THE STRING THEORY

THE STRING THEORY

1. All the things are made from structures of molecules made up of countless even smaller things: atoms

   • The atoms are divided into elementary particles but we had a problem; they are so small that we could no longer look at them.
   • THE HEISENBERG UNCERTAINTY PRINCIPLE
     • basis of quantum physics
       • To see something we need light, an electromagnetic wave
         • But particles are very small, so small that the electromagnetic waves we used to see are too big to touch them. Visible light just passes over them.
           • So, when we touch a particle with a wave that has a lot of energy it alters it. By looking at a particle, we change it
             • So, we can't measure elementary particles precisel
   • QUANTUM FIELD THEORY
     • The " point particle"
       • A particle is a point in space: any electron is a point with a certain electric charge and a certain mass, all indistinguishable from one to the other.
         • Charge=0 Mass= 0
           • While particles are not really points, if we treat them as if they were, we can get a very good picture of the universe
             • But there's a huge problem: Gravity.
   • GRAVITY
     • gravity is a theory of geometry. The geometry of space-time itself.
     • Of distances, which we need to describe with absolute precision.
     • But since there is no way to precisely measure things in the quantum world, our story of gravity doesn't work with our story of quantum physics

2. is the union of gravity together with quantum physics plus the standard model

   • it describes many different elementary particles
     • as different modes of vibration of the string. a string can give you different particles
       • String theory promised to unify all fundamental forces of the universe. and requires 10 dimensions to work out.