“We reach forth and strain every nerve, but we seize only a bit of the curtain that hides the infinite from us.”
By Maria Popova
Autumn is the season of ambivalence and reconciliation, soft-carpeted training ground for the dissolution that awaits us all, low-lit chamber for hearing more intimately the syncopation of grief and gladness that scores our improbable and finite lives — each yellow burst in the canopy a reminder that everything beautiful is perishable, each falling leaf at once a requiem for our own mortality and a rhapsody for the unbidden gift of having lived at all. That dual awareness, after all, betokens the luckiness of death.
But autumn is also the season of revelation, for the seeming loss unveils a larger reality: Chlorophyll is a life-force but it is also a cloak, and when trees shed it from their leaves, nature’s true colors are revealed.
Photosynthesis is nature’s way of making life from light. Chlorophyll allows a tree to capture photons, extracting a portion of their energy to make the sugars that make it a tree — the raw material for leaves and bark and roots and branches — then releasing the photons at lower wavelengths back into the atmosphere. A tree is a light-catcher that grows life from air.
Although the human mind has puzzled over why leaves fall and change color at least as far back as Aristotle, chlorophyll — which shares chemical kinship with the hemoglobin in our blood — was only discovered and named in 1817, by the French pharmacist-chemist duo Joseph Bienaimé Caventou and Pierre Joseph Pelletier. In a lovely touch of humility that distinguishes, always, the scientist from the explorer — the explorer, so eager to name the lands and landmarks he has “discovered” after himself — they wrote in their landmark paper:
We have no right to name a substance long-known, and to the story of which we have added only a few facts; however, we will propose, without granting it any importance, the name chlorophyll, from chloros, color, and φυλλον, leaf: a name that would indicate the role it plays in nature.
But chlorophyll, which is yet to be fully understood, is not the only pigment in trees. Throughout a leaf’s life, four primary pigments course through its cells: the green of chlorophyll, but also the yellow of xanthophyll, the orange of carotenoids, and the reds and purples of anthocyanins. In spring and summer, when the day grow long and bright, chlorophyll saturates leaves as the tree busies itself converting photons into the sweetness of new growth. As daylight begins fading in autumn and the air cools, deciduous trees prepare for wintering and stop making food — an energy expenditure too metabolically expensive in the dearth of sunlight. Enzymes begin breaking down the decommissioned chlorophyll, allowing the other pigments that had been there invisibly all along to come aflame. And because we humans so readily see in trees metaphors for our emotional lives, how can this not be a living reminder that every loss reveals what we are made of — an affirmation of the value of a breakdown?
A similar process take place as fruit ripen from green to varying shades of red, purple, orange, or yellow. Two centuries after the discovery of chlorophyll, a new generation of scientists armed with a new arsenal of tools unimaginable in 1817, in that abiding way science has of only revealing new layers of reality when it lets go of its assumptions, placed bananas in various stages of ripeness under UV light and discovered that as the world’s favorite yellow fruit ripens and its chlorophyll breaks down, it not only reveals the xanthophyll of yellow, but produces the chlorophyll catabolite hmFCC — a previously unknown blue fluorescent compound.
Subsequent research has found signs of this blue pigment in devil’s ivy — the evergreen golden pothos thriving in the corner of my library in Brooklyn at this very moment — rendering the mystery of chlorophyll ongoing and filling the human heart with exhilaration. How thrilling to think that something we discovered two centuries ago, something nature created more than one thousand million years ago when the first green plants evolved from prokaryotes, can still shimmer with mystery — a molecular microcosm of the ultimate thrill: the knowledge that however much we might uncover, nature will never cease to be filled with surprise ripe for the reaping. And how humbling to think that we too are animals doing their best to make sense of the world with their creaturely limitations — animals whose vision evolved to peak in so narrow a band of the spectrum, in the tiny wavelength range between red and violet, blind to everything between radio and cosmic rays, blind to ultraviolet light. But if we were butterflies or reindeer, bees or sockeye salmon, bananas might be blue.
The poetic astronomer Maria Mitchell captured this best in her rueful and rapturous observation that “we have a hunger of the mind which asks for knowledge of all around us, and the more we gain, the more is our desire,” and yet “we reach forth and strain every nerve, but we seize only a bit of the curtain that hides the infinite from us.”
But amid our slender repertoire of agency are the labels we choose for our labors of love — the works of thought and tenderness we make with the whole of who we are.
