One of the biggest mysteries surrounding the evolution of the cosmos is how molecules went from very simple to large and complex. It is hardly surprising that we as a species are so interested in solving this puzzle; after all, without complex molecules, particularly the organic molecules containing oxygen, hydrogen, nitrogen, and most importantly, carbon, we couldn’t exist.
In a paper published in the journal Angewandte Chemie, a team of scientists investigated the impact of high-energy photons called gamma-rays on the formation of complex organic molecules in the early Universe. In particular, the researchers focused on the development and evolution of methane, a molecule in which one carbon atom is bonded to four hydrogen atoms.
“We live in a molecular universe with abundant and widespread molecules and a rich organic inventory, particularly in regions of star and planet formation,” said team leader and University of Science and Technology of China researcher Weixin Huang. “The study of the evolution of molecules in the early Universe will help to understand the formation of stars, the evolution of galaxies, and the first steps toward life.”
How gamma rays made the Universe a bit more interesting
The gamma rays in the early Universe that impacted the development of methane and other complex molecules would have been created by the nuclear decay of unstable atomic variations of elements called “isotopes.” The gamma rays would have been delivered within cosmic rays, beams of high energy particles, passing through vast clouds of gas and dust called the interstellar medium.
“These conversions were believed to occur during the lifecycle of the interstellar medium, which plays a central role in the evolution of galaxies,” Huang said. “The gamma rays provided external energy to activate the stable molecules into reactive radicals which further reacted to produce complex molecules.”
Of course, to investigate the effect of gamma rays on methane, the team turned to the University of Science and Technology of China’s carbon-60 radiation source, which allowed them to simulate the cosmic rays of the early cosmos. Despite facing challenges in the form of unexpected products, the team was able to obtain a clearer picture of the action of gamma rays in the infant Universe.
“The rich conversion network of methane driven by gamma-rays represents a likely formation network of initial complex organic compounds in the Universe which, together with previous research, suggests unimaginable possibilities of the molecular evolution in the Universe,” said team member Xiao Sun, also hailing from the University of Science and Technology of China.
While the value of determining a better model of chemical conversions in the early Universe is invaluable to our understanding of how stars, planets, moons, and life benefited from molecular complexity, the team’s research could have a practical application to use here today.
Team member and University of Science and Technology of China researcher Fei Fang explained that an aspect of the conversions called acetic acid selectivity could reach levels as high as 82% by controlling the reaction conditions. That could deliver a safe and clean source of carbon as an alternative to the burning of fossil fuels.
“This truly provides an alternative strategy for efficiently utilizing methane, a clean and rich carbon source on Earth, to produce value-added products at mild conditions driven by gamma-rays, which, although exhibiting a strong and dangerous radiation effect, is being utilized safely at a large scale and represents an easily available and sustainable energy,” Fang concluded. “Such an approach is learned from the Universe for solving a long-standing challenging task in chemical productions.”
Reference: W. Huang., F. Fang., X. Sun., et al., γ-Ray Driven Aqueous-Phase Methane Conversions into Complex Molecules up to Glycine, Angewandte Chemie, (2024), DOI: 10.1002/anie.202413296
Feature image credit: NASA
