Principle Of String Theory Essay

In this essay, I am going to describe and explain the basic principles in string theory. String theory is a theoretical framework in which particles are replaced by strings. The strings are like ordinary particles with mass, charge but other properties are determined by the vibrational state of the string and they are only in one dimension. String theory originated from the Kaluza-Klein theory in 1921. In 1970 the official string theory is formulated. In 1971 supersymmetry is invented in two contexts: 1. particle field theory 2. Because of introducing fermions into string theory. In 1974 gravitons were theorised. This was when string theory was proposed as a unified theory for the four fundamental forces of nature. In 1976 supersymmetry was added to gravity making supergravity. Then in 1980 string theory and supersymmetry combine giving an excitation spectrum that has equal numbers of fermions and bosons. This showed that string theory is supersymmetric, the resulting objects are called superstrings. In 1984 String theory was finally accepted as an actual candidate theory uniting quantum mechanics, particle physics and gravity. In 1995 M-theory was

The brane ingredients are wrapped up on small rolled-up dimensions of space. Because string theory lives in 10 dimensions rolling up 5 dimensions leaves 5 dimensions left over for the resulting blackhole. The resulting 5D blackhole, carrying mass and 3 charges, was constructed by A. strominger and C. vafa in 1996. They calculated the entropy of the string/brane system using Boltzmann’s formula and got exactly the Bekenstein- Hawking entropy which was predicted many years earlier. To create Hawking radiation, if the opposite momentum open strings meet as a pair, they can join to create closed strings, which can escape from branes and give the same spectrum of emitted radiation which hawking discovered 40 years ago. This can also be found for 4D blackholes with four types of