A team of astrophysicists has just spawned 8 million unique universes in a supercomputer and left them to evolve from just peaks to old jizers. Their purpose? To eliminate the role that an invisible substance called dark matter played in the life of our universe after the Big Bang, and what it means for our destiny.
Following discovering that our universe is made up mostly of dark matter in the late 1960s, scientists speculate on its role in galaxy formation and their ability to give birth to new stars over time .
According to the Big Bang theory about the Big Bang not after the universe was born, invisible and elusive substances called the dark matter that began to accumulate along with the force of gravity in massive clouds called halos of dark matter. As the halos increased, they attracted the scarce hydrogen penetrating the universe to gather and form the stars and galaxies we see today. In this theory, dark matter acts as the backbone of galaxies, dictating how they form, merge and evolve over time.
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"We can create many different universes on the computer and compare them to the actual ones. This allows us to conclude which rules lead to the one we see," Behrozy says in a statement . While previous simulations focused on modeling single galaxies or generating limited-parameter model universes, UniverseMachine is the first of its scope. The program continuously creates millions of universes, each containing 12 million galaxies, and each allows them to evolve in almost the entire history of the real universe from 400 million years after the Big Bang to the present day.
"The big question is, 'How do galaxies form?' "Says research researcher Riza Wexler, a professor of physics and astrophysics at Stanford University. "The really cool thing about this study is that we can use all the data we have about the evolution of galaxies – the number of galaxies, how many stars they have and how they form stars – and put that together in an overall picture of the last 13 billion years of the universe . "
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Creating a replica of our Universe, or even a galaxy, will require an inexplicable amount of computing Thus, Behroozi and his colleagues narrow their focus to two key properties of galaxies: their combined mass of stars and the rate at which they give birth to new ones.
"Simulating a galaxy requires a 10th to 48th computation operation," Behroozi explained, referring to octillion surgery, or 1 followed o of 48 zeros. "Not all computers on Earth combined can do this for a hundred years. So just to simulate a single galaxy, let alone 12 million, we had to do it differently."
While the computer program gives birth to new universes, it makes you know how the rate of star formation in a galaxy is related to its age, its past interactions with other galaxies, and the amount of dark matter in its halo. It then compares each universe with real observations, fine-tuning the physical parameters with each iteration to better match reality. The end result is a universe almost identical to ours.
According to Wechsler, their results indicate that the speed at which galaxies give birth to stars is closely related to the mass of their halos of dark matter. Galaxy with halos of dark matter masses, most similar to our Milky Way, had the highest rate of star formation. She explained that star formation is strangled in more massive galaxies than the abundance of black holes
Their observations also challenge long held beliefs that dark matter is stifling star formation in the early universe.
"Going back earlier and earlier through the universe, we would expect dark matter to be denser and therefore gas to become hotter and hotter. This is bad for star formation, so we were thought that many galaxies in the early universe should have stopped forming stars before, "Behrozy said. "But we found the opposite: Galaxies of a size are more likely to form stars at higher speeds, contrary to expectations."
The team now plans to expand UniverseMachine to test more ways in which dark matter can affect galaxy properties, including how their shapes develop, the mass of their black holes, and how often their stars go . .
"What is most exciting to me is that we now have a model by which we can begin to ask all these questions in a framework that works," Wexler said. "We have a model that is cheap enough computationally that we can essentially calculate an entire universe in about a second. Then we can afford to do it millions of times and explore the entire parameter space."
The Research Group publishes their results in the September issue of the Journal Monthly Newsletter of the Royal Astronomical Society .
Originally published by Live Science .