We explain what string theory is 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 everything.”
This scientific hypothesis and founding model maintains that the material particles we know like the constituent elements of the atom They are actually vibrational states of a “string” or “filament.”
String Theory proposes that space-time has many more dimensions than we can perceive (eleven, to be exact). Therefore, the fundamental “strings” can vibrate in many ways in all these dimensions.
Each mode of vibration corresponds to a fundamental particle: an electron, a photon, a quark, or any other particle of the standard model. It is a theory that tries to move away from the idea of the point-particle.
Although this theory emerged as a way to respond to the contradictions and irresolvable dilemmas of contemporary physics, there are currently five superstring theories. Each one is linked to a way of implementing the string model to the theory of supersymmetry, which assumes that for each elementary particle, there is a supersymmetric partner.
Some of these variant theories are:
- Type I string theory Consisting of strings and both open and closed D-branes, vibrating in a ten-dimensional spacetime.
- Type IIA string theory Which consists of strings and only closed D-branes, along with gravitinos.
- Type IIB string theory Which differs from Type IIA in that it is non-chiral (preserving parity).
- SO(32) heterotic string theory Also called Heterotic-O, based on the O(32) symmetry group.
- Heterotic string theory E8xE8 Also called Heterotic-E, based on the exceptional Lie group E8.
See also: Theory of relativity
String theory controversy
Although string theory could explain in an innovative way some of the most challenging physical phenomena in nature, it also has notable limitations. For example, its mathematics is valid only in 11-dimensional space-time.
On the other hand, predictions made following this model have not been sufficiently concrete to contrast them with an experimental model. For many, it is a theory so ambitious and encompassing that It is impossible to prove or disprove it scientifically for which it has often been accused of pseudoscience.
References
- “String theory” on Wikipedia.
- “String theory in 7 minutes” (video) at the IFT Institute of Theoretical Physics.
- “The decline of string theory” in Cuadernos de Cultura Cientifica.
- “What is String Theory?” on LiveScience.
- “String Theory Explained” (video) in Kurzgesagt.
- “String Theory” in The Encyclopaedia Britannica.