A challenge arises when we make something over a long period of time. As we evolve — as we add experiences, impressions, memories, deepening knowledge and self-knowledge to the combinatorial pool from which all creative work springs — what we make evolves accordingly; it must, if we are living widely and wisely enough. Eventually, the name we once chose for it begins to feel not like a choice but like a constraint, an ill-fitting corset ribbed with the ossified sensibility of a former self. Joan Didion may be right that “we are well advised to keep on nodding terms with the people we used to be, whether we find them attractive company or not,” but we are also well advised to welcome with a largehearted embrace the blooming possibilities within us — the people we are in the ongoing course of becoming, the people we will have been when our atoms give way to our afterglow.
Brain Pickings was born on October 23, 2006 as an improbable idea in a young mind only just becoming literate in the language of life. Fifteen years hence, it is reborn as The Marginalian — reborn as what it has always been beneath the ill-fitting name chosen by a twenty-two-year-old immigrant in whose ear the tired puns and idioms of a non-native language rang fresh and full of wonder: an evolving record and ongoing celebration of my readings and my loves, of all that makes me feel most alive.
Over the years, I grew up and grew on these pages — more than six million of them, if one were to paginate and print everything I have published on the site over the years, dwarfing the 600 pages of Figuring and microscopizing the The Snail with the Right Heart. I filled this infinite scroll with my reflections on what I was reckoning with — my marginalia on life and the most important things I was learning about it along the way, often through reading, often from people and ideas marginalized by culture, erased by the collective selective memory we call history, because they were in some way too other, too ahead of their time or apart from its mores, saw too clearly through the willful blindnesses of their era or bent their vision too far past its horizons of possibility.
In the margins of books, in the margins of life as commonly conceived by our culture’s inherited parameters of permission and possibility, I have worked out and continue working out who I am and who I wish to be — a private inquiry irradiated by the ultimate question, the great quickening of thought, feeling, and wonder that binds us all: What is all this?
More and more, the curatorial aspect — the “picking” part of Brain Pickings — subsided, as did the purely cerebral aspect — the “brain” part — giving way to the editorial, the contemplative, the full integration of thought and feeling that pulsates beneath all things creative and alive. And so there is no change in course beneath the change in name — nothing about the site or its weekly email summary will alter, other than my daily despair at living with a name that neither fits nor foments the private well of wonder from which it all springs. It remains freely offered and supported by donations, as it always has been. (It is not always easy to make a life and a labor of love in the margins of possibility — if you have lent a helping hand over the years, I appreciate you.) It remains an exercise in marginalia on readings and reckonings, a discourse with these works of wonderment.
This is always, at bottom, a discourse with oneself: me with myself, in writing it; you with yourself, in reading it. We bring to anything — a book, a love — the whole of what we are, projecting onto it every experience we have ever had and every unanswered question reverberating through the deepest chambers of our being. If it is worthy — the book, as the love — and if we are lucky, it reflects us back to ourselves magnified yet transformed, luminous with a larger self-image of possibility, more alive, more awake. Better able to see how our temporal, marginal lives shimmer with meaning. Better able to see ourselves as the makers of it, whether we call it love or art.
I thank you,
for the smallest sound,
for the way my ears open
even before my eyes,
as if to remember
the way everything began
with an original, vibrant, note,
and I thank you for this
everyday original music,
always being rehearsed,
always being played,
always being remembered
as something new
and arriving, a tram line
below in the city street,
gull cries, or a ship’s horn
in the distant harbour,
so that in waking I hear voices
even where there is no voice
and invitations where
there is no invitation
so that I can wake with you
by the ocean, in summer
or in the deepest seemingly
and be with you
so that I can hear you
even with my eyes closed,
even with my heart closed,
even before I fully wake.
I thank you, light, again,
for helping me to find
the outline of my daughter’s face,
I thank you light,
for the subtle way
your merest touch gives shape
to such things I could
only learn to love
through your delicate instruction,
and I thank you, this morning
most intimately and secretly
for your visible invisibility,
the way you make me look
at the face of the world
so that everything, becomes
an eye to everything else
and so that strangely,
I also see myself being seen,
so that I can be born again
in that sight, so that
I can have this one other way
along with every other way,
to know that I am here.
The great gift of science is that it continually reveals to us what is real, unpeeling the wallpaper of our knowledge to reveal newer and newer layers of nature, deeper and deeper substrata of reality. The great peril of science — this eternal impulse of human nature — is that the human mind continually limits what is possible, erecting walls of assumption between itself and the reality of nature. And yet the entire fact of life — your individual life, and mine, and life itself as a feature of the universe — is a matter of probable impossibilities.
