Arnold Sikkema
Trinity Western University, Physics, Faculty Member
- Philosophy of Physics, Science & Christianity, Quantum Physics, Reformational Philosophy, Phase Transitions, Philosophy of Science, and 12 moreEmergent Phenomena, Physics, Condensed Matter Physics, Optics, Physics Education, General Relativity, Emergence, Condensed Matter Theory, Philosophy Of Religion, Evolution, Ideology, and Science and Religionedit
- Theoretical and philosophical biophysicist, studying relations between physics and biology with the lens of emergenceedit
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Reviewed Title: Morris, Tim, and Don Petcher. Science & Grace: God’s Reign in the Natural Sciences. Wheaton Illinois: Crossway Books, 2006. 352pp. ISBN 978-1-58134-549-0
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From a consideration of emergence in physics, I outline how reformational philosophical concepts such as idionomy, encapsis, and anticipation can help nuance the claims of emergentism, whether within or beyond the discipline of physics.... more
From a consideration of emergence in physics, I outline how reformational philosophical concepts such as idionomy, encapsis, and anticipation can help nuance the claims of emergentism, whether within or beyond the discipline of physics. The methodological reductionist project has given physics significant success from Democritus through Newton to Hawking. Other sciences seek to employ, extend, and emulate physics with its theoretical precision and verisimilitudinous mathematical laws. Triumphalistic practitioners in disciplines from biology through psychology to sociology—hoping to position their theories as inexorable consequences of physics, touted for its firm foundation, solid knowledge, and clear vision—are applauded by public spokespersons of thoroughgoing ontological and naturalistic reductionism. Such optimism persists even when the so-called stratified nature of reality is acknowledged, especially if the concept of emergence is brought into view. But in addition to being poorly defined, emergence is used in exactly opposite senses: claims of unproblematic scientific explanation for a multileveled reality and claims of the intractable impossibility of such explanation. Sometimes enlisted in support of the former is the notion that emergence within physics is fully understood. A sober assessment of predictability and critical realism in physics, however, demonstrates that the nature of emergence within physics renders physics incapable of bearing its supposed grand foundational responsibility. Examples in various physics subfields are analyzed, demonstrating common themes and principles. Collective physical phenomena are strikingly characterized by robustness of the ordered macroscopic whole relative to variations in microscopic parts, universality near phase transitions, and symmetry breaking, but most importantly by surprise and incalculability.
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It has been observed that it sometimes seems to rain harder a few seconds after a lightning strike (so-called ``rain gush lightning'' phenomenon). The conventional way to study this type of phenomena is with radar. To... more
It has been observed that it sometimes seems to rain harder a few seconds after a lightning strike (so-called ``rain gush lightning'' phenomenon). The conventional way to study this type of phenomena is with radar. To investigate this in a more direct way, an apparatus was designed and ...
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An essay review of the treatment of physics and the physical aspect in Jacob Klapwijk, "Purpose in the Living World? Creation and Emergent Evolution" (Cambridge: Cambridge University Press, 2008).
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ABSTRACT It is important to develop a Christian perspective or worldview on how the world “works” and about how God relates to the creation. Without such grounding, we join in some of the fallacies plaguing today’s culture, such as... more
ABSTRACT It is important to develop a Christian perspective or worldview on how the world “works” and about how God relates to the creation. Without such grounding, we join in some of the fallacies plaguing today’s culture, such as philosophical materialism, naturalism, and the dualisms between science and religion and between the natural and the supernatural. In this article, I will discuss what we — both scientists and members of the general public — mean when we speak about natural scientific laws, or laws of nature, as well as what the Bible says about God’s ordinances for creation, particularly in terms of his showing covenant faithfulness toward his creation. Along the way, we will consider examples of natural scientific laws, and the ways they are used. Habits of mind and ways of thinking relating to science generally will be explored by considering what we have historically understood by natural laws, not only in the grand sweep of the history of science but also in the development, training, and work of individual scientists.
