
doi: 10.2514/6.2006-7520
During the 1980’s, the first astronomical evidence was obtained that appeared to indicate spiral galaxies, (see Figure 1) do not rotate according to Newton’s’ Second Law of Motion: F=MA. The observations suggest that the outer stars in galaxies seem to rotate too fast for the amount of matter we see in the galaxy. Astronomers calculate that galaxies require approximately 5 times more matter than we see via electromagnetic radiation. Scientists assert that the results can only be explained by assuming there is “dark matter” located in a halo surrounding every galaxy that holds it together. In other words, a typical galaxy is rotating so rapidly that if there were only the visible atomic matter present the galaxy would be pulled apart by centrifugal force. The dark matter theory asserts that the necessary additional dark matter generates the additional gravitational force that creates galactic stability. There have been alternative explanations for the galaxy rotational curves besides dark matter. It has been supposed that gravitational forces became stranger than the Newtonian approximation at great distances. There is no way to test this hypothesis and many others that all run into difficulties explaining the different galaxy types and star clusters.
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