This interplay, and how to liberate our search for truth from our craving for certainty, is what Italian physicist Chiara Marletto explores in The Science of Can and Can’t: A Physicist’s Journey through the Land of Counterfactuals (public library) — part field guide to her particular realm of study, part manifesto for the countercultural courage to keep unmasoning the walls of the imaginable and bending the mind beyond the accepted horizons of the possible. What emerges is an impassioned, scrumptiously reasoned insistence that all breakthroughs in science require “as much imagination and perceptiveness as you need to write a good story or a profound poem.”
Counterfactuals — explanations about what could or could not be caused to happen in the physical universe, as distinct from the standard scientific theories about what is bound to happen based on what has happened in the past — are one such thrilling mode of rotating in the palm of the mind the unsolved mysteries of nature in order to examine them from revelatory new perspectives, perspectives blind-spotted by our present assumptions. Counterfactuals are the science of otherwise — the physics counterpart to Jane Kenyon’s excellent poem — shimmering with new ways of understanding everything from information to time to free will.
In the foreword, Marletto’s collaborator David Deutsch observes that the rate of scientific discovery over the past few centuries has been increasing exponentially, but the discovery of new fundamental truths about nature has stalled and an indolence about attempting new modes of explanation has set in. He writes:
There has never been a time when there have been more blatant contradictions, gaps, and unresolved vagueness in our deepest understanding of nature, or more exciting prospects to explore them. Sometimes this will require us to adopt radically different modes of explanation.
Illustrating the validity of counterfactuals as a mode of understanding, he gives the example of a computer, which could record and process nothing new if every change to the contents of its memory were pre-set in the factory — a computer “can hold information only if its state could have been otherwise.”
Marletto places at the heart of her case for counterfactuals the notion of resilience — not resilience in the creaturely sense, to which we aspire and which trees so perfectly embody, but a deeper kind of resilience, existing on the fundamental level of information yet giving rise to all the physical reality that makes the creaturely kind possible — resilience as the dazzling, rare feature of our universe, even within the no-design fundamental laws of which a system can continue existing in an ever-changing environment. With an eye to genes — those recipes for keeping a species in existence, peppered with mutation — she writes:
What distinguishes helpful changes in the recipe from unhelpful ones? It is a particular kind of information: information that is capable of keeping itself instantiated in physical systems. It is resilient information.
“Knowledge” merely denotes a particular kind of information, which has the capacity to perpetuate itself and stay embodied in physical systems — in this case by encoding some facts about the environment… Knowledge is the key to resilience… In fact, knowledge is the most resilient stuff that can exist in our universe.
There are no absolute sources of certain truth: any good solution to a problem may also contain some errors. This principle is based on fallibilism, a pillar of Popper’s explanation of rational thinking. Fallibilism makes progress feasible because it allows for further criticism to occur in the future, even when at present we seem to be content with whatever solution we have found. It leaves space for creating ever-improving theories, stories, works of art, and music; it also tells us that errors are extremely interesting things to look for. Whenever we try to make progress, we should hope to find more of them, as fast as possible.
She turns to the two ways in which nature and human nature generate new knowledge, the generative process we call creativity — “by conjecture and criticism, in the mind; by variation and natural selection, in the wild” — and considers the crucial difference between the two:
Natural selection, unlike conjecture and criticism, cannot perform jumps: each of the recipes that leads to a new resilient recipe must itself be resilient — i.e., it must code for a successful variant of a trait of the particular animal in question that permits the animal’s survival for long enough to allow replication of that recipe, via reproduction. But there may be viable, resilient recipes coding for useful traits that can never be realised because they would require a sequence of nonresilient recipes to be realised first, which is impossible, as those recipes produce animals that cannot survive and cannot pass on their genes.
The thinking process, in contrast, can perform jumps… The sequence of ideas leading to a good idea need not consist entirely of good, viable ideas. Nonetheless, knowledge creation in the mind, too, can enter stagnation and stop progressing. We must be wary of not entering such states both as individuals and as societies. Particularly detrimental to knowledge creation are the immutable limitations imposed by dogmas, as they restrain the ability to conjecture and criticise.
Woven into Marletto’s case for counterfactuals is her love letter to science and the art of explanation:
Physics is a dazzling firework display; it is profound, beautiful, and illuminating; a source of never-ending delight. Physics is about solving problems in our understanding of reality by formulating explanations that fill gaps in our previous understanding. The point of physics is not the particular calculation about the fall of an apple. It is the explanation behind it, which unifies all motions—that of the apple with that of a planet in the solar system, and beyond. The dazzling stuff consists of explanations: for they surprise us by revealing things that were previously unknown and very distant from our intuition, with the aim of solving a particular problem.
