Citation
Caves, Carlton Morris (1979) Theoretical investigations of experimental gravitation. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/H3T8FQ06. https://resolver.caltech.edu/CaltechTHESIS:03152016161054898
Abstract
This thesis has two basic themes: the investigation of new experiments which can be used to test relativistic gravity, and the investigation of new technologies and new experimental techniques which can be applied to make gravitational wave astronomy a reality.
Advancing technology will soon make possible a new class of gravitation experiments: pure laboratory experiments with laboratory sources of nonNewtonian gravity and laboratory detectors. The key advance in techno1ogy is the development of resonant sensing systems with very low levels of dissipation. Chapter 1 considers three such systems (torque balances, dielectric monocrystals, and superconducting microwave resonators), and it proposes eight laboratory experiments which use these systems as detectors. For each experiment it describes the dominant sources of noise and the technology required.
The coupled electromechanical system consisting of a microwave cavity and its walls can serve as a gravitational radiation detector. A gravitational wave interacts with the walls, and the resulting motion induces transitions from a highly excited cavity mode to a nearly unexcited mode. Chapter 2 describes briefly a formalism for analyzing such a detector, and it proposes a particular design.
The monitoring of a quantum mechanical harmonic oscillator on which a classical force acts is important in a variety of highprecision experiments, such as the attempt to detect gravitational radiation. Chapter 3 reviews the standard techniques for monitoring the oscillator; and it introduces a new technique which, in principle, can determine the details of the force with arbitrary accuracy, despite the quantum properties of the oscillator.
The standard method for monitoring the oscillator is the "amplitude andphase" method (position or momentum transducer with output fed through a linear amplifier). The accuracy obtainable by this method is limited by the uncertainty principle. To do better requires a measurement of the type which Braginsky has called "quantum nondemolition." A wellknown quantum nondemolition technique is "quantum counting," which can detect an arbitrarily weak force, but which cannot provide good accuracy in determining its precise timedependence. Chapter 3 considers extensively a new type of quantum nondemolition measurement  a "backactionevading" measurement of the real part X_{1} (or the imaginary part X_{2}) of the oscillator's complex amplitude. In principle X_{1} can be measured arbitrarily quickly and arbitrarily accurately, and a sequence of such measurements can lead to an arbitrarily accurate monitoring of the classical force.
Chapter 3 describes explicit gedanken experiments which demonstrate that X_{1} can be measured arbitrarily quickly and arbitrarily accurately, it considers approximate backactionevading measurements, and it develops a theory of quantum nondemolition measurement for arbitrary quantum mechanical systems.
In Rosen's "bimetric" theory of gravity the (local) speed of gravitational radiation v_{g} is determined by the combined effects of cosmological boundary values and nearby concentrations of matter. It is possible for v_{g} to be less than the speed of light. Chapter 4 shows that emission of gravitational radiation prevents particles of nonzero rest mass from exceeding the speed of gravitational radiation. Observations of relativistic particles place limits on v_{g} and the cosmological boundary values today, and observations of synchrotron radiation from compact radio sources place limits on the cosmological boundary values in the past.
Item Type:  Thesis (Dissertation (Ph.D.))  

Subject Keywords:  Physics  
Degree Grantor:  California Institute of Technology  
Division:  Physics, Mathematics and Astronomy  
Major Option:  Physics  
Thesis Availability:  Public (worldwide access)  
Research Advisor(s): 
 
Group:  TAPIR, Astronomy Department  
Thesis Committee: 
 
Defense Date:  8 May 1979  
NonCaltech Author Email:  ccaves (AT) unm.edu  
Funders: 
 
Record Number:  CaltechTHESIS:03152016161054898  
Persistent URL:  https://resolver.caltech.edu/CaltechTHESIS:03152016161054898  
DOI:  10.7907/H3T8FQ06  
Default Usage Policy:  No commercial reproduction, distribution, display or performance rights in this work are provided.  
ID Code:  9621  
Collection:  CaltechTHESIS  
Deposited By:  Benjamin Perez  
Deposited On:  16 Mar 2016 20:18  
Last Modified:  10 Mar 2020 23:39 
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