**Research teams in both Europe and the United States of America, alongside a cosmologist from the University of Portsmouth have started building a model of the universe for the first time with the help of Einstein’s full general theory of relativity. The teams each created a new set of computer codes that they say will lead to the most accurate models of the universe possible as well as provide new insights into gravity and its direct effects.**

Einstein’s theory remains the best theory of gravity, even one hundred years since its development. It is consistently passing high-precision tests in the solar system and successfully able to predict phenomena like gravitational waves that were discovered earlier in the year. Due to the equations involved being so complex, physicists have been forced until now to simplify the theory when applying it to relate to the universe.

The two new codes are the first that use Einstein’s complete general theory of relativity to account for the effects of the clumping of matter in certain regions and the minimal amount of matter in other regions. Dr. Marco Bruni from the Institute of Cosmology and Gravitation, Portsmouth says the development is really exciting and will help cosmologists create the most accurate possible model of the universe. Over the next decade, he says the teams expect a deluge of new data coming from next generation galaxy surveys, which use extremely powerful telescopes and satellites to obtain high-precision measurements of cosmological parameters. This is an area the ICG researchers are going to play a major role in.

In order to match the precision, Bruni says the team needs theoretical predictions that are not only just as precise but also accurate at the same level. These new computer codes will apply general relativity in full and aim precisely at this high level of accuracy, and in the future they should become the benchmark for any work that makes simplifying assumptions.

Both groups of physicists were trying to answer the question of whether small-scale structures in the universe are able to produce effects on a larger distance scales. Both have found that to be the case, but they present concrete tests that show a departure from a purely averaged model. The researchers explain that the computer simulations employing the full power of general relativity are the key to being able to produce more accurate results and a much deeper and new understanding of the whole concept.

Professor Glenn Starkman from the American team says no one has been able to model the full complexity of the problem before. These papers are an important step forward, using the full machinery of general relativity to model the universe, without unwarranted assumptions of symmetry or smoothness. The universe does not make these assumptions and neither should the people closely studying the universe.

Both groups of researchers independently created software that applied the Einstein Field Equations. These equations describe the complicated relationships between the matter content of the universe and the curvature of space and time, at billions of places and times over the history of the universe. By comparing the outcomes of these new simulations to the outcomes of traditional simplified models, the researchers discovered that approximations break down.

Dr. Bruni says much more work will be needed in the future in order to fully comprehend the importance of the differences between simulations based on Einstein equations and those making simplifying assumptions. In the end, he believes that, as always in physics, it will be the interplay between theory and observations that will further our understanding of the universe.

The teams are looking forward to continuing their work and seeing what their final models end up looking like. This is a huge breakthrough in the science community and something that may completely reshape how we view the world and universe around us. Understanding gravity and how it affects the locations around it could completely change how we view our universe and give us insights that could be life changing. All we can do is wait patiently for the results and see what happens next.