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Two computer models to the universe described by Einstein.

The relativistic cosmology enters part full of models that describe the universe thanks to computer programs written by two research groups that make less of the simplifications in use for a century. These models confirm that the small-scale structures affect those on a large scale, but the evolution of the universe qualitative description remains unchanged. Published more than a century ago, Albert Einstein’s general theory of relativity is the best theory of gravitation formulated, and is a consistent pattern to describe the birth and evolution of the universe. The predictions of general relativity, also, many times and with great precision have been verified, also thanks to the recent detection of gravitational waves by the LIGO-Virgo collaboration.

However it is still a significant open question, which concerns the simplifications that are made to apply the theoretical model to the real conditions of the universe and to find solutions to complex equations of general relativity. One of these simplifications, for example, requires that the material is uniformly distributed in space, while it is obvious that it can be concentrated for example on planets and galaxies. To explain the existence of the latter, cosmologists speculate that initially there were regions of the universe with an excess of mass density, but only on a small scale, while keeping the rest of the universe for the hypothesis of a uniform distribution. The advancement of technology has not fundamentally changed the situation, since the full calculations of relativistic equations are difficult even for supercomputers.

Now, two independent research groups have investigated the matter with similar approaches, writing computer code that generated the most accurate representation ever produced of relativistic cosmology. Both approaches have confirmed that small-scale facilities producing effects at larger scales, although they are not noticeable qualitative changes on the cosmos expansion mechanisms. In this way, it was discovered that the rate of expansion of the universe varies from point to point: in the more dense mass regions, is 28 percent higher than the average value. On the other hand, the high density regions begin the gravitational collapse, the process in which the mass is increasingly focused to the effect of its force of gravity, in a shorter time than provided by other models. This could have important implications for theories of the formation of the first galaxies and even larger structures. Our approach allows us to understand a broader class of observational effects that emerge most likely in a precision cosmology. Attention then focused on the expansion of the universe mode, using some relativistic numerical calculation methods developed for the study of extreme objects in the cosmos like the blacks holes, compact objects such as neutron stars.

The starting point of the study was a “toy model universe” (toy universe) containing a distribution of material fitted to the observations, left to evolve according to the laws of general relativity. In this way they are discoveries localized differences in the evolution compared to conventional relativistic models. In addition it is also analyzed the curvature of the cosmos, which is produced in the vicinity of the masses, and how this curvature affects the propagation of light, according to the predictions of the relativistic theory. These articles are an important step forward, because they exploit the whole machinery of general relativity to model the universe, doing less than unverified assumptions.



To open the video click on the image, good view from your Alessandro Brizzi.