Cosmologists, physicists, and astronomers theorized that dark matter could explain the strange gravitational behavior of galaxy clusters for decades. But new research suggests that it might not exist.
Dark matter has never been seen or observed. So how can we even debate its existence?
What is Dark Matter?
According to the National Aeronautics and Space Administration (NASA), roughly 5% of the cosmos is normal matter, while 68% is dark energy, and the remaining 27% is dark matter. So what is dark matter?
CERN explains that dark matter has no interaction with electromagnetic force. Hence it does not emit, reflect, or absorb light making it extremely difficult to locate. In truth, scientists have only been able to theorize dark matter due to the gravitational effect on the visible matter in the galaxy.
Scientists hypothesize that dark matter could contain "supersymmetric particles" that work together with known Standard Models.
Many theorize that dark matter particles might be light enough to be produced in the Large Hadron Collider-- the world's largest particle accelerator started in September 2008. If that is so, dark matter would seep out unnoticed but would carry energy and momentum that physicists could infer.
Dark Energy vs. Dark Matter
On the other hand, dark energy consists of approximately 68% of the known universe and is mostly associated with the vacuum in space. It is evenly distributed throughout the cosmos, not just in space but in time as well. In short, dark energy's effects do not dilute as the universe expands.
In addition, dark energy doesn't have a local gravitational effect; it has a global impact on the entirety of the universe as a whole. This phenomenon leads to a repulsive force that is liable for the acceleration of the expansion of the universe.
Why Dark Matter Might Not Exist
In a study published in The Astrophysical Journal, scientists report minuscule discrepancies in the orbital speed of distant stars that reveal almost nonexistent gravitational effects. This theory might put an end to prevailing theories on dark matter.
The study inclines that the lack and insufficient understanding of gravity are behind the gravitational strength of both galaxy clusters and known galaxies, rather than clouds of dark matter.
In short, mathematics holds the key to explaining galaxy behavior and not invisible matter, explains co-author Stacy McGaugh, the head of the astronomy department at Case Western Reserve University.
The research states that "External field effect," or EFE, is a faint gravitational tide that is statistically observable in stars' orbital speed in over 150 galaxies.
According to the team, the phenomenon cannot be explained by dark matter. However, it has been predicted by the modified Newtonian dynamics theory(MOND).
Nevertheless, more research is needed to further advance our understanding of the galaxy and the factors at play.
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