130 research outputs found
Two Cognitive Dimensions of Students’ Mental Models in Science: Fidelity of Gestalt and Functional Fidelity
No full textA poorly elaborated learner’s understanding of models has been reported to be one of the major sources for learning difficulties in the quantum domain. To be able to provide physics education in schools with evidence as to how this problem can be tackled, a deeper theoretical understanding of the structure of learners’ mental models in quantum physics seems essential. In this respect, previous research has proposed two dimensions in learners’ mental models in the atomic hull context, labelled Fidelity of Gestalt and Functional Fidelity. In this article, we investigate whether this proposed two-factorial structure can be transferred to quantum concepts beyond the atomic hull context. To approach this, we surveyed the structure of students’ mental models in the context of photons’ properties and behavior. We conducted a questionnaire study: 170 secondary school students completed a survey instrument adapted from the literature. Using exploratory factor analysis, the two factors Fidelity of Gestalt and Functional Fidelity to describe the students’ mental models could be replicated for the photon context. We provide a selection of results from physics education literature to reveal that our two-factor framework to describe the students’ mental models seems to be a promising endeavor in the landscape of science education research in general
A Haptic Model of Entanglement, Gauge Symmetries and Minimal Interaction Based on Knot Theory
No full textThe Heegaard splitting of S U ( 2 ) is a particularly useful representation for quantum phases of spin j-representation arising in the mapping S 1 → S 3, which can be related to ( 2 j , 2 ) torus knots in Hilbert space. We show that transitions to homotopically equivalent knots can be associated with gauge invariance, and that the same mechanism is at the heart of quantum entanglement. In other words, (minimal) interaction causes entanglement. Particle creation is related to cuts in the knot structure. We show that inner twists can be associated with operations with the quaternions ( I , J , K ), which are crucial to understand the Hopf mapping S 3 → S 2. We discuss the relationship between observables on the Bloch sphere S 2, and knots with inner twists in Hilbert space. As applications, we discuss selection rules in atomic physics, and the status of virtual particles arising in Feynman diagrams. Using a simple paper strip model revealing the knot structure of quantum phases in Hilbert space including inner twists, a h a p t i c model of entanglement and gauge symmetries is proposed, which may also be valid for physics education
Typisierung des Verständnisses mentaler Modelle mittels empirischer Datenerhebung am Beispiel der Quantenphysik
No full textVerständnisprozesse sind zentraler Teil des Lernens und der Bildung. Vor allem in den Naturwissenschaften und in der Mathematik ist es jedoch häufig der Fall, dass diese Prozesse nur teils oder gar nicht stattfinden. Ausgehend von dieser Problematik wird hier eine Studie vorgestellt, die mentale Modelle der Atomhülle und allgemein das Modellverständnis in der Physik gemeinsam untersucht. Aus den gewonnen empirischen Daten werden dabei vier Verständnistypen mentaler Modelle abgeleitet und mittels Literaturvergleichs in die Literatur der naturwissenschaftlichen Didaktik eingeordnet. Somit liefert die vorliegende Arbeit nicht nur eine mögliche Erklärung für das Festhalten an klassischen, mechanistischen Modellvorstellungen trotz der Einführung in die Quantenphysik, sondern auch generell für Probleme beim Verständnisprozess, die in der naturwissenschaftlichen Didaktik beim Lernen mit Modellen und bei Vorstellungen auftreten. (DIPF/Orig.
