bear positive charge and smaller droplets bear negative charge; as the two droplets came near each other, the electrons leaped over the divide. The outcome was “microlightning,” which was the invisible relative of a thunderstorm spark. Molecules with carbon-nitrogen bonds such as glycine and uracil were chemically analyzed based on the reaction chamber and this related the experiment to the main requirements of biochemistry as opposed to a favored origin story.
The editorial worth of that change is not as much a shift in one dramatic trigger with another but a shift in what is considered a plausible source of planetary power. Water spray, unlike a cloud-to-ground strike, is not hard to contemplate repeating everywhere: at a shore, waterfalls, wave crashing rocks and wind blowing puddles. The issue of concentration is also altered by a mechanism that functions in numerous small outbursts. Organic products need not be formed in a single, marvelous place, they can be formed in an infinite variety of micro environments, where droplets and gases are mixed, which can be collected in thin films, cracks, and shallow pools, and which naturally recycle wet and dry and can enhance chemistry.
This is not the end of the debate on the origin of life, as origin-of-life chemistry lacks several missing links between synthesizing several key molecules. The hydrothermal vent models, such as, are centered on a pressure and flowing gradient minerals energy and catalysis. Physical context, or pressure, flow, and reactive minerals were shown to replace atmospheric sparks as the “push” to initiate carbon chemistry, in one NASA Jet Propulsion Laboratory simulation of seafloor-like conditions, which generated formate and trace methane under high-pressure when mixed by a high-pressure, vent-style mixing.
The contribution of electricity is also not restricted to organics building. A 2021 study in Nature Communications claimed that lightning can unlock phosphorus, forming reduced phosphorus species of fulgurites, and estimated that 1–5 billion lightning flashes per year on early Earth (in some models) and that 10100 kg/year of phosphide were made in some of its models (with Hadean-to-Archean assumptions). The availability of phosphorus is commonly considered a silent limit on prebiotic chemistry; electrified geology reduces it to a more active variable.
Then there is the chance that certain ingredients were brought in complete. Sample returns by asteroid Bennu provided 14 out of 20 amino acids utilized in life on Earth and all five nucleobases utilized to store and transmit genetic information, as well as indicated the presence of long-lived saltwater brines that might have been used as reactants. Such results do not find evidence of life, but do indicate that it is possible to have “starter kit” molecules to survive in wet chemistry outside of the earth.
The mist-spark concept falls into that larger trend: origin-of-life studies are increasingly considering early earth not as a single laboratory flask but as a planet with overlapping reactors the spray, the rocks, the sun, the pressure, the salts, can all interact to push unbiologic matter towards biology.
