PROOF THAT DARK MATTER EXISTS
According to an article at Spaceflight Now that reports on a NASA news release, a cosmic event has given evidence for the existence of dark matter. I learned the following from the article:
Dark matter and normal matter were separated when two large clusters of galaxies collided. This collision was discovered recently by NASA. According to Spaceflight Now, "'This is the most energetic cosmic event, besides the Big Bang, which we know about,' said team member Maxim Markevitch of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass."
Although scientists have already found significant evidence for dark matter, the observations of this collision of galaxies provides the strongest evidence yet. In clusters of galaxies matter is in the form of atoms that are concentrated as hot gas and stars. There is more hot gas in between the galaxies than the mass of all the stars combined. This matter is held within the cluster of galaxies by gravity, but the gravity is too strong to account for the gravitational force that acts on the matter observed. Therefore scientists proposed the existence of dark matter that has mass and therefore has gravity. In the cluster of galaxies there is far more dark matter than matter. It is invisible and it is detected through its gravity. Without dark matter, the galaxies would not be able to stay together and would drift apart.
Scientists studied the galaxy clusters using NASA's Chandra telescope as well as the Hubble Space Telescope, the European Southern Observatory's Very Large Telescope and the Magellan optical telescopes. According to Spaceflight Now they measured gravitational lensing, in which "gravity from the clusters distorts light from background galaxies as predicted by Einstein's theory of general relativity. The hot gas in this collision was slowed by a drag force, similar to air resistance. In contrast, the dark matter was not slowed by the impact, because it does not interact directly with itself or the gas except through gravity. This produced the separation of the dark and normal matter seen in the data."
According to an article at Spaceflight Now that reports on a NASA news release, a cosmic event has given evidence for the existence of dark matter. I learned the following from the article:
Dark matter and normal matter were separated when two large clusters of galaxies collided. This collision was discovered recently by NASA. According to Spaceflight Now, "'This is the most energetic cosmic event, besides the Big Bang, which we know about,' said team member Maxim Markevitch of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass."
Although scientists have already found significant evidence for dark matter, the observations of this collision of galaxies provides the strongest evidence yet. In clusters of galaxies matter is in the form of atoms that are concentrated as hot gas and stars. There is more hot gas in between the galaxies than the mass of all the stars combined. This matter is held within the cluster of galaxies by gravity, but the gravity is too strong to account for the gravitational force that acts on the matter observed. Therefore scientists proposed the existence of dark matter that has mass and therefore has gravity. In the cluster of galaxies there is far more dark matter than matter. It is invisible and it is detected through its gravity. Without dark matter, the galaxies would not be able to stay together and would drift apart.
Scientists studied the galaxy clusters using NASA's Chandra telescope as well as the Hubble Space Telescope, the European Southern Observatory's Very Large Telescope and the Magellan optical telescopes. According to Spaceflight Now they measured gravitational lensing, in which "gravity from the clusters distorts light from background galaxies as predicted by Einstein's theory of general relativity. The hot gas in this collision was slowed by a drag force, similar to air resistance. In contrast, the dark matter was not slowed by the impact, because it does not interact directly with itself or the gas except through gravity. This produced the separation of the dark and normal matter seen in the data."
posted by Caroline at 2:54 PM
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