Historical research guide · 0510 · 2012
Experimental Considerations in Superconductor Gravity Experiments
George Hathaway · Harald Reiss
In one minute
George Hathaway and Harald Reiss wrote the chapter every experimenter in this field should read first. Reports of gravity changing over a rotating superconductor, or of a sample gaining or losing weight as it is cooled through its transition, have sent many groups to the bench — and, the authors argue, those reports have rarely dealt in enough depth with how hard the measurement really is. Their subject is the long list of ordinary phenomena that can imitate the effect people are looking for: the subtle thermal behaviour of a superconductor near its critical temperature, boundary conditions nobody wrote down, heat exchange between the cryogen and the sample, and instrumentation that is answering to something other than what the experimenter thinks. They stay on instrumentation and interpretation rather than theory, and they end with a standard — state your precision, account for the boundary conditions, understand the thermal exchange, do the error analysis, report the whole experiment. Meet it and an anomaly becomes a result.
Connection
Chapter 11 lives or dies on measurements at the very edge of what a cryogenic laboratory can resolve, and this is the chapter that says where that edge is and how to prove you are past it. Read it alongside Martin Tajmar’s two reports of a gravitomagnetic signal around a spinning niobium ring, at /library/stm-21102decd7 and /library/stm-1cb16dd1bc — those are the experiments Hathaway and Reiss’s standard is written for, and this is what gives chapter 1’s evidence ladder its rungs.
From the source
Reports of experimental modifications of gravity over rotating superconductors, or of a weight increase or decrease during cool-down, have prompted many researchers to design their own experiments, but many of these reports have not dealt in sufficient depth with the considerable difficulties attendant on this type of experiment.Abstract, opening sentences
There is a large class of phenomena that can mask the sought-after effect and produce spurious or artefactual results which are actually due to prosaic and mundane, albeit subtle, phenomena.Abstract
Specific and subtle thermal phenomena occur during the transition of a superconductor near its critical temperature, and these are examined in the chapter as a distinct source of apparent mass and gravity-field anomalies.Abstract; the chapter’s treatment of the transition near T-critical, pages 203 to 228
The chapter concentrates on experiments designed to detect mass anomalies and gravity field anomalies rather than superconductor-mediated detection of gravitational waves, while noting that many of the issues raised are germane to both types of experiment.Abstract
Minimum standards of experimental precision, accounting for boundary conditions, an understanding of the thermal exchange between cryogen and superconductor, error analysis and thorough reporting of the experiment are necessary to distinguish a true anomaly from prosaic explanations and artefacts.Abstract, closing sentence
The way in
https://doi.org/10.2174/978160805399511201010203How to cite it
George Hathaway, Harald Reiss (2012) Experimental Considerations in Superconductor Gravity Experiments doi:10.2174/978160805399511201010203