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Special relativity
Published in Andrew Norton, Dynamic Fields and Waves, 2019
This is an extremely important result, and will be used throughout the rest of this chapter. What Equation 4.13 implies is that an object whose measured length is L0 when at rest, contracts by the factor 1−V2/c2 when measured by an observer relative to whom it moves at a speed V in a direction parallel to its measured length. This startling effect is called the Lorentz contraction (or sometimes Fitzgerald-Lorentz contraction). The formula was originally derived by the Dutch physicist H. A. Lorentz (Figure 4.31a), and independently by the Irish physicist G. F. Fitzgerald (Figure 4.31b), to explain the null result of the Michelson-Morley experiment by a real contraction of a body along its direction of motion through the ether. In their explanation, the speed V was relative to the ether and the contraction was actually caused by the ether. It was Einstein’s special theory of relativity which was able to show the correct explanation for this effect.
Necessary Characteristics of Quality Bioelectromagnetic Experimental Research
Published in Marko Markov, Dosimetry in Bioelectromagnetics, 2017
Logically, an experiment giving a null result can only show that any field effect is smaller than the level of the noise, though many published reports simply say, “no effect.” Here, “noise” refers to all variations in repeated measurements of the same parameter not directly related to the fields’ influence on it. The noise may include random fluctuations in the apparatus, biological variation among the organisms or systems being tested, uncontrolled environmental changes, and other confounders.
Systematic reviews in engineering education: a catalyst for change
Published in European Journal of Engineering Education, 2021
Preregistration requires the researcher to record the hypotheses, study design and analysis plans prior to the commencement of a research project. Fundamentally this is based on the differences between exploratory and confirmatory research designs (Vicente-Sáez and Martínez-Fuentes 2012). Vicente-Sáez and Martínez-Fuentes (2012) observe a worrying trend where researchers do not commit themselves to a method of data analysis until after they have seen the data. This results in a temptation to select tests that are more likely to provide the desired result. Analyses that do not follow the preregistration procedure should be clearly labelled as ‘exploratory’, while analyses that follow the preregistration process can be considered ‘confirmatory’ and should be held in higher regard. The authors continue to outline how this approach could reduce the publication of inflated results as well as tackling biases that all researchers carry, whether implicit or explicit. The strength of this approach is starting to gain traction; there are now limited examples of journals committing to publishing results based on the strength of a preregistration. This reduces publication bias, allows researchers to publish null results and crucially does not punish researchers for lack of a novel result. These are called registered reports (see Figure 1) and are presented as a mechanism that can ‘counter perverse incentives’ (Chambers 2019).