Traveler, there is no road;
you make your own path as you walk.
— Antonio Machado
When I was studying for my PhD, I spent three years working in a microbiology lab becoming intimately acquainted with a bacterium named Campylobacter jejuni. At first, I got to know ‘Campy’ as slimy, yellow-green colonies that spread lazily across a Petri dish and smelled like old socks. But under a microscope, the cells came to life. They were graceful, spiral-shaped and fast. Like miniature corkscrews, each propelled by a spinning tail – called a flagellum – they darted around almost too speedily to see. Campylobacter causes gastroenteritis, and it thrives in the thick mucus that lines our gut wall. Other bacteria would get bogged down in such viscous conditions, but Campy’s corkscrew path enables it to fly through the slime at up to 100 micrometres per second (equivalent to a human swimming through corn oil at hundreds of miles per hour).
But these bacteria aren’t just fast. They’re clever too. My job was to investigate how these cells decide where to swim. Even at these high speeds, Campylobacter is super sensitive to its environment, sniffing out chemical clues to hunt down nutri-ents and oxygen as well as the mucus it calls home. It does this through receptors fixed to the membrane that surrounds the cell. When these receptors bind to target chemicals in the environment they change shape, triggering a cascade of protein interactions inside the cell that ends with the flagellum, influencing its direction of rotation. If the concentration of a favourable nutrient is increasing, the cell is more likely to keep swimming in the same direction. If the gradient is decreasing,it is more likely to switch and try another route. The bacteria can also integrate signals from a range of receptors, tuned to different nutrients, to work out their best swimming strategy overall.
This is a single-celled creature with a small genome: one of the simplest life-forms on the planet. It has no neurons or brain. As far as we know, it isn’t thinking or aware. Yet it can sense a fast-changing environment and compare each present situation against the previous one: a basic form of memory. It has likes and dislikes, and can weigh up different factors to work out, moment by moment, which actions will give it the best chance to stay alive.
So far in this book, considering the origins of the present moment has led us to the perspective that, ultimately, all our mental experience, effectively our mind itself, emerges out of homeostasis. The ingredients that create our Now – presence, agency, our sense of time and self, our point of view – all emerge from the need to persist, to keep our bodies alive. This basic survival mechanism is what has shaped the workings of our brains. So is Now just a human characteristic? A mammalian one? Did meaning and perspective emerge from the blank canvas of the universe with the evolution of neural circuits? Or can we push it even further back, perhaps to the origins of life itself? The deep links between mind and homeostasis suggest that the prediction-perception-action loops we’ve learned about aren’t just an add-on that popped up later in the human frontal cortex but a guiding principle behind the workings of all organisms, part of the fundamental drive that pushes living creatures to persist and evolve.
Again, this idea doesn’t sit easily with traditional cognitive science, which defines mental processes as complex calculations that can only be achieved by neurons. As our understanding of behaviour improves, however, some biologists are arguing that we need a broader concept of mind, that reaches beyond the brain. And that means extending cognition not just into our bodies and our interactions with the environment, as we’ve touched on, but across the tree of life. When we look closely, it turns out that plenty of living organisms without any trace of brains or nervous systems are apparently making intelligent decisions. Fungi can optimally distribute resources among the trees whose roots they connect. Slime moulds can solve mazes. Like bacteria, pea plants will seek out areas of soil where nutrient levels are increasing. Lavatera (tree mallow) plants adjust their position during the night, ready to face the coming sunrise. Mimosa usually fold their leaves in response to a fall, but, if subjected to several such falls without damage, will learn not to bother.
It reminds me of the plant time-lapse video we heard about in Chapter 3, and the little boy who shouted, ‘It’s looking for something!’ With a shift in perspective, we see a natural world full of decision-making and purpose to which we were previously oblivious. Creatures very different from us are searching, learning, remembering, weighing up pros and cons. Does it really make sense to see no connection between their behaviours and our own? An alternative to seeing minds as confined to skulls comes from a revolutionary kind of cognitive science called ‘enactivism’. Rather than understanding our experience by starting with the brain and working down, this builds up from the bottom, beginning with the most basic principles of what it means to be alive.
