Future possible educational selves and the many worlds interpretation of quantum mechanics

Introduction

In a recent work Markus Gabriel, the philosopher, argues that the self emerges from socially situated reason-giving practices that establish various forms of self-knowledge. By means of agential identity work, ‘we project self-portraits of ourselves, who we are and who we want to be’ (Gabriel, 2019, p. 17). For their part, psychologists argue that future-oriented self-knowledge about who we do (or do not) want to become anchors our ‘possible selves’ (Markus & Nurius, 1986). Scholars have applied the idea that we envisage different possible versions of our idealised selves to young people in a range of educational settings (Oyserman et al., 2002; Henderson et al., 2018). There is a certain timeliness to this approach since the Covid-19 pandemic has brought to the fore the educational aspirations of the young and how they envision their future selves – given the disruptions to schooling and higher education that many have endured. The prospect of rampant technological unemployment due to robotization and artificial intelligence adds another layer of long-term uncertainty, as does climate change. Understanding precisely what these challenges mean for how the youth of today see themselves in the future, and likewise how the envisioning of their future possible selves affects their behaviour in the present, is a pressing matter. It is especially so given that negative health and educational outcomes have been empirically linked to ‘foreshortened future self-concepts’ (Prince, 2014, p. 705).

Important as they are, empirical findings about the psychological function of self-imaginings and future orientations are not my concern here. Rather, this piece addresses a neglected philosophical point about the very concept of future possible selves. The use of the term ‘possible’ gives the self a modal twist that, in turn, raises questions about the ontological status of the worlds in which these selves might unfold.

In the standard social psychological view, an individual’s possible selves diverge or coalesce in one world, within a single timeline, as their self-conceptions are challenged or verified (Markus & Nurius, 1986). Certainly people can (and do) look backwards and forwards as they form self-conceptions to which they are more or less attached. In this sense, each possible future self is merely a member of the individual’s ‘parliament of selves’ (Wieck, 1995, p. 18) – past, present and future. This social psychological view does not, however, exhaust the philosophical questions that arise. Are future possible selves nothing more than multiplicitous imagined alternatives? Are there possible worlds in which at least some of these selves might be simultaneously actualised beyond our interiorized imaginings? That is to say, worlds where we might really become (or not become) who we want to be? If so, how is logical and metaphysical contradiction to be avoided? Arguably, insightful answers to these questions can be found in the Many Worlds Interpretation of quantum mechanics.

Origins of the many worlds interpretation

This interpretation’s origins lie in the maverick physicist and nuclear-era game theorist Everett Hughes’s pathbreaking doctorate in physics, completed in 1957 at Princeton, together with a longer unpublished manuscript – the labyrinthine genesis of which is explained in a masterful biography of Hughes (Byrne, 2017). Both of Everett’s works were made widely available in 1973 in an edited volume that coined the phrase ‘many worlds interpretation’ (DeWitt & Graham, 1973). Everett’s ideas ultimately generated a novel solution to the quantum measurement problem. What is the nature of this problem? Well, within quantum mechanics, a longstanding debate has been had over precisely how to reconcile the wave-like properties of elementary particles with actual experimental results. In the quantum-mechanical view, how any particular particle is indefinitely distributed cloud-like in space is represented by a mathematical wave function, as described by the Schrödinger equation. As Becker notes, this equation predicts ‘with perfect accuracy how any wave function will behave’ (2018, p. 17). Yet a scientific measuring device, when applied to a quantum particle such as a photon or an electron, will locate the particle at a precise point – in one location and not another, that is.

A particle’s momentum has spin, and technically, prior to measurement, the particle was in a superposition – a physical state – of being, for example, both ‘spin-up’ and ‘spin-down’ (Carroll, 2019, p. 114). An analogy sometimes used to describe superpositionality is a photograph that has been double-exposed, with one image superimposed on the other. The particle is, in essence, co-located. Immediately after the measurement, however, the particle is located in just one of these physical positions. The problem is that it seems as if the Schrödinger equation is momentarily held in abeyance as ‘the wave function collapses everywhere except a random point’ (Becker, 2018, p. 18). This is, in fact, the standard Copenhagen interpretation of quantum mechanics associated with Niels Bohr: the wave function only obtains as long as macroscopic objects – namely, people and measuring devices – are not looking or measuring.

