Forget the multiverse. In the pluriverse, we create reality together

J R Eyerman/The LIFE Picture Collection/Shutterstock

The concept of “now” has always intrigued me due to the inherent paradox it presents. From a personal viewpoint, the present is all-encompassing: it is the sole point where we can act, make decisions, and truly experience life. What did you eat for breakfast? Where do you plan to go tomorrow? Even our memories and future plans are created in the present; they exist only in the now.

However, in the realm of physics, “now” is considered non-existent. According to Albert Einstein’s theory of relativity, all points in time are equal, meaning events can already have happened or are yet to occur, depending on the perspective. There is no cosmic timeline through which reality unfolds.

This presents a challenge for us as sentient beings. If the present is an illusion, then we cannot influence the future because all events and times already exist. Without “now,” we lose a fundamental aspect of our being.

In my book, In Search of Now, I explored whether there is an alternative perspective. Can we align scientific data with a universe that involves us and our decisions? The answer, I discovered, is yes, but it requires us to radically redefine our understanding of reality and ourselves. “The world is such that you cannot separate yourself from it,” states Michel Bitbol, a philosopher of physics at the École Normale Superieure in Paris.

Quantum paradoxes

To understand this, consider a thought experiment proposed in the 1970s by renowned physicist John Wheeler. It illustrates that the universe and time may operate differently than we assume.

Wheeler’s experiment is a variation of the famous double-slit experiment in quantum physics, where the observer’s choice of measurement influences the outcome. When photons are directed at a screen with two slits, if their path is not observed, they behave like waves, passing through both slits. But if observed, they act as particles, moving through just one slit.

This peculiar shift from uncertainty to determinacy occurs the moment we observe (quantum physicists call this “collapse”). Wheeler took this further by asking what would happen if the decision to observe the photon’s path was made after its journey. Experiments over the years have confirmed Wheeler’s hypothesis: the decision affects the photon’s trajectory.

Variations on the famous double-slit experiment mess with our understanding of time and causality

CHRISTIAN KOCH, MICROCHEMICALS/SCIENCE PHOTO LIBRARY

Wheeler described this as “a strange inversion of the normal order of time,” implying that our choices impact not just the present, but the past as well. Physicists have tried to explain this and other quantum paradoxes with innovative ideas: proposing branching realities where all possibilities exist simultaneously in a vast multiverse, or suggesting an unseen guiding force, or pilot wave, that can instantaneously connect different parts of reality. However, Wheeler believed that quantum mechanics teaches us that our reality is intertwined with us. We can’t determine a particle’s state until we observe it, as what lies beyond is potential, not certainty. By posing questions, we shape the answers we receive.

Wheeler reasoned that if a phenomenon does not exist until measured, then what we perceive must include both its present and past. He proposed that our universe—near and far, past and future—is continuously created through the questions we ask. Different questions, or asking them in a different sequence, would yield different outcomes. He encapsulated this idea with the phrase “it from bit”: the particles we observe originate from information we participate in creating.

Wheeler’s insights led to the successful field of quantum information, which supports technologies like quantum computing and cryptography. Yet, as this field grew, Christopher Fuchs, a quantum physicist at the University of Massachusetts Boston and a former student of Wheeler, became frustrated. His peers discussed information as if it were a new fluid in the world. Fuchs felt this overlooked Wheeler’s central point: there is no answer until we pose the question.

“
Nature is being hammered out as we speak
“

From the 1990s, Fuchs developed his own interpretation of quantum physics, called QBism. This theory suggests that the outcome of a measurement is inseparable from the measurement itself. Fuchs and his colleagues have spent years revising quantum mechanics equations using a first-person perspective.

The approach they used is Bayesian probability, which interprets the world from an internal standpoint: instead of claiming “how things are,” you continually update predictions based on past experiences. “Probabilities are not things out in the world, but rather measures of what somebody knows,” says Fuchs. Alongside his QBist colleagues, Fuchs demonstrated that expressing quantum mechanics in this way is entirely feasible. This led to intriguing revelations.

At the heart of quantum mechanics is the Born rule, an equation devised by physicist Max Born in 1926. Traditionally, it was seen as providing objective probabilities for physical outcomes based on a particle’s quantum state. The Born rule, when rewritten in QBism, doesn’t describe objects in the outside world. Instead, it serves as a connection between personal probabilities—beliefs—across various experiments.

