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|How This Book Is Put Together|
|I||Origins of the Earth||3|
|II||Origins of Life||17|
|III||How Life Works||33|
|IV||How an Organism Works||49|
|V||How Evolution Works||63|
|VI||The Evolution of Biodiversity||77|
|VIII||Emotions and Meaning||105|
|XI||Multicellularity and Death||143|
|Emergent Religious Principles||167|
|Notes and Further Reading||175|
Origins of the Earth
INFINITIES AND INFINITESIMALS
Everything in our universe, including the Earth and its living creatures, obeys the laws of physics, laws that became manifest in the first moments of time. Much of what we know to be true about the physical universe, like the curvature of spacetime and the fact that electrons are both particles and waves, is very difficult to visualize, even for people who spend their lives thinking about such topics. Moreover, as physicists and mathemeticians probe ever more deeply, they present us with ever more mind-boggling concepts, like the idea that sub-atomic particles may in fact be minute, vibrating "superstrings" of space, that our four-dimensional universe may actually be ten-dimensional, that the observable universe may be much smaller than the true universe, and that there may be many other universes besides our own.
Fascinating as these known and speculative manifestations of physics may be, they prove not to be central to our story of life. Why? Because when Earth life was coming into being, some ten billion years after the universe had come into being, the laws of physics were a given. Life had no choice but to evolve in the context of quantum indeterminacy and gravitational fields and quarks held together by gluons. Therefore, while these facts underlie all of life, and constrain what can and cannot occur during biological evolution, we can describe how life works without referring to them, in much the same way that we can describe what a painting looks like without referring to the absorption spectra of its pigments.
What is central to the origin of Earth life is the history of the universe--the cosmic dynamics that yielded our star, our planet, and the atoms that form living things. We can tell the story sparingly, without pausing to define terminology, allowing the flow of events to suggest the enormous times and distances involved.
THE UNIVERSE STORY
The observable universe is about fifteen billion years old. In the beginning, everything that is now that universe, including all of its space, was concentrated in a singularity, maybe the size of a pinhead, that was unimaginably hot at least 100,000,000,000,000,000,000,000,000,000 degrees and unimaginably dense. It all let loose during an event called the Big Bang, a misleading term in that there wasn't really an explosion. What happened was that the compacted space expanded very rapidly, carrying everything else along with it.
During the first three minutes of this expansion, all sorts of high-energy physics took place that yielded the current tally of subatomic particles in the universe, including protons, neutrons, and electrons. Some of the protons and neutrons fused to form helium ions, and random clumps developed in the expanding material so that it was not perfectly homogeneous. And then things started to settle down, with the space continuing to expand and cool until, after several hundred thousand years, temperatures were low enough that the protons and helium ions could acquire electron shells and become stable hydrogen and helium atoms. The expansion continued for another 15 billion years, yielding the present observable universe, 1,000,000,000,000,000,000,000,000 miles in diameter. Whether it will continue to expand or start to contract back again the Big Crunch is one of the many unknowns of cosmic evolution.
Because the early hydrogen and helium atoms were distributed inhomogeneously in the expanding space, close neighbors tended to move closer and then closer together, attracted by gravity. The result was that the universe became "lumpy," with vast gaseous clouds scattered here and there, occasionally colliding and merging with one another. These protogalaxies then differentiated, and continue to differentiate, into billions of galaxies, each giving rise to billions of stars.
A star starts out as a gaseous cloud, about three-quarters hydrogen and one-quarter helium. The atoms are brought together by gravitational attraction and, as they fall closer together, they speed up until the temperature is so high that they are stripped of their electrons and the hydrogen nuclei start to fuse, forming helium ions. These fusion reactions release heat, causing the gas to expand and counterbalancing its tendency to contract. As a result, the star stabilizes in temperature and size, often for billions of years, burning its hydrogen fuel.
Once the hydrogen begins to run out, the rate of nuclear fusion slows down and the gases no longer expand as readily. As a result, the star begins to contract again, eventually becoming so dense and hot that its helium nuclei start to fuse together, forming larger nuclei like carbon, oxygen, calcium, and other "light" elements of the periodic table.
What happens next depends on the size of the star. A small star becomes unstable at this stage and puffs away its outer layers, seeding the galaxy with its newly minted light elements and leaving behind a remnant known as a white dwarf. A giant star keeps collapsing, getting hotter and hotter and forming heavier and heavier nuclei until it starts to make iron, which it can't burn. When a critical amount of iron accumulates, the core of the star is crushed by gravity into what is called a neutron star, and the shock waves generated by the crushing process cause a huge explosion in the star's outer layers--a supernova. Very heavy nuclei, including radioactive elements like uranium, are created during the supernova phase, and all the new kinds of nuclei are released into gaseous clouds where they cool, acquire electrons, and become atoms.
The gaseous clouds now go on to aggregate into second-generation stars that are more complex than their predecessors because they include some of the new kinds of atoms. The second-generation stars proceed to burn their hydrogen and collapse, forming more new elements in the process, and the released detritus then reaggregates into third-generation stars that are yet again more complex. Such birth-and-death stellar cycles are apparently destined to continue for billions of years into the future.
