New observations from the James Webb Space Telescope (JWST) continue to provide amazing insights into the early universe. The results seem to contradict what scientists thought for years about the formation of galaxies, according to a study by the American Case Western Reserve University.
In the academic journal The Astrophysical Journal, astronomers describe how the first galaxies looked very different than expected. Until now, scientists believed that galaxies grew gradually, like an ever-growing snowball. Small clumps of matter would gradually accumulate into larger structures, aided by the gravity of so-called dark matter – a mysterious type of matter that we can’t see but that is necessary to explain how things could be. galaxies exist.
Early galaxies are too big
“The most important observation is that early galaxies are more massive than expected based on dark matter. Large galaxies such as the Milky Way were thought to form gradually over billions of years by the accretion and merging of many small protogalactic particles. We hoped to see that process immediately by JWST. Instead, we see fully formed galaxies – younger, with stars of an age consistent with formation in the universe very early, but already gathered into the island world . At first glance, this invalidates the prediction of the dark matter structure formation paradigm,” lead researcher Stacy McGaugh told Scientias.nl.
Does gravity work differently?
The findings, on the other hand, fit wonderfully with another theory: MOND (Modified Newtonian Dynamics). This theory predicted as early as 1998 that galaxies would form much faster than expected. According to MOND, there is no need for dark matter – instead, gravity works in a different way than we think. “Some galaxies have been seen that contain stars that were already old by that time in the universe (about 12 billion years ago, less than 2 billion years after the Big Bang, ed.) . They are bigger than expected, but also made like stars. This is not expected in dark matter simulations, where galaxies are still forming from protogalactic particles and are actively forming stars. This happens naturally in MOND, consistent with some of the more prominent models built over the years,” said McGaugh.
“Another example is provided by observing many spiral galaxies up to at least redshift 6.” Redshift is a measure of how far away galaxies are from us and how fast they are moving away. from us, caused by the expansion of the universe. A redshift of 6 refers to objects we see as they looked about 12.7 billion years ago, when the universe was still very young – about 1.1 billion years after the Big Bang. “The original prediction of dark matter was that these things would arise only at a redshift of 1 (7.7 billion years ago, ed.). The goalposts have moved in that direction, but it’s really surprising in terms of dark matter: the early universe should have been a chaotic place of frequent mergers; instead, there are pristine spirals without distraction,” says McGaugh.
What about general friendship?
But although the observations seem to agree with MOND, there is one major problem with the theory, which is that it is difficult to connect it to general relativity. McGaugh also admits this. “The closest theory so far is the Aether-Scalar-Tensor-teorie by Skordis & Zlosnik. Whether it passes all the tests, or is just another step on a long road to a more complete theory, requires a lot of research. I would note that when it comes to cosmology, scientists are reluctant to consider possibilities outside of general relativity (even if they include dark matter and dark energy you must call to save it). But when it comes to a deeper theory, everyone recognizes that general relativity cannot be the final word without a quantum theory of gravity. Consideration of changes to general relations is therefore both valued and necessary.”
A major obstacle scientists face is abandoning an established paradigm like dark matter, McGaugh says. “Before we’re willing to do that, we have to be sure it’s not right. But how do we know when an invisible mass is impossible to find because it doesn’t exist, rather than just hard to find? I have suggested ways to do this, but ultimately it is up to each scientist to determine his own criteria. But they must set criteria, because it is not science if it cannot be justified. Furthermore, I haven’t seen any of the outspoken dark matter advocates answer a question I’ve been asking for years: If MOND space is dark matter, why are so many of prediction successes at MOND? Sometimes we can explain these amazing observations (like JWST’s) with dark matter, but they are rarely satisfactory. Furthermore, why did MOND correctly predict what we see while dark matter did not?” the scientist concludes.
2024-11-15 12:02:00
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