Reproducibility

Reproducibility is one of the main principles of the scientific method, and refers to the ability of a test or experiment to be accurately reproduced, or replicated. The term is closely related to the concept of testability. A related concept is the need for measured parameters to have an operational definition, that is, that the parameter or component of a theory have a defined procedure for its measurement.

Reproducibility of experimental data is not an absolute scientific requirement in all of sciences; some fields, such as history and astronomy, rely in part upon the observation of singular phenomena. It is also the case that some phenomena are so unusual that an experiment is practically not reproducible, for example we can not take probes frequently from Comet Halley. However, in most of natural sciences we expect experiments to be designed in a way that makes them potentially independently reproducable.

Whether a given experiment is in fact replicated independently largely depends on whether the outcome of the experiment was unexpected with potentially important implications. Indeed, direct replication of an experiment is something quite unusual (and indeed it is generally difficult to publish results that are mere confirmations of previous work). In general, scientists will prefer to repeat the test but by independent scientific means, on the grounds that if two independent lines of evidence both come to the same, unexpected conclusion, an artefactual explanation for the unexpected result is less likely. Thus direct replication of an original experiment is something that usually takes place only when the validity of the original result is explicitly challenged. Experiments which cannot in principle be reproduced are generally not considered to provide scientific evidence as useful as those that can.

Reproducibility is also the variation in measurements taken by different persons or instruments on the same item and under the same conditions.

Famous problems

See main article at Cold Fusion

In the late 1980's there was a rush to publish on the subject of cold fusion, a technology that offered promise of low-cost energy. In March 1989, University of Utah chemists Stanley Pons and Martin Fleischmann reported the production of excess heat that could only be explained by a nuclear process. The report was astounding given the simplicity of the equipment: it was essentially an electrolysis cell containing heavy water and a palladium cathode which rapidly absorbed the deuterium produced during electrolysis. The newsmedia reported on the experiments widely, and it was a front-page item on many newspapers around the world. Over the next several months others tried to replicate the experiment, but were unsuccessful. At the end of May the US Energy Research Advisory Board formed a special panel to investigate cold fusion. The scientists in the panel found the evidence to be unconvincing. Pons and Fleischmann later apparently claimed that there was a "secret" to the experiment, a statement that infuriated the majority of scientists to the point of dismissing the experiment out of hand. The science of cold fusion was severely damaged by the affair, although research continues quietly around the world.

See main article at Wilhelm Reich

In the 1930's the German scientist Wilhelm Reich claimed to have discovered a physical energy he called "orgone," and which he said existed in the atmosphere and in all living matter. He developed instruments to detect and harness this energy that he said could be used to treat illness or control the weather. His views were not accepted by the mainstream scientific community; in fact, he was villified for his claims. In the early 1940's Reich encouraged Albert Einstein to test an orgone accumulator, which Einstein did, but he disagreed on the interpretation of the results. In 2001, Canadian researchers Paulo Correa and Alexandra Correa claimed to have successfully reproduced the experiment.

See main article at Nikola Tesla

Nikola Tesla claimed as early as 1899 to have used a high frequency current to light gas-filled lamps from over 25 miles away without using wires. In 1904 he built Wardenclyffe Tower on Long Island to demonstrate means to send and receive power without connecting wires. The facility was never fully operational and was not completed, supposedly due to economic problems. Tesla's experiments have never been replicated.

See also

Accuracy Contingency Corroboration Falsifiability Hypothesis

Inquiry Pathological science Precision Pseudoscience Scientific method Tautology Testability

References

• Turner, William (1903), History of Philosophy, Ginn and Company, Boston, MA, Etext. See especially: "Aristotle".

• Definition (PDF)