Torsion Balance Investigation of the Casimir Effect

TL;DR

This paper reports a torsion balance experiment measuring the Casimir force between a flat and spherical conductor from 1 to 8 microns, providing evidence for finite temperature effects and constraining short-range physics.

Contribution

It presents a novel measurement of the Casimir force at larger separations using a torsion balance, supporting finite temperature theories and bounding new physics.

Findings

Indications of finite temperature effects above 3 microns

Supports finite temperature Casimir force theories

Bounds on short-range inverse square law violations

Abstract

The presence of finite energy in quantum vacuum has profound implications to physics at the microscopic and macroscopic levels. One of the direct consequences of vacuum energy is the Casimir Force, which is a force of attraction experienced by a pair of infinite planar conductive plates placed in vacuum. Experiments to measure Casimir force have been carried out since the 1950s. This thesis presents a measurement of Casimir force between a flat and a spherical conducting surface using a torsion balance for separations in the range of 1 micron to 8 micron. The details of the construction of the torsion balance apparatus, the experimental procedure and the analysis to obtain the Casimir force as a function of separation are described. There are indications of the finite temperature effects which become important for separations greater than ~ 3microns. The combined import of this experiment with others at shorter distances is to favor the finite temperature theory of Casimir forces. The contributions of this experiment towards bounding the strength of inverse square law short-range violating interactions are presented.