1. Mihir John What are the most basic constituents that make up the universe around us? String Theory

2. Why use String Theory? • String Theory is believed to bridge the gap between General Relativity and Quantum Mechanics • This is because Relativistic Quantum Field Theory only works when gravity is ignored (very weak) • General Relativity only works when we can assume the universe can be described by classical physics (no quantum mechanics)

3. String Theory Suppositions • In string theory, particles come from excitations of the string • The theorized particle with gravitational force, with zero mass and two units of spin, is called the Graviton • Even though the graviton is compatible with quantum theory, the mathematics of the interactions does not follow • String Theory allows that these particles collide over a small, finite distance

4. String Theory Basics • With string theory attempting the explain Quantum Gravity, the strings exist near Planck length (10^-33cm) • Multiple types of string theory exist, and are classified by open/closed strings and also supersymmetry. (bosons and fermions) • Different string theories require different spacetime dimensions to work—Range from 10 to 26

5. String Theory Unification • If “strings” are the most basic constituents of the universe, and all particles arise from their excititation, then all matter and the forces of nature arise from strings • If everything arises from one system, is a unified theory not possible?

6. Supporting String Theory • Experimental data from particle accelerators such as CERN could provide insight • Primarily, comparing energy levels from collisions could support the theory of additional dimensions • Particle accelerators could also provide data for theorized particles such as the graviton

7. Additional Sources • TEDTalk- Brian Greene-Making Sense of String Theory