Assignment 3 Example | Topics and Well Written Essays - 500 words - 8

3 - Assignment Example Astronomers can notice the changes of the rate of expansion of the universe through measurements of the recession speeds and distances of very distant galaxies (Materrese & Sabino 2010). The assumption of the dark energy is that it is a gravitationally repulsive force which does not appear to cluster in galaxies. It has last been seen to stretch the space–time apart and certainly fits the accelerating-expansion scenario. Therefore acceleration of the expansion implies clearly the existence of some force that acts to push galaxies apart, and the source of this force is the dark energy. In this scenario large structure size galaxy clusters are formed first then they are segmented into galaxies. This scenario is based on radiation smoothed out the matter density fluctuations to produce large pancakes which then gradually build-up matter after recombination and grow until they collapse and fragment into galaxies. In this type, small dwarf Galaxies form first then they merge into clusters of galaxies. The density enhancements at the time of recombination are close to the size of small galaxies and the enhancements collapses from self-gravity to form dwarf galaxies. This is a theory that was proposed by mordehai milgrom and it attempts to explain the galaxy rotation problem by modifying the Newton’s second law of motion, so as the acceleration at very low values such as between distant stars is not strictly linear. It tries to resolve the problem that when astronomers observe galaxies and apply the current theory of gravity, the result shows the stars within the galaxy should go spinning apart from each other. Most astrophysicists and cosmologists do not believe that MOND fits the evidence. This falls in the somewhat less-informal category of an alternative gravity theory since it proposes fundamental changes to the understanding of the way