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 very closely related to the concept of testability and, depending on the particular field, may require the test or experiment to be falsifiable. A related concept is the need for measured parameter to have an operational definition, that is that the parameter or component of a theory have a defined procedure for its measurement.
Note that reproducible experiment is not a necessary scientific requirement in all of sciences. For example in history and astronomy we can not expect experimenting at all. It may also be that in a given fields phenomena are so unique that an experiment is practically not reproducible, for example we can not take probes frequently from Comet Halley. In most of natural sciences however we can expect an experiment to be reproducable.
The results of an experiment performed by a particular researcher or group of researchers are generally evaluated by other independent researchers by reproducing the original experiment. They repeat the same experiment themselves, based on the original experimental description, and see if their experiment gives similar results to those reported by the original group. The result values are said to be commensurate if they are obtained (in distinct experimental trials) according to the same reproducible experimental description and procedure.
Experiments which cannot be reliably reproduced are generally not considered to provide useful scientific evidence. Results which prove to be highly reproducible are typically given more credence by scientists than those which are less reproducible, although this is based on an intuitive application of the principle of induction, rather than on the strict application of the principles of falsifiability.
The basic idea can be seen in Aristotle's dictum that there is no scientific knowledge of the individual, where the word used for individual in Greek had the connotation of the idiosyncratic, or wholly isolated occurrence. Thus all knowledge, all science, necessarily involves the formation of general concepts and the invocation of their corresponding symbols in language (cf. Turner).
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
References
- Turner, William (1903), History of Philosophy, Ginn and Company, Boston, MA, Etext. See especially: "Aristotle".