Computer simulations suggest that planetesimals and water-rich environments may have formed just 100 million years after the Big Bang. Researchers found that early supernova explosions enriched the pristine cosmos with heavy elements far earlier than traditionally expected, pushing back the timeline for potential habitable worlds.
The cosmic timeline for rocky worlds and the ingredients of life is getting a drastic rewrite. Traditional scientific models held that the early universe was far too barren for complex chemistry or planet formation for billions of years after the Big Bang. New computer simulations reveal that the universe’s first generation of stars helped kick-start the formation of planetary building blocks much earlier than anyone anticipated.
Cosmic Dawn and the Birth of Heavy Elements
When the universe began roughly 13.8 billion years ago, nucleosynthesis produced overwhelmingly hydrogen and helium, accompanied by mere traces of lithium and beryllium. Carbon, oxygen, iron, silicon, and other critical ingredients required to build rocky worlds simply did not exist in meaningful quantities.
Avi Loeb of Harvard University stated that for 100 million years, the universe did not have the building blocks of life, like oxygen or carbon, adding that once nuclear fusion started in stellar interiors, the universe became far more interesting.
Those crucial heavier elements had to wait for the arrival of Population III stars, the extremely massive first generation of stars in the cosmos. When these ancient stellar bodies exhausted their nuclear fuel, certain types detonated in violent supernovae, dispersing freshly forged elements across pristine clouds of gas. One specific and extreme event predicted to occur in exceptionally massive stars is the pair-instability supernova. Rather than leaving behind a conventional stellar remnant, this cataclysmic blast completely tears the star apart and ejects immense quantities of heavy elements into surrounding space, drastically raising the metallicity of nearby gas clouds.
Supernovae as Ancient Cosmic Water Factories
Beyond scattering the solid materials required for rocky planets, these early stellar explosions also manufactured water. A study published in Nature Astronomy demonstrated that supernova explosions from pristine primordial stars could forge water-rich pockets of gas just 100 million to 200 million years after the Big Bang.
Researchers modeled the explosions of two primordial stars: one roughly 13 times the mass of the Sun and a colossal specimen 200 times more massive. The smaller star survived for approximately 12 million years before ejecting 17,000 Earth masses of oxygen, while the larger counterpart lasted only 2.5 million years and produced 55 solar masses of oxygen, translating to more than 18 million Earth masses. As these shock waves expanded, turbulence created dense clumps of gas.
Shmuel Bialy of the Technion–Israel Institute of Technology noted that at high gas temperatures, a set of very efficient chemical reactions that lead to water formation kick in.
These high temperatures accelerated chemical reactions that allowed water to form despite low initial oxygen concentrations and destructive ultraviolet radiation. Although total water production across an entire supernova remained modest, particular dense clumps achieved astonishing concentrations.
Daniel Whalen of the University of Portsmouth explained that their simulations showed that one could get sites for planet formation already enriched with water levels similar to those in the solar system today only 200 million years after the Big Bang.
Simulating Planetesimals 100 Million Years After the Big Bang
Water alone cannot sustain life without a stable footing, which for terrestrial organisms typically means a rocky planet. Researchers led by scientists at the University of Portsmouth modeled the aftermath of these primordial explosions to see if solid planets could follow the water.
The simulations followed enriched gas as it collapsed under gravity, birthing a low-mass, long-lived star surrounded by a rotating protoplanetary disc. In this model, the emerging star possessed roughly 70 percent the mass of the Sun. Within that ancient disc, solid material accumulated to create planetesimals—the solid precursors to planets.
Daniel Whalen of the University of Portsmouth reported that in their computer simulations of the early Universe, they found one such disc around a young star about 70 percent as massive as the Sun, noting that within that disc, enough solid material accumulated to create several Earth-masses’ worth of planetary building blocks at roughly the same distance from the star as Earth is from the Sun.
A Shifting Timeline for Habitable Worlds
These findings compress the timeline of cosmic evolution, demonstrating that planetesimals could emerge when the universe was less than 1 percent of its current age of 13.8 billion years. While planetesimals represent only the starting material from which rocky planets grow—and numerous gravitational disruptions could interrupt the process—producing several Earth masses of solid material at cosmic dawn alters fundamental assumptions in astrobiology.
The research does not prove that life actually existed 100 million years after the Big Bang. Instead, it establishes that the physical raw materials required to construct rocky, potentially habitable worlds were available far earlier than previously believed, widening the window for when life’s ingredients could have first assembled.
