The Causal Universe
GEORGE F.R. ELLIS
Table of Contents
Michael Heller. Introduction
Part I. Top-Down Causality and Complexity
George F.R. Ellis. Why Are the Laws of Nature as They Are? What Underlies Their Existence?
Top-Down Causation as the Key to the Emergence of Complexity
Jean-Philippe Uzan. Models of the Cosmos and the Emergence of Complexity
Derek Raine. Causality and Complexity
Part II. Causality and the Structure of the Universe
Marek Kuś. The Uncertain Future and the Ambiguous Past in Classical, Quantum and General Non-signaling Settings
Julian Barbour. Reductionist Doubts
Andrzej M. Sołtan. X-ray Background and Cosmology
Andrzej Sitarz. Causality and Noncommutativity
Michael Heller. Bottom-Up Causality in a New Setting
Mariusz P. Dąbrowski. Varying Physical Constant Cosmologies and the Anthropic Principle
Part III. Ultimate Causality
Bogdan Dembiński. Causality Issues in Ancient Greek Philosophy
William R. Stoeger, S.J. Cosmology, Evolution, Causality and Creation: The Limits, Compatibility and Cooperation of Scientific and Philosophical Methodologies
Thomas Tracy. God and the Causal Structures of Nature: Some Puzzles
Willem B. Drees. God as Ground? Cosmology and Non-Causal Conceptions of the Divine
Cover design: MARIUSZ BANACHOWICZ
Editing: AEDDAN SHAW
Layout: MIROSŁAW KRZYSZKOWSKI
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Konwersja: eLitera s.c.
The nature of causation is a core issue for science, which can be regarded as the move from a demon-centered world to a world based on reliable cause and effect, tested by experimental verification.
(...) Physics is the basic science, characterized by mathematical descriptions that allow predictions of physical behavior to astonishing accuracy and underlies the other sciences. The key question is whether other forms of causation such as those investigated in biology, psychology, and the social sciences are genuinely effective, or are they rather all epiphenomena grounded in purely physical causation?
(...) I will claim here that there are indeed other types of causation at work in the real world, described quite well by Aristotle’s four types of causes. There are of course many contexts in which different kinds of causality are experienced: in physics and chemistry, where particles and forces interact in a way described by variational principles and symmetries; in biochemistry and cell biology, where information is important and adaptation takes place; in zoology, where purpose, planning, and anticipation are important; and in psychology and sociology, where analytic reflection, symbolic understanding, values and meaning all are causally effective.
George Ellis, On the Nature of Causation in Complex Systems
Physics is heavily marked by its philosophical origins. It is enough to relax methodological control and the physicist almost immediately slips into philosophical speculation. The only scientists who are immune to this danger are those who never go beyond their calculations or laboratory measurements. This phenomenon is, at least in part, due to the fact that many concepts which are of crucial importance for physics have been transported from philosophy to physics and still preserve a propensity towards their family home. One can speak about a process of the migration of concepts from philosophy to physics (or more generally to science) and quote a host of its examples. Concepts like: space, time, force and mass first come to mind. But concepts never appear in isolation from other concepts, and are always situated within certain problems. And when they migrate to the scientific environment, they take with them all of this baggage. Of course, when they are already well placed in their new context, they are clothed in new connotations and a new conceptual network. Moreover, quite often a given concept goes back to philosophy, and when it does so, it never returns to exactly the same place as before (certainly, no concept ‘ever steps in the same river twice’). This is one of the ways of enriching philosophical inquiries and opening them up to new perspectives.
The concept of causality belongs to the family of those selected concepts that have covered the distance between philosophy and physics many times. This makes this process a fascinating subject matter for interdisciplinary debate, and this is why, when George Ellis suggested the ‘Causal Universe’ as the title for this volume, the idea seemed so obviously correct that there were no counterproposals. The volume is the outcome of the 16th Cracow Methodological Conference ‘The Causal Universe’, held in Cracow, Poland, on 17–18th of May 2012, with George Ellis as its Honorary Guest. The chapters contained in this book have evolved from the contributions presented by their authors during the conference.
The manifold migration of the causality concept between philosophy and physics is beautifully reflected in the content of the volume. It is divided into three parts. The first part, TOP DOWN CAUSALITY AND COMPLEXITY, initiates the discussion around two of the main notions which reappear time and again in many contributions. The second part, CAUSALITY AND THE STRUCTURE OF THE UNIVERSE, transfers the discussion into the cosmological context. It culminates in the third part, ULTIMATE CAUSALITY, where we move to the philosophical and theological aspects of the problem. Although we go beyond the realm of science, we try not to lose our scientific perspective.