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ABSTRACT Relativistic wave equations are solved exactly in the classical space-time background of a two-dimensional gravitational theory. In the simplest nontrivial geometry without horizons, the solutions are necessarily bound states and... more
ABSTRACT Relativistic wave equations are solved exactly in the classical space-time background of a two-dimensional gravitational theory. In the simplest nontrivial geometry without horizons, the solutions are necessarily bound states and the constraints on the energy eigenvalues are determined. Aspects of quantum field theory in the background of the (1+1)-dimensional black hole are also examined.
Research Interests: Field Theory, Physics, Quantum Physics, Quantum Gravity, General Relativity, and 14 moreQuantum Mechanics, Quantum Field Theory, Medicine, Space Time, Wave Equation, Eigenvalues, Black Hole, Relativity Theory, Bound States, Differential equation, Klein-Gordon equation, Semiclassical Approximation, Semiclassical Physics, and Elementary Particles
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Phase transitions are well defined in physics through concepts such as spontaneous symmetry breaking, order parameter, entropy, and critical exponents. But emergence --- also exhibiting whole-part relations (such as top-down influence),... more
Phase transitions are well defined in physics through concepts such as spontaneous symmetry breaking, order parameter, entropy, and critical exponents. But emergence --- also exhibiting whole-part relations (such as top-down influence), unpredictability, and insensitivity to ...
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In Dooyeweerd’s modal scale, the physical aspect is flanked by the kinematic and biotic. While physics and mathematics have mutually benefited one another for hundreds of years, connections between biology and physics are only now... more
In Dooyeweerd’s modal scale, the physical aspect is flanked by the kinematic and biotic. While physics and mathematics have mutually benefited one another for hundreds of years, connections between biology and physics are only now beginning to emerge. Understanding the defining characteristics of these three disciplines helps detail their mutual irreducibility as well as their possibilities for fruitful engagement, especially when considering the developments of modern physics. Furthermore, a critical-realist and model-oriented approach to the laws of physics can encourage humble epistemology and limited ontology, much needed correctives to rampant reductionist and atheist claims. Casting all this within a trinitarian, covenantal, and creation-fall-redemption narrative, in which divine revelation as well as creation are taken seriously, provides a nuanced perspective which, among other benefits, offers hope for resolving conflicts the scientific community experiences with many laypersons.
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We discuss the various themes addressed in the preceding talks in the emergence stream, drawing connections with and implications from them. We will also bring forward other relevant issues in emergence by engaging with recent works in... more
We discuss the various themes addressed in the preceding talks in the emergence stream, drawing connections with and implications from them. We will also bring forward other relevant issues in emergence by engaging with recent works in fields such as biology, physics, biophysics, biosemiotics, information science, and philosophy of science, particularly being informed by reformational philosophical perspectives. After initial presentations by each panelist, and a brief trialogue among us, we will lead a general conversation with presenters and attendees of the emergence stream. [Audio recording and PDF of screen presentation available online; see links.]
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From a consideration of emergence in physics, I outline how reformational philosophical concepts such as idionomy, enkapsis, and anticipation can help nuance the claims of emergentism, whether within or beyond the discipline of physics.... more
From a consideration of emergence in physics, I outline how reformational philosophical concepts such as idionomy, enkapsis, and anticipation can help nuance the claims of emergentism, whether within or beyond the discipline of physics. The methodological reductionist project has given physics significant success from Democritus through Newton to Hawking. Other sciences seek to employ, extend, and emulate physics with its theoretical precision and verisimilitudinous mathematical laws. Triumphalistic practitioners in disciplines from biology through psychology to sociology — hoping to position their theories as inexorable consequences of physics, touted for its firm foundation, solid knowledge, and clear vision — are applauded by public spokespersons of thoroughgoing ontological and naturalistic reductionism. Such optimism persists even when the so-called stratified nature of reality is acknowledged, especially if the concept of emergence is brought into view. But in addition to being poorly defined, emergence is used in exactly opposite senses: claims of unproblematic scientific explanation for a multi-levelled reality and claims of the intractable impossibility of such explanation. Sometimes enlisted in support of the former is the notion that emergence within physics is fully understood. A sober assessment of predictability and critical realism in physics, however, demonstrates that the nature of emergence within physics renders physics incapable of bearing its supposed grand foundational responsibility. Examples in various physics subfields are analyzed, demonstrating common themes and principles. Collective physical phenomena are strikingly characterized by robustness of the ordered macroscopic whole relative to variations in microscopic parts, universality near phase transitions, and symmetry breaking, but most importantly surprise and incalculability.
