Understanding is an ability manifested by grasping relations of a phenomenon and articulating new explanations. Hence, scientific understanding is inextricably intertwined with and not possible without explanation, and understanding is not a type of propositional knowledge. Anna Elisabeth Höhl provides a novel philosophical account of scientific understanding by developing and defending necessary and sufficient conditions for the understanding that scientists achieve of the phenomena they are researching. This account of scientific understanding is based on and supported by a detailed investigation (...) of an episode from scientific practice in biology. (shrink)

'The arrow of time' refers to the curious asymmetry that distinguishes the future from the past. Reversing the Arrow of Time argues that there is an intimate link between the symmetries of 'time itself' and time reversal symmetry in physical theories, which has wide-ranging implications for both physics and its philosophy. This link helps to clarify how we can learn about the symmetries of our world, how to understand the relationship between symmetries and what is real, and how to overcome (...) pervasive illusions about the direction of time. Roberts explains the significance of time reversal in a way that intertwines physics and philosophy, to establish what the arrow of time means and how we can come to know it. This book is both mathematically and philosophically rigorous yet remains accessible to advanced undergraduates in physics and the philosophy of physics. This title is also available as Open Access on Cambridge Core. (shrink)

For over a century the definitions of mass and derivations of its relation with energy continue to be elaborated, demonstrating that the concept of mass is still not satisfactorily understood. The aim of this study is to show that, starting from the properties of Minkowski spacetime and from the principle of least action, energy expresses the property of inertia of a body. This implies that inertial mass can only be the object of a definition—the so called mass-energy relation—aimed at measuring (...) energy in different units, more suitable to describe the huge amount of it enclosed in what we call the “rest-energy” of a body. Likewise, the concept of gravitational mass becomes unnecessary, being replaceable by energy, thus making the weak equivalence principle intrinsically verified. In dealing with mass, a new unit of measurement is foretold for it, which relies on the de Broglie frequency of atoms, the value of which can today be measured with an accuracy of a few parts in 109. (shrink)

This book argues that a plausible account of emergence requires replacing the traditional assumption that what primarily exists are particular entities with generic processes. Traversing contemporary physics and issues of identity over time, it then proceeds to develop a metaphysical taxonomy of emergent entities and of the character of human life.

I describe recent developments of Conway and Kochen on the physical meaning of freewill and their theorem that the assertion of freewill for human beings, in their specific sense, implies the same for elementary particles. This description is given in simplified metaphorical terms that nonetheless address the key physical axioms and essential analytic content of their argument. I then give points of contact of our metaphor with the full technical analysis of the cited authors and conclude with some associated metaphysical (...) speculations. These include the implications of the freewill theorem for dual aspect theories and, in particular, for process metaphysics. (shrink)

In the popular literature of physics the electromagnetic field isoften treated as though it has an intrinsic particle nature. When thetheory is examined carefully, quantum theory only makes the weakerrequirement that the emission and absorption of light are restricted todiscrete amounts of energy. There are very few realizable experiments inoptics for which the classical Maxwell theory and the quantum theorymake a different prediction. I discuss some of these experiments with anemphasis on the distinction between what the experiments tell us aboutthe (...) measurement process, and what they tell us about the nature of thelight field. (shrink)

In A Thousand Plateaus, Deleuze and Guattari carve out an image of thought and a path for philosophy that is connected to the figure of the cosmic artisan. This article situates the artisan in relation to both past and future, comparing this figure to that of the artist in the work of another great philosopher who desired to bring forth a new beginning for philosophy, Martin Heidegger. After discussing multiple ways that Deleuze and Guattari's thought is world-destroying in terms of (...) past ontological and epistemological commitments, the article considers the cosmic artisan/philosopher's diagrammatic role in light of the technological-scientific advancements within the field of quantum physics. Through these elaborations, it becomes clear that Deleuze and Guattari are articulating the need for a new sensibility – to the imperceptible, the virtual, the compossible and the molecular. Deleuze and Guattari's noological nomadism opens a way forward, where world-destroying becomes linked to creation, and the figure of modernity becomes the possibility of a new relation to the earth – a cosmic earth. (shrink)

It is argued that a realistic interpretation of quantum mechanics is possible and useful. Current interpretations, from “Copenhagen” to “many worlds” are critically revisited. The difficulties for intuitive models of quantum physics are pointed out and possible solutions proposed. In particular the existence of discrete states, the quantum jumps, the alleged lack of objective properties, measurement theory, the probabilistic character of quantum physics, the wave–particle duality and the Bell inequalities are analyzed. The sketch of a realistic picture of the quantum (...) world is presented. It rests upon the assumption that quantum mechanics is a stochastic theory whose randomness derives from the existence of vacuum fields. They correspond to the vacuum fluctuations of quantum field theory, but taken as real rather than virtual. (shrink)

