Published: Sunday, May 19, 2024
![The Andromeda galaxy, with its older stars in blue. A new quantum gravity theory could explain why distant galaxies appear to be retreating more quickly than those closer.](https://cdn.mos.cms.futurecdn.net/2mam5h3ey9Jeap2433wAvh.jpg)
New research suggests that a variation of the theory of quantum gravitation — the unification between quantum mechanics, Einstein’s general realism and Einstein himself — could solve one of the most difficult puzzles of cosmology.
Scientists have known for nearly a hundred years that the universe expands. In recent decades, however, physicists discovered that different measurements of the Hubble parameter – the rate of expansion – produced puzzling contradictions.
A new study proposes incorporating quantum effects in a popular theory that is used to determine expansion rates.
P.K., a co-author of the study, said: “We tried to explain and resolve the mismatch in the Hubble parameters values from two prominent types of observation.” Suresh, a professor of Physics at the University of Hyderabad, India, spoke to Live Science by email.
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An expanding problem
Edwin Hubble first observed the expansion of the universe in 1929. Edwin Hubble’s observations, made with the largest telescope at that time, revealed that galaxies further away from us appeared to be moving faster. Hubble’s initial overestimation of the expansion rate was corrected by subsequent measurements, which have confirmed the reliability of the Hubble parameter.
In the late 20th century astrophysicists developed a new technique for gauging the expansion rate of the universe by looking at the “afterglow” or cosmic microwave background.
A serious problem was encountered with these two measurements. The newer method resulted in a Hubble value that was almost 10% lower than what could be deduced by astronomical observations. These discrepancies, also known as the Hubble tensions, can indicate flaws in the evolution of the universe.
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Related: Study suggests that a newfound ‘glitch in Einstein’s theory of relativity’ could change the rules of the Universe.
In a paper published in the Journal of Classical and Quantum Gravity, Suresh, along with B. Anupama from the University of Hyderabad proposed a way to reconcile these results. They emphasized that physicists indirectly infer the Hubble parameters by using our universe’s evolution model based on Einstein’s theory of general gravitation.
A representation of galaxies bent by gravity. (Image credit: Image from Peace,love.happiness on Pixabay). The team argued that this theory should be revised to include quantum effects. These effects are intrinsic to fundamental interaction and include random field fluctuations as well as the creation of particles spontaneously from space vacuum.
Quantum gravity is still elusive despite scientists’ ability integrate quantum effects in theories of other fields. This makes detailed calculations difficult or impossible. In order to study these effects, scientists must reach temperatures and energies that are orders of magnitude above those possible in a laboratory.
Suresh and Anupama, in recognition of these challenges focused on the broad quantum-gravity effect common to many proposed theoretical models.
Suresh stated that “our equation does not need to account everything but this doesn’t prevent us from testing the effects of quantum gravity and its effects experimentally.”
Theoretically, they found that accounting for quantum effects in describing gravitational interactions during the first stage of expansion of the universe, known as cosmic inflation, would alter the predictions of the theory regarding the properties of microwave background today, resulting in the consistency of both types of Hubble parameters measurements.
Even though the findings are preliminary, they are still encouraging. The team also said that the link between quantum gravitational and cosmic microwave effects could be studied experimentally in the future.
Suresh explained that measurements of the properties in the cosmic microwave background can reveal the effect of quantum gravity.
Some future missions dedicated to studying this electromagnetic backdrop are highly likely and promising to test the quantum gravity. This is a promising idea to validate and resolve inflationary models in cosmology by using quantum gravity.
The authors also suggest that quantum gravitational effects in the early universe may have influenced the properties of the gravitational wave emissions during that time. The detection of these waves by future gravitational wave observatories may provide more information about quantum gravitational properties.
Suresh stated that “Gravitational Waves from different astrophysical source have only been observed to date, but Gravitational waves from the early Universe have yet to be detected.” “Hopefully, our research will help identify the correct inflationary models and detect the primordial gravitational wave with quantum gravity characteristics.”
Andrey received his B.Sc. Andrey received his B.Sc. He holds a M.Sc. He is a science journalist who specializes in physics and space. His articles have appeared in Elements N+1 and AdvancedScienceNews.