What Might Time in Quantum Mechanics Mean for the Doctrine of Salvation?

1. Introduction
2. Fields of Study
   
   • 2.1 Quantum Mechanics and the Nature of Time
   • 2.1.1 Metaphysics of Time
   • 2.1.2 Physics of Time
   • 2.1.3 Indefinite Causal Order
   • 2.2 Salvation
3. Discussion
   
   • 3.1 Indefinite Causal Order and a B-theory of Time
   • 3.2 Salvation as Mind-Dependent Becoming
4. Conclusion

• Bibliography
• Cite this article

1. Introduction

Time is an inescapable feature of lived experience – it structures our lives in so profound a way that it is almost impossible to imagine a life not bound by temporality. Despite its inescapable presence, there is remarkably little philosophical or scientific consensus about the fundamental nature of time. What is time? Does time really pass? Why can we remember the past but not the future? Philosophers have been asking these questions since the classical period. Indeed, as Huw Price rightly notes, the philosophy of time “is unusual even by philosophical standards for the durability of some of its main concerns” (Price 1996, 12).

Examining the nature of time is in the wheel-house of both physics and metaphysics, and between them philosophers and scientists have made excellent progress unpacking many of its important features. Nevertheless, on its fundamental characteristics no consensus has been reached. Perhaps this is because physics is profoundly incomplete – until the scientific community find a so-called ‘theory of everything’ (more specifically, a unification of General Relativity and Quantum Mechanics) many persistent questions about the world must remain open. Despite this somewhat pessimistic point for our present situation, meaningful work can still be done in the continuous journey towards understanding time. In this article, we tackle this task head-on. We are motivated by the belief that as the frontier of science advances we are travelling ever closer toward ultimate truth about the nature of reality. With this comes progress with regards to understanding the complex and nebulous entity that is time.

Our focus here is on a cutting-edge finding from Quantum Mechanics which, we argue, might just be the key to unlocking the nature of time. This approach depends on the assumption that physics can illuminate that which philosophers have struggled with by bringing empirical evidence into the debate. As Tim Maudlin writes, “metaphysics is ontology. Ontology is the most generic study of what exists. Evidence for what exists, at least in the physical world, is provided solely by empirical research. Hence the proper object of most metaphysics is the careful analysis of our best scientific theories” (Maudlin 2007, 104). Here, we do just that. After a general introduction to Quantum Mechanics and the approaches to understanding time that occur within it, we dive straight into the specific finding with which we are concerned: Indefinite Causal Order. 

With this in hand, we turn to the doctrine of salvation. Time and salvation are inherently connected, and it is puzzling that this has received almost no philosophical or theological attention thus far.^[1] Salvation requires change – an individual is transformed from a state of fallenness to a state of redemption. For such change to be possible, one needs a theory of time that can metaphysically substantiate such change. If time does not pass, then how can an individual change from being fallen at one point to being saved at another? Without an objective distinction between moments in time, it is difficult to understand how an objective change from one property to another might occur. Insofar as salvation requires a transformation in time, then, theology and physics have a shared interest in the metaphysical questions we present here.

Our theological puzzle is this: a recent finding from Quantum Mechanics termed Indefinite Causal Order seems to indicate that temporal order is not fixed at the quantum level. This, we argue, offers empirical support for a B-theory of time. A B-theory seems incompatible with the kind of change required to substantiate a salvation-transformation. How should theological formulations of the doctrine of salvation respond?

This puzzle emerges out of an ongoing project between a scientist and a philosopher who share an interest in the physics and metaphysics of time. Conversations between science and theology on the issue of time have been overwhelmingly focused on how the nature of time should inform our understanding of God’s relationship to time, and vice versa. The focus on God has generated excellent work, particularly from authors such as William Lane Craig (2000a, 2000b, 2001) and Richard Swinburne (1993, 1996, 2008). Nevertheless, with the exception of Robert Russell (2012), there is a significant gap in the literature when it comes to the issue of time and salvation. Our research is, therefore, cutting-edge in two domains. It employs recent data from quantum mechanics, which is yet to receive significant metaphysical engagement, and applies it to salvation, itself a neglected dimension of the “theology and time” debate thus far.