PART ONE. George Ellis in his opening chapter (‘Why Are the Laws of Nature as They Are? What Underlies Their Existence?’) not only sets the stage for the entire volume, but also draws the main lines of the plot that unfolds in it. The laws of physics define the possibility space within which the universe and everything in it come into being. If we aspire to understand the universe and ourselves within it, we cannot avoid inquiring as to what underlies the existence of the laws of physics. If we take the existence of the laws of physics for granted, as is usually done in many otherwise penetrating discussions, our understanding cannot be complete. We are living in an evolving Universe that was initially structureless. Structures emerge from the underlying basis of physical laws. Complexity arises in modular hierarchical structures in manifold ways. No biological evolutionary processes of any kind would be possible if physical laws were substantially different. Is the ultimate reason underlying the lowest-level laws on which everything else is based pure chance, probability, necessity, or purpose? Although neither science nor philosophy can give a definite answer, Ellis argues that if one wants to relate one’s understanding to the deeper meaning of personal life, the last option is the most attractive one.
The second of Ellis’ papers (‘Top-Down Causation as the Key to the Emergence of Complexity’) has a more technical character. He quotes persuasive arguments for the existence of top down causality and its crucial role in the emergence of complexity. A key assumption underlying most contemporary scientific work is that causation is bottom up all the way: particle physics underlies nuclear physics, nuclear physics underlies atomic physics, atomic physics underlies chemistry, and so on and, consequently, all the higher level structures are at least in principle reducible to particle physics. Ellis argues that this view is wrong in general and, in particular, in the case of physics. The top-down form of causation does not occur by violating physical laws but, on the contrary, it occurs through the laws of physics, by setting constraints on lower level interactions. He also claims that the emergence of true complexity is not possible through bottom up effects alone; it requires a reversal of information flow from bottom-up to top-down.
In his chapter (‘Models of the Cosmos and the Emergence of Complexity’) Jean-Philippe Uzan places Ellis’ analysis of top-down causality and the growth of complexity in the context of the contemporary standard cosmological model. To do so, he first discusses hypotheses underlying the physical representation of the universe and observational data as potential tests of these hypotheses. This shows a deep connection between theoretical physics and cosmology. The cosmological model provides a context for the emergence of complexity. The universe is the largest embedding structure in which all the phenomena of lower complexity levels develop. It is thus important to understand how the structure of the universe and its evolution offers the possibility for the emergence of other levels. In this cosmological context, the role of effective phenomena and the concept of causality are central. Uzan underlines what he calls the scale decoupling principle; it refers to the fact that there exist energy scales below which effective theories are sufficient to understand a given set of physical phenomena. They give a successful explanation at a given level of complexity based on concepts of that particular level. For instance, we do not need to understand string theory in order to formulate nuclear physics and we do not need to know anything about nuclear physics to develop atomic physics or chemistry. It is also interesting to notice that the appearance of levels of complexity is localized both in time and space, so that the region of the universe in which top-down causation is efficient is limited. This remains in agreement with the usual relativistic causality; however, the typical propagation speed of the action of higher levels on lower levels is much smaller than the speed of light, so that the future light cone of inﬂuence is expected to be very narrow.
Derek Raine (‘Causality and Complexity’) plays the role of an advocatus diaboli and argues that the arguments on behalf of top down causality are unconvincing. In linear systems there is a direct link between cause and effect. This is not the case in non-linear systems where causes are inter-related. For instance, what was the cause of the First World War? This is clearly an unanswerable question. The difficulty in assigning a cause arises because the situation is non-linear: that is, there is feedback. In a linear system if we add causes, we must add their effects: if a causes A and b causes B, then a and b acting together cause the outcomes A and B together. Once we introduce interactions, hence non-linearity, either between different parts of a system or self-interaction, this simple link between cause and effect is lost. After discussing several examples of apparent top down causality (some of these examples are quite technical), Raine concludes that ‘there is no denying that there is more to causality than the Aristotelian ‘efficient cause’ (the sculptor’s chisel on the stone)’. In Raine’s opinion, supporters of top-down causality are well aware of all of this. However, they are not satisfied with calling it adaptive evolution but call it top-down causality. He remarks that ‘calling things by different names is harmless except when it isn’t: in particular when it leads to category errors such as the attribution of existence to the thing from the existence of the idea of the thing’.
