Locally covariant quantum field theory and the problem of formulating the same physics in all spacetimes

Understand

The framework of locally covariant quantum field theory is discussed, motivated in part using "ignorance principles".

• It is shown how theories can be represented by suitable functors, so that physical equivalence of theories may be expressed via natural isomorphisms between the corresponding functors.
• The inhomogeneous scalar field is used to illustrate the ideas.
• It is argued that there are two reasonable definitions of the local physical content associated with a locally covariant theory; when these coincide, the theory is said to be dynamically local.