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Review of ‘Dark Matter and the Dinosaurs, by Lisa Randall
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By MARIA POPOVA NOV. 24, 2015, nytimes.com
unknown while grounded in the firmest foundations of the known. In “Dark
Matter and the Dinosaurs,” the Harvard cosmologist Lisa Randall proposes
that a thin disk of dark matter in the plane of the Milky Way triggered a minor
perturbation in deep space that caused the major earthly catastrophe that
decimated the dinosaurs. It's an original theory that builds on a century of
groundbreaking discoveries to tell the story of how the universe as we know it
came to exist, how dark matter illuminates its beguiling unknowns and how
the physics of elementary particles, the physics of space, and the biology of life
intertwine in ways both bewildering and profound.
If correct, Randall’s theory would require us to radically reappraise some
of our most fundamental assumptions about the universe and our own
existence. Sixty-six million years ago, according to her dark-matter disk
model, a tiny twitch caused by an invisible force in the far reaches of the
cosmos hurled a comet three times the width of Manhattan toward Earth at
least 700 times the speed of a car on a freeway. The collision produced the
most powerful earthquake of all time and released energy a billion times that
of an atomic bomb, heating the atmosphere into an incandescent furnace that
killed threequarters of Earthlings. No creature heavier than 55 pounds, or
about the size of a Dalmatian, survived. The death of the dinosaurs made
possible the subsequent rise of mammalian dominance, without which you
and I would not have evolved to ponder the perplexities of the cosmos.
A necessary primer: Dark matter is the invisible cosmic stuff that, like
ordinary matter — which makes up the stars and the stardust, you and me and
everything we know — interacts with gravity but, unlike ordinary matter,
doesn’t interact with light. Although scientists know that dark matter exists
and accounts for a staggering 85 percent of the universe — billions of dark
matter particles are passing through you this very second — they don’t yet
know what it’s made of. For Randall the possibilities within that mystery are
among the most thrilling frontiers of human knowledge.
Ordinary matter contains an entire ecosystem of particles — among them
various quarks and neutrinos, the electron, and the newly discovered Higgs
boson. So far, scientists have assumed that dark matter comprises only one
type of particle. Randall, however, posits that dark matter might also comprise
a variety of building blocks that interact through different forces. No prior
theory has considered the simple yet profound possibility that while most dark
matter doesn’t interact with ordinary matter, a portion of it might. Because
dark matter carries five times the energy of ordinary matter, that tiny fraction
could have enormous consequences.
Randall calls the force driving that fraction “dark light” — an
appropriately paradoxical term confuting the haughty human assumption that
the world we see is all there is. Her hypothesis that dark matter might interact
with itself through its own unique form of invisible light calls to mind the
poetic title of a 2003 paper by the physicist Brian Josephson about Einstein’s
famous conversation with the Indian philosopher Rabindranath Tagore: “We
Think That We Think Clearly, but That’s Only Because We Don’t Think
Clearly.”
As stimulating as the substance of the book is, however, Randall doesn’t
quite join the ranks of such masterly science-storytellers as Stephen Jay
Gould, Diane Ackerman, Alan Lightman or James Gleick. Giants like the late
Oliver Sacks — working scientists who are also enchanting writers — come
about once or twice a century, if we’re lucky. Randall is first and foremost a
working scientist — but while she isn’t a natural storyteller of Sacks’s caliber,
she is an excellent explainer, and her affection for her subject matter is
infectious.
“Anyone who writes down to children is simply wasting his time,” E.B.
White told The Paris Review in 1969. “You have to write up, not down.” What
is true of children’s books turns out to be true of science books. While you
need not be a physicist to metabolize the narrative, you are certainly called
upon to do your own chewing — a rare opportunity in a culture where we are
taken for so intellectually inept that our own conclusions are fed to us in
listicles of bitesize buzz.
To be sure, Randall does have her lyrical moments — it’s hard to imagine
that someone this genuinely enamored with the cosmos wouldn’t, much less a
scientist who alludes to Blake in explaining cosmological inflation and weaves
a description of a Renaissance fresco into the history of comets. Above all, she
takes care to reveal the inherent poetry of science: The dinosaurs, who walked
the earth for much longer than we have, perished, but from them evolved the
birds that animate our skies; meteorites, for all their deadly capacity, once
deposited the very amino acids that became the seeds of earthly life.
“Extinctions,” Randall writes, “destroy life, but they also reset the conditions
for life’s evolution.” The universe is strewn with dualities, which Randall
insightfully exposes.
Therein lies the book’s greatest reward — the gift of perspective. The
existence of parallel truths is what gives our world its tremendous richness,
and the grand scheme of things is far grander than our minds habitually
imagine. “The future enters into us in this way in order to transform itself in us
long before it happens,” Rilke wrote. Although it took the deadly comet an
immeasurably long time to reach its earthly victims, the dinosaurs’ destiny —
and, in consequence, our own — was sealed in the cosmic blink when dark
matter jolted that icy body out of orbit. It’s a sobering revelation of the
gestational period of consequences. As Randall peers into the universe’s 13.8
billion-year history, she notes that in her lifetime alone, human population has
more than doubled, straining Earth’s resources and undermining cosmic work
billions of years in the making. Although her periodicity model projects that a
major meteoroid isn’t expected to hit us for another 32 million years or so, our
civilization’s impact on the planet is like that of a slowmoving comet headed
for doom — but unlike the one that killed the dinosaurs, Randall reminds us,
we still have a chance to avert its course.
Almost more interesting than the theory itself is Randall’s tour of the
process of scientific endeavor, in which scientists traverse the abyss between
the known and the unknown, suspended by intuition, adventurousness, a large
dose of stubbornness and a measure of luck. Her account of how scientists
proved that a meteoroid killed the dinosaurs — a hypothesis that was first
considered preposterous but that later precipitated a worldwide detective story
30 years in the making — is one of the most thrilling tales in the history of
science. Only time will tell whether Randall’s own model ends up as the kind of
work that merits a Nobel Prize or as one of those trailblazing wrongs that steer
future scientists toward the truth.
Randall’s work, which she approaches with equal parts passion and
precision, is perhaps best described as creative computational cosmology.
Although she is one of the world’s most prominent working scientists, her
theory is essentially a thought experiment in the tradition of philosophy,
bridging metaphysics with the most strenuous experiment and observation of
science. What emerges is an imaginative and ambitious model of how we
ended up where we are now. Science, after all, isn’t merely about advancing
information — it’s about advancing understanding. Its task is to disentangle
the opinions and the claims from the facts in the service of truth. But beyond
the “what” of truth, successful science writing tells a complete story of the
“how” — the methodical marvel building up to the “why” — and Randall does
just that.
DARK MATTER AND THE DINOSAURS
The Astounding Interconnectedness of the Universe
By Lisa Randall
412 pp. Ecco/HarperCollins Publishers. $29.99.
Maria Popova is the founder of BrainPickings.org and an M.I.T. Futures of Entertainment fellow.
A version of this review appears in print on Nov
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