Expectation values in quantum gravity
The purpose of this dissertation is to develop new methods for calculating expectation values of field operators, in situations where particle creation is important. The goal is to apply these techniques to quantum gravity, to see if the initial singularity in the universe might be avoided in the quantum theory. Standard effective action theory is modified to produce effective field equations satisfied by the expectation value of the field in an in state, as opposed to the usual in-out amplitude. Diagrammatic rules are found for calculation of the new field equations, and are used to show that the equations are real and causal up to two loop order. The theory also provides a simple check of unitarity, which is carried out, again up to two loops. Just as the standard effective field equations can be derived by analytic continuation from a theory defined in Euclidean space, so can the modified equations be obtained from a modified contour rotation of the Euclidean theory. This result is used to prove a recent conjecture which yields a simple rule for finding the real, causal equations. The new formalism is applied to two gravitational systems. First, the stability of flat space time is studied by finding the equation satisfied by small perturbations of Minkowski space.
- Research Organization:
- Texas Univ., Austin (USA)
- OSTI ID:
- 6163975
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
QUANTUM GRAVITY
EXPECTATION VALUE
ACTION INTEGRAL
COSMOLOGY
CREATION OPERATORS
EUCLIDEAN SPACE
FIELD EQUATIONS
GRAVITATION
MINKOWSKI SPACE
PERTURBATION THEORY
QUANTUM OPERATORS
SINGULARITY
SPACE-TIME
WILSON LOOP
EQUATIONS
FIELD THEORIES
INTEGRALS
MATHEMATICAL OPERATORS
MATHEMATICAL SPACE
QUANTUM FIELD THEORY
RIEMANN SPACE
SPACE
645400* - High Energy Physics- Field Theory