The Rhythm of the Cosmos
By Eric Chaisson
Wright Center and Eric Chaisson's Evolutionary Path
once in a long while, a window
of opportunity opens for scholars to integrate their work into a
larger, coherent whole. Perhaps once in a generation, or even only
once in a century, the academic climate ripens to allow a synthesis
of powerful ideas and abundant data that have been accumulating
for decades. Those who provide the regular stream of information
content are the specialists--hard-working researchers who toil on
a daily basis to advance knowledge, often incrementally. Those who
occasionally champion the large-scale integration are the interdisciplinarians--the
mavericks of academia bold enough to propose whole new worldviews.
After 50 years of government-sponsored science--the
legacy of Tufts' graduate Vannevar Bush, A13--when the focus was
on intense, even myopic, specialization during the second half of
the 20th century, universities are now beginning to change, albeit
slowly and perhaps only briefly. Interdisciplinarity is in; researchers
are routinely crossing departmental boundaries. Specialization remains
important--and is still funded--but a search for the "larger scheme
of things" is receiving tolerance, if not honor. No one knows how
long this new-found attitude will last among the community of educated
men and women, but it seems clear that we are now entering a new
age of synthesis.
Cosmic evolution is one such interdiscipline--a
unifying subject spanning the entire spectrum of the natural sciences.
It is an attempt to identify common denominators and underlying
laws among all structured things seen around us in Nature--the land,
sea and air, the stars in the nighttime sky, life itself.
Can we create a modern worldview that integrates
all of the sciences into a unified whole? Is there some process
or mechanism at work in the Universe that guides the emergence and
growth of all ordered systems? Where did all the order come from
anyway? Of course, some would say the answers are obvious: God.
But natural scientists have a calling to seek to explain Nature,
in all its wondrous manifestations, by using only reasoned logic
and scientific principles. Tempered skepticism and experimental
evidence comprise our central dogma.
Simply stated, cosmic evolution is the study of
change. More technically, it is the study of the many varied generative
and developmental changes among all radiation, matter and life throughout
the history of the Cosmos. If there is one aspect of the Universe
that seems ubiquitous--for all things in all spaces at all times--it
is change. The ancient Greek Heraclitus, a noted thinker of some
25 centuries ago, had it correct when he stated, "There is nothing
permanent except change." His was an innate idea--a hunch--but what
a powerful idea it was. For no matter how we examine Nature today,
we see change, some of it subtle, some dramatic. Stars change, climates
change, plants and animals change, civilizations themselves change.
The whole Universe is awash in change, and it is that universal
change that we call "cosmic evolution."
From galaxies to snowflakes, from stars and planets
to life itself, scientists are now weaving a neoplatonic pattern,
penetrating the fabric of all the natural sciences--a sweepingly
inclusive synthesis of order and structure among every known class
of object in our richly endowed Universe. Neither new science nor
appeals to nonscience are needed to understand the impressive hierarchy
of the cosmic-evolutionary story, from quark to quasar, from microbe
Major features of cosmic history are sketched
along the "arrow of time," from big bang to humankind. Seven
construction phases are identified, each displaying increased
complexity among all material things: particulate, galactic,
stellar, planetary, chemical, biological and cultural evolution.
Cosmic evolution encompasses all of these phases--it unifies
the sciences. This figure is a reproduction of an educational
poster produced by the Wright
Center, designed by the author and painted by Dana Berry.
More than 22,000 copies have been distributed to schools nationwide
during the past few years.
The Cosmic-Evolutionary Scenario
An accompanying figure on this page shows the
archetypal symbol of the cosmic-evolutionary scenario--the "arrow
of time." This intellectual road map stretches from the origin of
the Universe to the present, from big bang to humankind. We astrophysicists
debate the exact age of the Universe all the time, battling back
and forth whether it's 8 or 10, or 15 or 18 billion years; most
of us, as this figure implies, currently take 12 billion as the
Regardless, what's remarkable is not only that
we can pin down reasonably well the ages of the Cosmos, the Milky
Way, our Sun, the Earth and life, but also that these ordered structures
fall along a temporal line that accords well with their degree of
complexity. A well-ordered sequence of known systems--from stars
to planets to life to intelligence--maps along the arrow of time,
revealing simplicity changing into complexity, chaos into order,
inorganic into organic. There is a story here, a historical narrative.
And it's a story about ourselves--our origins.
