The Mysteries of String Theory With Brian Greene
The theoretical framework where point like particles in particle physics are replaced by one dimensional objects called strings is known as string theory.
This theory describes how strings instead of point like particles propagate through space and interact with each other. Strings look just like ordinary particles with mass, charge and other properties that are determined by the vibrational state of the string.*
Brian Greene is an American theoretical physicist, mathematician, and string theorist. Greene was a physics professor at Cornell University from 1990-1995, and has been a professor at Columbia University since 1996 and chairman of the World Science Festival since co-founding it in 2008. Brian Greene has worked on mirror symmetry, relating two different Calabi–Yau manifolds. In this video he explains string theory in detail.
One of the many vibrational states of the string corresponds to a quantum mechanical particle that carries gravitational force known as a graviton. Therefore string theory is a quantum gravity theory.
The theory attempts to address a number of broad and deep questions in fundamental physics. There are quite a few contributions of advances to mathematical physics from string theory that come to mind. Including: Black hole physics, early universe cosmology, nuclear physics, condensed matter physics etc.
Physicists have been dreaming about a theory of everything for a long time and because string theory provides a unified description of gravity and particle physics, it is a candidate for a theoretical model that describes all fundamental forces and forms of matter.
String theory was first studied in the late 1960s as a theory of the strong nuclear force, before being abandoned in favor of quantum chromodynamics. However, it was realized that the very properties that made string theory unsuitable as a theory of nuclear physics made it a promising candidate for a quantum theory of gravity.
« Bosonic string theory » is the earliest version of what is today string theory but it incorporated only the class of partciles known as bosons. However the theory later developed into « Superstring theory » where the connection between bosons and the class of particles known as fermions is called « Supersymmetry »