It appeared that at weak communication and small energy, the M-theory turns into the 11-dimensional theory of supergravitation. Thus, the latest theory which before was standing independently joined in an overall picture of the world. However 11 regularity can generate only two theories of superstrings. Other three could not come from the first two and the step to increase in dimension was taken. The conclusion from one source of all theories of superstrings requires 12-dimensional space where along with 10-spatial measurements there are two times. But while each of five theories of a supersimmetrichn, any supersymmetry in 12-dimensional space is not present.
The majority of successful theories of physics of elementary particles are based on calibration symmetry. In such theories various fields can pass one into another. These transitions completely are defined by calibration group of the theory. If it is possible to carry out a certain calibration transformation in a point of space and thus the theory will not change, say that the theory has local calibration symmetry.
This theory concerns open superstrings. In it there is only one (N = supersymmetry in a desyatimeriya. Open strings can transfer calibration degrees of freedom on the ends and to avoid anomalies, the calibration group has to be SO(3 (SO(N) - N x N Group of orthogonal matrixes with the determinant equal to unit. Orthogonality means that the transposed matrix is equal to the return). Besides, in it D-brany with 1,5 and 9 spatial measurements rassmtrivatsya.
It is the theory of the closed superstrings with two (N = supersimmetriya in a desyatimeriya. Two gravitino (the superpartner a graviton move in opposite directions according to a world leaf of the closed string and have opposite kiralnost in relation to 10-dimensional group of Lorentz so it is the nekiralny theory. Also in it it is not considered calibration group, but is D-brany with 0,2,4,6 and 8 spatial measurements are considered.
Thus, theories of a field known earlier appeared a limit of the theory of superstrings, and their symmetry part of symmetry of the string theory. However, 11-dimensional supergravitation is represented superfluous, and therefore not quite clear here.
Five superstring theories described above strongly differ from the point of view of the weak and connected perturbative theory (the theory of indignations described. But actually, as it became clear in the last some years, all of them are connected among themselves by various string dualities. (We will call theories dual if they describe the same physics).
Speaking about the fundamental theory, usually mean the quantum theory described by the equations of quantum mechanics. However the equations describing a gravitational field (the fourth interaction - classical, but not quantum. They serve as approach to the true quantum equations and cease to work if the distance between objects is not enough or their energy are too great. The classical gravitational equations (in the General Theory of Relativity) at small distances (~) cease to describe really proceeding processes. However with quantization of gravitation scientists had problems, to solve which they do not manage and to this day though such phenomenon as electromagnetism is easily quantized. The developed theories contained contradictions. Gravitation describes not properties of space time, and directly its physical essence. For elimination of contradictions, scientific mathematicians and physicists made the assumption of existence of strings, having created the new theory.
Today it is not known how the choice between different options to twist and breakdowns is carried out. However possibilities of such choice are built in the theory of superstrings as superstrings generate gravitation which defines space time geometry. It is possible to define, whether there can be this or that six-measured space selected by a superstring that from a desyatimeriya the observed four-dimensional world turned out. As the defining criterion supersymmetry for this purpose serves — not in any space there can be a superstring, the structure a shestimeriya has to be coordinated with properties of the observed world. The matter is that when twisting excess measurements in very small spaces, properties of the theory reflect some geometrical characteristics of these spaces in the remaining measurements.