The dominance of string theory in the research landscape of quantum gravity physics (despite any direct experimental evidence) can, I think, be justified in a variety of ways. Here I focus on an argument from mathematical fertility, broadly similar to Hilary Putnam’s ‘no miracles argument’ that, I argue, many string theorists in fact espouse in some form or other. String theory has generated many surprising, useful, and well-confirmed mathematical ‘predictions’—here I focus on mirror symmetry and the mirror theorem. These predictions (...) were made on the basis of general physical principles entering into string theory. The success of the mathematical predictions are then seen as evidence for the framework that generated them. I shall attempt to defend this argument, but there are nonetheless some serious objections to be faced. These objections can only be evaded at a considerably high (philosophical) price. (shrink)

Discoveries in physics imply two elements. The firstone is the belief that formal tools, already foundedin the framework of existing mathematical theories,may offer the solution to a puzzling anomaly. Thesecond one is the ability to assign a physical meaningto the adopted formalism, and to consider all itstheoretical implications.Discussing an historical case where the adoption of aparticular formalism represents the real motor of thecreative intuition, we mean to delineate scientificdiscovery both as a discontinuous change with respectto previous achievements and as a (...) linear process ofknowledge enrichment. (shrink)

Classical (Bayesian) probability (CP) theory has led to an influential research tradition for modeling cognitive processes. Cognitive scientists have been trained to work with CP principles for so long that it is hard even to imagine alternative ways to formalize probabilities. However, in physics, quantum probability (QP) theory has been the dominant probabilistic approach for nearly 100 years. Could QP theory provide us with any advantages in cognitive modeling as well? Note first that both CP and QP theory share the (...) fundamental assumption that it is possible to model cognition on the basis of formal, probabilistic principles. But why consider a QP approach? The answers are that (1) there are many well-established empirical findings (e.g., from the influential Tversky, Kahneman research tradition) that are hard to reconcile with CP principles; and (2) these same findings have natural and straightforward explanations with quantum principles. In QP theory, probabilistic assessment is often strongly context- and order-dependent, individual states can be superposition states (that are impossible to associate with specific values), and composite systems can be entangled (they cannot be decomposed into their subsystems). All these characteristics appear perplexing from a classical perspective. However, our thesis is that they provide a more accurate and powerful account of certain cognitive processes. We first introduce QP theory and illustrate its application with psychological examples. We then review empirical findings that motivate the use of quantum theory in cognitive theory, but also discuss ways in which QP and CP theories converge. Finally, we consider the implications of a QP theory approach to cognition for human rationality. (shrink)

I discuss the nature of the puzzle about the time‐asymmetry of radiation and argue that its most common formulation is flawed. As a result, many proposed solutions fail to solve the real problem. I discuss a recent proposal of Mathias Frisch as an example of the tendency to address the wrong problem. I go on to suggest that the asymmetry of radiation, like the asymmetry of thermodynamics, results from the initial state of the universe.

We formalize the notion of isolated objects, and we build a consistent theory to describe their evolution and interaction. We further introduce a notion of indistinguishability of distinct spacetime paths of a unit, for which the evolution of the state variables of the unit is the same, and a generalization of the equivalence principle based on indistinguishability. Under a time reversal condition on the whole set of indistinguishable paths of a unit, we show that the quantization of motion of spinless (...) elementary particles in a general potential field can be derived in this framework, in the limiting case of weak fields and low velocities. Extrapolating this approach to include weak relativistic effects, we explore possible experimental consequences. We conclude by suggesting a primitive ontology for the theory of isolated objects. (shrink)

Although the present paper looks upon the formal apparatus of quantum mechanics as a calculus of correlations, it goes beyond a purely operationalist interpretation. Having established the consistency of the correlations with the existence of their correlata, and having justified the distinction between a domain in which outcome-indicating events occur and a domain whose properties only exist if their existence is indicated by such events, it explains the difference between the two domains as essentially the difference between the manifested world (...) and its manifestation. A single, intrinsically undifferentiated Being manifests the macroworld by entering into reflexive spatial relations. This atemporal process implies a new kind of causality and sheds new light on the mysterious nonlocality of quantum mechanics. Unlike other realist interpretations, which proceed from an evolving-states formulation, the present interpretation proceeds from Feynman’s formulation of the theory, and it introduces a new interpretive principle, replacing the collapse postulate and the eigenvalue–eigenstate link of evolving-states formulations. Applied to alternatives involving distinctions between regions of space, this principle implies that the spatiotemporal differentiation of the physical world is incomplete. Applied to alternatives involving distinctions between things, it warrants the claim that, intrinsically, all fundamental particles are identical in the strong sense of numerical identical. They are the aforementioned intrinsically undifferentiated Being, which manifests the macroworld by entering into reflexive spatial relations. (shrink)