PART TWO. In this part, by the universe we understand not only the cosmos as it is investigated by cosmology, but also all its substructures as investigated by other physical theories. We start with quantum mechanics, general relativity and astrophysics, and then go to more exotic research areas: physical theories based on noncommutative geometry and the multiverse idea.
Very interesting, and well experimentally documented, things related to causality happen in quantum mechanics. Any discussion of causality would remain incomplete without even a brief presentation of the problems of causal relations and causal explanations specific to quantum mechanics. This task has been taken up by Marek Kuś (‘The Uncertain Future and the Ambiguous Past in Classical, Quantum and General Non-signaling Settings’). With only a slight exaggeration, one can say that physics is the art of determining correlations between various parts of the physical world. Kuś gives a short but very lucid presentation of some aspects of this topic exhibited by recent developments in the theory of quantum correlations. Local theories, admitting only local correlations put some limits on possible correlations among results of measurements called Bell inequalities. Their violation, confirmed experimentally, testifies to the nonlocal character of the quantum world, and should be regarded as proof of the nondeterministic nature of quantum mechanical reality and its intrinsic, ontological randomness. In the classical setting, uncertainty about future events had an epistemological character – an event is random for us due to our lack of knowledge about all of its causes, whereas in quantum physics the future seems ontologically undetermined.
The issue of causality and the emergence of structures is strictly linked with the problem of reductionism. If its strong version is true, we should exclude top-down causality and reduce complex structures to their simplest elements. The problem, as it appears in general relativity, is considered by Julian Barbour (‘Reductionist Doubts’). He notices that if general relativity implements Mach’s principle, reductionism is challenged. Mach’s principle asserts that parts of the universe and their interactions do not determine the whole; on the contrary, the whole determines the way the parts behave. Whether general relativity implements Mach’s principle has been a matter of controversy every since Einstein created his theory of gravitation. Barbour has given what he believes is the correct definition of Mach’s principle and proposes an alternative interpretation of general relativity in which this theory appears much more holistic than in the usual interpretation. The Machian interpretation of general relativity radically changes the way we conceive of the parts and not just the way they interact. At the end, Barbour discusses the possible implications of a holistic quantum view of the universe.
In the last hundred years, many branches of astrophysics have contributed to the advancement of cosmology. For instance, the hot beginnings of the Universe were conﬁrmed observationally in the 1960’s with the discovery of cosmic microwave background (CMB) radiation. Investigation of CMB, in turn, has allowed us to develop the Big Bang theory further. The X-ray background (XRB) constitutes another section of quasi-isotropic radiation ﬂux reaching the Earth. The X-ray window was opened for astrophysics 50 years ago. The goal of Andrzej M. Sołtan’s paper (‘X-ray Background and Cosmology’) is to inform us how this window has contributed to our understanding of the universe. One of the revolutionary turns which changed our perception of galaxies as the basic building blocks in the Universe, was due to X-ray observations of quasars and Seyfert galaxies and the activity of their nuclei. These two classes of extragalactic objects were known of earlier, but neither optical nor radio data provided an inkling that supermassive black holes are responsible for virtually all kinds of the nuclear activity of galaxies. Clusters of galaxies were the ﬁrst extragalactic objects which were clearly recognized as X-ray sources. The detection of X-ray emissions from clusters bolstered the idea of dark non-baryonic matter as a dominating component of the matter density of the Universe. X-ray observations of hot intracluster gas allowed for the quantitative investigation of a gravitational ﬁeld within clusters and the common acceptance of the reality of dark matter. Until recently, the question of ‘dark matter’ was accompanied by similar one of ‘dark baryons’. This term was used to label a discrepancy between the density estimates of the baryonic matter in the early Universe and the present-day observations in the local Universe. X-ray observations have also alleviated this problem. It was possible because in soft X-rays, below 1 keV, a fraction of ‘missing’ baryons are not completely ‘dark’.
