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Unformatted text preview: Sara Levine 3/1/08 Cosmology Professor Bullock M-Theory One of the fundamental questions in the field of cosmology is how did the universe begin. There are many different propositions in this problem and one of them begins with the string theory. One of the reasons things that the string theory will help in many concepts of cosmology because many string theorists feel that the string theory will be able to unify all of the natural forces by using the same set of equations for all of them, and therefore derives a theory of everything. There are many different version so the string theory and in cosmology the major one is the superstring theory. There are five different superstring theories and now there is one theory that unifies all of them. This is called the M-theory, which was proposed in 1995 by leading string theorist, Edward Witten. The main idea behind all of the superstring theories is that each particle is actually a string that is not attached to anything but still have tension and vibrates at frequencies that are specific for that particle. Each string is one-dimensional and for string theory to be applied to a theory of quantum gravity then the length of the string would be the Planck Length. The equation of the Planck Length is below. These strings are so small that it is obviously impossible to see with todays technology and therefore scientists must come up with other ways to test their theory. Each different string theory is classified by whether or not the strings are in closed or open loops, and also whether it includes fermions, which is a particle that makes up matter. In order for the scientists to include fermions in the theory there must also be supersymmetry, which means that for every bosom, or particle, there much be a corresponding fermion. Although these supersymmetric partners have not be observed in the current experiments, theorists believe its because the particles are too massive to be seen with the current accelerators....
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- Winter '08
- String Theory