Ghostly 'mirror world' might be cause of cosmic controversyDate: May 19, 2022
Source: University of New Mexico
Summary: New research suggests an unseen 'mirror world' of particles that interacts with our world only via gravity that might be the key to solving a major puzzle in cosmology today -- the Hubble constant problem. The Hubble constant is the rate of expansion of the universe today. Predictions for this rate are significantly slower than the rate found by our most precise local measurements. This discrepancy is one that many cosmologists have been trying to solve by changing our current cosmological model.
New research suggests an unseen 'mirror world' of particles that interacts with our world only via gravity that might be the key to solving a major puzzle in cosmology today -- the Hubble constant problem.
The Hubble constant is the rate of expansion of the universe today. Predictions for this rate -- from cosmology's standard model -- are significantly slower than the rate found by our most precise local measurements. This discrepancy is one that many cosmologists have been trying to solve by changing our current cosmological model. The challenge is to do so without ruining the agreement between standard model predictions and many other cosmological phenomena, such as the cosmic microwave background. Determining whether such a cosmological scenario exists is the question that researchers, including Francis-Yan Cyr-Racine, assistant professor in the Department of Physics and Astronomy at The University of New Mexico, Fei Ge and Lloyd Knox at the University of California, Davis have been trying to answer.
According to NASA, cosmology is the scientific study of the large-scale properties of the universe as a whole. Cosmologists study concepts such as dark matter, and dark energy and whether there is one universe or many, sometimes called a multiverse. Cosmology entails the entire universe from birth to death with mysteries and intrigue at every turn.
Now, Cyr-Racine, Ge, and Knox have discovered a previously unnoticed mathematical property of cosmological models which could, in principle, allow for a faster expansion rate while hardly changing the most precisely tested other predictions of the standard cosmological model. They found that a uniform scaling of the gravitational free-fall rates and photon-electron scattering rate leaves most dimensionless cosmological observables nearly invariant.
"Basically, we point out that a lot of the observations we do in cosmology have an inherent symmetry under rescaling the universe as a whole. This might provide a way to understand why there appears to be a discrepancy between different measurements of the Universe's expansion rate."
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Source:
https://www.sciencedaily.com/releases/2022/05/220519132750.htm
