Law Enforcement: Realism and Laws of Nature, Classical and Quantum
- 1:30–2:00 John Bigelow - Laws’ Dominions
- 2:00–2:30 Martin Leckey - Galileo and Idealizations in Laws of Nature
- 2:30–3:00 Adrian Flitney - Realist Interpretations of Quantum Mechanics
Organiser: Martin Leckey
University of Melbourne
The topic of the session is a realist philosophical account of laws of nature, and its engagement with two case studies, one from Classical Physics, and another from Quantum Mechanics. The general orientation of the papers in this session maintains that, in a law that is expressed by an equation, the symbolism in that equation is not just a meaningless tool that enables us to predict outcomes of experiments. The symbolism in a good law of nature represents things that exist in the world.
The first paper “Laws’ Dominions” offers a philosophical account of laws of nature – a revised version of one of the 'necessitarian' theories according to which laws are to be understood as relations among universals. Something is a law just in case it is entailed by the set of properties that demarcate a given domain of application – provided they take on states that fall entirely within this domain.
The second paper “Galileo and idealizations in laws of nature” aims to use a case study of Galileo’s experiments and derivations of laws regarding balls rolling down inclined planes. It looks at challenges to any realist account of laws, in particular the account provided in the first paper, provided by the use in laws of nature of idealizations such as frictionless surfaces, which cannot in fact exist.
The third paper “Realist interpretations of quantum mechanics” considers realism about the laws of quantum mechanics and will look at challenges provided by quantum mechanics to a realist understanding of laws, and of the objects and properties described by those laws. The orthodox interpretation of quantum mechanics is generally thought to be anti-realist. This paper looks at the prospects for fruitful realist interpretations, in particular a new spontaneous collapse interpretation
It is easy to see how people’s behaviour can deviate from what is laid down by the laws that govern their jurisdiction. But it is harder to understand what the invisible ‘laws of nature’ might be, that govern the material world—or to understand how material things could ever fail to obey those laws of nature. Many philosophers since Hume have found it hard to see how a law of nature could be anything other than a regularity that can be observed among the things that happen in the material world. Nevertheless, we will argue that the laws of nature and the legislation governing a human population are, in principle, more similar than many philosophers have imagined. In the first place, laws of nature characteristically hold dominion only within a given, and sometimes relatively limited, domain of application. We will offer a revised version of one of the ‘necessitarian’ theories according to which laws are to be understood as relations among universals. Something is a law just in case it is entailed by the set of properties that demarcate a given domain of application—provided they take on states that fall entirely within this domain.
John Bigelow is Emeritus Professor of Philosophy at Monash University. He studied at the University of Canterbury, NZ, Simon Fraser University, Canada, and the University of Cambridge, England. He has held positions at Victoria University of Wellington, NZ and at La Trobe and Monash Universities, Australia, where he taught courses in the history and philosophy of science, metaphysics, and the philosophy of language. After retirement, he completed a Ph.D. at Monash University in English Literature, investigating the influence of Platonism in Shakespeare’s sonnets, and has continued tutoring and lecturing in Philosophy for University of Tasmania, the University of Melbourne, and (currently) the Australian Catholic University. He has recently completed research on modal ontology with Martin Leckey for a forthcoming collection of papers on the philosophy of David Lewis.
Galileo and idealizations in laws of nature
University of Melbourne
A challenge to any account of laws of nature is posed by the idealizations that figure in many laws of nature. A clear example is furnished by Galileo’s law of free fall, along with his discussion of a ball rolling down a frictionless inclined plane. But there are deep physical reasons why frictionless planes could not exist. We will argue that our realist understanding of laws of nature can give a good explanation of the content and utility of laws like these, which describe mathematical relationships between idealized physical quantities that are never actually instantiated. We will respond to recent work on idealizations in science, for instance by Peter Tan (2021). We will also look at Galileo’s own comments on the role of idealizations in laws of nature.
Martin Leckey is an Associate in History and Philosophy of Science, University of Melbourne. He has a Bachelor of Science with Honours in physics and an MA in history and philosophy of science from the University of Melbourne, and a PhD in philosophy from Monash University. There he began a long-term collaboration with his supervisor, John Bigelow, working on the metaphysics of laws of nature, and the metaphysics of properties, and more recently on Platonism in renaissance art. His PhD was on the metaphysics of space and time and quantum theory. This included looking at the consequences for quantum theory of adopting a completely discrete physics. This led to a modified quantum mechanics which provides a solution to the ‘measurement problem’. Recently, he has been collaborating with Adrian Flitney on working out the theory’s empirical predictions. He also has interests in later Heidegger, and philosophy of disability.
Realist interpretations of quantum mechanics
In physics, we often construct models that can successfully make numerical predictions about the results of experiments, but which don’t model the way we believe reality actually operates. Although few physicists argue about the predictions of quantum mechanics, which have been borne out by numerous detailed experiments, there is division about the interpretation of the wavefunction which governs the probabilistic predictions of quantum mechanical systems. In the orthodox interpretation of quantum mechanics, the wavefunction is simply a calculational tool for making predictions about experimental results but does not correspond to what is really there. Indeed, we often write down wavefunctions of one or a few particles, which are inevitably approximations since there are no truly isolated systems in the Universe. However, the concept of a ‘wave’ can often correspond to an element of reality: one can after all surf on a (water) wave! We consider prospects for a realist view of quantum mechanics, in particular models of spontaneous collapse of the wavefunction. Motivated by a realist interpretation of the wavefunction and a fully discrete physics, we propose a novel spontaneous collapse process. In doing so, we discover a new solution to the measurement problem in quantum mechanics. Reflecting on the theme of this session, we discuss some consequences of a realist interpretation of the laws and of matter in this modified quantum mechanics.
Adrian Flitney is a quantum physicist, mathematics and physics tutor, and chess coach, in addition to recently working as a research assistant in the field of sociology at RMIT University, where he is currently an Associate in the School of Science. He received a PhD from the Department of Electrical and Electronic Engineering, University of Adelaide in 2005 and held an ARC Postdoctoral Research Fellowship at the School of Physics, University of Melbourne, 2005-8, publishing widely in an area of quantum information theory known as quantum game theory, a field in which he is considered a world expert. Flitney’s current research interests are the measurement problem in quantum mechanics (with Dr Martin Leckey) and Islamophobia in Australia (with Dr Val Colic-Peisker). He co-authoured a recent book in the area of political philosophy with Val Colic-Peisker entitled The Age of Post-Rationality: Limits of economic reasoning in the 21st century (Palgrave- Macmillan: 2017).