How can you tell a robot from a human? A Mars rover from a Martian? Or a mouse trap from a Venus fly trap? In the 1970s, Chilean biologists Humberto Maturana and Francisco Varela noted that the one thing all living organisms have in common is that they must constantly work to keep themselves in existence. They argued that non-living structures such as cars or robots must be made or maintained by something else, some-thing external. However sophisticated or well-designed these things are, if a mechanic doesn’t fix them, they eventually fallapart. What distinguishes living creatures, on the other hand, is their ability to actively push back against the forces of chaos and decay, to keep making themselves from the resources in their environment. Think of it as a kind of self-sustaining drive, or agency, that comes from within. Maturana and Varela called this process ‘autopoiesis’ (literally ‘self-production’).
A theme we’ve repeatedly touched on in this book is how traditional cognitive science is based on ideas relating to information processing – brains as computers. But in their definition of life, Maturana and Varela took inspiration instead from complex dynamic systems. As we’ve heard, these are systems with multiple components that are changing over time and can interact with each other. This feedback means that even though the individual components – ants, sand grains or water molecules – might act according to simple rules, complex collective behaviours can emerge that drive the behaviour of the system as a whole. These effects can occur even in very basic systems where the components influence each other, such as a pendulum with a second pendulum attached to its end (also known as a chaos pendulum): within just a few swings, the tip traces out intricate, unpredictable patterns. From waves, earthquakes and stock-market crashes to starling murmurations and improvised jazz, new behaviours and phenomena arise that can’t be predicted or forecast just by looking at the individual parts.
We already discussed how researchers inspired by Varela are modelling brain activity as a complex dynamic system. But this is a stronger argument, that living organisms as a whole can be seen in this way. Not all such systems are alive, of course. So autopoiesis provides the vital extra step. Life, Varela suggested, is a special kind of complex dynamic system that becomes autonomous. Integrated processes and behavioursemerge in just the right combination to maintain or perpetuate the whole, so that whenever the system veers away from a state (or set of states) compatible with survival, other processes will kick in to bring it back. If a pond dries out, it stays dry until it rains. But if we get thirsty, we drink.
Researchers call such self-perpetuating collectives ‘closed-loop systems’. This doesn’t mean they are completely closed off from their environment. In fact, they must be delicately balanced between distinguishing themselves and being open to exchange. Philosopher Hans Jonas called this life’s ‘primordial tension’. An organism needs energy and resources from its surroundings to survive but must also carefully regulate what goes in and out, so that it doesn’t disintegrate. If it separates itself from the world either too much, or too little, it will die.
To exist, an organism must constantly walk the line between these two extremes. It’s like an acrobat teetering across a tight-rope or Danny MacAskill flying along the Cuillin Ridge with a fatal drop on either side: to stay balanced, you have to keep moving. Philosopher Ezequiel Di Paolo, a leading proponent of enactivism, describes life as an ‘ongoing achievement’ – like surfing – because we’re constantly having to work to avoid succumbing to the forces of nature. This is a philosophy of life with the ever-changing present moment at its core. In this view, life doesn’t reside in our organs or cells; it’s not sitting there in any persistent ‘body’ or ‘self ’. Life is in the balancing act itself. In the ever-advancing action of making ourselves.
Evolutionary biologist David Barash makes a similar point when he describes living stuff as always dancing: constantly replenished by, and created from, non-living components. Your body might seem to be the same one that you had last week, or last year, but its components are always turning over. Every cell, every atom that we’re made from is in flux. We’re taking molecules from the environment – oxygen, water, proteins, fats, sugars – and rearranging them to generate energy, repair damage and grow new tissues while getting rid of waste prod-ucts we no longer need. There’s no avoiding this process: if westop, we die. Life can never be captured, or held immobile, says Barash: ‘At every moment, our existence takes place only on the instantaneous knife-edge of Now.’
Barash argues that this view resonates with Buddhist philosophy. For Buddhists, he points out, living things or selves don’t exist as rigid things but transient processes: more wave or whirlpool than lump of clay. All organisms are necessarily, gloriously impermanent. This concept of impermanence (expressed in the Sanskrit word anitya and also found in Hinduism and Jainism) is beautifully embodied in the fragile sand mandalas made by Tibetan monks. These intricate, laborious patterns are proxies for us, Barash says, and can take weeks to build before they are ceremonially swept away.