Now, it seems unusual – if not downright odd – that measurement (or observation) can educe a specifically located physical particle by collapsing a mathematical function that otherwise obtains. Indeed, the notion that the quintessentially human act of measuring features in ‘the collapse law’ is, for many, scientifically ‘repugnant’ (Lewis, 2004, p. 10). For others, it presents the opportunity for speculative philosophising. For example, on the basis of the Bohrian interpretation alone, Barad (2007), resorts to strange entanglements of mind and matter and thereby opts for social constructionism over scientific realism – which, apart from sheer empiricism, are the two main alternatives within contemporary philosophy of science (Haig, 2018). Any philosophical framework erected on the basis of a single scientific interpretation of a physical phenomenon that has several different interpretations is, at best, incomplete and open to being challenged when the science changes.

As Rob Koons points out, what is wrong with the Bohrian interpretation is that macroscopic objects are not uniformly describable in non-quantum, ‘purely classical terms’ because ‘it is interaction with the classically described realm of measurement devices that collapses the wave-function in Bohr’s model’ (Koons, 2021, p. 2762). The Many Worlds Interpretation (hereafter MWI) solution to the measurement problem that stems from Hughes’ doctoral work, as the MIT physicist Max Tegmark puts it pointedly, is this: ‘The wave function never collapses’ (Tegmark, 2014, p. 186, emphasis omitted). Instead, it accurately, comprehensively and consistently describes real features of quantum systems. Rather than being a discovery, the so-called collapse law is thus reframed by the MWI as an invention – a convenient scientific fiction, if you will.

From the microscopic to the macroscopic view

It is perhaps easier to explain the MWI-relevant implications of the non-collapse idea with reference to the macroscopic – rather than the microscopic (quantum) – world. There is no risk of misplaced metaphorical displacement because of the reassurance given to the MWI by decoherence theory (Halliwell, 2013). The phenomenon of decoherence explains (a) that superpositions apply equally to macroscopic objects, and (b) why we cannot directly observe superposed everyday objects ‘such as cannonballs or the Eiffel Tower’ (Byrne, 2017, pp. 393-394). Perhaps the most well-known such object used for illustrative purposes is Schrödinger’s hypothetical cat (Bruce, 2004). In this thought experiment, a cat is contained inside a box with a decaying radioactive isotope and a Geiger counter hooked to a trigger that will release a lethal substance when activated by the decay. Due to the cat becoming entangled with the decaying atoms, its fate appears to be a result of the observer (measurer) looking inside the box – but the paradox is that, until this happens, the cat ‘is in a superposition of being both alive and dead’ (Hobson, 2018, p. 21). At the macroscopic level, such a superposed state is not intelligible since, of course, it is an egregious contradiction. How the Everett-inspired MWI resolves this conundrum is that the wave function remains intact but it bifurcates and, in so doing, replicates the cat. In the course of quantum measurement, the level of entanglement between the objects involved is so great that the world literally splits in two: one featuring a dead cat and one featuring a living cat, as well as duplicates of the observer, the box and everything else entangled with it. As one leading physicist who is a proponent of the MWI puts it, ‘decoherence causes the wave function to split, or branch, into multiple worlds. Any observer branches into multiple copies along with the rest of the universe’ (Carroll, 2019, p. 119, emphasis omitted). Further, branching occurs well beyond quantum experimentation; it is a pervasive phenomenon. To take just one example, the ongoing radioactive decay of atoms in the human body also periodically splits ‘the wave function in two’ (Carroll, 2019, p. 120).

For advocates of the MWI, the notion of multiple worlds and branching is not a colourful façon de parler. It is entirely serious. The multifarious worlds that stem from branching are not ‘mere possibilities’ but rather are all ‘on an ontological par: if one is actual, they all are’ (Lewis, 2016, p. 61). Any lingering Aristotelian notions of moving from possibility (or potentiality) to actuality are thereby consigned to the philosophical dustbin (Putnam, 2005). Now, if there are branching worlds, then there are ‘branching people’ (Lewis, 2004, p. 12). If there are branching people, then there are ‘branching selves’ (Lewis, 2007). The implications of the MWI for personal self-identity are clear: our many future selves are not possible but rather actual. Within the limits of physical possibility, delimited by the laws of nature, all of our life-chances play out equally across the different branches.