With the chapter by Andrzej Sitarz (‘Causality and Noncommutativity’) we turn from the world of quasars and black holes to the most fundamental level of physics. In contemporary physics reigns a certain schizophrenic duality. On one hand, we have gauge theories, which nicely allow the formulation of classical and perturbative quantum field theory; on the other hand, we have a purely geometrical theory of gravity, mathematically set in the Riemannian (or pseudo-Riemannian) geometry that gives no hints as to its quantum version, the mythical quantum gravity. So far, the attempts have been directed towards the modifications of general relativity in order to assimilate it into a gauge theory. An attempt, stemming from the works of Alain Connes, consists in looking in the opposite direction. Instead of regarding gravity as some sort of gauge theory, we should rather consider gauge theories as some modifications of pure gravity. Such a modification proposed by Connes with this aim is the so-called noncommutative geometry. The models of noncommutative geometry pose a big challenge to the standard concepts of locality and causality. Can we formulate a version of causality which would correspond to the deformed symmetries? Most of our intuitions and approaches, also in the quantum field theory, are based on the notion of time as a continuous variable. What can we do if time is supposed to be a noncommutative variable? Can one allow at all for noncommutative time? Sitarz offers us a thorough discussion of these fundamental questions.
Michael Heller’s paper (‘Bottom-Up Causality in a New Setting’) is, in a sense, complementary with respect to that of Sitarz. Heller tries to reconstruct an ‘ontology of the Planck level’ based on the structural properties presupposed or suggested by noncommutative geometry. Such an ontology, which could be timeless and nonlocal, is drastically different from the ontologies presupposed by classical physics. In particular, the concept of causality should be modified accordingly. If we agree that causality is more than a simple sequence of events then it is just the dynamics that gives a causal nexus between cause and effect. In the noncommutative setting we are confronted with a generalized, nonlocal sort of dynamics. We should forget about ‘the cause here and the effect there’ since the concepts ‘here’ and ‘there’ are not available. They are totally engulfed by the global dependencies between various aspects of the physical world. If we agree that the main characteristics of top-down causality is a holistic type of explanation, and the main characteristic of bottom-up causality is a reductionist type of explanation, then what happens on the ‘bottom’, i.e., on the Planck level, looks more like a top-down than a bottom-up causality: global properties are not reduced to local properties but, vice versa, local properties are derived from global ones. It is rather a top-down than a bottom-up causality. Heller speaks here about a top-down causation with the reversed top-down arrow (pointing from ‘down’ to ‘up’).
We have just considered the most fundamental and the ‘smallest’ level of physics; at the other end, as it were, of the scale of magnitude there is (if it is) what is called the multiverse. It is considered by Mariusz P. Dąbrowski (‘Varying Physical Constant Cosmologies and the Anthropic Principles’). He discusses the roots of the idea of cosmologies with varying physical constants and its realization in specific models of particle physics. He also considers some examples of anthropic coincidences which limit the variability of physical constants in our piece of the universe. In this context, the idea of the multiverse appears in a natural way. The discussion is underpinned by questions such as: Why are the physical constants which we measure of the values that they are? Do these constants change in time and space? How different would our world have been if the constants had had different values from what they have in our corner of the universe? Are there any regions of space in which physics does not allow for our type of life? And, in the theological context, we may ask whether there was initially any freedom in choosing physical constants, and why they have been chosen in a way they are now. Dąbrowski argues that, philosophically, the idea of varying fundamental constants is very attractive since it gives an opportunity for considering all of the possible options of the evolution of the universe which are logically possible and mathematically admissible.
PART THREE. The problem of causality is a typical problem that has migrated from philosophy to physics, and any discussion of this problem would be painfully incomplete without turning to the great metaphysical issues. We start, by the way of introduction, with a glance at the origins of the concept of causality.
All important philosophical questions have their origins in Greek philosophical thought. It is also true as far as the causality issue is concerned. Bogdan Dembiński (‘Causality Issues in Ancient Greek Philosophy’) gives us an in-depth overview of the Greek concepts of causality in which he goes beyond the ‘common knowledge’ on this subject. According to the Greeks, the decisive role in creating the form of the visible world was played by a system of limits which determine the cosmic order and harmony. This structure is shaped by the interactions and relations among its constituent elements. They are expressed by proportions, arrangements and locations and, consequently, the understanding of the cosmic order is strictly connected with its mathematical description. This approach reached its full development in Plato’s Academy (in the works of Eudoksos of Knidos, Speuzipos, Xenokrates and Herakleidos Pontikos). But what is the cause of the existence of limits, their form and multiplicity? The Greeks found the explanation in the theory of the Supreme Principles of Being. These Principles are: the One, One and Many, the Opposites, the Limit and the Limitlessness, Love and Hatred, the Cosmic Intellect (Logos), the Divine Mind or the Divine Organizer of the World (Demiurg). The Principles constitute the end of any justification; one cannot go beyond them. To uncover the truth is to reveal the implicit cosmic order. Only the intellect can accomplish it and it does so because it is itself a part of this order.