But this impermanence contains within it something else. Because life is so precarious – defined by the ever-present risk of death – this means that no interaction is ever neutral. Everything an organism does takes it either closer to or further away from the sweet spot of continued existence. Nothing lasts for ever, so there’s meaning from the beginning. Even a simple bacterial cell swimming up or down a sugar gradient has a perspective, a point of view. Its interactions are defined by what they mean for its future ability to survive. Campylobacter’s sensations aren’t passive, objective measurements. They’re active and value-laden: there is only worse and better, forwards and back. And for enactivists, this is the beginning of everything. This ever-evolving, meaningful interaction between a self-perpetuating system and its environment is where we can find the origins of both life and mind, the driving force that powers behaviours, perceptions, choices and decisions, that ultimately carves out self and time. This doesn’t mean that simple life forms are necessarily conscious or self-aware. It just means that things matter for them, and this mattering drives what they perceive and what they do.
At first, strategies for doing this are baked in by natural selection – systems that respond to sensations in a way that helps them survive longer will be more likely to persist andreplicate; those that don’t will perish. So organisms evolve to become better and better at surfing that sweet spot, hardwired to respond to the environment in a way that keeps them on that knife-edge of continued existence. This biological self-regulation is of course the process of homeostasis. At its most basic, this might involve immediate responses to specific stimuli. But as we’ve heard, homeostasis becomes more efficient when an organism can integrate multiple signals, weaving together different sensory cues and moments in time. This integration enables creatures to benefit from experience, anticipate future changes and take into account a bigger picture: like a Mimosa plant that learns not to fold its leaves when it falls or a bacte-rium that weighs up different chemical gradients when selecting which way to swim.
And, eventually, the drive towards better homeostasis has led to the evolution of brains. In this view, brains are just continuing the same job, except in a more sophisticated way. Essentially, they are hierarchical networks that take integration to a whole new level, especially (but not exclusively) with respect to time. Brains help creatures to select actions based on combining different senses, taking into account multiple timescales at once, reconstructing the past and making predictions about the future, and, eventually, if they get intricate enough, modelling different hypothetical trajectories to choose which one will serve them best. Instead of seeing mind, even consciousness, as something extra or different that popped into existence when brains evolved, enactivists see our mental lives as simply an extension of the same process of sensation and response with which all life is engaged. The fundamental dance between life and non-life – organisms and their environments – is the seed from which different layers of awareness and self later grew.
In some ways, these ideas fit very well with the framework of predictive coding and active inference that we’ve been exploringthrough this book. A theory called the ‘free energy principle’ (FEP) extends the statistical, predictive approach beyond brains to give an account of life in general, and it shares some simi-larities with enactivism. FEP was devised by the British neuroscientist Karl Friston, and his original description of the idea, published in 2006, has become one of the most-cited papers in neuroscience.
Friston argues that self-perpetuating complex systems (living organisms) must continually resist the pull of entropy by moving towards a limited, stable set of probable states, through which they cycle. He suggests that’s simply what existing means. It’s to be found in a particular set of configurations, and if such a system deviates from these states, it must act to bring itself back. Any system that doesn’t do this – that strays outside the physical boundaries that define it as an organism – won’t continue to exist.
But all organisms face the same fundamental problem with perception that we do: they don’t have direct access either to their own internal states or the state of their environment, only to the sensations arising from their actions. So they take a probabilistic approach, using Bayesian principles to predict the sensory signals associated with their preferred (or most prob-able) state, then act to reduce the difference between the two. Although the brain is a particularly sophisticated example, Friston argues that this error squashing is the core principle that defines all living creatures, from a bacterium sniffing out sugar to a Mimosa plant shying away from a predator’s touch. By acting to reduce the gulf between your expectations and your sensations, you are essentially maximising the evidence for your preferred model of your situation (the model in which you continue to exist). Friston calls this ‘self-evidencing’. All life is continually predicting itself into the world.
