According to a new study, an invisible “mirror world” of particles that interacts with the universe only by gravity may be the key to solving a crucial cosmological problem – Hubble’s constant problem.
Performed by COBE Satellite by artist. Image Credit: Matthew Verdolive, UC, Davis.
Hubble’s constant is the current velocity of cosmic expansion, but the velocity predicted by the standard model of cosmology is much slower than the velocity found by the most accurate local observations. Many cosmologists have tried to resolve this difference by changing the current cosmological paradigm.
The goal is to do this without compromising the consistency of the predictions of the standard model with many other cosmological phenomena, such as space microwave background.
The question that scientists such as Francis-Jan Sir-Racine, an assistant professor in physics and astronomy at the University of New Mexico, Faye Ge, and Lloyd Knox of the University of California, Davis, are seeking to answer is whether there is a space scenario. .
Cosmology, according to NASA, is a scientific study of the scale characteristics of the universe. Cosmologists study topics such as dark matter and dark energy, and whether there is only one universe or multiverse. Cosmology encompasses the entire cosmos from conception to death and is full of mysteries and intrigues.
Cyr-Racine, Ge, and Knox have already identified a previously neglected mathematical feature of cosmological models that could theoretically allow a faster rate of expansion without affecting the most accurately proven other predictions of the basic cosmological model.
Most dimensionless space observables are essentially invariant when the gravitational free fall rates and photon-electron scattering rates are scaled uniformly.
In general, we point out that many of the observations we make in cosmology have an inherent symmetry in the re-scaling of the universe as a whole. This may provide a way to understand why there seems to be a mismatch between the various measurements of the rate of expansion of the universe.
Francis-Jan Sir-Racine, Assistant Professor, Department of Physics and Astronomy, University of New Mexico
The study is published in the Physical Review Letters.
This discovery offers a new way to reconcile cosmic microwave background measurements and a scale structure with high Hubble constant values H0 by discovering a cosmological model in which scale transformation can be demonstrated without compromising any measurements of values that are not protected by symmetry.
This effort paved the way for a new approach to tackling a difficult challenge. Further development of the model may ensure the homogeneity of the two remaining constraints: the derived primary abundance of deuterium and helium.
Researchers have come to an incredibly compelling conclusion if the universe somehow uses this symmetry: there is a mirror universe that is remarkably identical to ours, but unseen, except through the gravitational influence of this world.
The dark sector of the “mirror world” would lead to an effective scaling of gravitational free fall velocities, while maintaining the precisely calculated average photon density currently reported.
“In practice, this large-scale symmetry can only be realized by including a mirror world in the model – a parallel universe with new particles, all of which are copies of known particles. The idea of the mirror world first appeared in the 1990s, but has not previously been recognized as a potential solution to the problem of the Hubble constant, “said Sir-Racine.
He went on to say: “This may seem crazy, but such mirror worlds have a great deal of literature on physics in very different contexts, as they can help solve an important problem in particle physics. Our work allows us to connect, for the first time, this great literature with an important problem in cosmology. “
Researchers also ask whether the constant Hubble difference can be caused in part by measurement errors, in addition to searching for missing elements in the current cosmological model.
Although this is still possible, it is worth noting that the discrepancy has increased in importance, as better data have been included in the analysis, suggesting that the data should not be blamed.
According to Sir-Racine, “It went from two and a half Sigma to three and three and a half to four Sigma. So far we are almost at level five Sigma. This is the key number that makes this a real problem, because you have two dimensions of the same thing, which, if you have a consistent picture of the universe, just have to be completely compatible with each other, but they differ by a very statistically significant amount. ”
He concluded: “This is the premise here and we thought about what could be causing this and why these measurements are inconsistent? So this is a big problem for cosmology. We just don’t seem to understand what the universe is doing today. “
Journal reference:
Cyr-Racine, F., et al. (2022) Symmetry of the cosmological observables, the dark sector in the mirror world, and the Hubble constant. Physical examination letters. doi: 10.1103 / PhysRevLett.128.201301.
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