Watch the First Stars In the Universe Being Born In This Incredible Simulation

"Cosmic dawn," when the first stars formed, is a murky period of history of the universe. Watch it happen in this simulation from MIT scientists.
Watch the First Stars In the Universe Being Born In This Incredible Simulation
Screengrab: YouTube/MIT

Scientists at MIT have simulated the origins of the first stars in the universe in more detail and depth than ever before.

Detailed in a series of papers—the most recent of which was published in the Monthly Notices of the Royal Astronomical Society on Thursdaythe THESAN project, named after the goddess of the dawn in Etruscan mythology, uses existing models of galaxy formation and cosmic dust to visualize the Epoch of Reionization (EOR), the period in which the the arrival of the first stars and gasses formed after the birth of the universe.


This period is widely understood to have occured hundreds of millions of years after the Big Bang—when a single infinitely hot, dense point stretched into the universe as we understand it today. This kicked off an initial dark age in the universe, but  free-floating neutrons and protons eventually joined to create the first ionized atoms of hydrogen and deuterium, which became helium. This hydrogen and helium joined with electrons and became neutral atoms. Neutral matter in the universe began to clump together, cooling and collapsing and creating the first stars and galaxies. This period is known as the Epoch of Reionization, also known as the cosmic dawn. 

“In principle you could work this out with pen and paper,” Aaron Smith, first author on the paper and NASA Einstein Fellow at MIT told MIT News on Thursday. “But at some point gravity starts to pull and collapse matter together, at first slowly, but then so quickly that calculations become too complicated, and we have to do a full simulation.”

Learning about this early era of the universe could teach us a lot about fundamental physics and the origin of, well, everything, and so scientists are searching for observational signs of this neutral hydrogen without concrete success. 


In the meantime, Smith and his team created a vivid image of exactly what this process might’ve looked like. Using existing models of the early universe and of cosmic dust, matched with new code created to interpret how light and gas interacted with one another, they created a visual depiction of the growth of the universe. With time, the video shows stars seemingly bursting out from one another, exponentially, populating an otherwise black image. The simulation shows galaxies forming along gas filaments in what scientists now know as the “cosmic web” that connects the universe and gives it structure.   

“Thesan follows how the light from these first galaxies interacts with the gas over the first billion years and transforms the universe from neutral to ionized,” Rahul Kannan, second author on the paper and associate professor of physics at MIT told the institution’s news site. “This way, we automatically follow the reionization process as it unfolds.”

The authors are taking pride in both the scope and the detail of their simulation, both of which they broke new ground on.

“There are a lot of moving parts in [modeling cosmic reionization],” Mark Vogelsberger, fourth author on the paper and associate professor of physics at MIT said. “When we can put this all together in some kind of machinery and start running it and it produces a dynamic universe, that’s for all of us a pretty rewarding moment.”