Il sistema geometrico E8, dove ciascun simbolo corrisponde al campo associato alle particelle elementari. Credit: A. Garrett Lisi
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E' possibile che le particelle elementari e le forze della natura, ai livelli più fondamentali, siano la manifestazione di una particolare forma di geometria? Nel 1687, Newton gettò le basi Physics of the "modern" when he showed that a wide variety of physical laws, celestial mechanics, the tides, the motion of the pendulum could be described by a single law universal gravitation. Since then, the unification of the laws of physics has played a central role for the study of natural phenomena. For example, in the mid-nineteenth century, Maxwell was found that electricity and magnetism were two different aspects of a single physical phenomenon: electromagnetism. About a century later, electromagnetism was unified with the weak nuclear force, responsible for radioactivity, in what physicists have called electroweak force. The exciting quest for unification the laws of physics is mainly driven by practical reasons, philosophical, and perhaps also by the "search for beauty." Many physics experiments of the twenty-first century, such as those that are made at the LHC, is designed to discover new phenomena that are partly under the unified electroweak theory. The advantage of having a unified theory is that it provides a very satisfactory aesthetic of how the universe works. In fact, many physicists believe that the most fundamental level all physical phenomena are described in a set of laws that make a mathematical structure. Today, the best theory that allows us to describe the three fundamental forces known as the Standard Model, introduced negli anni '70, che però ha un tallone d'Achille: essa non comprende la gravità. Dal punto di vista matematico, la teoria descrive queste tre forze e le particelle elementari in termini della dinamica di una serie di oggetti geometrici, ed eleganti, che sono chiamati gruppi di Lie e fiber bundles. Si tratta cioè di un modello matematico dove ogni oggetto geometrico governa una determinata forza. C'è da dire, però, che nel corso degli anni, i fisici teorici hanno proposto varie teorie di grande unificazione, o GUT, in cui ogni singolo oggetto geometrico potrebbe descrivere tutte queste forze, anche se nessuno sa, finora, quale di queste teorie sia quella più vicina alla realtà. In più c'è un altro problem that has fascinated scientists in a completely unified theory, gravity and the matter should be combined in a natural way with the other forces, since all parts of a single mathematical structure, in a single description: the theory of everything. This has led theorists to formulate the so-called string theory, since as early as the '80s, in order to describe within a single theoretical framework gravity with the other three fundamental forces, drawing geometric shapes called 'strings' and 'membrane' that vibrate in a multidimensional space. But string theory is not only the only model that has been taken into account. Another alternative model, called loop quantum gravity, is based on a mathematical structure less complicated, somewhat similar to that of the standard model. Based on this model, the theoretical physicist Antony Garrett Lisi has proposed, in 2007, a new unified theory. The idea is to extend the theories of grand unification and include them in gravity as a significant component of the geometric model. In this unified model, called E8 theory, all forces of nature and matter are described in terms of "rotation" of a single geometric object (see Elementary Particle Explorer). It must be said that although many physicists are skeptical in accepting this model, since the theory is incomplete, it reveals some deep secrets of the laws nature and allows us to make predictions on the possible discovery of new particles that could be detected even by LHC.
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source: www.altrogiornale.org
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