Approaches to the interpretation of physical theories provide accounts of how physical meaning accrues to the mathematical structure of a theory. According to many standard approaches to interpretation, meaning relations are captured by maps from the mathematical structure of the theory to statements expressing its empirical content. In this article I argue that while such accounts adequately address meaning relations when exact models are available or perturbation theory converges, they do not fare as well for models that give rise to (...) divergent perturbative expansions. Since truncations of divergent perturbative expansions often play a critical role in establishing the empirical adequacy of a theory, this is a serious deficiency. I show how to augment state-space semantics, a view developed by Beth and van Fraassen, to capture perturbatively evaluated observables even in cases where perturbation theory is divergent. This new semantics establishes a sense in which the calculations that underwrite the empirical adequacy of a theory are both meaningful and true, but requires departure from the assumption that physical meaning is captured entirely by the exact models of a theory. (shrink)

There are two distinct interpretations of the role that Feynman diagrams play in physics: (i) they are calculational devices, a type of notation designed to keep track of complicated mathematical expressions; and (ii) they are representational devices, a type of picture. I argue that Feynman diagrams not only have a calculational function but also represent: they are in some sense pictures. I defend my view through addressing two objections and in so doing I offer an account of representation that explains (...) why Feynman diagrams represent. The account that I advocate is a version of that defended by Kendall Walton, which provides us with a basic characterization of the way that representations in general work and is particularly useful for understanding distinctively pictorial representations - in Walton's terms, depictions. The question of the epistemic function of Feynman diagrams as pictorial representations is left for another time. (shrink)

In "Why Feynman Diagrams Represent", I argued that Feynman diagrams have two distinct functions: they are both calculational devices, developed to keep track of the long mathematical expressions of quantum electrodynamics,1 and they are pictorial representations. This challenges the common view that FDs are calculational devices alone and that it is misleading, if not an outright error, to think of them as pictorial. Following Kendall Walton's account of representation, I drew out what it means to think of FDs as pictures, (...) which in turn explained why FDs represent. However, my defence conceded an important point: not all of... (shrink)

The purpose of this work is to carry out a systematic, detailed analytical study, together with the direct interpretations, as they follow from the analytical expressions obtained, of three basic “experiments” which have been classical examples in our understanding of quantum mechanics. The experiments considered are: the single- and double-slit (-hole) experiments, and the final one, which, in particular, deals with the situation where a particle is “reflected off” the detection screen in the single-slit experiment. Special emphasis is put on (...) pointing out some purely quantum mechanical results, which follow from the analytical expressions, as well as on making a comparison with classical physics. Needless to say, the analysis of such experiments has been extremely important in laying the foundations of quantum physics. (shrink)

Richard Swinburne has given a defense of arguments for the existence of God (and in particular of teleological arguments) in his book "The Existence of God" (1979/1991). This paper argues that such theistic arguments fail, and poses some general problems for theistic arguments. Swinburne's use of a principle of simplicity is not given adequate justification and, if justified, works against theism. There are adequate rebuttals to Swinburne's arguments that depend upon there being few particles of basic physics, universal laws of (...) nature, cogent cosmological argument, and temporal order in the universe. Theistic arguments falter on malleability, on going well beyond evidence, on anthropomorphism, on treating consistency as if it were evidence or explanation, on selective and inconsistent use of principles, and on a lack of any serious attempt to disprove hypotheses. All of this serves to support the conclusion suggested by Hume's posthumous theological writings that theistic arguments are so malleable, profligate, overreaching, equivocal, anthropomorphic, selective, inconsistent, and uncritical as to be inept. (shrink)

“The universe is expanding, not contracting.” Many statements of this form appear unambiguously true; after all, the discovery of the universe’s expansion is one of the great triumphs of empirical science. However, the statement is time-directed: the universe expands towards what we call the future; it contracts towards the past. If we deny that time has a direction, should we also deny that the universe is really expanding? This article draws together and discusses what I call ‘C-theories’ of time — (...) in short, philosophical positions that hold time lacks a direction — from different areas of the literature. I set out the various motivations, aims, and problems for C-theories, and outline different versions of antirealism about the direction of time. (shrink)