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Religion is in the science classroom. It’s already there for reasons of all sorts, and so it’s not the teacher’s choice whether or not to engage it, but how. Humans are irreducibly religious. Science is a human cultural activity,... more
Religion is in the science classroom. It’s already there for reasons of all sorts, and so it’s not the teacher’s choice whether or not to engage it, but how. Humans are irreducibly religious. Science is a human cultural activity, motivated in part by the desire to answer deep questions. Many questions science addresses today touch upon, or indeed dive into, matters that members of religious communities have considered (and still do consider) their territory. And so the manner in which teachers present such questions and the scientific approaches to their answers can alienate some of their students and thus be a roadblock to science education. It is incumbent upon teachers to become aware of the religious connections that science carries with it and to create pedagogical strategies correspondingly.
See https://goo.gl/N8wxme where you can read the chapter via Google Books.
See https://goo.gl/N8wxme where you can read the chapter via Google Books.
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An essay review of the treatment of physics and the physical aspect in Jacob Klapwijk, "Purpose in the Living World? Creation and Emergent Evolution" (Cambridge: Cambridge University Press, 2008).
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[Summary] The idea that our expanding Universe was born in a 'bounce'—the re-expansion of a previously contracting universe—is an old cosmogonical hypothesis, and continues to resurface despite being overshadowed recently by hypotheses... more
[Summary] The idea that our expanding Universe was born in a 'bounce'—the re-expansion of a previously contracting universe—is an old cosmogonical hypothesis, and continues to resurface despite being overshadowed recently by hypotheses inspired by Guth's inflationary model. Here we show how recent developments in the physics of black-hole interiors force a major revision of our ideas of the final moments of a contracting universe, and remove a thermodynamic difficulty which had appeared to rule out any kind of bounce origin for our Universe. As the black hole formed by the collapse of a rotating star settles down, it absorbs part of the gravitational radiation emitted during the last moments of collapse. This radiation, strongly blue-shifted near the inner horizon, enormously increases the mass of the black hole's core. External observers cannot detect this mass, but it manifests itself dramatically when the black holes in a collapsing universe merge, a few minutes before the 'big crunch'. The mass of a rebounding universe is enormously inflated, and its specific entropy correspondingly reduced. This allows the expansion to begin from a state of relatively low disorder.
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We examine a model Hamiltonian for the heavy-fermion URu2Si2 based on two crystal-field-split singlets for the uranium spin coupled by on-site exchange to the conduction electrons. It is equivalent to an Ising-Kondo lattice with... more
We examine a model Hamiltonian for the heavy-fermion URu2Si2 based on two crystal-field-split singlets for the uranium spin coupled by on-site exchange to the conduction electrons. It is equivalent to an Ising-Kondo lattice with transverse magnetic field. Within the mean-field approximation, we find a logarithmic response of the conduction electrons to moment formation. Over an appreciable range of parameters, the moments in the antiferromagnetic state are anomalously small as observed, and a reasonable Néel temperature is obtained. The model also gives a qualitatively correct temperature-dependence, but not magnitude, of the specific heat, and we find that the majority of the specific heat jump at the Néel temperature arises from the formation of a spin gap in the conduction electron spectrum.