Fuchs argues that quantum physics probabilities do not pertain to external reality. Rather than acting as a flashlight illuminating external truths, quantum physics becomes a guide or “handbook” for predicting likely experiences following specific actions. Another individual, with different experiences and beliefs, might reach an entirely different conclusion.

QBism tells us that reality is more like a jazz improvisation than a static brick of space-time

zerocreatives/DEEPOL/plainpicture.com

Suggesting that quantum physics guides personal experience rather than objective reality might seem radical. But a key reason for considering QBism is that it reframes quantum states as beliefs, which dissolves the quantum oddities. Why does a quantum state “collapse” when measured? In QBism, it’s because the physicist experiences an outcome, prompting an immediate adjustment of future beliefs.

Take Wigner’s friend paradox, proposed by Eugene Wigner: Wigner’s friend measures a particle, while Wigner, outside the lab, remains unaware of the result. They observe different quantum states, suggesting physical reality is two conflicting things simultaneously. But if quantum states are personal beliefs, this contradiction is logical. Similarly, Wheeler’s delayed-choice experiment doesn’t require back-in-time effects since no particle “out there” changes. Each measurement, even regarding the past, is an individual experience becoming true when the result is obtained.

QBism has faced criticism and dismissal, labeled as confusing or meaningless, or accused of denying reality. But stepping back from particles to consider daily experiences—planting a tree, voting, reading, checking on a friend—shows our choices and actions shape outcomes. Is it so strange to say our truths depend on the questions we pose?

The physical world is a hallucination

Neuroscientists are drawing similar conclusions about how we perceive our surroundings. Traditionally, perception is seen as experiencing the world directly: seeing a mug on a desk because light travels from the mug to your eyes. But evidence suggests we don’t directly experience the outside world, but rather a personal, continually updated model or prediction.

A popular framework, predictive coding, posits the brain takes a probabilistic—Bayesian—approach, updating beliefs about the world as new sensory information arrives. The objects we perceive—mugs, cats, sofas—are the brain’s “best guesses,” says Anil Seth, a neuroscientist at the University of Sussex, UK, dependent on personal history and beliefs. “We will never see things as they really, really are,” he states. “It’s hard to know what that would even mean.” Remember the dress that went viral in 2015? Some people saw it as blue and black, others as white and gold. It demonstrated that we each perceive the world differently. According to Fuchs, quantum physics aligns with this, acting as a sophisticated approach to experience. Even a photon or atom is a personal prediction, inseparable from our point of view.

However, unlike most physicists, neuroscientists often assume there’s a solid, true environment beyond perception. The probabilistic models inside our minds—our conscious experience—are a “controlled hallucination,” as Seth describes it. We are living in an illusion, unable to access the real world.

QBism flips the refrain that our perceptions are hallucinations. What if physical reality is the hallucination?

Camerique/Getty Images

However, if there is no solid landscape beyond, it might redefine predictive coding entirely. Fuchs’s main idea is that there is no ultimate truth; nothing exists from a “God’s eye” perspective, regardless of how we look. Instead of treating our personal worlds as hallucinations or models of the physical world, what if our experiences are parts of a different reality with inherent powers? While Wheeler viewed the universe as composed of information, Fuchs considers it in terms of actions and outcomes. “If you don’t take the action, you have a different universe than if you do take an action,” he says. “And if you do take an action, it depends on which kind of action you take.”

This concept, the pluriverse, is a dynamic tapestry of interacting perspectives that Fuchs describes as “a living community of nows”. Rather than a set of pre-existing, independent things, this pluriverse is a collection of experiences continuously created through choices and actions. It encompasses all elements of our personal worlds that shape our perception and behavior: not just physics’ atoms and fields, but every irrational belief and unique experience, from particle detector clicks and imaginary monsters to autumn leaf crunches.

Bitbol describes QBism as offering a fascinating “twist” on reality. Einstein’s theory of relativity views reality as a four-dimensional block universe: a static space-time block where any event can be past or future relative to another, with no global unfolding or change. Instead of this monolithic block, the pluriverse resembles a jazz improvisation, a wild forest, or a jubilant crowd: an unpredictable, ever-evolving joint project with no master plan and the freedom to shape its own future. “It’s continual creation,” says Fuchs. “Nature is being hammered out as we speak.”