“Stars Falling to Earth”—Mental Models of Comets and Meteors
No full textThe present study examines students’ conceptions of comets and meteors using qualitative research methods. A total of 35 semi-structured interviews were conducted with students in grades 7 and 9 in Germany, aiming to gain a richer understanding of how learners conceptualize these phenomena. We identified and categorized distinct mental models related to both the appearance (gestalt) and function of comets and meteors, which are reported in detail in this article. Ideas about meteors tend to align with scientific explanations, whereas answers about comets vary widely and often lack a basic understanding. Based on our data, we recommend that educational approaches begin with a clear introduction to physical properties to establish a solid foundation of knowledge. Both aspects of the gestalt and functionality of comets and meteors should be considered and emphasized in the teaching and learning process
The Topological Origin of Quantum Randomness
No full textWhat is the origin of quantum randomness? Why does the deterministic, unitary time development in Hilbert space (the ‘4π-realm’) lead to a probabilistic behaviour of observables in space-time (the ‘2π-realm’)? We propose a simple topological model for quantum randomness. Following Kauffmann, we elaborate the mathematical structures that follow from a distinction(A,B) using group theory and topology. Crucially, the 2:1-mapping from SL(2,C) to the Lorentz group SO(3,1) turns out to be responsible for the stochastic nature of observables in quantum physics, as this 2:1-mapping breaks down during interactions. Entanglement leads to a change of topology, such that a distinction between A and B becomes impossible. In this sense, entanglement is the counterpart of a distinction (A,B). While the mathematical formalism involved in our argument based on virtual Dehn twists and torus splitting is non-trivial, the resulting haptic model is so simple that we think it might be suitable for undergraduate courses and maybe even for High school classes
A Knot Theoretic Extension of the Bloch Sphere Representation for Qubits in Hilbert Space and Its Application to Contextuality and Many-Worlds Theories
No full textWe argue that the usual Bloch sphere is insufficient in various aspects for the representation of qubits in quantum information theory. For example, spin flip operations with the quaternions I J K = e 2 π i 2 = − 1 and J I K = + 1 cannot be distinguished on the Bloch sphere. We show that a simple knot theoretic extension of the Bloch sphere representation is sufficient to track all unitary operations for single qubits. Next, we extend the Bloch sphere representation to entangled states using knot theory. As applications, we first discuss contextuality in quantum physics—in particular the Kochen-Specker theorem. Finally, we discuss some arguments against many-worlds theories within our knot theoretic model of entanglement. The key ingredients of our approach are symmetries and geometric properties of the unitary group
Role of oxygen vacancies for resistive switching in noble metal sandwiched Pr<sub>0.67</sub>Ca<sub>0.33</sub>MnO<sub>3-δ</sub>
No full textNon-volatile resistance change under electric stimulation in oxides is a promising path to next generation memory devices. However, the underlying mechanisms are still not fully understood. We report here on the study of switching in Pr0.67Ca0.33MnO3-delta (PCMO) films sandwiched by noble metal Pt electrodes, where electrode oxidation can be excluded. In order to develop an understanding of the switching induced oxygen migration, its initial concentration is modified by post-annealing of the deposited PCMO films. The oxygen distribution is obtained by manganese valence determination using spatially resolved electron energy loss spectroscopy in scanning transmission electron microscopy mode. We observe correlations between virgin state resistance, resistive switching properties, oxygen vacancy distribution, and stress/strain state of the PCMO films and propose a simplified interface resistance model based on the measured valence distribution. It assumes a linear correlation of oxygen vacancy concentration with conductivity and a metal to insulator transition above a critical vacancy concentration threshold. Our results suggest that resistance changes can take place at both interfaces of symmetric devices and only requires small changes in oxygen vacancy concentration. (C) 2017 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).DFG [Jo 348/10-01
From the Big Bang to Life beyond Earth: German Preservice Physics Teachers’ Conceptions of Astronomy and the Nature of Science
No full textThis article reports the findings of a qualitative study that aimed to explore the ideas of 22 preservice physics teachers regarding astronomy concepts both within and beyond the solar system, as well as their understanding of the Nature of Science in the context of astronomy. The study employed a combination of open-ended vignette tasks and ranking tasks, which were adapted from previous research. The results reveal that while the majority of the preservice teachers held appropriate conceptions of astronomy concepts, some of their ideas lacked depth and were superficial. Moreover, their understanding of the Nature of Science in the context of astronomy was found to be limited. This study highlights the importance of providing further education and training in this area, as well as the need to develop and test effective teaching strategies to enhance preservice teachers’ and physics education students’ understanding of astronomy concepts and the Nature of Science
Quantum science in a nutshell: fostering students' functional understanding of models
No full textFostering students' understanding of models is a challenge. However, in particular for learning quantum physics an elaborate understanding of models is required. We investigated activities to foster students' functional thinking about (quantum) models in a synchronous online course. The results of an evaluation study (N = 59) showed that the participants improved in their quantum physical thinking about photons and had slightly improved their understanding of physics models in general. A correlation analysis indicates that there are no significant correlations between the students' general understanding of models in physics and their functional understanding of quantum models. Implications of our findings for both teaching and future research with regard to quantum physics education are discussed.</p
Quantum science in a nutshell: fostering students' functional understanding of models
No full textFostering students' understanding of models is a challenge. However, in particular for learning quantum physics an elaborate understanding of models is required. We investigated activities to foster students' functional thinking about (quantum) models in a synchronous online course. The results of an evaluation study (N = 59) showed that the participants improved in their quantum physical thinking about photons and had slightly improved their understanding of physics models in general. A correlation analysis indicates that there are no significant correlations between the students' general understanding of models in physics and their functional understanding of quantum models. Implications of our findings for both teaching and future research with regard to quantum physics education are discussed
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