Why the universe is expanding faster and faster stays considered one of the most important open questions in physics. Current theories cannot fully explain this accelerating growth. Today’s standard picture of the universe is built on Einstein’s general theory of relativity and the usual model of particle physics. Inside this framework, scientists often assume the presence of a mysterious force referred to as “dark energy” to account for the speeding expansion of space. Despite its widespread use in cosmology, the true nature and origin of dark energy are still unknown.
Now, researchers from the Center of Applied Space Technology and Microgravity (ZARM) on the University of Bremen, working with colleagues on the Transylvanian University of Brașov in Romania, suggest a unique way of taking a look at the issue. Their work indicates that the universe’s expansion is perhaps explained — at the least partially — without invoking dark energy in any respect.
Why Dark Energy Was Added within the First Place
Cosmologists use Einstein’s general theory of relativity together with the Friedmann equations to explain how the universe changes over time. Nevertheless, when these equations are applied to real astronomical observations, they fall short. To match what telescopes see, scientists must manually add an additional “dark energy term” to the equations. This addition just isn’t derived naturally from the idea itself, which has long made it an unsatisfying solution.
A Recent Approach Using Prolonged Gravity
For this reason limitation, the team at ZARM and their Romanian collaborators explored another idea. Their results, published within the Journal of Cosmology and Astroparticle Physics, depend on an extension of general relativity (GR) referred to as Finsler gravity. This approach has been developeded over recent years and uses a broader description of spacetime geometry.
Unlike the usual formulation of GRT, Finsler gravity can describe the gravitational behavior of gases more precisely. This difference seems to be crucial when modeling the large-scale behavior of the universe.
Accelerated Expansion Without Dark Energy
When the researchers applied Finsler gravity to the Friedmann equations, they uncovered a striking result. The modified equations, referred to as the Finsler-Friedmann equations, naturally predict an accelerating universe even in empty space. No extra assumptions are required, and no additional “dark energy” term must be added by hand.
“That is an exciting indication that we may give you the option to elucidate the accelerated expansion of the universe, at the least in parts, without dark energy, on the premise of a generalized spacetime geometry,” says Christian Pfeifer, ZARM physicist and member of the research team. “This latest geometric perspective on the dark energy problem opens up latest possibilities for higher understanding the laws of nature within the cosmos.”