The widely accepted model of galaxy formation in the early universe suggested that the James Webb Space Telescope (JWST) would detect faint signals from small, early galaxies. However, the data does not support the well-known theory that invisible dark matter aided in the clumping of the first stars and galaxies.
The widely accepted model of galaxy formation in the early universe suggested that the James Webb Space Telescope (JWST) would detect faint signals from small, early galaxies. However, the data does not support the well-known theory that invisible dark matter aided in the clumping of the first stars and galaxies.
New research from Case Western Reserve University, published on Tuesday, November 12, in The Astrophysical Journal, indicates that instead, the oldest galaxies are both large and bright, aligning with an alternative gravity theory. This research poses challenges to current astronomers’ comprehension of the early universe.
“What dark matter theory predicted does not match our observations,” stated Stacy McGaugh, an astrophysicist at Case Western Reserve, whose paper discusses structural formation in the early universe.
As a professor and director of astronomy at Case Western Reserve, McGaugh explained that modified gravity may have influenced these structures rather than dark matter. He referenced a theory called MOND, which stands for Modified Newtonian Dynamics, predicting in 1998 that structures in the early universe formed significantly faster than what Cold Dark Matter theory, known as lambda-CDM, suggests.
The JWST was intended to tackle essential questions about the universe, such as the time and manner of star and galaxy formation. Prior to its launch in 2021, no other telescope had the capability to peer this deeply into the universe and back in time.
According to lambda-CDM, galaxies formed gradually through the accumulation of matter from smaller structures, aided by the gravitational effects of dark matter.
“Astronomers proposed dark matter to clarify how we transition from an extremely smooth early universe to the enormous galaxies filled with vast empty spaces we observe today,” explained McGaugh.
The idea is that small components grouped together to form larger structures, leading to galaxy formation. JWST was expected to spot these small galaxy precursors as faint light.
“The assumption was that every significant galaxy we observe nearby originated from these tiny fragments,” he added.
Nevertheless, even at increasingly higher redshift—looking further back in the universe’s evolution—signals are appearing more substantial and brighter than anticipated.
MOND predicted a rapid assembly of mass into galaxies, initially expanding outward alongside the universe. The gravitational force intensifies, halting and eventually reversing this expansion, causing the material to collapse and create a galaxy. Within this framework, dark matter does not exist.
The large and bright formations observed by JWST early in the universe align with predictions made by MOND over 25 years ago, according to McGaugh. He co-authored this study with Federico Lelli, a former postdoctoral researcher now at INAF—Arcetri Astrophysical Observatory in Italy, and Jay Franck, a former graduate student. The fourth co-author is James Schombert from the University of Oregon.
“In the end, my point is, ‘I told you so,’” McGaugh remarked. “I was brought up to think that expressing that was impolite, but it encompasses the essence of the scientific method: Make predictions and then verify which ones hold true.” He noted that finding a theory that reconciles both MOND and General Relativity remains a significant challenge.