The appearance of the dark sky at night… can be explained in terms of unexpected underlying phenomena involving things like photons, the remarkable fact that the universe is expanding, and so on. None of those elements is apparent in the sky itself, but they are all part of the explanation for why it looks as it does, in terms of what is really out there. Explanations are accounts of what is seen in terms of mostly unseen elements.
“What we see, we see / and seeing is changing,” Adrienne Rich wrote in her ode to astrophysics. It is changing, however, only when we change the way we look, change our tools for looking, be they physical instruments — the microscope and the telescope, revealing unseen layers of reality — or the instrument of the mind, which devises the microscope and the telescope and the theory. I hear Thoreau bellowing his admonition down the hallway of time as he puzzled over what it takes to see reality unblinded by our preconceptions: “We hear and apprehend only what we already half know.” Marletto writes:
The traditional conception of physics cannot possibly capture counterfactual properties, because it insists on expressing everything in terms of predictions about what happens in the universe given the initial conditions and the laws of motion only — in terms of trajectories of apples or electrons, forgetting the other levels of explanation. But these other levels of explanation are essential sometimes to grasp the whole of physical reality.
Drawing on the example of Neptune and the neutrino — both discovered not by direct observation of the previously unseen planet or particle but by observing curious contradictions in the surrounding system and deducing from them that something in the set of assumptions about what the system is and how it works must be revised. She writes:
As always happens with contradictions, something in the assumptions has to give.
Declaring something impossible leads to more things being possible.
Theseus, son of Aegeus, king of Athens, went to Crete to kill the Minotaur. Theseus made an agreement with his aged father that if he defeated the Minotaur, on their return his crew would raise white sails on the ship; if he perished, they would raise black sails. So off went Theseus, and he defeated the Minotaur. But on his way back, distracted by all sorts of things (including, possibly, the presence of his fiancée, Ariadne, on the ship!), he forgot to tell the crew about the sails. The crew left the black sails on, and Aegeus, who from the highest tower of Athens could see the ship approaching, thought his son was dead. So he threw himself into the sea and drowned. This tragic story is why the sea is now called the Aegean.
Now suppose we asked our master storyteller to tell that story with the constraint that he can formulate statements only about what happens — that is, he must report the full story without ever referring to counterfactual properties. In particular, he cannot refer to properties that have to do with what could or could not be done to physical systems.
This task turns out to be impossible: for the story to make sense, and to convey fully its meaning, two attributes of the ship are essential: one, that it can be used to send a signal, by assuming one of two states — white sail showing or black sail showing; the other, that the state of having black or white sails can be copied onto other physical systems — such as Aegeus’s eyes and brain. The copiability property tells us that the flag contains information.
Without these two counterfactual properties, the myth would be robbed of sense and could not possibly produce in the mind of the reader the tragic feeling, the shift in understanding, that gives rise to its millennia-wide moral. The myth of Theseus — a sensical story of tangible things like continents and oceans, a story of profoundly human things like ships and sons — helps grasp the analogous counterfactuals at work in more abstract things. A bit — that unit of information powering our digital universe — may seem like an abstract thing, but it is essentially a Thesian ship’s sail: there are the two binary states that can switch from one to the other, there is the ability to be copied. Any system endowed with these two counterfactual properties is an information medium — a conduit of knowledge.
Adopting counterfactuals brings entities that look superficially like immaterial abstractions into the domain of physics. Information and knowledge, for example, have been traditionally considered as mere abstractions — as things that do not belong to the physical world. However, by considering the counterfactual properties of physical systems that enable information and knowledge, one refutes this idea: because whether or not a physical system has those properties is set precisely by the laws of physics.
The ultimate promise of counterfactuals as portals to possibility comes most vibrantly abloom in one of the several short genre-bending vignettes Marletto composes to illustrate the scientific concepts — a story-upon-story set in the crucible of materialism, Ancient Greece. She imagines the childhood of the legendary conqueror Alexander the Great — who by his death at thirty-two would have created one of the vastest empires in the history of our species — and his time as an uncommonly broad-minded pupil of Aristotle: a boy asking the vastest unasked questions, hungry to fathom his own mind. In one of their conversations, Alexander wonders what it is in him that endows him with the capacity for wonder — with the ability to savor poetry and philosophy and the abstract art of mathematics — if he is made of the same material as concrete things like rocks and grass. Marletto’s Aristotle answers:
What’s clear is that the mind has characteristic properties that make it capable of relating to things that are abstract. I suspect that it obeys the same laws as rocks and grass, though we have yet to find these laws and understand how to apply them to the mind.