String theory. It is a fundamental model of physics that basically assumes that apparently point material particles are actually vibrational states of a more basic extended object called a rope or filament .
Summary
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- 1 Ideas on string theory
- 1 Later development
- 2 Variants of the theory
- 2 Source
Ideas on string theory
The following formulation of a string theory is due to Jöel Scherk and John Schwuarz, who in 1974 published an article demonstrating that a theory based on one-dimensional objects or strings rather than point particles could describe the gravitational force. Although these ideas did not receive much attention at the time until the First Superstring Revolution of 1984.. According to the formulation of string theory that emerged from this revolution, string theories can in fact be considered a general case of quantized Kaluza-Klein theory.
There are two fundamental ideas: The basic objects of the theory would not be point particles but extended one-dimensional objects (in the five conventional string theories these objects were one-dimensional or strings; currently in the M-theory they are also admitted of higher dimension or “p -branes “). This renormalizes some infinity of perturbative calculations. The space-time in which the strings and p-branes of the theory move would not be the ordinary 4-dimensional space-time but a space of the Kaluza-Klein type, in which 6 compact dimensions in the form of a Calabi-Yau variety are added to the four conventional dimensions. Therefore conventionally in string theory there is 1 temporal dimension, 3 ordinary spatial dimensions and 6 compactified dimensions that are unobservable in practice.
Later development
After the introduction of string theories, the need and convenience of introducing the principle that the theory was supersymmetric was considered; that is, that it admits an abstract symmetry that relates fermions and bosons. Currently most string theorists work on supersymmetric theories; hence string theory is now called superstring theory . This last theory is basically a supersymmetric string theory; that is, it is invariant under supersymmetry transformations.
There are currently five superstring theories related to the five known ways of implementing supersymmetry in the string model. Although this multiplicity of theories baffled specialists for more than a decade, current conventional wisdom suggests that the five theories are limiting cases of a single theory about an 11-dimensional space, the 3 of space, 1 temporal, and 6 additional compacted and 1 that includes them forming membranes from which part of their gravity could escape in the form of gravitons. This unique theory, called M-theory, of which only a few aspects would be known, was conjectured in 1995 .
Variants of the theory
Outer space superstring theory is current. In its early mid- 1980s , about five string theories appeared, which were later identified as the particular limits of a single theory: Theory M. The five currently existing versions of the theory, among which various duality relationships can be established They are:
- Type I theory, where both open and closed strings and D-branes appear, moving over a 10-dimensional space-time. D-branes have 1, 5, and 9 spatial dimensions.
- Type IIA theory is also a 10-dimensional theory but uses only strings and closed D-branes. It incorporates two theoretical particles associated with the graviton gravitons by supersymmetry relationships. Use D-branes of dimension 0.2, 4, 6, and 8.
- Type IIB theory.
- The heterotic-O theory, based on the O symmetry group (32).
- The heterotic-E theory, based on the exceptional Lie group E8. It was proposed in 1987 by Gross, Harvey, Martinec, and Rohm.
The term tightrope theory actually refers to 26-dimensional bosonic string theories and 10-dimensional superstring theory, the latter discovered by adding supersymmetry to bosonic string theory. Today string theory often refers to the supersymmetric variant, while the old one is known by the full name of bosonic string theory. In 1995Edward Witten surmised that the five different superstring theories are limiting cases of an unknown 11-dimensional theory called M-Theory. The conference where Witten showed some of his results started the so-called Second Superstring Revolution. In this theory M not only one-dimensional strings, but a whole variety of non-disturbing objects, extended in various dimensions, collectively called p-branes are involved as fundamental physical animate objects. This name is a membrane apocope. Until now, scientists have described the basic components of matter atomsand subatomic particles like small spheres or dots. String Theory states that the soul of these particles are vibrating strings of energy called strings. The strings vibrate in certain ways, giving the particles their unique properties, such as mass and charge . The origin of this theory dates back to 1968 when the physicist Gabrielle Veneziano discovered that the 200-year-old Euler’s equations described strong nuclear interaction, thus initiating a movement that would lead, thanks to the physicist Leonard Susskind, to the appearance of the vibrating threads as an interpretation of said formula.