What this MWI-derived philosophical anthropology means for the care of future selves goes well beyond anything captured in the psychology academic literature. This is because, strictly speaking, we are not talking about possible selves – in the sense of selves that are contingent and thus can fail to exist. Rather, our ‘future selves are coexisting actualities, not alternative possibilities’ (Lewis, 2004, p. 12). What do young people think of this idea? What implications does it have for how they think and act right now? To get an answer, this present author asked their 14 year-old son. The answer: ‘I don’t care about those people because I don’t know them’. This is indeed the concerning side of the MWI. Since each of ‘the branches evolve independently’ our ‘successors in different branches will not be aware of each other’ (Lewis, 2007, p. 2). And this is precisely the issue at hand: why should the young care about their future selves and what happens to them? The problem of self-care, however, goes far beyond the lack of awareness of our branched selves. Whenever a person faces a stark educational life-choice, since both results will pan out irrespective of which way the decision is made, why care about choice-making at all? Moreover, since the evolution of the wave-function is deterministic, is there any sense in which the educational (and other) choices they make will influence what happens to their future selves? In fact, do they really make choices at all?

Uncertainty and choice-making

To date, philosophers have not framed the knock-on effects of the MWI in the humanistic manner set out above. Instead, much of the debate about the care of future selves has been about how to factor uncertainty and probability back into the MWI; it is tainted by the arid formalism of the analytic tradition; and it employs contestable utilitarian notions of the maximally rational actor (Greaves, 2004; Papineau & Durà-Vilà, 2009). Nevertheless, continental philosophers who are both MWI-sympathetic and interested in young people’s future orientations should to take account of this discussion. There are two reasons for doing so. Firstly, as noted, many of the difficulties facing today’s youth stem from making decisions about their lives under conditions of considerable uncertainty. Secondly, in such circumstances, it is still rational to assign subjective probabilities (or credences) to the outcomes of known stark choices (Pol & Reveley, 2017). Yet, in the MWI, all choices and all outcomes that result from them will actually happen. Talk of assigning any type of probability weighting then becomes literally meaningless – as does choice-making when confronted with alternative courses of action.

Simply put, the MWI apparently leaves little room for anyone to be uncertain about what choices to make. If the MWI is correct, and worlds evolve deterministically in accordance with statistically-described wave functions subject to branching, the decision over whether to attend university or to engage in risky cliff-jumping is of no consequence either way a school-leaver makes it. If one jumps off a cliff and is hurt, there is a successor self who decided not to do this and is fine. One unfortunate consequence of this interpretation, therefore, is this: it can imply that a care-less attitude is, at a certain level, quite tenable and perhaps even desirable. The upshot is that finding some room for uncertainty, credences and meaningful choice-making is paramount. Until comparatively recently, however, philosophical efforts to do so have not borne much fruit. Lewis (2007) argues that attempts to insert uncertainty into the MWI using different ontological conceptions of personal identity ultimately do not work. After systematically considering three different identity theories – those of Derek Parfit, David Lewis and Theodore Sider – the author (Lewis) concludes that none of them provide any room for uncertainty to enter into the many-worlds equation. Nevertheless, in more recent writings, Lewis has identified some leeway for the MWI to accommodate a modicum of meaningful choice-making as it applies to future selves. Exactly how this might work is worth quoting at length:

Consider a case in which an agent has two competing self-conceptions, and two corresponding possible actions furthering one self-conception each….[T]he superposition of two distinct actions results in branching rather than collapse. Each action occurs in its own separate branch of reality. But each of the resultant people can ask themselves, “What is it that resulted in in me making this choice rather than the other one,” and in each case the answer has to be “Nothing.” That is, for each postchoice person, there is nothing in the prechoice physical state that necessarily leads to one choice rather than the other. (Lewis, 2016, pp. 146-147, original emphasis).

The upshot is that are reasons to think that choices are not predetermined in the MWI. More work is required to explore what this view means for young people’s choice-making – not only in the domain of education but also when facing momentous decisions such as whether or not to transition.

From many worlds (and selves) to minds

There is no reason to doubt that future possible selves fulfil important psychological functions for young people as they seek to fulfil their goals and to craft their life-projects. Still, as this discussion has shown, there is much more to the concept of a future self than the psychological literature suggests. When viewed through a MWI lens, our future selves are not mere imaginings or potencies waiting to be actualised. They are real in the strongest possible metaphysical sense. Though many of the key philosophical questions that arise remain to be answered, the MWI provides the basis for productive discussion. Finally, it is delightful to see that a quantum-mechanical view of mind has recently featured as a ‘Big Idea’ in this journal (Turner, 2021). There are many ways of cashing out quantum mechanics within philosophical discourse. Within the domain of the philosophy of education specifically, what would be interesting is if connections can be made between the many worlds and branching selves view, on the one hand, and that of ‘many minds’ (Barrett, 2003), on the other hand.

James Reveley
University of Wollongong, Wollongong, NSW, Australia
[email protected]