String theory

String theory was first proposed by Jöel Scherk and John Henry Schwarz in 1974 with a paper explaining one-dimensional pillars instead of point particles explaining the gravitational force.

String theory is a model of physics that clarifies the nature of matter and its interactions. It also states that space-time has several dimensions in addition to the ones we can perceive. So the whole universe is created by filaments. To understand this theory we have to understand an electron as a vibration that has the possibility of giving rise to other particles. Thanks to the theory we could later come to another quantum theory of gravity.

The 4 forces of string theory

String theory is composed of 4 forces:

• Electromagnetic force: through the particle known as the photon.
• "Strong" or nuclear force
• "Weak" force
• Gravity

The entire universe is made up of tiny strands of energy, known as strings. Each subatomic particle is born from one of the vibration nodes of a single type of string.

String theory together:

1. Einstein's theory of relativity → tells us what gravity is.
2. quantum mechanics → the world of stars.

Drawbacks:

According to string theory we live in a world of 10 dimensions (11 if we count time). These are divided into 9 spatial and 1 temporal. However, we can only perceive 4 of them: length, height, width, and time; so the other 7 are related to themselves.

On the other hand, the theory produces a superabundance of possible universes compatible with our own, at least of the order of 10 >500.

In 1982 Michael Green and John Schwarz created 3 models of string theory

• Model I: It has closed and open strings. Closed strings are block-shaped. The open strings do not touch each other.

• Model IIA: This type of string has symmetrical vibration patterns. This type of string is connected to structures that have an odd number of dimensions.

• Model IIB: unlike Type IIA, this type of string has asymmetrical vibratory partons. This type of string is connected to structures that have an even number of dimensions.