Unified field theory

Unified field theories aim, all matter and fields of force of the universe in a formula, the " unified " or " unified field " summarize. A unified field theory, sometimes called the world formula, should the properties of all interactions and the properties ( spin, mass, charge ) explain all elementary particles.

History

A first stage of standardization by the work James Clerk Maxwell was historically achieved - the four Maxwell 's equations could explain electric and magnetic phenomena uniform and showed especially the close connection between electricity and magnetism. The hidden symmetries in the equations led to the Lorentz transformation, and thus later to the discovery of special relativity by Albert Einstein.

Einstein formulated after a relativistically correct theory of gravity, general relativity. From the 1920s he spent the rest of his life, to seek a unification of electromagnetism and gravitation, which he was not able. One approach, the Einstein pursued, was the so-called Kaluza - Klein theory, which attempts to find a unified field theory in spaces with more than four dimensions. The Kaluza-Klein theory is considered the forerunner of today's popular string theory. The experiments of Einstein labeled simultaneously the temporary end of the effort is a " classic " unified field theory.

With the discovery of quantum mechanics and two other interactions - the strong and the weak nuclear force - in the 1930s shifted the goal of a unified theory in the distance. The connection between relativity and quantum mechanics led to quantum field theory.

In the 1950s and 1960s tried Heisenberg and his students, starting from the Dirac equation to derive a non-linear field theory. Thus, the large number of newly discovered elementary particles should be explained and organized. However, this approach turned out to be a dead end. Gell-Mann brought the quarks finally in a completely different way, namely with a quantum field theory, order in the " particle zoo ".

Today's approaches

Today quantum field theories are well known for three of the four interactions. Only for the oldest known interaction, gravitation, there is no quantum theory. The quantum electrodynamics and quantum Flavor dynamics were unified in the 1970s by Steven Weinberg, Sheldon Lee Glashow and Abdus Salam for the electroweak theory. However, approaches to unify the electroweak theory and quantum chromodynamics failed (see eg proton decay ).

A promising approach for a unified field theory is superstring theory, in which, under the name M-theory much progress has been achieved in the 1990s. Here, it seems possible, all four interactions actually unify, but the theory is still in its early infancy. Another approach to formulating a quantum theory of gravity is the so-called loop quantum gravity.

There are other, usually controversial or little perceived approaches. Antony Garrett Lisi example, published in 2007 an approach, which he published under the title "An Exceptionally Simple Theory of Everything " in arXiv and which is due to the underlying mathematics called E8 theory.