The Chemistry of Life

Water – the essential ingredient for life – may have existed in the Universe far earlier than previously thought, long before the first galaxies appeared.

In a new study, a research team conducted a series of simulations where they found evidence that the building blocks of life appeared just 100 to 200 million years after the Big Bang – a discovery that reshapes our understanding of cosmic history, researchers said.

“Before the first stars exploded, there was no water in the Universe because there was no oxygen,” Daniel Whalen, an astrophysicist at Britain’s University of Portsmouth and lead author of the study, said in a statement. “Only very simple nuclei survived the Big Bang – hydrogen, helium, lithium, and trace amounts of barium and boron.”

Whalen and his colleagues used computer models to simulate how the first stars – massive, short-lived beacons of nuclear fusion – produced heavier elements, such as oxygen, which then combined with hydrogen to form water molecules.

They explained that when these stars reached the end of their lives, they exploded as supernovae that spewed out heavy elements into space. This process resulted in vapor clouds of water that ranged from Earth’s mass to Jupiter’s mass – depending on the size of the dying star.

The simulations showed that this early water wasn’t just randomly dispersed across the void: It eventually concentrated in dense clumps of gas – known as cloud cores – which are the birthplaces of new stars and planets.

The discovery has major implications for the search for life beyond Earth.

“Although the total water masses were modest, they were highly concentrated in the only structures capable of forming stars and planets,” added Whalen. “And that suggests that planetary discs rich in water could form at cosmic dawn, before even the first galaxies.”

The team is now wondering whether this early water survived the violent conditions of galaxy formation and still exists today, with further investigations to include exploring whether these early water molecules produced billions of years ago could still be present in modern planets – or even on Earth itself.

The study paves the way for future research using instruments like the James Webb Space Telescope to search for second-generation stars and their potentially water-rich planets.

“The chemistry of life as we know it requires liquid water,” Avi Loeb of Harvard University, who did not participate in the study, told New Scientist. “And that you can get only on a planet or some object that has a surface with an atmosphere.”