Explaining the unobserved: why quantum mechanics is not only about information

A remarkable theorem by Clifton, Bub and Halvorson (2003)(CBH) characterizes quantum theory in terms of information--theoretic principles. According to Bub (2004, 2005) the philosophical significance of the theorem is that quantum theory should be regarded as a ``principle'' theory about (quantum) information rather than a ``constructive'' theory about the dynamics of quantum systems. Here we criticize Bub's principle approach arguing that if the mathematical formalism of quantum mechanics remains intact then there is no escape route from solving the measurement problem by constructive theories. We further propose a (Wigner--type) thought experiment that we argue demonstrates that quantum mechanics on the information--theoretic approach is incomplete.Comment: 34 Page

The Topology of Branching Universes

The purpose of this paper is to survey the possible topologies of branching space-times, and, in particular, to refute the popular notion in the literature that a branching space-time requires a non-Hausdorff topology

What Is a Macrostate? Subjective Observations and Objective Dynamics

We consider the question of whether thermodynamic macrostates are objective consequences of dynamics, or subjective reflections of our ignorance of a physical system. We argue that they are both; more specifically, that the set of macrostates forms the unique maximal partition of phase space which 1) is consistent with our observations (a subjective fact about our ability to observe the system) and 2) obeys a Markov process (an objective fact about the system's dynamics). We review the ideas of computational mechanics, an information-theoretic method for finding optimal causal models of stochastic processes, and argue that macrostates coincide with the ``causal states'' of computational mechanics. Defining a set of macrostates thus consists of an inductive process where we start with a given set of observables, and then refine our partition of phase space until we reach a set of states which predict their own future, i.e. which are Markovian. Macrostates arrived at in this way are provably optimal statistical predictors of the future values of our observables.Comment: 15 pages, no figure

Local Causality and Completeness: Bell vs. Jarrett

J.S. Bell believed that his famous theorem entailed a deep and troubling conflict between the empirically verified predictions of quantum theory and the notion of local causality that is motivated by relativity theory. Yet many physicists continue to accept, usually on the reports of textbook writers and other commentators, that Bell's own view was wrong, and that, in fact, the theorem only brings out a conflict with determinism or the hidden-variables program or realism or some other such principle that (unlike local causality), allegedly, nobody should have believed anyway. (Moreover, typically such beliefs arise without the person in question even being aware that the view they are accepting differs so radically from Bell's own.) Here we try to shed some light on the situation by focusing on the concept of local causality that is the heart of Bell's theorem, and, in particular, by contrasting Bell's own understanding with the analysis of Jon Jarrett which has been the most influential source, in recent decades, for the kinds of claims mentioned previously. We point out a crucial difference between Jarrett's and Bell's own understanding of Bell's formulation of local causality, which turns out to be the basis for the erroneous claim, made by Jarrett and many others, that Bell misunderstood the implications of his own theorem.Comment: 10 pages, 4 figure

Quantum Theory: a Pragmatist Approach

While its applications have made quantum theory arguably the most successful theory in physics, its interpretation continues to be the subject of lively debate within the community of physicists and philosophers concerned with conceptual foundations. This situation poses a problem for a pragmatist for whom meaning derives from use. While disputes about how to use quantum theory have arisen from time to time, they have typically been quickly resolved, and consensus reached, within the relevant scientific sub-community. Yet rival accounts of the meaning of quantum theory continue to proliferate . In this article I offer a diagnosis of this situation and outline a pragmatist solution to the problem it poses, leaving further details for subsequent articles

Interpreting Quantum Mechanics in Terms of Random Discontinuous Motion of Particles

This thesis is an attempt to reconstruct the conceptual foundations of quantum mechanics. First, we argue that the wave function in quantum mechanics is a description of random discontinuous motion of particles, and the modulus square of the wave function gives the probability density of the particles being in certain locations in space. Next, we show that the linear non-relativistic evolution of the wave function of an isolated system obeys the free Schrödinger equation due to the requirements of spacetime translation invariance and relativistic invariance. Thirdly, we argue that the random discontinuous motion of particles may lead to a stochastic, nonlinear collapse evolution of the wave function. A discrete model of energy-conserved wavefunction collapse is proposed and shown to be consistent with existing experiments and our macroscopic experience. In addition, we also give a critical analysis of the de Broglie-Bohm theory, the many-worlds interpretation and dynamical collapse theories, and briefly analyze the problem of the incompatibility between quantum mechanics and special relativity

