Minimum experimental standards in the laboratory search for gravity effects

Peer-reviewed reports of experimental modifications of gravity over rotating superconductors (Podkletnov, 1992), or of a weight increase during cool-down of superconductors (Reiss, 2003), have stimulated considerable recent discussion. Precise descriptions of sample composition, ancillary apparatus and balance specifications were not given by Podkletnov. Accordingly, a carefully-designed replication (Hathaway, 2003) could not confirm the experimental findings possibly because detailed information was unavailable. On the other hand Tajmar et al. (Tajmar, 2005) failed to replicate previous results due to lack of serious analysis of weight measurements of solids in atmosphere and subject to buoyancy and wetting forces. Also an acceptable measuring technique and a detailed analysis of the sample's temperature excursions versus time were not performed. Both examples clearly indicate that minimum standards of experimental precision, accounting for boundary conditions, error analysis and thorough reporting of the experiment are necessary to distinguish a true anomaly from prosaic explanations and artefacts. We will discuss some types of errors that can occur and how standards of analysis and reporting should be improved to allow others a thorough physical understanding.