Salvar las apariencias, anticipar experiencias y la meta de la teorización científica

Mi objetivo es presentar la idea de que la ciencia no sólo da cuenta de los hechos de experiencia sino que también persigue la innovación teórica, una tarea tan importante como la otra. Aunque la primera labor encomendada históricamente a la ciencia es efectivamente la de dar cuenta de los hechos de la experiencia, después de dos milenios y medio, sigue siendo una cuestión candente del debate filosófico si ésta debe consistir en (i) explicar las observaciones, es decir, hacer explícitas las razones de las cosas, o (ii) salvar las apariencias, es decir, ajustar las observaciones a una teoría. Y en el primer caso, aún está en discusión si la explicación científica tiene que ser causal o no. En esta presentación, argumentaré que no lo es. Y vaya por delante que lo que me concierne es la posibilidad de explicaciones causales, no la de la causalidad misma. Pero cuestionar la existencia de explicaciones causales no significa renunciar a explicaciones en absoluto. La alternativa es la explicación teórica, es decir, la explicación por referencia a marcos teóricos, que presento como la tercera vía, y ayuda a aliviar la tensión entre los partidarios de la explicación causal y los de salvar los fenómenos. Hay además un componente principal de la actividad científica al que la filosofía contemporánea ni le ha hecho justicia ni le ha prestado la atención que merece. Lo llamo innovación teórica y consiste en idear propuestas novedosas, inesperadas, a veces sorprendentes y, en todo caso, útiles para el avance de la ciencia y la cultura

Oxygen vacancies in strained SrTiO3_{3} thin films: formation enthalpy and manipulation

We report the enthalpy of oxygen vacancy formation in thin films of electron-doped SrTiO$_{3}$, under different degrees of epitaxial stress. We demonstrate that both compressive and tensile strain decrease this energy at a very similar rate, and promote the formation of stable doubly ionized oxygen vacancies. Moreover, we also show that unintentional cationic vacancies introduced under typical growth conditions, produce a characteristic rotation pattern of TiO$_6$ octahedra. The local concentration of oxygen vacancies can be modulated by an electric field with an AFM tip, changing not only the local electrical potential, but also producing a non-volatile mechanical response whose sign (up/down) can be reversed by the electric field.Comment: Physical Review B (accepted for publication

Discovery practices in natural sciences: from analogy to preduction

In this paper I face up to Charles Peirce’s view that deduction can never originate any idea whatsoever. According to him new ideas come to science only by means of abduction. I affirm on my side that deductive reasoning can be extended to the context of discovery in mathematical physics. Thus a new form of discovery becomes recognizable. I call it preduction and I claim that it is the way by which many factual hypotheses, theoretical laws and theoretical models are anticipated in physics. I point also to the fact that both, abduction and preduction, provide us with intrinsically fallible hypotheses. The fallibility of abductive inferences was already recognized by Peirce himself. The fallibility of preductive inferences follows directly from the fact that the available background, on which the preductive way of reasoning grounds, can be not true. Since moreover many other creativity practices, like induction, analogy and serendipity, are worthy to be taken into consideration in the methodology of natural sciences, it becomes reasonable to assume the existence of a plurality of fallible strategies in scientific discovery.In this paper I face up to Charles Peirce’s view that deduction can never originate any idea whatsoever. According to him new ideas come to science only by means of abduction. I affirm on my side that deductive reasoning can be extended to the context of discovery in mathematical physics. Thus a new form of discovery becomes recognizable. I call it preduction and I claim that it is the way by which many factual hypotheses, theoretical laws and theoretical models are anticipated in physics. I point also to the fact that both, abduction and preduction, provide us with intrinsically fallible hypotheses. The fallibility of abductive inferences was already recognized by Peirce himself. The fallibility of preductive inferences follows directly from the fact that the available background, on which the preductive way of reasoning grounds, can be not true. Since moreover many other creativity practices, like induction, analogy and serendipity, are worthy to be taken into consideration in the methodology of natural sciences, it becomes reasonable to assume the existence of a plurality of fallible strategies in scientific discovery

Polymer-assisted deposition of epitaxial oxide thin films

Traballo de Fin de Grao en Química. Curso 2014-2015The possibility of growing epitaxial thin-films has been intensely studied during the last decades. The development of the physical deposition techniques, such as Pulsed Laser Deposition (PLD), Sputtering or Molecular Beam Epitaxy (MBE) made possible the production films and multilayers of very high quality, although they have the serious drawback of the huge price of the equipment, particularly for small-laboratory basic research. For this reason, there is a great interest in developing more cost-effective chemical methods of deposition, which however must produce films of a quality similar to the physical techniques to meet the requirements of demanding applications. In this work we use a chemical method to grow metal-oxide thin films of a structural and morphological quality which is similar to that obtained by traditional physical high-vacuum methods. The process basis is the preparation of solutions containing the metal-cations precursors of the thin film; a soluble metal salt, a complexing agent and a polymer for retaining the cations are the basic components of the precursor solutions used in this study. By spin-coating the solutions over commercial monocrystalline substrates (like (001) oriented SrTiO3) and after a thermal treatment, thin-films of the materials of interest are obtained. A good control over the thickness and stoichiometry can be achieved through the control of the initial concentration of the solutions and the gaseous atmosphere during the annealing. In this study we obtained thin films epitaxially grown of BiFeO3, SrRuO3, La0.7Sr0.3MnO3 and a bilayer of BiFeO3/La0.7Sr0.3MnO3. These compositions were selected due to their scientific and technologic relevance. The structure and morphological characterization was carried out by X-ray and microscopy techniques. The electric and magnetic properties are also investigated to study the effect of the low dimensionality and epitaxial strain in these materials

Observaciones sobre "El significado del teorema de Bernoulli para la teoría de la inferencia estadística"

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