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Investigations in cosmogenesis have taken many approaches throughout history. In this paper, I discuss in particular the cosmic bounce scenario which has recently been revived because of theoretical advances in the physics of black-hole... more
Investigations in cosmogenesis have taken many approaches throughout history. In this paper, I discuss in particular the cosmic bounce scenario which has recently been revived because of theoretical advances in the physics of black-hole interiors and in quantum gravity. The perceived difficulty associated with the thermodynamic requirement of entropy increase is removed by the phenomenon of mass inflation which accompanies the gravitational collapse of a generic astronomical body, since it both affects our view of the merging of black holes in a cosmological collapse and produces the sharp deflation in specific entropy required for the regeneration of order in a subsequent smooth big bang. Despite the physical plausibility of such a scenario, I present fundamental limitations on any cosmogonical model.
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We reply to the comments made by Cooperstock and Faraoni concerning (1+1)-dimensional gravity.
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Phase transitions are well defined in physics through concepts such as spontaneous symmetry breaking, order parameter, entropy, and critical exponents. But emergence --- also exhibiting whole-part relations (such as top-down influence),... more
Phase transitions are well defined in physics through concepts such as spontaneous symmetry breaking, order parameter, entropy, and critical exponents. But emergence --- also exhibiting whole-part relations (such as top-down influence), unpredictability, and insensitivity to microscopic detail --- is a loosely-defined concept being used in many disciplines, particularly in psychology, biology, philosophy, as well as in physics[1,2]. I will review the concepts of emergence as used in the various fields and consider the extent to which the methods of phase transitions can clarify the usefulness of the concept of emergence both within the discipline of physics and beyond.
1. Robert B. Laughlin, A Different Universe: Reinventing Physics from the Bottom Down (New York: Basic Books, 2005).
2. George F.R. Ellis, "Physics and the Real World'', Physics Today, v. 58, n. 7 (July 2005) pp. 49-54.
1. Robert B. Laughlin, A Different Universe: Reinventing Physics from the Bottom Down (New York: Basic Books, 2005).
2. George F.R. Ellis, "Physics and the Real World'', Physics Today, v. 58, n. 7 (July 2005) pp. 49-54.
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The phase diagram of a one-dimensional tight-binding model with a pair-hopping term (amplitude V) has been the subject of some controversy. Using two-loop renormalization-group equations and the density matrix renormalization group with... more
The phase diagram of a one-dimensional tight-binding model with a pair-hopping term (amplitude V) has been the subject of some controversy. Using two-loop renormalization-group equations and the density matrix renormalization group with lengths L≤60, we argue that no spin-gap transition occurs at half-filling for positive V, contrary to recent claims. However, we point out that away from half-filling, a phase-separation transition occurs at finite V. This transition and the spin-gap transition occurring at half-filling and negative V are analyzed numerically.
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The success of a light ray's transmission to a medium of lower index of refraction depends upon its incident angle at the boundary. If this angle, when measured from the normal, is greater than a certain critical angle, the ray will... more
The success of a light ray's transmission to a medium of lower index of refraction depends upon its incident angle at the boundary. If this angle, when measured from the normal, is greater than a certain critical angle, the ray will reflect totally, remaining in the high-index medium. Snell's law, which says that n1 sin θ1 = n2 sin θ2, easily gives the critical angle as θ1 = arcsin(n2/n1) by setting the angle of refraction to θ2 = 90°. Demonstrations of the critical angle phenomenon usually work with this operational definition. For example, as in Fig. 1, one directs a beam of light radially through the curved surface of a semicircular piece of glass and rotates the semicircle until no ray is seen exiting the flat surface. We describe here a demonstration of the critical angle that does not employ rays leaving the higher-index medium but entering it.