2. Fields of Study

2.1 Quantum Mechanics and the Nature of Time

2.1.1 Metaphysics of Time

Though the philosophy of time can be traced back as far as the Ancient Greeks,^[2] the contemporary debate took its current form after J.M.E. McTaggart published “The Unreality of Time” (1908). This article employs McTaggart’s distinction between A-series and B-series time to denote distinct temporal theories.^[3] We use the term “A-theory” to denote any theory in which time has the following properties: tensed truths are real and fundamental; time is dynamic in the sense that it passes, with successive moments possessing the objective properties of future, present, then past; there is an objective and universal present moment, at which point potential future events become real.

The B-theory, on the other hand, is a static theory of time insofar as it holds that all events in time eternally co-exist. For this reason, it is called the “block universe”. In the block universe time does not actually flow and temporal passage is an illusion. When you look out of the window of a moving train, for example, you perceive the landscape as flowing past you. This is not an ontological property of the space; it is a phenomenological property of your perception. There is no sense in which the various spatial points you currently observe are any more real than those you observed previously. Those locations still exist, even if you can no longer see them. The perceived dynamism is a result of your movement through the space as opposed to the space itself exhibiting flux or passage. The B-theory models temporal passage as analogous to space in this way. The finer details of how this universe operates will generally be filled in by the prevailing physical theory,^[4] but a B-theorist must be committed to the claim that a complete account of temporal reality can be given with “an exhaustive catalogue of which events occur, and how they are temporally related” (Pooley 2013, 324).

2.1.2 Physics of Time

There have been several epochs in physics’ understanding of time. Pre-relativistic Newtonian physics, for example, described time as a fundamental flowing feature of the universe. Mechanics was formed within this framework as the scientific description of the laws that govern changing physical systems through time. Time was considered absolute, meaning it is universal, and it flows equitably.^[5] Hence ‘now’ is an objective property of events, meaning it is the same for all observers regardless of their motion or location.

The Special and General Theories of Relativity fundamentally transformed the Newtonian understanding of time. Special Relativity showed that simultaneity is not absolute, meaning there is no absolute perspective from which one can say whether two events are objectively simultaneous. Different observers were shown to measure temporal passage differently – this shocking revelation left a powerful legacy.^[6] Moreover, in General Relativity, “there isn’t a preferred and observable quantity that plays the role of independent parameter of the evolution, as there is in non-relativistic mechanics” (Rovelli 2009, 3). Instead, spacetime curves with the presence of matter and energy – this then affects the behavior of local clocks. In both theories time is determined by local classical variables but is no longer understood as passing uniformly for all observers. Such a move marked physics’ departure from the Newtonian conception of absolute and universal time. Quantum Mechanics looks set to bring a new epoch for time in physics.

Quantum mechanics is a formal theory with several interpretations.^[7] Until disputes between rival interpretations, each of which paints a slightly different picture of the nature of time, are resolved, time remains an open question. Answers may only be provided when a quantum theory of gravity is developed, in which a relativistic understanding of spacetime is incorporated into quantum mechanics. When describing the large-scale interactions of massive bodies in curved spacetime, General Relativity models time as continuous. Quantum mechanics describes the counter-intuitive behavior of sub-atomic systems; it introduces discreteness into a multiplicity of properties, e.g. energy and length. The need to reconcile what these disparate understandings mean for time is known as “the problem of time” (Anderson 2017, Muga et al 2008). Though the “problem of time” is very much an open question, useful insights may still be found from an analysis of quantum findings.^[8] On this basis, we suggest ways in which the new finding we consider, namely Indefinite Causal Order, may make productive contributions to the metaphysics of time. We do this while remaining cognizant that any such conclusions inevitably require some form of hedging one’s bets.

