Water Existed in the Universe Billions of Years Earlier Than Thought, Astronomers Say

Water—the thirst-quenching molecule considered necessary for life as we know it—existed early in the universe’s lifetime, according to a study published today in Nature Astronomy.

In a first, a team of researchers modeled water in the primordial universe. The researchers found that habitable worlds could have formed much earlier in the universe’s timeline than previously believed—up to billions of years earlier than previously thought.

According to the team’s simulations, water molecules began to form after the first supernovae—the explosive ends of stellar life. Supernovae were necessary for creating the first heavy elements, including oxygen, which (perhaps straightforwardly) is the O in H20.

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

“Oxygen, forged in the hearts of these supernovae, combined with hydrogen to form water, paving the way for the creation of the essential elements needed for life,” Whalen added.

In the study, the team investigated two types of supernovae, called core-collapse supernovae and Population (or Pop) III supernovae. Core-collapse supernovae produce modest amounts of heavy elements when they explode, whereas Pop III supernovae are known to expel more than 10 times the mass of the Sun worth of metal when they go off. Both events form water-enriched clumps of gas that waft through the cosmos.

“The primary sites of water production in these remnants are dense molecular cloud cores, which in some cases were enriched with primordial water to mass fractions that were only a factor of a few below those in the Solar System today,” the research team wrote in a preprint of the paper hosted on arXiv. “These dense, dusty cores are also likely candidates for protoplanetary disk formation.”

“Besides revealing that a primary ingredient for life was already in place in the Universe 100 – 200 [millions of years] after the Big Bang, our simulations show that water was likely a key constituent of the first galaxies,” the team added.

In other words, one of the most fundamental conditions for life existed much earlier than previously known, indicating that the early universe may have been a surprisingly, uh, lively place.

Having instruments that can detect extremely faint, distant light—which is to say light from the early universe—will help experts in their quest to understand the history of life as we know it, as well as the evolution of the cosmos.

Observatories including the Webb Space Telescope are critical to this mission, as each observation helps astronomers peel back the layers of the universe, and untangle its timelines, from the formation of the first galaxies to the chemical composition of those structures.

We’ve not yet discovered life beyond Earth, but work like the team’s recent simulations are helping scientists creep towards an understanding of how it may have come to be.