Einstein’s other theory of gravity could have the recipe to relieve ‘Hubble trouble’
A recent study has delved into the potential of teleparallel gravity to address the persistent tension surrounding the expansion of the universe, a challenge that general relativity has yet to resolve.
Unraveling the Expanding Universe
In the early 20th century, Edwin Hubble’s observations revealed that the cosmos is expanding, a discovery that fundamentally altered our understanding of the universe. This realization became more complex at the end of the century when two separate research teams observed distant supernovas, revealing that not only is the universe expanding, but the rate of this expansion is accelerating. This acceleration has been attributed to a mysterious force termed “dark energy,” with the leading explanation being the cosmological constant, which accounts for vacuum energy.
The Hubble Constant and Its Tension
The Hubble constant quantifies the rate at which the universe expands, describing the relationship between the distance of a galaxy from Earth and its recessional velocity. However, physicists face a significant challenge: the two primary methods of determining the Hubble constant produce conflicting results, a problem known as the “Hubble tension.” One proposed solution is to extend Einstein’s general relativity, formulated in 1915.
Exploring Teleparallel Gravity
In a groundbreaking paper published in the journal Physics of the Dark Universe, Celia Escamilla Rivera, a cosmologist at Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, and her colleagues explore teleparallel gravity as a means to address dark energy and the Hubble tension.
“We found that by using gravitational models extended beyond general relativity and new cosmological datasets [observations of distant quasars] we can confront the Hubble tension and the dark energy issue at local scales,” says Rivera.
Using numerical and computational methods, the researchers analyzed various proposed models in teleparallel gravity, tested with two different cosmological samples measuring distances in the local universe.
Teleparallel Gravity: An Alternative to General Relativity
Teleparallel gravity, an alternative theory to general relativity also devised by Einstein, uses a different framework to explain gravity without relying on the curvature of spacetime. It also seeks to unify gravity with electromagnetism, one of the universe’s fundamental forces.
“Recently, teleparallel gravity has been gaining popularity due to the promise that it could solve the cosmological issue related to the Hubble tension and could explain the nature of the late-time cosmic acceleration without invoking a cosmological constant,” Rivera explains.
Rivera and her team tested this theory using new datasets of distant, highly red-shifted quasars observed in ultraviolet, X-ray, and visible light. These quasars are the bright centers of galaxies powered by supermassive black holes.
“We are interested in the subject because teleparallel gravity is a suitable candidate for an alternative proposition to general relativity that solves different cosmological issues, as well as having some interesting theoretical properties,” Rivera concludes.
For a broader audience, this research is intriguing as it tests alternative models to general relativity to better understand the universe. For experts in the field, it provides an update on the state-of-the-art models in teleparallel gravity, utilizing relatively new quasar samples at high redshifts.
References
This post highlights the innovative research exploring teleparallel gravity’s potential to solve some of the universe’s most perplexing issues, presenting a promising alternative to general relativity.
