What does our universe look like on a large scale?

Multiple studies have found that galaxies make up an astonishingly low portion of the volume of our universe, and that the vast majority of the universe consists of massive voids of dark matter and dark energy. Now, a new simulation has seemingly confirmed this conception of the universe, and as a bonus, has discovered that the “missing matter” of the nearby universe may be hiding within these voids.

Over the last five years or so, simulations of the universe that take into account all known aspects of cosmology–the expansion of the universe, the gravitational pull of matter, the motion of cosmic gas, the formation of stars, planets, galaxies, etc–have revealed that the universe resembles a gigantic spiderweb, in which galaxies compose the filaments that are thinly stretched around huge, dark, empty voids. As a result, galaxies make up approximately 50% of the universe’s total mass, but only .2% of the total volume.

Now, a new study by a team from the Institute of Astro- and Particle Physics at the University of Innsbruck, with the help of Illustris, which claims to be the “most ambitious computer simulation of our Universe yet performed,” claims that their simulation confirms the theory of the “cosmic web.” The large-scale simulation modeled physical processes starting with the initial conditions of the young universe (300,000 years after the Big Bang) all the way to the present, spanning over 13.8 billion years of cosmic evolution. The simulation created tens of thousands of galaxy in high detail, many of which align with real galaxies we have observed in the universe thus far.
In the simulation, the universe is represented as a giant cube consisting of intricate webs of thin galaxy filaments, which spans 350 light years on each side and is 12 million years old.

The simulation may have also provided an answer to the long-running “missing matter” mystery. Observations of our cosmic microwave background demonstrate that approximately one-sixth of the total matter in the universe is “ordinary” matter, while the rest is dark matter. We have a rough estimate of the total mass of our universe based on the movement of distant objects in relation to the Sun, but the observable stars, planets, and other ordinary matter objects only account for approximately 50% of that calculated mass. Some of that “missing matter” has been found in the filamentary structures that surround galaxies and provide scaffolding for the “cosmic web,” but there’s still a significant amount of matter than is unaccounted for. According to this study, a large portion of that matter may be hiding in those massive voids between galaxies.

“As much as 30% of the Universe’s observable matter could be hiding in enormous cosmic voids, where it is too sparse for scientists to observe,” the researchers wrote in their paper, published today in Nature.

The simulation showed that the culprit for the missing matter may be supermassive black holes. When matter falls into black holes, it is converted into energy, which is transferred to the surrounding gas. This leads to a violent emission of matter from supermassive black holes that send the matter thousands of light years past our galaxy, where it likely languishes within these huge empty spaces.

“[This] simulation, one of the most sophisticated ever run, suggests that the black holes at the centre of every galaxy are helping to send matter into the loneliest places in the universe,” said team leader Dr. Markus Haider.

Source: 3tags.org