Experimentum Crucis vs. Exploratory Experiments

 

  The idea that science advances through a combination of experiment and mathematically based theory is relatively new. It originated in Florence only 350 years ago, yesterday in comparison with span of human history. The originator was Galileo, the first modern scientist, who saw that science proceeds by considering a narrow range of phenomena and that the result will be laws that can be described in precise mathematical terms. This was among the greatest and most productive discoveries in the entire history of ideas.

   Actually Galileo is said to perform his famous experiment at the Leaning Tower of Pizza only in his mind − it was a so-called thought experiment. Unlike this famous experiment, a field experiment is carried out in real circumstances. Experimental evidence is crucial for establishing a hypothesis as a law. Unlike the method of observation a controlled experiment restricts the aspects of the phenomenon under study to a manageable number.

   It is common practice in the scientific community to share the findings of the research in articles and presentations so that the experiments might be reproduced or replicated by other scientists under the same conditions and by the same techniques thus proving the validity of the obtained data.

   Experiments are designed with previously formulated theories in mind and serve primarily to test or demonstrate them. The theoretician puts certain definite questions to the experimenter, and the latter, by his experiments tries to give a decisive answer o them. It makes sense to perform an isolated experiment, and in particular, experimentum crucis, designed to judge between the competing hypotheses. Newton followed such an approach in his experiments on color.

   Such was the case of the ether experiment, in which the answer was definitely “No”: such substance on which existence a lot of scientific theories depended merely did not exist. Thus, negative results of controlled experiments designed to test a hypothesis or theory are as important as positive ones. By contrast, the defining characteristic of exploratory experimentation is the systematic and extensive variation of experimental conditions to discover which of them influence or are necessary for the phenomenon under study.

    Textbook accounts of the history of physics usually highlight discoveries involving simple systems, that is, those consisting of relatively few interacting elements. Such systems lend themselves to study by means of isolated experiments designed to demonstrate directly the underlying physical principle. Most of the celebrated experiments in physics, from Galileo’s with balls on inclined planes to Robert Millikan’s with oil drops are of this type. The physicist studying a simple system deliberately removes the complicating influences.

    Physicists studying complex systems that consist of numerous interacting elements face a task different from that confronting Newton. They often start with a multitude of empirical findings whose interconnections and underlying principle s are unclear. They must use the experiments to develop concepts needed to make sense of multiplicity. The student of complexity must be an explorer, performing numerous laboratory or numerical experiments under different conditions.

    Exploratory experimentation has proved successful not only in optics, but also in other fields of physics. In the field of electricity and magnetism the work of A. von Humboldt can be noted. It was a reaction to L. Galvani’s discovery of animal electricity in the 1890s. W. Roentgen’s investigations of X-rays are also an example of exploratory experiments. In his methodological essay The experiment as a Mediator between Object and Subject Goethe described the result of exploratory experimentation approach as “ a series of experiments that border on one another closely and touch each other directly “. Such experiments often result in establishing the hierarchy within the realm of phenomena. By contrast, isolated experiments are not very informative, let alone, demonstrative, as they well might be theory-oriented work. However, Newton’s point of view is nicely expressed: “try only the experimentum crucis, for where one will do, what need for many?”

TALKING POINT

8. Discuss in pairs:

· types of experiments

· most famous experiments in physics

 

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