Recent observations from the James Webb Space Telescope at NASA are challenging some previously long-held theories about gravity and how early galaxies formed. A new study, led by astrophysicist Stacy McGaugh of Case Western Reserve University, claims the observations Webb has documented run counter to the conventional model of how galaxies form. This offers new insight into the early universe.
Galaxies Much Larger and Brighter Than Expected
The standard model predicted that distant galaxies, as seen at such great distance, should appear small and dim since they formed nearly 13 billion years ago when the universe was just a few hundred million years old. Nevertheless, Webb has brought into view large and bright galaxies. Such findings run opposite of what has been expected, begging new questions about the evolution of the cosmos.
The expectation had been that every big galaxy we see in the nearby universe would have started from these ittybitty pieces,” said McGaugh. Instead, the galaxies viewed by Webb appear larger and more mature than would be expected.
A New Hypothesis Takes Shape: Modified Newtonian Dynamics, MOND
The conventional explanation until today for the birth of galaxies requires some dark matter, a mysterious substance that supposedly provides the extra gravity to form such galaxies. However, the team of McGaugh says those big and bright galaxies that Webb has seen could, after all, be explained by a different theory: Modified Newtonian Dynamics, or MOND for short. MOND assumes that gravity behaves differently in weak gravitational fields, like those further out from the centers of galaxies.
If MOND is correct, McGaugh says, it would be a conceptual sea change in how we understand gravity and dark matter. “It would mean we have been barking up the wrong tree with dark matter,” he said.
Implications to Physics and the Future
McGaugh believes that if MOND is confirmed, there would be a sea change in how to view the evolution of the Universe. It would also question not only the role of dark matter but our understanding of gravity itself, much as the development of quantum mechanics one century ago led to a paradigm shift.
As scientists continue to analyze the data the Webb telescope provides, its implications for what we know about cosmic history could be really important.
