Scientists challenge dark matter theory with new galaxy rotation findings

Credit: DALL.E.

In a groundbreaking discovery, scientists at Case Western Reserve University have found new evidence that could change our understanding of the universe.

Tobias Mistele, a post-doctoral scholar in the Department of Astronomy, used a technique called “gravitational lensing” to study dark matter.

His research shows that the rotation curves of galaxies stay flat for millions of light-years, which goes against previous beliefs.

Traditionally, scientists thought that stars farther from the center of a galaxy should move slower because of weaker gravitational pull.

However, observations have shown that stars on the outskirts of galaxies move at the same speed as those closer in.

This led to the idea of dark matter, an invisible substance that makes up most of the universe’s mass and affects how galaxies behave. But even dark matter was thought to have limits, with its influence ending at some point.

Mistele’s findings, published on the pre-print server arXiv, challenge this idea. He found that the effect of dark matter stretches at least a million light-years from the center of a galaxy, much farther than previously thought.

This could mean that dark matter, as we currently understand it, might not exist at all.

“This discovery challenges existing models,” Mistele said. “It suggests either that dark matter halos are much larger than we thought or that we need to fundamentally rethink our understanding of gravity.”

Stacy McGaugh, professor and director of the Department of Astronomy, said Mistele’s research, soon to be published in the Astrophysical Journal Letters, pushes the boundaries of current theories.

“The implications of this discovery are profound,” McGaugh said. “It could redefine our understanding of dark matter and make us explore alternative theories of gravity, challenging the core of modern astrophysics.”

The technique Mistele used, gravitational lensing, was predicted by Einstein’s theory of general relativity. It happens when a massive object, like a galaxy, bends the light from a distant source. This bending effect has been observed over much larger scales than expected.

Mistele also examined the Tully–Fisher relation, which shows a connection between a galaxy’s visible mass and its rotation speed. His findings suggest that this relationship holds true even at great distances, which was previously thought impossible.

Mistele’s discovery highlights the need for further exploration and collaboration within the scientific community. McGaugh noted the ongoing, yet so far unsuccessful, efforts to detect and identify dark matter particles.

“Either dark matter halos are much bigger than we expected, or the whole paradigm is wrong,” McGaugh said. “The theory that predicted this behavior is the modified gravity theory MOND, proposed by Moti Milgrom in 1983 as an alternative to dark matter.

The controversial interpretation of this result is that dark matter might not exist; instead, the evidence could be pointing to a new theory of gravity beyond what Einstein taught us.”