Session 3: Natural Selection as a Causal Theory

Proceedings of the Pittsburgh Workshop in History and Philosophy of Biology, Center for Philosophy of Science, University of Pittsburgh, March 23-24 2001 Session 3: Natural Selection as a Causal Theor

Demarcating misconduct from misinterpretations and mistakes

Within recent years, scientific misconduct has become an increasingly important topic, not only in the scientific community, but in the general public as well. Spectacular cases have been extensively covered in the news media, such as the cases of the Korean stem cell researcher Hwang, the German nanoscientist Schön, or the Norwegian cancer researcher Sudbø. In Science's latest annual "breakthrough of the year" report from December 2006, the descriptions of the year's hottest breakthroughs were accompanied by a similar description of "the breakdown of the year: scientific fraud". Official guidelines for dealing with scientific misconduct were introduced in the 1990s. At this time, research agencies, universities and other research institutions around the world developed guidelines for good scientific practice and formed committees to handle cases of scientific misconduct. In this process it was widely debated how to define scientific misconduct. Most definitions centered on falsification, fabrication, and plagiarism (the so-called FFP definition), but suggestions were also made for definitions that were broader and more open-ended, such as the 1995 suggestion from the US Commission of Research Integrity to replace FFP with misappropriation, interference and misrepresentation (the so-called MIM definition). The MIM definition was not adopted in the US, but MIM-like definitions have been adopted in several other countries. In this paper, I shall describe these MIM-related definitions of scientific misconduct and analyze the arguments that have been advanced in their favor. I shall discuss some of the difficulties inherent in the MIM-related definitions, such as the distinction between misrepresentation and mistake, and the demarcation of misrepresentation in areas characterized by uncertainty or by diverging research paradigms. I shall illustrate the problems inherent in the MIM-definition through a particular case: the ruling of the Danish Committee on Scientific Dishonesty (DCSD) about Bjørn Lomborg's best-selling book The Skeptical Environmentalist in which he argued that contrary to what was claimed in the “litany” of the environmentalists, the state of the environment is getting better rather than worse. Lomborg was reported to the DCSD by several environmental scientists, and this controversial case from 2003 ended with a verdict that characterized Lomborg’s conclusions as misrepresentations, but acquitted Lomborg of misconduct due to his ignorance. I shall analyze this verdict and the problems it reveals with respect to the MIM-related definitions of misconduct

Explaining the Unobserved: Why Quantum Theory Ain't Only About Information

A remarkable theorem by Clifton, Bub and Halvorson (2003) (CBH) characterizes quantum theory in terms of information--theoretic principles. According to Bub (2004, 2005) the philosophical significance of the theorem is that quantum theory should be regarded as a ``principle'' theory about (quantum) information rather than a ``constructive'' theory about the dynamics of quantum systems. Here we criticize Bub's principle approach arguing that if the mathematical formalism of quantum mechanics remains intact then there is no escape route from solving the measurement problem by constructive theories. We further propose a (Wigner--type) thought experiment that we argue demonstrates that quantum mechanics on the information--theoretic approach is incomplete

The Kuhnian mode of HPS

In this article I argue that a methodological challenge to an integrated history and philosophy of science approach put forth by Ron Giere almost forty years ago can be met by what I call the Kuhnian mode of History and Philosophy of Science (HPS). Although in the Kuhnian mode of HPS norms about science are motivated by historical facts about scientific practice, the justifiers of the constructed norms are not historical facts. The Kuhnian mode of HPS therefore evades the naturalistic fallacy which Giere’s challenge is a version of. Against the backdrop of a discussion of Laudan’s normative naturalism I argue that the Kuhnian mode of HPS is a superior form of naturalism which establishes contact to the practice of science without making itself dependent on its contingencies