Crucial experiments

Author(s):  
Peter Achinstein

A ‘crucial experiment’ allegedly establishes the truth of one of a set of competing theories. Francis Bacon (1620) held that such experiments are frequent in the empirical sciences and are particularly important for terminating an investigation. These claims were denied by Pierre Duhem (1905), who maintained that crucial experiments are impossible in the physical sciences because they require a complete enumeration of all possible theories to explain a phenomenon – something that cannot be achieved. Despite Duhem, scientists frequently regard certain experiments as crucial in the sense that the experimental result helps make one theory among a set of competitors very probable and the others very improbable, given what is currently known.

Author(s):  
Víctor Manuel Hernández

Although Pierre Duhem is well known for his conventionalist outlook and, in particular, for his critique of crucial experiments outlined in his thesis on the empirical indeterminacy of theory, he also contributed to the scholarship on the psychological profiles of scientists by revising Pascal’s famous distinction between the subtle mind and the geometric mind (esprits fins and esprits géométriques). For Duhem, the ideal scientist is the one who combines the defining qualities of both types of intellect. As a physicist, Duhem made important theoretical contributions to the field of thermodynamics as well as to the then-nascent physical chemistry. Due to his rejection of atomism and his unrelenting critique of Maxwell’s electrodynamics, however, in his later years, Duhem’s work was surpassed and abandoned by the dominant tendencies of physics of the time. In this essay, I will discuss whether Duhem himself can be understood through the lens of his own account of the scientist’s psychological profile. More specifically, I examine whether the subtle mind – to which he seems to assign greater cognitive value – in fact plays a key role in Duhem’s critique of the English School (école anglaise), or if his preference for the axiomatic structure of theoretical physics shows a greater affinity with the geometric mind.


2020 ◽  
Vol 62 (1) ◽  
pp. 73-93
Author(s):  
Piotr K. Szałek

Abstract The high point of the falsification of physical theories in a standard view of the philosophy of science is the so-called crucial experiment. This experiment is a kind of manipulated empirical test, which provides the criterion for distinguishing between two rival hypotheses, where one is an acceptable theory due to passing the test, and the other turns out to be an unacceptable theory as it does not pass the test. The crucial experiment was supposed to play a significant role because, in virtue of an empirical disconfirmation of one theory, the experiment was assumed to confirm the other as true. However, in 1906, in La théorie physique, son object et la structure (hereafter quoted in English translation as The Aim and Structure of Physical Theory (1906/1954)), Pierre Duhem famously argued against this view and stated that crucial experiments in physics are impossible as they are necessarily ambiguous and logically incomplete. His contention rested on the claim that, “[a] physical theory is not an explanation [of true reality in itself in virtue of some broad metaphysical ramification of physics]. It is a system of mathematical propositions, deduced from a small number of principles, which aim to represent as simply, as completely, and as accurately as possible a set of experimental laws” (ibid., p. 19). Furthermore, different theories could be equally suitable to represent a given group of experimental laws. And, assuming holism, no hypothesis could be tested in isolation, but merely as a part of a set of an entire scientific theory. The problem which Duhem identified in 1906 was slightly overshadowed and neglected in mainstream philosophy of science until the appearance of a challenging paper by Willard Van Orman Quine published in 1951 and entitled “Two Dogmas of Empiricism”. Quine’s paper caused a revival of interest in Duhem’s original formulation and gave a new impulse towards the problem in the form of the so-called Duhem-Quine thesis. The aim of this paper is to reconsider whether Duhem was right to argue that there are no crucial experiments in physics. In order to assess the validity of the thesis, first, this paper makes an exposition of Duhem’s arguments in their favour, and analyses the major criticisms of this position offered in the subject-literature of Adolf Grünbaum, who explicitly attacked the arguments for the thesis as inconclusive and false. Then, this paper presents possible modes of defence of the Duhem-Quine thesis and argues that the original formulation of the thesis is well qualified and plausible. Finally, this paper offers a pragmatic interpretation of the theory choice.


Author(s):  
Y. Kikuchi ◽  
N. Hashikawa ◽  
F. Uesugi ◽  
E. Wakai ◽  
K. Watanabe ◽  
...  

In order to measure the concentration of arsenic atoms in nanometer regions of arsenic doped silicon, the HOLZ analysis is carried out underthe exact [011] zone axis observation. In previous papers, it is revealed that the position of two bright lines in the outer SOLZ structures on the[011] zone axis is little influenced by the crystal thickness and the background intensity caused by inelastic scattering electrons, but is sensitive to the concentration of As atoms substitutbnal for Siatomic site.As the result, it becomes possible to determine the concentration of electrically activated As atoms in silicon within an observed area by means of the simple fitting between experimental result and dynamical simulatioan. In the present work, in order to investigate the distribution of electrically activated As in silicon, the outer HOLZ analysis is applied using a nanometer sized probe of TEM equipped with a FEG.Czodiralsld-gown<100>orientated p-type Si wafers with a resistivity of 10 Ώ cm are used for the experiments.TheAs+ implantation is performed at a dose of 5.0X1015cm-2at 25keV.


Author(s):  
G. McMahon ◽  
T. Malis

As with all techniques which are relatively new and therefore underutilized, diamond knife sectioning in the physical sciences continues to see both developments of the technique and novel applications.Technique Developments Development of specific orientation/embedding procedures for small pieces of awkward shape is exemplified by the work of Bradley et al on large, rather fragile particles of nuclear waste glass. At the same time, the frequent problem of pullout with large particles can be reduced by roughening of the particle surface, and a proven methodology using a commercial coupling agent developed for glasses has been utilized with good results on large zeolite catalysts. The same principle (using acid etches) should work for ceramic fibres or metal wires which may only partially pull out but result in unacceptably thick sections. Researchers from the life sciences continue to develop aspects of embedding media which may be applicable to certain cases in the physical sciences.


2019 ◽  
Vol 3 (1) ◽  
pp. 118-126 ◽  
Author(s):  
Prihangkasa Yudhiyantoro

This paper presents the implementation fuzzy logic control on the battery charging system. To control the charging process is a complex system due to the exponential relationship between the charging voltage, charging current and the charging time. The effective of charging process controller is needed to maintain the charging process. Because if the charging process cannot under control, it can reduce the cycle life of the battery and it can damage the battery as well. In order to get charging control effectively, the Fuzzy Logic Control (FLC) for a Valve Regulated Lead-Acid Battery (VRLA) Charger is being embedded in the charging system unit. One of the advantages of using FLC beside the PID controller is the fact that, we don’t need a mathematical model and several parameters of coefficient charge and discharge to software implementation in this complex system. The research is started by the hardware development where the charging method and the combination of the battery charging system itself to prepare, then the study of the fuzzy logic controller in the relation of the charging control, and the determination of the parameter for the charging unit will be carefully investigated. Through the experimental result and from the expert knowledge, that is very helpful for tuning of the  embership function and the rule base of the fuzzy controller.


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