This is post-Renaissance thinking, without the
strict, mechanistic determinism of Newton, Laplace et al. Cosmic
evolution embraces a more materialistic, synoptic posture, wherein
no obvious design or purpose is discernible scientifically; nothing
seems pre-ordained, nor is anything clearly predictable. Chance
mixes with necessity, reductionism with holism, physics with biology.
All ordered structures arise naturally, indeed with increasing complexity
over the course of time, owing largely to the expansion of the Universe
and the thermodynamic conditions that change with it.
Cosmic evolution traces a thread of change linking
the evolution of primal energy into elementary particles, the evolution
of those particles into atoms, in turn of those atoms into galaxies
and stars, and of stars into heavy elements, the evolution of those
elements into the molecular building blocks of life, of those molecules
into life itself and then intelligence, and of intelligent life
into the cultured and technological civilization that we now share.
Despite the compartmentalization of academic science, evolution--broadly
considered--knows no disciplinary boundaries.
These are the changes that have produced, successively
and successfully, our Galaxy, our Sun, our Earth and ourselves.
The result is a grand evolutionary synthesis bridging a wide variety
of scientific specialties--physics, astronomy, geology, chemistry,
biology and anthropology, among others--a genuine natural history
of epic proportions extending from the very beginning of time to
the here and now.
Thermodynamics in an Expanding Universe
Whether galaxy, gene or art, patterns in physical,
biological and cultural systems are manifest expressions of order
and complexity, and increasingly so over the course of time. For
all such systems, energy is key. Energy is needed to create and
maintain physical and biological structures (such as fusing stars
or functioning biomolecules), and it is also needed to build and
restore cultural artifacts (whether towering churches or elegant
paintings). The flow of energy, as dictated by non-equilibrium thermodynamics,
does seem to provide a powerful way to appreciate the growth of
order, form and structure everywhere.
Note that we are not talking about simple, everyday
equilibrium thermodynamics learned in school or practiced by engineers.
In closed, equilibrium systems, structures tend to break down; this
is the famous law of entropy, or disorder. Unattended households
grow more messy; lawns become unkempt, kitchens greasy, roofs leaky.
Even human beings who fail to eat will gradually become less ordered
and die. All things, when left alone, eventually degenerate into
chaotic, randomized and unordered states.
By contrast, in cosmic evolution, we emphasize
open systems and non-equilibrium states. And that's where the energy
flows come into play. About 100,000 years after the big bang, the
previously equilibrated Universe suffered a symmetry break, owing
solely to cosmic expansion, inevitably creating global conditions
that departed from equilibrium. In this way, environments naturally
arose suitable for the flow of energy, and eventually for the emergence
of organized structures. The resulting islands of increasing order--namely,
galaxies, stars, planets and life--are more than balanced by great
seas of increasing disorder elsewhere in the environments beyond.
All accords with the second law of thermodynamics--perhaps the most
cherished law in all of physics. By considering both systems per
se and their surrounding environments, we can prove that both structure
and entropy (which, as order and disorder, are seemingly at odds
with each another) can increase together--the former locally and
the latter globally.
Key questions flood the mind: What caused pockets
of localized order to arise, thus fashioning galaxies, stars, planets
and life? How has complexity emerged, and then increased, as systems
experienced, in turn, physical evolution, then biological evolution,
and, finally, cultural evolution? Have technological humans now
become the agents of change, able to tinker with both matter and
energy, including genes and environments, more than these factors
currently affect us? How did the neural network within human brains
acquire the sophistication needed to fashion societies, weapons,
cathedrals, philosophies and scenarios of cosmic evolution? In short,
what caused us to become sentient enough to contemplate our complex
The Rise of Complexity
Complexity itself is a slippery term. Few people
agree on its definition, let alone how it might be quantified. Even
among biologists, most of whom concur that complexity has generally
risen throughout the history of life on Earth, the word "complexity"
conjures up different metrics, almost all of them qualitative. In
my work, I wish to push the envelope beyond mere words, indeed beyond
biology. "The book of Nature is written in the language of mathematics,"
said Galileo, one of my intellectual heroes. Some see such an attitude
as reductionistic--an attempt to reduce all understanding to physics--but
I disagree. In cosmic evolution, like life itself, nothing is black
or white, governed by chance or necessity; rather, it resembles
shades of gray throughout, likely mixing specialization with synthesis,
reductionism with holism--a concept only now emerging in scientific
circles, especially in non-equilibrium complexity science.
