A groundbreaking study suggests that water might have formed far earlier in the universe than previously assumed—potentially billions of years before the first galaxies even took shape. Researchers running advanced numerical simulations now propose that water molecules could have emerged just 100–200 million years after the Big Bang, fundamentally reshaping our understanding of cosmic history.
Water, composed of hydrogen and oxygen, is one of the key ingredients for life. Hydrogen, the simplest and most abundant element in the universe, formed shortly after the Big Bang as the universe cooled. However, oxygen—the second component of water—was not created during the Big Bang. Instead, it emerged within the first generations of stars through nuclear fusion.
These early stars, known as Population III stars, were far more massive than our Sun and burned through their fuel rapidly. When they reached the end of their lifecycles, they exploded in supernovae, scattering heavy elements like carbon and oxygen into space. Until now, scientists believed that water only began forming after these elements gradually accumulated over billions of years. However, new simulations indicate that oxygen produced in these primordial explosions may have combined with hydrogen to form water much earlier than expected.
Water Before Galaxies
Astrophysicist Dr. Daniel Whalen and his team at the University of Portsmouth ran sophisticated simulations of core-collapse supernovae and Population III supernovae. Their findings suggest that high-density clouds of gas, rich in oxygen and hydrogen, created ideal conditions for water formation soon after these massive stars exploded.
This challenges the long-held belief that water only became widespread after galaxies formed. Instead, it appears that the earliest cosmic structures—before galaxies even existed—could have contained water in significant amounts.
“Before the first stars exploded, there was no water because there was no oxygen,” Dr. Whalen explained. “But as soon as the first supernovae enriched the universe with oxygen, it began combining with hydrogen to create water, paving the way for the essential ingredients of life.”
Could Water-Rich Planetary Systems Have Formed at Cosmic Dawn?
One of the most exciting implications of this discovery is the possibility that planets with significant water content could have formed much earlier than previously thought. The study suggests that planetary discs, rich in water, might have existed even before the first galaxies took shape.
“Although the total water masses were relatively modest, they were concentrated in the very regions where stars and planets were beginning to form,” Dr. Whalen noted. This raises the possibility that water was not just a late arrival in the cosmic timeline but an integral part of the earliest planetary systems.
While this research opens new doors in our understanding of the early universe, direct observational evidence is still needed. Scientists have yet to detect the elusive Population III stars, which are believed to have played a crucial role in this process. Future research, such as with the James Webb Space Telescope, may provide the first glimpses of these ancient stars, helping to confirm whether water truly existed at the dawn of cosmic history.
