Anomalies in the dissolution of star clusters defy Newton's law of gravity

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Anomalies in the dissolution of star clusters defy Newton's law of gravity

Star formation occurs mainly in dense clusters, but during their lifetime most of them are found alone or in pairs. Recently, observations of disintegrating clusters have been made and anomalies have been found. This discovery contradicts conventional Newtonian ideas about gravity, but it fits a possible alternative. However, it takes a lot of effort to challenge a theory as well established as Newton's.



Open clusters of stars form from large collections of gas within galaxies and orbit around the galactic center. Although some stars may move sideways, for example because of a nearby supernova, most eventually move away from the cluster or move forward, forming long tails in both directions.


According to Newtonian physics, roughly equal numbers of stars should become leaders and followers, and the larger the cluster, the more evenly it is distributed. So the claim in a new paper that more stars are leading the cluster they follow, at least within 150 light-years of the cluster center, suggests that something very strange is happening. This is a big step in questioning some of the most fundamental principles of physics, but the article supports the possibility. According to Dr. Jan Pflamm-Alternburg of the Hemlholz Institute for Radiology and Nuclear Physics, in order to determine this fact, it is necessary to determine the velocity and age of the stars in each cluster in order to distinguish those that are escaping the cluster from those that are randomly in the galactic vicinity.


Thanks to the Gaia space telescope, we are now able to make these distinctions, and the authors have analyzed four large clusters, including the famous Hyades and Pleiades. Another team did similar work on a fifth cluster, which was included in the analysis.


It is possible that the excess of stars in front of the cluster is a mistake by the authors or an extreme case, like flipping a coin a thousand times and getting 600 heads. But if not, it would suggest that the laws of motion we have relied on for nearly 400 years are not as universal as previously thought.



This would not be the first time that such an idea has been proposed. In fact, Einstein showed that Newton's laws did not accurately describe what happens when you travel near the speed of light or in strong gravitational fields. Many physicists subsequently proposed other exceptions, but most of these ideas proved invalid. One theory that has held up best is known as Modified Newtonian Dynamics (MOND), which was developed by Mordehai Milgrom in the 1980s to explain the galactic rotation speed without the need for dark matter. In simple terms, according to MOND, stars can leave a cluster through two different doors. One door leads to the rear tidal tail, while the other door leads to the front tidal tail. However, the first door is much narrower than the second, so a star is less likely to leave the cluster through it. Newton's theory of gravity, on the other hand, predicts that both doors should be the same width. The team found that their observations of cluster disruption agree with MOND's predictions. This applies not only to the direction in which the stars exit, but also to the rate at which the clusters dissolve, which appears to be faster than a purely Newtonian analysis would suggest.


According to MOND, the gravitational forces in the outer regions of galaxies do not weaken according to the inverse square law, as they do in the Solar System. There is no convincing explanation why this should happen, and most physicists consider it unlikely. Their skepticism is reinforced by observations of colliding galaxies that are more consistent with predictions based on classical Newtonian physics and the existence of dark matter.


Although these observations are puzzling to those who use dark matter to explain galactic rotation, they alone are unlikely to change the perception of MOND. However, the authors do make some testable predictions that, if confirmed, could help support their theory. The paper has been published in the Monthly Notices of the Royal Astronomical Society.






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