Both the free energy principle and enactivism describe life as not so much a thing as a process the ongoing activity of carving out our own perspective. Both theories highlight the deep roots of mind – awareness, decision-making, self, Now – not in brainsbut in life itself. But there’s a fundamental chasm between enactivism and most interpretations of predictive coding and FEP. Their disagreement goes beyond the nature of perception, to the nature of reality itself.
To understand the difference, let’s start with a very basic, naive view of perception. This is where we simply sense what’s out in the world around us. If we see a tree, it’s because light bounces off the tree in our surroundings and hits our retina, causing electrical signals to be sent along nerves to our visual cortex, which analyses the arriving signals and forms our inner perception of a tree. This is a ‘bottom up’ view of perception: information about the world is sent from our sensory organs to the brain, which then uses it to build what we see.
Predictive coding and FEP turn that view on its head. These frameworks emphasise the boundary that separates an organism on one side from its environment on the other. The argument goes that we can’t access the external world directly: we can only work with what our senses detect. We can only ever know the flow of visual sensations that we experience, not the actual tree. So perception is reframed as top down rather than bottom up, and as probabilistic rather than absolute. What we perceive – our lived world – is a statistical model or ‘controlled hallucination’, not reality. Self-related perceptions work just the same way, as we have no direct access to the state of our bodies either. With varying degrees of sophistication, we infer the most likely hidden causes of our sensations – both outer and inner – and use these inferences to predict or control what we’re likely to experience next.
This is an exciting development because it gives us an important role to play in what we experience. Rather than passively recording each moment of our lives, we actively create it. Through the brain’s ongoing predictive model, we infer the existence of our selves, our bodies, our surroundings. We infer friends and enemies, planets and stars, bats and balls, love and anxiety, kittens, coral reefs and cups of tea. But there is a downside: we must give up our contact with the real world.
In this view, our perceptions aren’t definite or direct; they’re just sophisticated, educated guesses about how things (probably) are.
According to one description, it’s like each of us is ‘a little person in a submarine’. The sub has thick iron walls and no windows, just an array of sensors that pick up limited, noisy information from what’s outside. Onboard computers use personalised algorithms, learned over time, to predict from the data what is most likely beyond the sub walls, and project the results onto a screen for us to watch. Everything we see, no matter how vivid it seems, is merely a Bayesian best guess: we are always one impenetrable step removed from the real ocean beyond.
Active inference appears to fortify this boundary, taking us even further from any hope of knowing the definitive ‘real world’. We can never perceive how things really are because all our interactions and sensations are defined by our physical abilities and tailored towards our survival concerns. Perhaps imagine that the inside of our submarine doesn’t even have screens but is instead covered with banks of computer-operated joysticks and pedals. The only way we can interact with our environment is to push on these levers and feel how the levers push back. We’ll never get to step outside these movements for a real picture of what’s beyond, and we’ll always be blind to any aspect of the world that isn’t encapsulated in an action we’re able to perform.
But if all we can ever perceive is our own predictions for the consequences for our actions, and it doesn’t even make sense to talk about a ‘true’ or independent representation of reality, what does that mean for what’s happening in the world out there without us? What is swimming beyond the submarine walls? This is where predictive coders and enactivists sharply disagree. And the stakes for who we are – and what Now really is – couldn’t be higher.
The traditional worldview that underpins science and that the modern western world is built on (though philosophers from Gottfried Leibniz to Immanuel Kant have expressed doubts about it) is that we live in a pre-existing landscape: a physical reality that’s out there independent of us and carries on whether we’re around to appreciate it or not. The moon is still in the sky when we’re not looking, as Einstein famously insisted. Physicists describe how the universe burst into existence billions of years before the appearance of life on Earth and speculate about how, long after the last conscious being has perished, it will end.
Most interpretations of predictive coding and FEP stay faithful to this view. The idea is that there are two separate realms, always separated by a boundary that we can never cross: the pre-existing reality, and our ‘hallucination’ of it. There’s the actual world – made up of mugs, moons, particles colliding or whatever – and then our model of that world. It’s a continuation of Plato’s story about the prisoners in the cave. The things we perceive are limited, imperfect copies: ghosts or shadows of what’s really there. However sophisticated the joysticks and pedals inside our submarine, we’ll never truly touch the ocean that lies beyond.
