Scientists recreate first molecule of the universe after 13 billion years

Time of India

3 days ago

In a groundbreaking breakthrough, scientists at the
Max Planck Institute
for Nuclear Physics in Germany have recreated one of the first chemical reactions to occur after the
Big Bang
: the formation of
helium hydride ion
(HeH⁺), believed to be the universe's
first molecule
. This experiment mimics conditions from more than 13 billion years ago and provides a clearer understanding of the chemical pathways that laid the foundation for star formation. By simulating these ancient reactions in the lab, researchers are helping to unravel the mysteries of the cosmos' earliest moments.
Universe's first molecule and why it matters
Helium hydride (HeH⁺) is a simple molecule formed from a neutral helium atom and a positively charged hydrogen nucleus (a proton). It likely formed just after the recombination era, about 380,000 years after the Big Bang, when atoms first stabilized and the universe became transparent to radiation. Though short-lived, HeH⁺ played a vital role in the cooling of primordial gas clouds, a key step in enabling gravitational collapse, the process that forms stars. Without these early molecules acting as coolants, the birth of stars and galaxies would have been significantly delayed or even altered.
How scientists simulated the early universe
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To recreate these ancient conditions, researchers employed the Cryogenic Storage Ring (CSR) in Heidelberg, a highly specialized instrument designed to simulate space-like environments. This 35-meter-diameter facility allows ions to circulate in an ultra-cold, vacuum-controlled environment, mimicking the near-zero temperatures of deep space. The team introduced HeH⁺ ions and bombarded them with a beam of neutral deuterium atoms (a hydrogen isotope with one proton and one neutron). This reaction formed HD⁺ (a deuterium-based analog to H₂⁺), closely simulating the early-universe chemistry that led to the creation of
molecular hydrogen
(H₂), the most abundant molecule in the universe today.
Defying theoretical predictions on molecular cooling
What surprised scientists was how efficient the reaction remained even at extremely low temperatures, contrary to long-held theoretical models. Earlier calculations had predicted a steep decline in reaction rates at near-zero temperatures, suggesting that HeH⁺ would be an insignificant player in the chemical evolution of the early cosmos. However, the experiment proved otherwise. The reaction was swift and showed no energy barrier, indicating it likely played a much greater role in dissipating heat from early gas clouds than previously thought. Theoretical physicists working alongside the experimental team also uncovered a critical flaw in earlier calculations, reinforcing the significance of the new results.
Rewriting the chemistry of the cosmic dark ages
After the universe cooled and neutral atoms formed, it entered a period known as the 'cosmic dark ages,' a time with no stars, no galaxies, and no visible light, only vast clouds of hydrogen and helium. During this time, molecular interactions like those involving HeH⁺ and H atoms were some of the few active chemical processes. These reactions laid the groundwork for the eventual formation of H₂, a molecule essential for radiative cooling and thus the gravitational collapse of gas clouds into stars. The new study suggests that HeH⁺ may have had a far more active and longer-lasting presence during this era than once believed.
Broader implications for star formation and cosmology
The results of this experiment have far-reaching consequences beyond HeH⁺ itself. By showing that barrierless, efficient reactions occurred under primordial conditions, the study enhances our understanding of how molecular hydrogen and its isotopic variants (like HD⁺) came into being and how they facilitated early star formation. This could help refine astrophysical models that simulate the formation of the first stars (Population III stars), galaxies, and ultimately the structure of the universe as we see it today. It also sheds light on the chemical evolution of the interstellar medium, where similar reactions continue to occur.
A major step in reconstructing the universe's origins
By successfully reproducing the earliest molecular reaction known to science, this experiment represents a major stride in astrochemistry and cosmology. It demonstrates how precise laboratory conditions on Earth can recreate moments from the dawn of the universe, helping scientists build a clearer picture of how matter evolved from chaos into complexity. With improved theoretical models and cutting-edge instrumentation, we are now better equipped than ever to answer some of the universe's oldest questions, including how the very first stars came to shine in the cosmic darkness.