PX156 - E3 - unification

forces:

• electric
• magnetic
• weak
• strong
• gravity

electric and magnetic: electromagnetic, maxwell (1800's), einstein (1900's)

electromagnetic and weak: electroweak (1970's)

electroweak and strong haven't been unified yet, very close

these forces are described by gauge theory

gravity is described by general relativity, which is very different

quantum gravity hopes to unify gravity with the rest: super force or grand unified theory (GUT)