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Dark Matter Does Not ExistGalaxies do in fact have enough normal matter |
By Gabriel Gache, Science News Editor
30th of October 2007, 08:06 GMT
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Or so two Canadian astronomers say. In august a group of astronomers from the University of Arizona at Tucson reported the collision of a cluster of galaxies situated 3 billion light-year away from Earth, known as the Bullet Cluster. Images from NASA's Chandra X-ray telescope, suggest that during the collision, two types of matter where observed, separated from each other, normal matter colored pink in the image on the left (click to enlarge), and dark matter represented in blue.
There is a strong debate currently taking place, regarding the dark matter and its role in the universe. It is well known that the calculations
using current theories about the origins of the universe, say that there is not enough visible matter in the galaxies to keep them from falling apart. So there must be something else to account for the extra gravitational pull exerted of the stars forming the galaxies from scattering. Dark matter was the candidate; however, it has never been directly observed or detected. In the science community this was no new feature, different theories predicting mysterious things that were not observed - like elementary particles - only to be discovered years later, is common.
John Moffat and Joel Browstein at the University of Waterloo in Canada, say that the announcements of the first ever detection of dark matter was premature, and the observed effect in the Bullet Cluster can be explained by a Modified Gravity theory. While studying images from NASA's Hubble Space telescope and Chandra X-ray telescope the scientists tried analyzing the light from a background galaxy, using light bent by the Bullet Cluster, effect known as gravitational lensing. Gravitational lensing was predicted by Einstein's Relativity Theory, and successfully observed while studying supermassive galaxies, and black holes. Light coming from a background source, into a massive object is bent and focused by its powerful gravity, thus amplifying the light.
During the study of the images, the Canadian team's calculations showed that there is in fact enough normal matter in the Bullet Cluster to account for the observed gravitational effect, and dark matter was not needed to explain the extra gravitational pull.
As it is well known in the physics community, the theory of General Relativity explains only part of the interactions taking place in our universe, especially the theory of gravity, thus making it imperfect, meaning it can not be used as a Theory of Everything. Several theories are being developed, but as far, none produced observable predictions, and has eluded to create experiments.
Some calculations show that there is in fact more dark matter in the hole universe than normal matter, but scientists are developing new theories in which the proportion of dark matter present might be considerably reduced. Meanwhile, Douglas Clowe, the astronomer who made the claim that dark matter was finally observed, sustains his beliefs.
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