Scientists from Harvard and MIT have simulated the evolution of the cosmos, showing how the first galaxies were formed around blocs of dark matter, which, with dark energy, are believed to make up 94 percent of the universe.
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The computer simulation provides the highest-resolution model of cosmic evolution ever. The study has just been published in the journal Nature.
The model was based on accepted theories and delved into the data on events following the Big Bang 14 billion years ago. One can traverse the period of powerful explosions and the formation of black holes to the emergence of the first galaxies and expansion of the universe.
A special computer program had to be developed to translate the theories into code and make them 3-D.
“This project is much more than a visual product depicting cosmic evolution,” Dr. Shy Genel, an Israeli physicist doing postdoctoral research at the Harvard-Smithsonian Center, told Haaretz. “It helps us get a sense of how the universe works, but we only did this part at the end of a three-year project. The bulk of the work was about taking the equations and getting the computer to solve them correctly,” said Genel, a member of the team that developed the simulation.
“Cosmic evolution involves a number of basic processes such as the force of gravity, the flow of gas, explosions of stars and the collapse of gas into black holes. We took these processes and did two things. In the first stage we formulated these processes as equations, and in the second stage we wrote computer code that could solve these equations.”
Astrophysicists have been doing similar work since the 1990s. “The computer models and the computer power of the ‘90s weren’t that strong,” Genel said. “You couldn’t aim that high; for example, to make such realistic models of galaxies.”
A video less than seven minutes long illustrates the high level of simulation. The full simulation consists of 250 terabytes and is saved on Harvard’s supercomputers.
“Twenty researchers are analyzing the information, and we expect many articles based on this information to be published in the coming years,” Genel said. “This will let researches analyze the virtual universe from many, many directions.”
The computer simulation doesn't present a new theory, it simply creates a coherent picture of existing theories on the various stages of the universe's evolution.
“We’re using the standard model of the cosmos, which says that most of the universe began with a process of ‘cosmic inflation.’ Up to now, the evidence for the standard model came from a measure of hundreds of millions of light years, and many people in the scientific community said that maybe the standard model can provide a rough explanation of the behavior of the cosmos, but not at the level of individual galaxies,” Genel said.
“In our work we showed that this model can create the structures that are formed in the cosmos – not just on a scale of hundreds of millions of light years, but on the level of the galaxy, of thousands of light years.”
The processes that Genel describes do a lot better than the old-fashioned telescope, with which researchers simply study a fixed picture. According to Dr. Mark Vogelsberger of MIT, who led the study, the simulation supports many of the current theories on cosmology.
“Many of the simulated galaxies agree very well with the galaxies in the real universe. It tells us that the basic understanding of how the universe works must be correct and complete,” he told the BBC, adding that dark matter is the scaffold on which the visible universe hangs. “If you don’t include dark matter [in the simulation], it will not look like the real universe.”