Gravity Causes Homogeneity of the Universe
upstart writes in with an IRC submission:
Gravity causes homogeneity of the universe:
From the Big Bang to the present
Gravity can accelerate the homogenization of space-time as the universe evolves. This insight is based on theoretical studies of the physicist David Fajman of the University of Vienna. The mathematical methods developed within the research project allow to investigate fundamental open questions of cosmology such as why the universe today appears so homogeneous.
The temporal evolution of the universe, from the Big Bang to the present, is described by Einstein's field equations of general relativity. However, there are still a number of open questions about cosmological dynamics, whose origins lie in supposed discrepancies between theory and observation. One of these open questions is: Why is the universe in its present state so homogeneous on large scales?
[...] Up to now it was not clear whether the homogenization of the universe can be explained completely by Einstein's equations. The reason for this is the complexity of the equations and the associated difficulty to analyze their solutions -- models for the universe -- and to predict their behavior.
In the concrete problem, the time evolution of the originally strong deviations from the homogeneous state as cosmological gravitational waves has to be analyzed mathematically. It has to be shown that they decay in the course of the expansion thus allowing the universe to get its homogeneous structure.
Such analyses are based on modern mathematical methods in the field of geometric analysis. Until now, these methods could only achieve such results for small deviations from the homogeneous space-time geometry. David Fajman from the University of Vienna has now succeeded for the first time to transfer these methods to the case of arbitrarily large deviations.
Journal Reference:
David Fajman. Future Attractors in 2+1 Dimensional Gravity, Physical Review Letters (DOI: 10.1103/PhysRevLett.125.121102)
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