This vision is part of quantum interpretations where existence depends on perspective. “QBism takes the most radical possible way of implementing that,” with no logical reason for consensus, says Matthew Leifer, a physicist specializing in quantum foundations at Chapman University, Irvine, California. Although Leifer views QBism as unnecessarily extreme, he acknowledges it’s a coherent and consistent standpoint.

Interestingly, QBism aligns with a revolutionary mind philosophy called enactivism, which asserts living beings—whales, plants, bacteria, even humans—are deeply interconnected with the worlds they perceive. Enactivists believe there are no pre-existing environments on one side or standalone organisms on the other. Instead, both arise through perception itself. Here, the internal models described by predictive processing serve as action recipes. Enactivists conclude that perceptions aren’t representations or hallucinations but inseparable from reality itself—as are all living beings’ perceptions. Ezequiel Di Paolo, a cognitive scientist and enactivist philosopher at Ikerbasque, the Basque Foundation for Science in Bilbao, Spain, describes existence as “an ever-changing moment of creation,” in which we are all shaping both ourselves and our worlds.

Whales and other living beings may take part in creating reality through their beliefs

Franco Banfi/naturepl.com

Both fields promise a living, open-ended cosmos, rooted in novelty and freedom. As appealing as that might sound, without a solid landscape beyond, what links all perspectives? How is this different from saying we’re each living in our own bubble, with reality entirely in our minds?

In QBism, nothing is fixed for you—not even the past—until you choose an action. But one universal rule applies to everyone: the QBists’ reinterpretation of the Born rule, which dictates how predictions must cohesively connect. “Quantum probabilities aren’t freewheeling,” says Fuchs. “They’re all tied together.” Adjust one belief, and another must shift accordingly. Details are flexible, but constraints exist within the experience’s underlying structure. The rule, in a sense, “exceeds us,” adds Bitbol, even as we cannot remove ourselves from the equation.

For this reason, Fuchs firmly rejects the notion that QBism means reality is all in our minds. What exists at any moment involves interlocking beliefs and perspectives, as well as the statistical framework binding them. This pluriverse is a unique form of external reality made up of other perspectives we can only “bump into,” says Fuchs. We can influence each other or be surprised by events, but we can never fully comprehend another’s perspective, force them to see things our way, or predict their next move.

Building shared realities

“People are literally experiencing different worlds,” agrees Di Paolo. “But, of course, that doesn’t mean we cannot share.” We are all navigating a path within an evolving “meshwork” of possibilities. Through interaction and communication, we can align perspectives and build shared realities, whether through cultural myths and stories or the structured universe of physics.

In this view, science becomes another form of shared perspective. This contrasts with conventional science, which traditionally seeks an objective God’s-eye view of reality. “That has been the dream of science,” says Di Paolo. But removing all perspectives means “you wouldn’t be able to say anything meaningful.” From scientific models of cells and molecules to supernovae and black holes, he argues, our universe understanding isn’t a pre-existing, external landscape, but a particularly rigorous and far-reaching experience guide. Perhaps it’s physical reality that is the illusion.

Fuchs and his colleagues are now collaborating with enactivists to explore mutual insights: while enactivists have delved deeply into perception and interaction, QBists offer a mathematical framework for predictions and probabilities. Ultimately, their aim is to develop a new scientific worldview that avoids dividing the world into mechanistic particles on one side and meaningless consciousness bubbles on the other.

Between these extremes lie the agents that contribute to the pluriverse’s creation. This includes physicists conducting quantum experiments, but broadly, all humans engaging in perception: predicting, acting, and shaping our worlds. This doesn’t mean we are the only ones. Enactivists extend this to all life forms—even plants turning towards the sun or bacteria swimming up a chemical gradient. But could other structures or processes be seen as having perspective: choosing actions and responding to results? Intriguingly, researchers find even simple biomolecule networks exhibit some agency, striving toward their goals. Fuchs hopes to expand his approach to encompass all forms of agency, aiding in understanding what it means for our experiences to be part of the world’s essence.

This brings us back to the concept of “now.” QBists and enactivists pursue a reality not born from a singular big bang left to unfold. It continuously emerges, as Wheeler suggested, in “billions upon billions” of small creative sparks sounding all around. This perspective sees us not as mere observers of reality, but as immersed within it. Through our choices and actions, moment by moment, we shape what exists and what follows.

Topics: