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Article by mathematicians from the University of California, Davis, published in the Proceedings of the Royal Society A, questions dark energy by pointing out instabilities in Friedmann space-times and in the Lambda-cold dark matter model, the basis of the standard cosmology used to explain the accelerated expansion of the universe
Study by mathematicians from the University of California, Davis, published in the Proceedings of the Royal Society A, questions the need for dark energy to explain the accelerated expansion of the universe and points out instabilities in the Friedmann models used by standard cosmology.
Dark energy, used for almost 30 years to explain the accelerated expansion of the universe, has been challenged by mathematicians from the University of California, Davis, in an article published in the Proceedings of the Royal Society A.
Dark energy and the standard model
The study questions the Lambda-cold dark matter model, the basis of the Big Bang in current cosmology. Blake Temple, emeritus professor at UC Davis and corresponding author, states that the calculations indicate instabilities in the Einstein-Euler equations.
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These equations combine general relativity and fluid dynamics to model galaxies, black holes, and cosmic expansion. According to Temple, the Friedmann space-times used in the expansion of the universe would be unstable at the Big Bang.
He compares the model to a pencil balanced on its tip: although it is a solution to the equations, any disturbance knocks it over. In the mathematician’s assessment, unstable solutions would not be observed in nature.
Expansion without cosmological constant
The cosmological constant appeared in Albert Einstein’s equations in 1915, when he was seeking a static universe. After the discovery of expansion by Edwin Hubble in 1929, Einstein abandoned this idea, which was revisited in the 1990s.
Temple and colleagues argue that acceleration can arise directly from the Einstein-Euler equations, without introducing dark energy. The group used a self-similar version of the Einstein equations to analyze the stability of the Friedmann models.
The article states that Friedmann spacetimes are unstable to radial perturbations on large scales, with or without dark energy. According to the authors, this casts doubt on the viability of the Lambda-cold dark matter model.
What changes in the reading of the universe
The calculations reignite the debate about the Copernican principle, which holds that Earth does not occupy a special position in the universe. Temple states that both the standard model and a spherically symmetric spacetime require a special place to be plausible.
More information at royalsocietypublishing.
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