Cosmologists from Case Western Reserve University in the US and Catania University in Italy have created an accurate model of the evolution of the universe using a supercomputer. The new simulation has confirmed that dark energy accelerated expansion of space is not an error in the old models. The results are published in the journal Physical Review Letters.
Some scientists believe that assumptions about the uniformity of the universe may have led to erroneous hypotheses, such as that space is expanding with acceleration. In the new study, cosmologists decided to keep assumptions to a minimum and show that dark energy is not the result of such an error. With the help of supercomputers, they simulated the expansion of the early universe, when matter began to concentrate in clumps, deforming the space around it and leaving rarefied regions.
The study is helping to resolve the debate over the accuracy of simplified modeling, the researchers said. Einstein's general theory of relativity explains gravity as the curvature of spacetime. According to the equations, gravity may be sufficient to close the universe, in other words, to compress it. With insufficient gravity, the universe will expand forever.
However, the solution of Einstein's equations on the scale of the entire universe would be impossible without simplifications. For example, earlier scientists assumed that matter is evenly distributed throughout outer space, and not concentrated in the form of galaxies. Now cosmologists are modeling the development of the Universe, starting with small regions in which dense structures are formed under the influence of gravity. At the same time, on a large scale, the Universe remains homogeneous.
The simulation revealed that high-density regions do not significantly affect the evolution of the universe, and this effect can be neglected in future calculations. Therefore, accelerated expansion and dark energy are not the result of erroneous assumptions by cosmologists. Scientists believe that the new method will not change the established views on the evolution of space. However, the work will help shed light on the early stages of the Big Bang and the propagation of elementary particles such as neutrinos in space.
Dark energy is hypothetical energy that has been introduced into the mathematical model of the universe to explain the observed accelerating expansion.