What is string theory in physics?
We explain to you what is string theory in physics, its main hypothesis and its variants. In addition, the controversy over its limitations.

What is string theory?
String theory is an attempt to solve one of the great enigmas of contemporary theoretical physics and create a unifying theory of its different fields, that is, a “theory for the whole.”
This scientific hypothesis and foundational model holds that the material particles we know , such as the constituent elements of the atom, are actually vibrational states of a “string” or “filament,” that is, a more basic object still.
String theory, thus, proposes that spacetime has many more dimensions than we can perceive (eleven, to be exact). Therefore, the fundamental “strings” can vibrate in different ways.
A fundamental particle corresponds to each mode of vibration: an electron , a photon, a quark, or any other particle of the standard model. It is a theory that, together with its different reinterpretations, tries to move away from the idea of the pointparticle.
While this theory emerged as a way of responding to the contradictions and irresolvable dilemmas of physics contemporary , there are currently five superstring theories. Each one is linked to a specific way of implementing the theory of supersymmetry in the string model, which implies a supersymmetric companion for each existing particle.
These variants are:
 Type I string theory , consisting of both open and closed strings and Dbranes, vibrating in a tendimensional spacetime.
 Type IIA string theory , consisting of only closed strings and Dbranes, together with gravitinos.
 Type IIB string theory , which differs from Type IIA in that it is nonchiral (retaining parity).
 Heterotic string theory SO (32) , also called HeteroticO, based on the symmetry group O (32).
 Heterotic string theory E8xE8 , also called HeteroticE, based on the exceptional Lie group E8.

Controversy of string theory
Although string theory could explain in an innovative way some of the most challenging physical phenomena of nature , it also has notable limitations. For example, his math is valid only in a spacetime of 11 dimensions.
On the other hand, the predictions made following this model have failed to be concrete enough to contrast them with an experimental model. For many, it is such an ambitious and comprehensive theory that it is impossible to prove or deny it scientifically , which is why it has often been accused of pseudoscience .