Scientific Methodology: A View from Early String Theory

This paper addresses the question as to whether the methodology followed in building and assessing string theory can be considered scientific in the same sense, say, that the methodology followed in building and assessing the Standard Model of particle physics is scientific, by focussing on the "founding" period of the theory. More precisely, its aim is to argue for a positive answer to the above question (there is no real change of scientific status in the way of proceeding and reasoning in fundamental physical research) in the light of a historical analysis of the early developments of the string theoretical framework.Comment: Contribution to the volume "Epistemology of Fundamental Physics: Why Trust a Theory?", eds. R. Dawid, R. Dardashti, and K. Thebault, Cambridge University Pres

Reductionism, Emergence, and Effective Field Theories

In recent years, a change in attitude in particle physics has led to our understanding current quantum field theories as effective field theories (EFTs). The present paper is concerned with the significance of this EFT approach, especially from the viewpoint of the debate on reductionism in science. In particular, it is a purpose of this paper to clarify how EFTs may provide an interesting case-study in current philosophical discussion on reduction, emergence and inter-level relationships in general.Comment: 18 pages, LateX2e, to appear in Studies in History and Philosophy of Modern Physic

Symmetries and invariances in classical physics

Symmetry, intended as invariance with respect to a transformation (more precisely, with respect to a transformation group), has acquired more and more importance in modern physics. This Chapter explores in 8 Sections the meaning, application and interpretation of symmetry in classical physics. This is done both in general, and with attention to specific topics. The general topics include illustration of the distinctions between symmetries of objects and of laws, and between symmetry principles and symmetry arguments (such as Curie's principle), and reviewing the meaning and various types of symmetry that may be found in classical physics, along with different interpretative strategies that may be adopted. Specific topics discussed include the historical path by which group theory entered classical physics, transformation theory in classical mechanics, the relativity principle in Einstein's Special Theory of Relativity, general covariance in his General Theory of Relativity, and Noether's theorems. In bringing these diverse materials together in a single Chapter, we display the pervasive and powerful influence of symmetry in classical physics, and offer a possible framework for the further philosophical investigation of this topic

Symmetries in Physics: Philosophical Reflections

This is the introductive paper to the volume "Symmetries in Physics: Philosophical Reflections", Cambridge University Press, 2003. We begin with a brief description of the historical roots and emergence of the concept of symmetry that is at work in modern physics. Then, in section 2, we mention the different varieties of symmetry that fall under this general umbrella, outlining the ways in which they were introduced into physics. We also distinguish between two different uses of symmetry: symmetry principles versus symmetry arguments. In section 3 we make some remarks of a general nature concerning the status and significance of symmetries in physics. Finally, in section 4, we outline the structure of the book and the contents of each part.Comment: 16 pages. To appear in K. Brading and E. Castellani (eds.), "Symmetries in Physics: Philosophical Reflections", Cambridge University Press, 200

Scientific Methodology: A View from Early String Theory

This paper addresses the question as to whether the methodology followed in building/assessing string theory can be considered scientific in the same sense, say, that the methodology followed in building/assessing the Standard Model of particle physics is scientific, by focussing on the "founding" period of the theory. More precisely, its aim is to argue for a positive answer to the above question – there is no real change of scientific status in the way of proceeding and reasoning in fundamental physical research – in the light of a historical analysis of the early developments of the string theoretical framework

LOW-ENERGY ELECTRON DAMAGE IN DNA

In this thesis, Photo-Electron Spectroscopy (PES) and Photo-Electron Imaging (PEI) have been exploited to study low-energy electron and photon-driven damage in DNA derivatives. After an introduction on photoelectron spectroscopy and DNA, an instrumental overview, together with a brief explanation of the theoretical methods used, is given. The results section is divided according to the different chemical systems that have been considered. First, the viability of a dipole-bound state, which are electronic non-valence states that play an important role in electron transfer in DNA, has been studied in a model molecule: despite the presence of an alkyl chain directly poking into it, the dipole-bound state is retained in all cases. Secondly, the possibility of achieving intra-molecular charge transfer as probe for low-energy electron damage has been explored in a carboxylated adenosine analogue. Although no conclusive evidence of charge-transfer from the carboxylic acid to the nucleobase has been observed, this approach has then been applied to different DNA derivatives. The object of the third section of the results chapter is, in fact, the photophysics of the doubly-deprotonated dianion of adenosine-5’-triphosphate, which exhibits electron tunneling through the Repulsive Coulomb Barrier (RCB) upon irradiation at 266 nm; excited states calculation and RCB simulations have been performed to support these findings. Lastly, the photophysics of other doubly-deprotonated di- and tri-phosphorylated purine dianions have been explored in the last section: only one of them, adenosine diphosphate ([ADP–H2]2–), shows evidence of intra-molecular charge transfer, however further research is needed to corroborate this hypothesis

Which Curie's Principle

Is there more that one "Curie's principle"? How far are different formulations legitimate? What are the aspects that make it so scientifically fruitful, independently of how it is formulated? The paper is devoted to exploring these questions. We start with illustrating Curie's original 1894 article and his focus. Then, we consider the way that the discussion of the principle took shape from early commentators to its modern form. We say why we think that the modern focus on the inter-state version of the principle loses sight of some of the most interesting significant applications of the principle. Finally, we address criticism of the principle put forward by Norton (2014) and purported counterexamples due to Roberts (2013, 2014)

Small-Scale Compressed Air Energy Storage Application for Renewable Energy Integration in a Listed Building

In the European Union (EU), where architectural heritage is significant, enhancing the energy performance of historical buildings is of great interest. Constraints such as the lack of space, especially within the historical centers and architectural peculiarities, make the application of technologies for renewable energy production and storage a challenging issue. This study presents a prototype system consisting of using the renewable energy from a photovoltaic (PV) array to compress air for a later expansion to produce electricity when needed. The PV-integrated small-scale compressed air energy storage system is designed to address the architectural constraints. It is located in the unoccupied basement of the building. An energy analysis was carried out for assessing the performance of the proposed system. The novelty of this study is to introduce experimental data of a CAES (compressed air energy storage) prototype that is suitable for dwelling applications as well as integration accounting for architectural constraints. The simulation, which was carried out for an average summer day, shows that the compression phase absorbs 32% of the PV energy excess in a vessel of 1.7 m(3), and the expansion phase covers 21.9% of the dwelling energy demand. The electrical efficiency of a daily cycle is equal to 11.6%. If air is compressed at 225 bar instead of 30 bar, 96.0% of PV energy excess is stored in a volume of 0.25 m3, with a production of 1.273 kWh, which is 26.0% of the demand

The Practice of Naturalness: A Historical-Philosophical Perspective

The fact that no evidence of "new physics" was found so far by LHC experiments has led some to call for the abandonment of the "naturalness" criterion. Others, on the contrary, have felt the need to break a lance in its defense by claiming that it should not be dismissed too quickly, but rather only reshaped to fit new needs. In this paper we argue that present pro-or-contra naturalness debates often miss an important historical point: that naturalness is essentially a hazily defined notion which, in the course of more than four decades, has been steadily, and often not coherently, shaped by its interplay with different branches of model-building in high-energy physics and cosmology on the one side, and new experimental results on the other side. The paper endeavours to clear up some of the physical and philosophical haze by taking a closer look back at the origin of naturalness in the 1970s and ‘80s, with particular attention to the early work of Kenneth Wilson

Symmetry breaking

A brief introduction to the physics and philosophy of symmetry breaking