Enactivists, however, see things differently. To understand what cognitive science is telling us, they argue that we need to go beyond biology, to rethink what nature even is. They agree that our perceptions are probabilistic, highly personal and geared towards keeping us alive. The things we perceive, even our own bodies and selves, aren’t concrete entities but inferences that we make and remake each moment. But enac-tivists (in common with several, particularly eastern, branches of philosophy) don’t accept that these inferences are copies or predictions of something else – something more accurate, more definite, more real – that exists forever beyond our reach. Rather than seeing the organism and the environment – us and the universe – as distinct, stand-alone realms, enactivists argue that neither can exist without the other. Just as there is no separate,concrete self that lies beyond our inferences, neither is there any hidden, ‘true’ world. ‘Nature is not independent of the perceiver or agent,’ says enactivist philosopher Shaun Gallagher. There is no little person and no submarine: no metal walls, no computer, no joysticks and pedals separating us from the truth beyond. The perceptions and sensations themselves – the call and response, the meeting or thwarting of predictions – these are reality. These are what existence is made of.
It’s worth taking a moment to think about this because it’s a reversal of everything we’re normally taught about how the world is. Meditators can spend years mulling on such concepts just to feel a glimpse of what such a unified reality might be like. In this view, our perceptions or experiences – the melancholy of raindrops on a window, the exhilaration of diving into an icy pool – are real in themselves. There is no separate, enduring landscape beyond that they’re based on, no solid reference point against which our sensations can be judged. It can be dizzying – or maybe freeing – to feel that there’s nothing firm or external to hold on to, like having guard rails removed or the ground falling away. For me, the image that comes to mind is of learning to ride a bike as a kid: you’re pedalling along safe in the knowledge that your mum is running along behind, holding the saddle to keep you upright, until you realise that she let go way back down the street and now there’s nothing else holding you up; it’s just you and the bike.
We often think of our sensations, feelings or beliefs as ephemeral, fallible impressions: mere shadows of the solid, properly existing, physical world. Advocates of predictive-coding models often describe our conscious experience as a hallucina-tion, to emphasise that our perceptions are distortions, even fabrications, that don’t represent things in the world as they really are. By contrast, in the enactivist view, you can’t ever disentangle the world from the perspective through which it is being experienced. The illusion is the notion of any separate, pre-existing stuff, sitting there without us. ‘Apples’, ‘pianos’ or even ‘people’ are ideas derived from the flow of our perceptions,names we give to statistical inferences that help us to make sense of our experiences and predict what we’re likely to perceive next. But the immediate experiences themselves – the taste of sweet fruit, the sound of a haunting chord or the warmth of hugging an old friend. That’s different. Now, we’re swimming directly in the ocean.
The enactive approach hints at a different view of what brains are for and what consciousness is. This fits well with the sensori-motor theory of consciousness that we heard about in Chapter 13, and the long-standing mystery of qualia: personal, subjective sensations like redness or softness. Philosophers argue about what qualia are and how the brain generates them from the sensory data it receives (this is the so-called ‘hard problem’ of consciousness). But if there’s nothing solid sitting behind our experiences – if our worlds instead emerge directly from our immersion in our surroundings – then there’s no need for qualia. There isn’t some pre-existing quality held in an object ‘out in the world’, information about which is transmitted through our skulls and then used to generate a separate perception of redness or softness ‘in the brain’. There is only the interaction. The flow of prediction-action – the call and response – simply is the sensation.
Rather than generating qualia, then, perhaps what brains do is enable this active flow: what Gallagher calls our ‘predictive engagement’ with the world. This is an extension of what all living organisms do, but brains structure our sensorimotor system ever more intricately so that we can use probabilistic rules to make and fulfil predictions, infer hidden causes – essentially make sense of our situation – in ever more complex and accomplished ways. The idea is that these more sophisticated, multilayered interactions directly equate to more complex and accomplished kinds of experience, culminating – eventually – in the mental capacities that we associate with being human, such as self-awareness, narrative memory and abstract thought.
