Ross McKenzie

Karl Barth’s Doctrine of Creation is argued to be fruitful for discussing the relationship between the natural sciences and theology. Barth saw distinct roles for each but acknowledged that the boundary between them is not clear. He argued that the existence of the world as a distinct objective reality is an article of faith, resonating with some modern philosophical and scientific discussions. The purpose of the Biblical account of Creation is not to give a scientific account of material origins but rather to describe the purpose of the Creation: the Covenant between Israel and the Creator God. The clear distinction between the Creation and the Creator can justify the methodological naturalism of science. Given that the Covenant is the internal basis of creation we should not be surprised that science has discovered reliable laws of regularity and uniformity. These laws reflect the covenantal faithfulness of the Creator.

In order to illuminate the similarities and differences between science and theology, we consider an epistemology and methodology for each that can be characterised as a dialectical critical realism. Our approach is deeply indebted to the work of the great Swiss theologian, Karl Barth. Key points are that the object under study determines the method to be used, the community of investigators and the nature of the possible knowledge to be gained; the necessity of a posteriori, rather than a priori reasoning; and that the dialogue between theology and science should account for both the similarities and differences between the two disciplines. The counterintuitive nature of quantum physics is used to illustrate how in science the dialectic element should lead to a critical dimension to realism, and one is forced to engage with reality on its own terms.

The success of reductionism as a method in the natural sciences has heavily influenced modern theology, much of which attempts to reduce theology to other disciplines. However, the past few decades in science have shown the limitations of reductionism and the importance of emergence. The properties of complex systems with many constituents cannot be understood solely in terms of the constituent components and their interactions. I illustrate emergent properties and concepts with specific examples from geometry, condensed matter physics, chemistry and molecular biology. Emergence leads to a stratification of reality which affirms that ontology determines epistemology. To show the significance of emergence for the dialogue between theology and the natural sciences parallels are drawn with the theology of Karl Barth. The approach here is distinctly different from most writing on emergence and theology which embraces ‘strong’ emergence (which most scientists consider speculative), an immanent God and does not engage with orthodox Christian theology. Aspects of Barth's theology which are particularly relevant include his view that theology is an autonomous discipline which is not reducible to anthropology or history, the irreducible character of revelation, and the emphasis that ontology determines epistemology.

We are familiar with solid, liquid, and gas as states of matter, but there are many more, including liquid crystal, glass, and superconductor, with new ones continually being discovered. Condensed matter physics investigates how the distinct properties of those states of matter emerge from the atoms of which a material is composed. In this Very Short Introduction, Ross H. McKenzie describes the basic concepts and approach of this exciting modern field of physics, exploring a range of phenomena including phase transitions, symmetry, ordering, macroscopie quantum effects, and emergence.

Many systems of interest to scientists involve a large number of interacting parts and the whole system can have properties that the individual parts do not. The system is qualitatively different to its parts. More is different. I take this novelty as the defining characteristic of an emergent property. Many other characteristics have been associated with emergence are reviewed, including universality, order, complexity, unpredictability, irreducibility, diversity, self-organisation, discontinuities, and singularities. However, it has not been established whether these characteristics are necessary or sufficient for novelty. A wide range of examples are given to show how emergent phenomena are ubiquitous across most sub-fields of physics and many areas of biology and social sciences. Emergence is central to many of the biggest scientific and societal challenges today. Emergence can be understood in terms of scales (energy, time, length, complexity) and the associated stratification of reality. At each stratum (level) there is a distinct ontology (properties, phenomena, processes, entities, and effective interactions) and epistemology (theories, concepts, models, and methods). This stratification of reality leads to semi-autonomous scientific disciplines and sub-disciplines. A common challenge is understanding the relationship between emergent properties observed at the macroscopic scale (the whole system) and what is known about the microscopic scale: the components and their interactions. A key and profound insight is to identify a relevant emergent mesoscopic scale (i.e., a scale intermediate between the macro- and micro- scales) at which new entities emerge and interact with one another weakly. In different words, modular structures may emerge at the mesoscale. Key theoretical methods are the development and study of effective theories and toy models. Effective theories describe phenomena at a particular scale and sometimes can be derived from more microscopic descriptions. Toy models involve minimal degrees of freedom, interactions, and parameters. Toy models are amenable to analytical and computational analysis and may reveal the minimal requirements for an emergent property to occur. The Ising model is an emblematic toy model that elucidates not just critical phenomena but also key characteristics of emergence. Many examples are given from condensed matter physics to illustrate the characteristics of emergence. A wide range of areas of physics are discussed, including chaotic dynamical systems, fluid dynamics, nuclear physics, and quantum gravity. The ubiquity of emergence in other fields is illustrated by neural networks, protein folding, and social segregation. An emergent perspective matters for scientific strategy, as it shapes questions, choice of research methodologies, priorities, and allocation of resources. Finally, the elusive goal of the design and control of emergent properties is considered.

Penrose and Hameroff have argued that the conventional models of a brain function based on neural networks alone cannot account for human consciousness, claiming that quantum-computation elements are also required. Specifically, in their Orchestrated Objective Reduction model [R. Penrose and S. R. Hameroff, J. Conscious. Stud. 2, 99 ], it is postulated that microtubules act as quantum processing units, with individual tubulin dimers forming the computational elements. This model requires that the tubulin is able to switch between alternative conformational states in a coherent manner, and that this process be rapid on the physiological time scale. Here, the biological feasibility of the Orch OR proposal is examined in light of recent experimental studies on microtubule assembly and dynamics. It is shown that the tubulins do not possess essential properties required for the Orch OR proposal, as originally proposed, to hold. Further, we consider also recent progress in the understanding of the long-lived coherent motions in biological systems, a feature critical to Orch OR, and show that no reformation of the proposal based on known physical paradigms could lead to quantum computing within microtubules. Hence, the Orch OR model is not a feasible explanation of the origin of consciousness. © 2009 The American Physical Society.