Scientists at the University of Vienna have explained the mystery of the uniformity of the universe. According to the findings of the researchers, gravity played a key role in this. This is reported in a paper published in Physical Review Letters, and the study is summarized in a press release on Phys.org.
The researchers analyzed the evolution of initially strong deviations from a homogeneous state in the form of cosmological gravitational waves, which are described by Einstein's equations, and found out whether they decay with expansion, providing a homogeneous structure.
Until now, it was not clear whether the homogenization of the entire Universe could be fully explained by the influence of gravitational forces. Methods using Einstein's theory were successfully used only for small deviations from the uniform geometry of space-time.
It is assumed that shortly after the Big Bang there were strong fluctuations in the curvature of space-time. In the course of a long expansion process, the Universe has evolved to its present state, characterized by homogeneity (independence from the place of observation) and isotropy (independence from the direction of observation). At the same time, the regions of the Universe that are so far from each other that they could not interact with each other also demonstrate the homogeneity of the background radiation.
This homogeneity is explained by the theory of inflation, according to which immediately after the Big Bang, the universe underwent an extremely rapid expansion. Thus, the entire volume of the Universe observed today and its homogeneity arose from a region that existed before the phase of inflationary expansion, in which all parts could interact with each other.
According to the results, it is not necessary to use the inflationary model to explain the state of the present Universe, since the influence of gravity is quite sufficient for the homogenization of space.
