Distant quasars, powered by supermassive black holes, offer a unique opportunity to explore new theories of gravity. A recent study has highlighted "teleparallel gravity" as a potential solution to the tensions surrounding the expansion of the Universe that general relativity fails to resolve.
Artist's rendition of the quasar 3C 279.
Credit: ESO/M. Kornmesser
In the early 20th century, Edwin Hubble revolutionized our understanding of the Universe by showing that its fabric was expanding. By the end of the same century, scientists discovered that this expansion was accelerating, a phenomenon attributed to dark energy, with the cosmological constant as the current best explanation.
The Hubble constant, describing the relationship between the distance of a galaxy and its recession speed, is at the heart of an intense debate in physics. The methods for calculating this constant do not agree, creating the "Hubble tension." To resolve this issue, some scientists are considering going beyond general relativity.
A study published in
Physics of the Dark Universe by Celia Escamilla Rivera and her colleagues from the Instituto de Ciencias Nucleares explores this path using teleparallel gravity. This alternative theory, also developed by Einstein, proposes a curvature-free approach to spacetime and seeks to unify gravity with electromagnetism.
The researchers tested this theory using recent cosmological data and observations of distant quasars. These quasars, observed in ultraviolet, X-rays, and visible light, provide precise measurements of distances in the local Universe, crucial for confronting theoretical models.
Teleparallel gravity is gaining popularity, promising to resolve the Hubble tension and explain cosmic acceleration without resorting to the cosmological constant. Rivera emphasizes that this theory could provide a viable alternative to general relativity, with interesting theoretical properties and potentially revolutionary implications for our understanding of the Universe.