Arguing that the worlds we perceive don’t exist without us doesn’t mean that reality is ‘all in our minds’ or that we cancontrol everything that happens. We hit against surprises and frustrations all the time. It’s just that rather than a single, physical world sitting ‘out there’, a multitude of interacting worlds is continually being brought to life. There must be some underlying statistical structure, emphasises Ezequiel Di Paolo, a common canvas or ‘meshwork’ of possibility that connects and constrains us, and enables our interactions to unfold in consistent, predictable ways. Without this, we wouldn’t be able to learn from mistakes, make reliable predictions, infer hidden causes or communicate and share with each other. But there isn’t a truer realm, beyond perception, made of solid objects or definite facts. We’re all negotiating continually evolving possibilities rather than enduring, stand-alone ‘things’.
To visualise how this works, let’s take an event that might seem incontrovertibly to involve a concrete, non-negotiable world, like two cars colliding head-on. The conventional way of thinking about this would be as pre-existing, physical cars speeding towards each other on a pre-existing, physical road. The drivers inside the cars would each experience the resulting events from their own point of view, forming a personal (but limited) impression of the actual, underlying impact. The crunching metal and unflinching tarmac are ‘real’; the drivers’ perceptions are fallible hallucinations formed as a result.
But what if there is no god-like, all-encompassing, ‘true’ version of events? In that case, we need to look at things differently. Let go of all your preconceptions for a moment, and put yourself back inside the world. Now, the crash unfolds in real time, chaotic and unpredictable, as a flow of split-second sensations and decisions. There’s a flash of colour, a last-ditch turn of the wheel, desperate slam of brakes, blur of trees. This is ‘happening’: definite and non-negotiable.
Notice that to witness this scenario you can pick one driver or the other, but not both. Our car crash isn’t an impact of physical objects but of perspectives. Worlds are colliding – in real time – in the most dramatic way. For enactivists, this is what reality is made of: dynamic worlds interacting, momentby moment. Life is essentially an ongoing torrent of such explorations, negotiations and collisions. The idea is that, over time, organisms evolve to make sense of this flow, getting ever better at spotting statistical patterns and predicting what actions are likely to lead to what results. As human beings, we can do this in a particularly sophisticated way, inferring the existence of layers upon layers of causes for the patterns we experience: cars, roads, bodies, selves. But however solid or reliable they seem, these things are always just that: inferences. We can say they exist. But they can’t ever be disentangled from our flow of action, sensation and prediction.
Without a definite truth beyond, how do we ever agree on anything? It follows that we can’t ever fully experience someone else’s reality. But by sharing a history, by doing things together, we can bring our perspectives closer and come to see things in a more similar way.* Together, we develop explanatory models, describing external entities and shared causes that lie behind our experiences, from myths and money to governments and gods. And, in turn, these frameworks and beliefs come to have their own existence, their own power, by influencing how we act and how we perceive the world.
In this view, even science is subjective. Scientists hope to remove personal biases and reveal what’s ‘really’ there: orbiting planets and gas-fuelled stars; carbon and nitrogen; ancient dinosaurs and spiralling DNA. But even in physics, astronomy or biology, ‘you can’t weed out the human contribution,’ insists Di Paolo. Scientific explanations are still valid, vital and powerful, but he sees them as ‘first person plural’ – dependent on shared histories, bodies and culture, rather than truly universal. From cells and molecules to supernovae and black holes, our scientific picture of the universe isn’t a pre-existing, external reality, but a rigorous and far-reaching guide to experi-ence. It’s an evolving model, a body of knowledge that helpsus to predict the outcomes of our ongoing actions rather than transcending human existence completely.
Perhaps understandably, this is terrain that many cognitive scientists prefer not to be drawn into. Clark once said that he would ‘deliberately avoid’ the enactivists’ interpretation of active inference and their questioning of a pre-existing, independent world. Even though our perceptions are action-oriented, they still represent aspects of objective reality, he insisted, and it would risk ‘obscuring the scientific value’ of the approach to link it to ‘the problematic idea that objects are not independent of the mind’.
