“General relativity is the cornerstone of cosmology and astrophysics. It has also provided the conceptual basis for string theory and other attempts to unify all the forces of nature in terms of geometrical structures.”
Particles are imagined as being point-like but in string theory it is reimagined as being one-dimensional strings. String theory was developed to explain the behaviour of hadrons (Protons, neutrons and all other particles that make up the atomic nucleus). It was abandoned by physicists as it requires extra, unseen dimensions. The strings are called branes and could have anything between 0 to 9 dimensions.
Interactions are based on the strings ability to have its end join and split apart.
String theory attempts to unite all four fundamental forces of nature (Electromagnetic force, the strong nuclear force and gravity). The fundamental forces were believed to be unified during the early stages of the universe.
The gravitational effects observed in our universe doesn’t correlate with the matter seen. The universe contains a form of matter that we can’t directly observe or see. There’s much more dark matter than ordinary matter, ordinary matter only makes up about 4% of our entire universe.
After the big bang , the energy of the event was transferred into matter and antimatter. This would have caused the different forms of matter to annihilate each other. The universe consists of more matter than antimatter which makes up the visible universe.
A theory of everything might explain why matter was favoured.
“Quantum mechanics brought an unexpected fuzziness into physics because of quantum uncertainty, the Heisenberg uncertainty principle. String theory does so again because a point particles replaced by a string, which is more spread out.”