Constellations is a captivating portrayal of the human condition on the stage of a bubbling multiverse, inviting audiences to ponder on its profound consequences. Moving back and forth in time and exploring multiple realities, it animates themes of love, free will and the nature of existence in a radically expanded reality. Throughout the play, Marianne and Roland revisit pivotal moments in their relationship, repeating scenes with slight variations, each iteration hinting at divergent paths and a multitude of possibilities.

As a theoretical physicist myself, I cannot help but think more about it. How closely does the multiverse of Constellations parallel the multiverses explored in theories of fundamental physics? Can it be subjected to a scientist’s gaze, and does doing so deepen our appreciation of the play?

Our quotidian experience is rooted in the world of classical physics. An apple is red, and remains so, irrespective of whether I look at it or not. My eyeglasses dutifully wait on the nightstand, where I tossed them aside last night as I drifted off. All things tend to stay put, unless something happens to disturb them. This classical world is incredibly predictable. To understand just how predictable, consider the Chandrayaan-3—its path was predicted to an accuracy of a few kilometres, thanks to the ingenious work of our ISRO scientists, even as it landed on the Moon over 384,400 km away from the Earth.

The quantum world is drastically different. Things jiggle and whizz about randomly, and often one cannot reliably speak of them. A particularly puzzling feature of quantum physics is that it forbids “local reality”. Here, “local” means that events can be influenced only by their surroundings, and that no influence can travel faster than light. “Real”, on the other hand, means that objects have definite properties independent of whether anyone is looking. Thus, the lack of local reality means that a quantum-apple cannot be said to when one is not observing. Quantum theory, in fact, predicts that objects do not have definite positions and trajectories, even in principle.

Sounds strange, doesn’t it? Yet, this facet of quantum reality has been repeatedly substantiated through rigorous experimental tests, a feat that earned Alain Aspect, John Clauser and Anton Zeilinger the 2022 Nobel Prize in Physics. This lack of a definite trajectory is best captured by Richard Feynman’s “sum over paths”. This view of quantum theory posits that all paths or sequences of events between two instants of time contribute to the evolution in between. This f lies in the face of the classical Newtonian view that a single definitive path determines the outcome. Even the Einsteinian shackles of causality are apparently not obeyed. The sum over paths includes paths that zig and zag backwards and forwards in time.

A subtle element of this idea is that all paths are individually equally likely, and yet the classical path appears most prominently in our everyday experience. This is because the paths near the classical path add in-sync—as if practised voices in a choir, whereas other paths, though individually as loud, melt into a cacophonous din. This is also why we do not easily feel quantum physics in play in our day-to-day life. The allowed quantum paths that effectively matter, are quite close to the classical path; the departures are prominent mainly for tiny subatomic particles.

This revised perspective on reality, as mandated by quantum mechanics, confers profound significance upon the act of observation itself. Objects persist in a superposition of potential states until observed, popularly known as a Schrödinger’s Cat state, and only the act of observation seemingly compels it to adopt a definitive state, albeit randomly and with calculable probabilities.

The many-worlds interpretation of quantum mechanics, proposed by Hugh Everett, provides a rationale for the probabilities associated with the result of an observation. Everett’s view, in a sense, extends Feynman’s “sum over paths” picture to also include a “sum over possibilities” associated with the results of observation. A sequence of observed events, connected by all possible paths, corresponds to “a world” within the multiverse of many worlds. The interpretation thus asks us to accept that we live immersed in a near-infinity of universes, all occupying the same physical space but evolving autonomously and incognisant of the others. In many of these universes there exist replicas of Marianne and Roland, indistinguishable in almost every way but living through different sequences of events.

These paradigm shifts fundamentally reshape our comprehension of human elements. Embracing the multiverse narrative not only highlights the kaleidoscopic richness of existence but also reimagines fundamental concepts like love, connections and relationships across a diverse array of timelines. Identifying with our counterparts in countless universes urges a re-evaluation, suggesting that connections transcend singular paths and extend across a myriad of potential histories. 

In a sense, central to the enigmatic allure of Constellations is also the portrayal of the universe as an unreliable narrator. Unlike Kurosawa’s cinematic masterpiece Rashomon though, where divergent viewpoints exist in the face of a singular truth, the different narratives in Constellations feel more equally true. Each branch of the multiverse is just as true as the others. The viewer, seemingly outside of the multiverse and aware of multiple realities, is thus presented with a narrative complexity that unveils the inherent subjectivity of human perception and our quest for coherence amidst the boundless tapestry of possibilities. This also prompts a re-evaluation of our roles in shaping the world. Our perceptions, intentions and interactions actively influence the unfolding reality, impacting not only our lives but also those of others around us. Embracing the uncertainty and complexity, recognising that every choice spawns a multitude of potential realities can generate empathy, kindness and compassion. Each individual contributes to the collective existence, simultaneously observing and participating. Sharing experiences and interpretations bridges realities, acknowledging our impact on others’ trajectories. This viewpoint empowers agency, encouraging mindful interactions and fostering a shared responsibility for the collective reality we shape.

By delving into the multiverse, Constellations not only fractures the notion of a singular truth but also reinforces the expansive nature of human existence. It challenges us to embrace the kaleidoscope of possibilities, to recognise our interconnectedness across infinite timelines and to wield the power of our observations and choices. In this dance of infinite realities, we are not just spectators but active participants, shaping and being shaped by the cosmic tapestry of existence.

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Basudeb Dasgupta is a theoretical physicist at the Tata Institute of Fundamental Research. His pioneering contributions to research on neutrinos and dark matter earned him the ICTP Prize in 2019 and the SS Bhatnagar Prize in 2022. Outside of physics, he takes avid interest in the arts, and can be found at www.bdasgupta.com