But for some, like Di Paolo and Gallagher, this is the logical next step: a new era in cognitive science that could finally kill off the dualism that still lurks within western thought and show us what it might mean for physical and mental realms to be entwined. Existence isn’t held either in us or the world but in the meeting between the two. There never were separate dancers, just the dance. It’s a philosophy that puts the creative force of Now squarely at the centre of not just our mental lives but reality itself. Rather than sitting on a pre-existing timeline, we’re in a constant process of ‘becoming’, says Di Paolo. Moment by moment, and working together, we create – or ‘enact’ – our worlds.
When we look at them too closely, the familiar things and objects that surround us, and even treasured concepts such as self and time, dissolve. Life, it seems, is like a Pointillist painting: when we approach the canvas, the vivid figures and landscapes fall apart into featureless flecks of colour. The deeper we delve into our experience, too, it seems that we find not truth or definiteness but fuzziness. We live in a world that is contingent, creative and based on probabilities. Our perceptions emerge from a statistical framework where we make predictions, or bets, about what we’ll experience next. Cognitive scientistsdescribe a kind of ‘circular causality’ where action, prediction and perception are entwined, and the bets we make help to bring each new moment to life. It’s a dynamic, interactive, Now-focused view of reality that promises to remove the centuries-long divide between mind and body, between us and what we think of as the external world.
But perhaps we should pause for a moment. What if, by approaching Now from a first-person perspective, we have biased the scales towards this conclusion? As we learned at the beginning of this book, there’s a huge edifice of scientific results apparently supporting the idea of a universe without any meaningful present moment. Most astronomers and cosmologists would argue that this unified and rigorously tested cosmos doesn’t need to be brought to life or ‘enacted’. It evolves on its own according to objective, mechanical laws, quite separately from anything that’s going on inside our heads. When we probe the world around us with the objective tools of physics, we find a solid and well-defined landscape, with galaxies and gravity, planets and stars, that existed perfectly well for billions of years before the first creatures ever gazed at the sky.
We started our journey staring into this very chasm between opposing perspectives on reality, between personal experience and the physical universe. We faced a stark choice between ‘Now is everything’ on one side and ‘Now is nothing’ on the other. Since then, we’ve learned how scientific results in fields from neuroscience and psychiatry to robotics and thermo-dynamics are transforming our understanding of what experience – even life – is. Enactivists have travelled the furthest, using this new understanding to build a tentative bridge out across the chasm of Now and suggest a more creative, holistic view of how our universe comes into being. It’s a revolutionary and evidence-based shift in perspective, but right now it seems they’re dangling precariously halfway over the void, stretching out their arms into the mist beyond.
Can anyone reach back towards the enactivists from the other side? Many physicists would argue that there’s no point.
Physics works so exquisitely well, there’s no need to adjust our understanding of the universe according to our point of view, no matter how compelling. Our experience might be meaningful for us, but it makes no difference to the physical world. Others argue, though, that if we truly want to understand reality – all of reality – then we have to find a way to put our own perspective back into physics. ‘The experience of the Now does indeed mean something special for me, something essentially different from my past and my future,’ writes US physicist David Mermin. That Now seems to be unavoidably missing from physics ‘is a clear indication that the world indeed makes no sense, if I insist on leaving my own experience out of the story I tell about it’.
In our concluding chapters, let’s return to physics to meet some of the researchers trying to put Now back into the funda-mental fabric of reality. Respected figures in fields from cosmology to quantum mechanics are going against the main-stream to argue that it is perfectly possible to do this in a way that accommodates all physicists’ experimental observations yet reveals a universe that makes more intuitive sense. They suggest that time isn’t just a convenient label but an active player, a quality that brings the future into existence, moment by moment. Whether or not they’re right, their ideas show that the block universe – the static, timeless, pre-existing cosmos that most physicists support – isn’t so much an evidence-based inevitability as a choice. The loss of Now from physics has more to do with scientists’ preferred philosophical assumptions than the data itself.
It’s an insight that will bring us, at last, to the physicists who are not so much adjusting our understanding of nature as smashing it to pieces, in order to forge something completely new.
Excerpted from In Search of Now: The Science of the Present Moment by Jo Marchant, published by W.W. Norton and Company, ©2026 by Jo Marchant. All Rights Reserved.