2.1.3 Indefinite Causal Order

At first glance, Indefinite Causal Order seems to cast doubt upon our common-sense understanding of time. Quantum mechanics operates at the scale of subatomic particles, a world of uncertainty.^[9] If Indefinite Causal Order is a feature of reality, then this uncertainty applies to temporal relations also. Through investigating the role of “causal order” in quantum mechanics, physicists examine whether within quantum theory the order of events can be objectively defined.

Schrödinger’s famous cat paradox brings to light the stark contrast between the goings on in the “classical” realm of our everyday experience and the rules that govern the quantum realm (Villars 1986). The paradox concerns a cat locked in a box with a vial of poison which will be released when a small amount of radioactive matter decays, and the probability of decay is set at 50%. On the Copenhagen Interpretation of Quantum Mechanics, until a measurement is made and the wave-function collapses, the atoms are neither decayed nor not decayed. They are, therefore, in a superposition. Until one measures the system (i.e. opens the box) and the state of the cat is determined, the cat must be held to be both alive and dead. The act of measurement itself disturbs the system and destroys the fragile quantum superposition.

Among other things, the paradox illuminates that quantum objects can simultaneously exist in a variety of states. The superposition principle applies to a variety of properties, a notable example being position, but it has only recently been proposed that it may extend to the order of events (Hardy 2009, Chiribella et al 2013). That is to say, not only is it possible for a quantum object to exist at multiple locations at once (following the application of the superposition principle to spatial location), e.g. at location A and location B, but it is also in principle possible for event A to happen before event B and for event B to happen before event A.^[10] This is Indefinite Causal Order.

The search for a quantum theory of gravity rages on, leaving many empirical questions open. More work must be done in order to establish whether and to what extent Indefinite Causal Order impacts the physical world.^[11] Nevertheless, experimental support for Indefinite Causal Order is found in a recent experiment (Goswami et al 2018). The experiment introduces the quantum switch, which is implemented using the superposition of two causal orders in an optical setting. It runs as follows: the experimenters constructed a maze which they sent photons through. This maze could be completed in two routes depending on the polarization of the photon. In this maze, there are two checkpoints labelled: A and B. One route hits A first and then B, the other route hits B first and then hits A. One polarization generates the causal order A then B, the other polarization generates the causal order B then A. Importantly, the photons go through a polarizing beam splitter, and the polarization of each photon determines whether it carries on in a straight line or is reflected at 90 degrees. If the photon is polarized in one orientation it follows one route through the experimental circuit, and if it is polarized in an orthogonal orientation it takes the alternative route. The route taken was readable at an endpoint C.

This seems fairly straightforward. Where it gets interesting, however, is when the superposition principle enters the fray. The photon can be prepared in a superposition with regards to its polarization. This means it can be polarized in both orientations at the same time. As the polarization of the photon determines the route it takes through the maze, and therefore the order it passes through each checkpoint, a photon in a superposition with regards to its polarization can be said to travel both paths at the same time.  There are, therefore, two causal paths (A then B, or B then A), and the paths are in superposition. To verify this, the scientists measured the causal non-separability of the process and found that a superposition of causal orders had taken place, viz. evidence for both A happening before B, and B happening before A.^[12] Thus, in this experimental setting, the order of two events was found to be indeterminate. Indefinite Causal Order, then, has the potential to throw everything we thought we knew about time out of the window. Before we address this, however, we must turn to the second piece of our theological puzzle.

2.2 Salvation

Salvation is a broad and multifaceted concept, and the human quest for salvation has an extremely rich history. It is arguably a universal feature of human experience, whether it is conceived as the search for fulfilment in earthly life, for the healing of individuals or groups, or the conservation of a natural world systematically exploited by humanity. A common thread that runs throughout all the formulations is that salvation is the search for authentic life. It requires change from a prior state in which an individual or group is unfulfilled or falling short personally or relationally, to a state of authenticity, fulfilment and rich relationality. The Christian faith is specific in its understanding of salvation. Paul Fiddes argues that the term “atonement” (at-one-ment), first introduced by William Tyndale in his 1526 early English version of the New Testament as a neologism to translate the notion of reconciliation aptly reflects the Christian belief that salvation is “dependent upon the restoring of a relationship between human beings and God, who are estranged from each other” (Fiddes 1989, 3-4). Such atonement depends upon a particular moment in time and space at which point Jesus of Nazareth was crucified on a cross. For Christians, this event is the centre point in human history; however, precise formulations of the Christian doctrine of salvation are multifarious.

“Salvation” is always salvation from something; it assumes that the life of human beings and world in which we live is distorted, self-destructive, or failing to reach its true potential (Fiddes 1989, 176). Typically, how one conceptualises salvation depends upon one’s understanding of the human predicament in the cultural context in which salvation occurs. As Fiddes notes, the task of theology is locating where the mystery in our midst is to be found (Fiddes 1989, 5). Our primary concern here is the mechanism of salvation, namely salvific change.

It is helpful to explore salvation through engagement with a particular scholar. Paul Tillich is a good example, as his doctrine of atonement is compatible with the kind of interpretive task with which we are here engaged (Tillich 1957). Tillich defines salvation as the transformation from Old Being to New Being. He describes fallenness through an existentialist lens, leading to an existential understanding of salvation – existence is characterised by the failure to actualise potential, fear of meaninglessness, and the threat of non-being, each of which causes deep anxiety. This is Old Being. Christ represents the soteriological potential latent in humanity by uniting that which finite existence draws asunder. He is God and human, he is the fullest realisation of human potential, he took on the conditions of existence and overcame them. In so doing, he represented and embodied New Being. Tillich argues that if individuals allow themselves to be grasped by the saving power of the Spirit, and accept the redemptive power of Christ, they undergo a salvific transformation from Old Being to New Being. A life of New Being involves reconciliation with God and an alleviation of the existentialist states of mind that plague Old Being.

3. Discussion

3.1 Indefinite Causal Order and a B-theory of Time

Indefinite Causal Order poses a significant challenge to the metaphysically orthodox bifurcation between the A-theory and B-theory, as it undermines both an objective present moment and fixed temporal order relations. These are core features of the traditionally defined A and B-theories respectively. Nevertheless, we argue that following modification, the coherence of the B-theory is preserved. The A-theory, however, must fail. Indefinite Causal Order is inconsistent with a fundamental claim of the A-theory, namely that there is an objective present moment. Such a claim requires this now to be both objective and universal, as it is the ontologically privileged point at which tense is defined. Classical A-theories claim that future objects and events come into being when they become present.

We argue that Indefinite Causal Order makes the present fuzzy, which is a big problem for the A-theorist. An objective present that sharply divides the future from the past is a necessary structural feature of the A-theory, yet Indefinite Causal Order requires the A-theorist to claim that future events both exist and do not exist. In this context, whilst the experiment is underway the event “the photon hits checkpoint A” has both happened and has not happened, making it both real and unreal. Following this, the future that holds this event both exists and does not exist. This claim vastly surpasses the findings of the initial experiment that a photon can be in a superposition which affects the order it traverses a maze. An object being in a superposition is not a surprising finding, though its implications for causal order are indeed novel and interesting. The A-theorist, however, would have to extrapolate those findings to claim that reality itself exhibits such fuzziness, as the A-theoretic now ontologically determines which events are real and which are not. On an A-theory in which the present is the point when future events become real, this experiment shows the future, and the objects therein, as both existing and not existing. This is incoherent, and therefore Indefinite Causal Order lays a fatal blow on the A-theory.

Indefinite Causal Order follows other areas of physics in presenting problems for an A-theory. Einstein’s Special Theory of Relativity similarly indicates that an objective present moment cannot be clearly defined, and thus stands in opposition to an A-theory of time.^[13] Indeed, a famous argument claiming that Special Relativity is incompatible with an A-theory can be adapted to show that Indefinite Causal Order is similarly incompatible with an A-theory. The argument, constructed by Hilary Putnam, argues that Special Relativity leads us to the conclusion that, viewed from different perspectives, one has reason to believe that “future things (or events) are already real!” (Putnam 1967, 242). This undermines the credibility of the claim that there exists a universal present moment at which point the future becomes newly and objectively real. If events that are future from one perspective already exist (as they are present from another perspective) then the present moment cannot be such a universal and objective feature of reality. Putnam begins with A-theoretic assumptions, arguing that everything that is simultaneous with me-now is real, as I-now am real by virtue of being present. As “is real” is a transitive relation, then everything standing in the simultaneity relation with “me-now” is real. Yet, as Special Relativity indicates, an observer simultaneous with me-now could experience events as present (and thus real) which lie in the future of me-now – making future events already real (Putnam 1967).

A similar argument can be applied to Indefinite Causal Order. During the experiment the causal order of the two operations is indefinite, so both A before B and B before A occurs. Therefore, from the perspective of A in the first case B is a future event; from the perspective of B in the second case A is a future event. In the system viewed as a whole both of these cases obtain, therefore from each perspective future events are already real. If this is the case, then the present cannot be the universal boundary at which point future events objectively come into existence. Both presentism and the growing block require such a knife-edge present moment. Therefore, Indefinite Causal Order is incompatible with the most successful A-theories.^[14]

We argue that the B-theory can remain coherent given Indefinite Causal Order, conditional on modification. The modification we propose is a shift in emphasis when considering the B-theory’s core features from temporal relations to the block universe. Such a move is not unprecedented. Though this has not received significant attention in the literature, Special Relativity also necessitates modification of the B-theory (Read and Qureshi-Hurst 2020, footnote 8). In its original form, the B-theory holds that a fundamental description of time can be given by the relations earlier than, later than, and simultaneous with. The objectivity of these relations is at least heavily implied. However, though timelike-separated events will stand in objective earlier than, later than, and simultaneous with relations to one another, this is not the case for spacelike-separated events.^[15] Special Relativity forces the B-theorist to conclude that the class of events standing in these ordering relations is more impoverished than the original B-theory maintained. Thus, following Special Relativity, core features of the B-theory, namely temporal ordering relations, underwent modification regarding their domain of applicability. The ordering relations hold objectively only for timelike-separated events.

We argue that if Indefinite Causal Order is true, temporal ordering relations must receive another narrowing of their domain of applicability. Rather than the relations of temporal order earlier than, later than, and simultaneous with being fundamental (viz. holding at the smallest scales), they apply only to large-scale classical systems in which quantum effects do not take force. This facilitates a change in emphasis in the B-theoretic account from the fine-structure of B-series relations to the large-scale block universe description.

The broad metaphysical picture (namely the block universe) should be held as the defining characteristic of the B-theory, we argue, given Indefinite Causal Order. The ordering relations are then understood as emergent properties which apply to classical objects and systems, and that do not apply at the quantum level. All that really changes is the emphasis one places on the defining features of a B-theory – on our view temporal relations are involved in a B-theoretical description of reality but do not hold at every level. Rather, at its core the B-theory describes reality as a block universe and is not dependent on objective ordering relations at every ontological level. This idea of time as an emergent property follows Carlo Rovelli’s idea, and similar arguments about spacetime’s non-fundamentality are made by Baptiste Le Bihan (2019), as well as Nick Huggett and Christopher Wüthrich (2013). Though quantum processes do not behave in a temporally ordered or B-theoretic fashion, the large-scale picture provided by the macro-world description of middle-sized objects is that of the block universe. Within this temporal ontology concepts as basic as change – and those moral theories and theological doctrines involving change – must be revisited.

3.2 Salvation as Mind-Dependent Becoming

If the B-theory is true, this has significant repercussions for soteriology. The primary problem the B-theory presents for salvation is that it seems to prohibit ontological change. If all things and events co-exist in the spacetime manifold, then in what sense can genuine change be accommodated? Change is defined as an act or process by which something becomes different. It is precisely such becoming that is prohibited by the static temporal ontology of the block universe. That change is a necessary feature of time was McTaggart’s primary reason for concluding time was unreal. He held that it is only within an A-series that genuine change is possible. The only conceivable B-series change is if “an event ceased to be an event, while another event began to be an event. But this is impossible … an event can never cease to be an event. It can never get out of any time series in which it once is” (McTaggart 1908, 459-460). Thus, McTaggart concludes that genuine change is impossible on the B-series.^[16]

The puzzle is clear. Salvation requires change from a prior state of sin to a subsequent state of atonement, and this change is generally understood to bring something fundamentally new to the life of the saved individual. Salvific change thus conceived seems incompatible with the block universe. We argue that solutions to this problem can be found in the literature on the philosophy of temporal experience. It is almost universally accepted that we experience time as though it passes, i.e. our experience seems to support an A-theory of time. Yet empirical evidence supports a B-theory. Philosophers of time have wrestled with this in the past – why do we experience time as passing if time does not in fact pass?

Adolf Grünbaum offers an explanation of temporal experience within a B-theory, and the framework he provides offers a productive solution to our theological puzzle. He writes, “what is necessary so to qualify the event is that at the time t at least one human or other mind-possessing organism M is conceptually aware of experiencing at that time either the event itself or another event simultaneous with it in M’s reference frame” (Grünbaum 1971, 206). All that is required of an event to be deemed as present is a conscious mind experiencing it as such. The successive experiences of events as present is sufficient to construct the experience of temporal passage, without requiring the truth of an A-theory. Grünbaum accepts McTaggart’s claim that the only real change is A-series change, in which an event goes from possessing one temporal property (i.e. being present) to another (i.e. being past), but he offers a weaker threshold for what counts as possessing a temporal property: a mind experiencing it as possessing that property. If event e is present for me, and then past for me, then phenomenologically e has changed from present to past.

On this view, agents subjectively experience the world as changing by virtue of their consciousness piecing together such change from a thread of events experienced in a certain order. Perceptual awareness is all that is required to phenomenologically substantiate the type of change required to transform an individual’s life from a state of fallenness to a state of salvation. This does not mean that salvation itself is illusory. On the contrary, the saved individual objectively possesses the property of being fallen at certain B-series points during their lives, and objectively possesses the property of being saved at later points. The experience of changing between these two states is illusory insofar as neither is a genuinely new state which was not already present in the block universe or the four-dimensional extension of an individual’s being. Yet just as the events in the block universe are real and ground an illusory sense of passage, so too are the properties of being fallen and being saved objectively real. It is the experience of a robust change from one to the other that is illusory and is accounted for by mind-dependent becoming. This qualitative change is both powerful and profound, and represents a soteriological transformation, despite not being the kind of change one might intuitively expect given an uncritical acceptance of an A-theory of time.

Returning to Paul Tillich, one can reorientate one’s focus away from an ontological understanding of the transformation from Old Being to New Being and onto its psychological dimensions. One can emphasise instead the psychological healing power of Christ the redeemer whose soteriological significance sits in the context of putatively universal human experiences of estrangement and anxiety. Christ brings atonement by embodying the unity of essential humanity with actual human existence. Though this sort of salvation transformation has traditionally been understood as an ontological transformation (i.e. one mode of being is transformed into another) our proposal for mind-dependent salvific becoming holds that it is more appropriate to focus on the psychological consequences of New Being. By this we mean an alleviation of anxiety, alienation, guilt, fear of meaninglessness, and the threat of non-being. A saved individual is reconciled to God, the ground of being, and this is detectable through, and experienced as, the aforementioned psychological dimensions of New Being. At this point the individual enters into a new relation with God, and the existentialist concerns that dominated their previous mode of existence melt away.^[17]

4. Conclusion