Having prepared a general stage, we proceed to ask essentially the same question in the contemporary setting. William R. Stoeger, S.J. (‘Cosmology, Evolution, Causality and Creation: the Limits, Compatibility and Cooperation of Scientific and Philosophical Methodologies’) provides an integrated sketch of the causality problem as it reveals itself in both our scientific image of the world and from our philosophical perspective. He also discusses different types and models of causality, and their relationships with one another. Then, after briefly reflecting on what we know of the Planck era and quantum cosmology, he explores a different kind of ‘causality’ which takes him beyond the natural sciences into the realm of philosophy. This is causality, often called ‘primary causality’, regarded as the ultimate source of existence and order. It is ‘causality beyond causality’ in the sense that it does not provide an alternative to physics or the other natural sciences, but rather gives the grounds for all other causes and their existence.
Thomas Tracy (‘God and the Causal Structures of Nature: Some Puzzles’) notices a strange coincidence: ‘talk about God has always been an exercise in the art of thinking about a subject matter that we know from the outset must exceed our comprehension’ and ‘contemporary physics... too leads us to the boundaries of what we can conceive’. His aim is to consider the impact of some concepts from contemporary physics, especially quantum theory, on thinking about God’s relation to the natural order. Crucial to this relation is the concept of creation, but the notion of ‘causing being’ should only, in this context, be understood as a metaphysical black box; the most we can do is to indicate the effect of the divine action. The idea of God as the Cause of Created Causes introduces the familiar scheme of primary and secondary causation. Creatures operate as causes solely by inducing changes in other things. One consequence of this view is that, contra intelligent design theory, we need not insist on the incompleteness of biological explanations in order to affirm that God’s purposes are at work in the history of life. The properties of quantum systems, such as indeterminateness, nonlocality and underdetermination seems to disrupt the classical theological scheme of divine action through secondary causes. The quantum world appears itself as an evolving structure of potentiality. The question arises: what is God’s relation to this underdetermined world? God acts as its creator, just as with every entity and event in the history of the universe, but the puzzle is how to conceive of what God creates. The author enters into all these questions with a responsible knowledge of modern physics and a profound theological expertise. His ‘modest conclusion’ is: ‘we theologians may wish to keep using the primary/secondary causation scheme, but if we do so, we ought to recognize and grapple with the fact that its metaphysical foundations have been undermined, and it is not clear how to provide a new basis for a comparable way of relating divine and created causes’. He finds some comfort in the statement ‘that theology is not alone in finding that old ways of thinking about causality have come unstuck in the encounter with quantum mechanics’.
Willem B. Drees (‘God as a Ground? Cosmology and Non-Causal Conceptions of the Divine’) continues Tracy’s line of thought. He takes into account the possibility that a ‘first cause’ view of God may not be integrated with cosmic natural history but nevertheless, in his view, the mystery of existence remains. After an excursion into some issues of natural theology in their newer incarnations, and those of Big Bang theory and its limitations, Drees embarks on his main topic. The development of current speculations, which go ‘beyond the Big Bang theory’, gives him a context to reflect further upon the idea of a first cause. With the development of new scientific theories, our knowledge of the world is not merely enlarged, but rather restructured. Entities and structures postulated by new theories had not been envisaged before. New theories lead to a reinterpretation of the world. This requires the rethinking of many philosophical and theological issues, the first cause problem included. One might envisage the end of a particular form of the cosmological argument, but the fundamental question remains: why does there exist something rather than nothing? Perhaps, the transcendent is not to be thought of in temporal terms. Given the role of mathematics, and its independence from the physical dimensions of time and space, one might try to draw on mathematics and logic to imagine ‘transcendence’. In mathematics, axioms are not so much the cause of the theorems, but rather a formal basis for all subsequent theorems. Is it a return to Anselm’s ontological argument which also argued for God along the lines of logic rather than of causality? This opens a perspective for reflecting upon a different way of conceptualizing God, as a ‘ground’ rather than as a ‘cause’. In the final section, Drees discusses the nature of theology as a particular type of human construction.
Why does the universe exist and why is it as it is? The reading of this book offers a unique opportunity to broaden our understanding of how to combine our vast knowledge of the laws governing the universe with responsible philosophical inquiry in the quest for the ultimate explanation of the world’s existence and its specific nature.