Three New High Precision Tests of Relativity and Mach's Principle.
Abstract
In 1881, the motivation for searching for an ether was to distinguish between a Stokes ether and a Fresnel ether. The conclusion from the work of Michelson and Morley was that it was a Stokes ether. This unappealing result incited theoretical work which eventually evolved the real ether into a mathematical ether. With the acceptance of Relativity in the early 1920's, the ether was no longer needed. However, it remains useful as a simple test theory for relativity. There is cosmological evidence as well as philosophical reasons why relativity might break down at some level of precision and a preferred direction in space would be evident. We present here the preliminary results from three different experiments that test for a preferred direction in space via an anisotropy in the speed of light. The previous best upper limit for an ether wind is v/c < 1 x 10('-8). Our first experiment looks for an anisotropy in the detected intensity of light from a light bulb with orientation. An ether wind will cause a dipole type emission anisotropy. We search for such an effect by rotating a light bulb with a silicon solar cell on either side and searching for a modulation in the difference intensity the two detectors see. The upper limit we reached was v/c < 5 x 10('-8). This was set by a relatively short finite averaging time. No attempt was made to search for sidereal variation. If the rotation rate is such that the detectors are shot noise limited, then for a reasonable photocurrent of 40mA ((TURN)100m watts) and searching sidereal variation, the ultimate limit on this experiment would be v/c < 7 x 10('-15). Our second experiment searches for a variation in the resonant frequency of a laser cavity. We servo a laser cavity length to the frequency of the inverse Lamp dip of methane and look for a periodic variation in the servo signal as the cavity rotates through space. Our measurements were limited to v/c < 7 x 10('-6) due to a systematic effect caused by a periodic acceleration of the rotating table. We have removed the effect by careful dynamic balancing and show how tilts of the vertical can be nulled to the same limit as the laser servo noise level. By searching for sidereal variation, the ultimate upper limit for this experiment is v/c < 4 x 10('-9). By comparing the servo response for a laser with a polarization axis horizontal and one polarized in the vertical, an upper limit to a spatial anisotropy in the absorption frequency of methane of (DELTA)(nu)/(nu) = 5 x 10('-18) of a cosmic origin can be reached. This result could be interpreted by one version of Mach's principle as a limit to a mass anisotropy of (DELTA)m/m < 10('-17). Our third experiment searches for a variation in the beat frequency between two lasers rotating on the rim of a six foot diameter table. An ether wind model predicts a first order variation of the beat frequency that depends on the lasers' velocity. Our current upper limit to an ether wind from this experiment is v/c < 6 x 10('-3). This was limited by mechanical problems and poor laser stability. We show how each of these factors can be reduced to more reasonable levels. By searching for sidereal variation, we estimate a limit from this experiment of v/c < 10('-10).
- Publication:
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Ph.D. Thesis
- Pub Date:
- 1980
- Bibcode:
- 1980PhDT.......142B
- Keywords:
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- Physics: General