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We show that the Kondo chain away from half filling has a spin gap upon the introduction of an additional direct Heisenberg coupling between localized spins. This is understood in the weak-Kondo-coupling limit of the Heisenberg-Kondo... more
We show that the Kondo chain away from half filling has a spin gap upon the introduction of an additional direct Heisenberg coupling between localized spins. This is understood in the weak-Kondo-coupling limit of the Heisenberg-Kondo lattice model by bosonization and in the strong-coupling limit by a mapping to a modified t-J model. Only for certain ranges of filling and Heisenberg coupling does the spin gap phase extend from weak to strong couplin
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Two aspects of strongly correlated electron systems are studied in this thesis. Hubbard type models are thought to be at the basis of highcritical-temperature superconductivity. One interaction which has not had much study is the... more
Two aspects of strongly correlated electron systems are studied in this thesis.
Hubbard type models are thought to be at the basis of highcritical-temperature superconductivity. One interaction which has not had much study is the nearest-neighbour hopping of on-site singlet pairs. We refine earlier renormalization group arguments and, using the density-matrix renormalization group method, numerically confirm their prediction that a spin gap opens at infinitesimal pair-hopping amplitude V>0 in the onedimensional tight-binding model. We also find a phase separation transition at a finite V>0 as well as a spin-gap transition at a finite V<0.
The exotic magnetic behaviour of heavy-fermion materials involves an interplay between the screening of local moments from each other and the formation of a magnetic state of long range order. While the single impurity Kondo Hamiltonian is thought to model some aspects of this behaviour, the properties of the Kondo lattice model away from half-filling are largely unknown. We determine the presence of a spingap region in the phase diagram of the onedimensional Heisenberg-Kondo lattice model and make predictions about certain concealed dimerization order parameters.
Hubbard type models are thought to be at the basis of highcritical-temperature superconductivity. One interaction which has not had much study is the nearest-neighbour hopping of on-site singlet pairs. We refine earlier renormalization group arguments and, using the density-matrix renormalization group method, numerically confirm their prediction that a spin gap opens at infinitesimal pair-hopping amplitude V>0 in the onedimensional tight-binding model. We also find a phase separation transition at a finite V>0 as well as a spin-gap transition at a finite V<0.
The exotic magnetic behaviour of heavy-fermion materials involves an interplay between the screening of local moments from each other and the formation of a magnetic state of long range order. While the single impurity Kondo Hamiltonian is thought to model some aspects of this behaviour, the properties of the Kondo lattice model away from half-filling are largely unknown. We determine the presence of a spingap region in the phase diagram of the onedimensional Heisenberg-Kondo lattice model and make predictions about certain concealed dimerization order parameters.
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We show that the Kondo chain away from half filling has a spin gap upon the introduction of an additional direct Heisenberg coupling between localized spins. This is understood in the weak Kondo-coupling limit of the Heisenberg-Kondo... more
We show that the Kondo chain away from half filling has a spin gap upon the introduction of an additional direct Heisenberg coupling between localized spins. This is understood in the weak Kondo-coupling limit of the Heisenberg-Kondo lattice model by bosonization and in the strong-coupling limit by a mapping to a modified t-J model. Only for certain ranges of filling and Heisenberg coupling does the spin gap phase extend from weak to strong coupling.
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We examine a model Hamiltonian for the heavy-fermion URu2Si2 based on two crystal-field-split singlets for the uranium spin coupled by on-site exchange to the conduction electrons. It is equivalent to an Ising-Kondo lattice with... more
We examine a model Hamiltonian for the heavy-fermion URu2Si2 based on two crystal-field-split singlets for the uranium spin coupled by on-site exchange to the conduction electrons. It is equivalent to an Ising-Kondo lattice with transverse magnetic field. Within the mean-field approximation, we find a logarithmic response of the conduction electrons to moment formation. Over an appreciable range of parameters, the moments in the antiferromagnetic state are anomalously small as observed, and a reasonable Néel temperature is obtained. The model also gives a qualitatively correct temperature-dependence, but not magnitude, of the specific heat, and we find that the majority of the specific heat jump at the Néel temperature arises from the formation of a spin gap in the conduction electron spectrum.