Making a long argument a good deal shorter, I
return to the physically intuitive concept of energy--admittedly
my physicist's bias, yet as universal a currency as anything known
in science. But not just energy; rather, a term called energy
rate density--the amount of energy flowing through open systems
per unit mass or volume. In that way, we can meaningfully judge,
or normalize, all ordered structures "on the same, level page,"
comparing their use of energy regardless of their size and scale.
And when that is done, we find that miniscule amoebas have much
higher energy flow densities than vastly larger galaxies; petite
human brains much larger values than huge redwood trees.
As might be expected for cosmic evolution--a unifying
proposal incorporating physical, biological and cultural evolution--a
sequential trend correlates well with the age of a given type of
system. The final figure (previous page) shows how all biological
systems have flows of energy density to and from their surrounding
environments far more than for any physical system. And, in turn,
cultural systems, such as cities, economies and all of civilization
utilize still much greater energy flows--an analysis that often
dismays sociologists and economists who find it amusing, at best,
to see their social studies analyzed thermodynamically. At least
Heraclitus would have been pleased, even if puzzled by the modern
details, given another of his succinct maxims: "All flows."
This is not to say, by any means, that galaxies
per se evolved into stars, or stars into planets, or planets into
life. Rather, our analysis suggests that galaxies gave rise to environments
suited to the birth of stars, that some stars spawned environments
conducive to the formation of planets, and that an untold number
of planets fostered environments ripe for the origin of life. This
is Nature writ large.
Evolution, Broadly Considered
The word "evolution" need not be the exclusive
purview of biologists. In fact, Darwin never did use that word as
a noun--and only once as a verb, in the very last sentence of his
1859 classic, On the Origin of Species. Biological evolution
is merely a subset, albeit an important one, of a much grander evolutionary
scheme stretching across all of space and time. For the more we
examine Nature, the more everything seems related to everything
else. Indeed, the concept of evolution, broadly considered, has
become a powerful unifying factor in all of science, underlying
the rise of complexity everywhere.
Selection, adaptation and reproduction--terms
that biologists often take as their sole province--might well apply
to physical and cultural systems beyond biology. The word "selection"
itself is a bit of a misnomer, as there is no known agent or active
force that deliberately selects. I prefer the term "non-random elimination,"
suggested to me several years ago by the foremost living evolutionist,
Ernst Mayr, implying that selection is less a force than a passive
editor or pruning device to weed out the unfit. Accordingly, selection
can be broadly taken to mean preferential interaction of any object
with its environment--a more liberal interpretation that also helps
widen our view of evolution.
As for "replication," one hears the word increasingly
used in astronomical circles. Given recent studies in sequential
star formation among interstellar clouds--wherein the death of some
stars actively triggers the birth of others and repeatedly so--it
is not inconceivable that a kind of replication is at work in the
dark recesses of the Cosmos. Said leading astrophysicist Patrick
Thaddeus recently, "If you consider long enough intervals of time,
stars are as replicative as any bugs in a petri dish."
There is no question that biological evolution
(neo-Darwinism) is much richer than any kind of physical evolution
among inanimate objects. No one is saying otherwise. There is real
added value to the genetic information stored in living systems,
and that's partly--along with enhanced energy flows noted above--what
makes us more complex. Likewise, cultural evolution (mostly Lamarckism)
is richer still, capable of producing cities, states and empires
that are so socially complex as to play havoc with our very well-being
as a civilization.
These are heady issues, vital issues, indeed,
deep intellectual issues that ought to be raised more often in university
settings. Humankind is now moving toward a time, possibly as soon
as within a generation or two, when we shall no longer be able to
expect Nature spontaneously to provide for us the environmental
conditions needed for survival. Rather, society itself will have
to create artificially the very conditions of our own ecological
existence. From the two, society and the biosphere, will likely
emerge a socially controlled bioculture. Here the components become
ideas, artifacts, technology and humans, among other living organisms
and machines on Earth--the epitome (thus far) of complexity in Nature.
Perhaps Vannevar Bush's wartime colleague, Harvard
president James Byrant Conant, was right when he quipped that "education
is what's left after all you've learned has been forgotten." I'd
like to think that the grand theme and historical narrative of cosmic
evolution--an interdisciplinary survey of all the sciences, indeed
a powerful worldview for the 21st century--are among those bits
of education that will indeed be remembered long after all the details
of conventional course work are forgotten.
I'd also like to think that the scenario of cosmic
evolution grants us unparalleled "big thinking," from which may
well emerge the global ethics and planetary citizenship likely needed
if our species is to survive to play a role in that same cosmic-evolutionary
Eric Chaisson is director of the Wright Center for Science Education
and professor of physics and of education.