THE EARTH STORY
So now we can look at our own context. The Milky Way is a medium-sized galaxy, and the Sun, located in one of its spiral arms, is a second- or third-generation medium-sized star that formed from the atoms released by a nearby supernova. The Sun has existed for about 4.5 billion years and has enough hydrogen to burn for another 5 billion years or so. During its terminal phases it is expected to become so hot that the Earth will turn into a cinder.
While the Sun was forming, some of the surrounding material assembled into small aggregates that grew and collided and merged with one another and eventually stabilized as its orbiting planets, moons, and comets. Importantly, some of these aggregates, including what is now Earth, contained generous quantities of the atoms spewed out by supernovae: These include the iron and radioactive elements that form the Earth's broiling core, the silicon that forms its crust, and the carbon, oxygen, nitrogen, and other elements that are essential for life. Moreover, comets colliding with the young Earth provisioned it with yet more atoms from distant supernovae, and also brought in a great deal of water in the form of ice. Gases trapped in the Earth's interior were released through fissures and volcanos and became trapped by gravity to form the early atmosphere, and the floating surface settled into large masses that drift and crash into one another in continuous geological activity, defining and redefining the continents and ocean basins. After about half a billion years of consolidation, the physical conditions on Earth became such that life could originate and continue.
I've had a lot of trouble with the universe. It began soon after I was told about it in physics class. I was perhaps twenty, and I went on a camping trip, where I found myself in a sleeping bag looking up into the crisp Colorado night. Before I could look around for Orion and the Big Dipper, I was overwhelmed with terror. The panic became so acute that I had to roll over and bury my face in my pillow.
* All the stars that I see are part of but one galaxy.
* There are some 100 billion galaxies in the universe, with perhaps 100 billion stars in each one, occupying magnitudes of space that I cannot begin to imagine.
* Each star is dying, exploding, accreting, exploding again, splitting atoms and fusing nuclei under enormous temperatures and pressures.
* Our Sun too will die, frying the Earth to a crisp during its heat-death, spewing its bits and pieces out into the frigid nothingness of curved spacetime.
The night sky was ruined. I would never be able to look at it again. I wept into my pillow, the long slow tears of adolescent despair. And when I later encountered the famous quote from physicist Steven Weinberg--"The more the universe seems comprehensible, the more it seems pointless"--I wallowed in its poignant nihilism. A bleak emptiness overtook me whenever I thought about what was really going on out in the cosmos or deep in the atom. So I did my best not to think about such things.
But, since then, I have found a way to defeat the nihilism that lurks in the infinite and the infinitesimal. I have come to understand that I can deflect the apparent pointlessness of it all by realizing that I don't have to seek a point. In any of it. Instead, I can see it as the locus of Mystery.
* The Mystery of why there is anything at all, rather than nothing.
* The Mystery of where the laws of physics came from.
* The Mystery of why the universe seems so strange.
Mystery. Inherently pointless, inherently shrouded in its own absence of category. The clouds passing across the face of the deity in the stained-glass images of Heaven.
The word God is often used to name this mystery. A concept known as Deism proposes that God created the universe, orchestrating the Big Bang so as to author its laws, and then stepped back and allowed things to pursue their own course. For me, Deism doesn't work because I find I can only think of a creator in human terms, and the concept of a human-like creator of muons and neutrinos has no meaning for me. But more profoundly, Deism spoils my covenant with Mystery. To assign attributes to Mystery is to disenchant it, to take away its luminance.
I think of the ancients ascribing thunder and lightning to godly feuds, and I smile. The need for explanation pulsates in us all. Early humans, bursting with questions about Nature but with limited understanding of its dynamics, explained things in terms of supernatural persons and person-animals who delivered the droughts and floods and plagues, took the dead, and punished or forgave the wicked. Explanations taking the form of unseen persons were our only option when persons were the only things we felt we understood. Now, with our understanding of Nature arguably better than our understanding of persons, Nature can take its place as a strange but wondrous given.
The realization that I needn't have answers to the Big Questions, needn't seek answers to the Big Questions, has served as an epiphany. I lie on my back under the stars and the unseen galaxies and I let their enormity wash over me. I assimilate the vastness of the distances, the impermanence, the fact of it all. I go all the way out and then I go all the way down, to the fact of photons without mass and gauge bosons that become massless at high temperatures. I take in the abstractions about forces and symmetries and they caress me, like Gregorian chants, the meaning of the words not mattering because the words are so haunting.
Mystery generates wonder, and wonder generates awe. The gasp can terrify or the gasp can emancipate. As I allow myself to experience cosmic and quantum Mystery, I join the saints and the visionaries in their experience of what they called the Divine, and I pulse with the spirit, if not the words, of my favorite hymn:
Immortal, invisible, God only wise,
In light inaccessible hid from our eyes,
Most blessed, most glorious, the Ancient of
Almighty, victorious, thy great name we
Unresting, unhasting, and silent as light,
Nor wanting, nor wasting, thou rulest in
Thy justice like mountains high soaring
Thy clouds which are fountains of goodness
To all, life thou givest, to both great and
In all life thou livest, the true life of all;
We blossom and flourish as leaves on the
And wither and perish, but naught changeth
Thou reignest in glory; thou dwellest in
Thine angels adore thee, all veiling their
All laud we would render: O help us to see
'Tis only the splendor of light hideth thee.
Walter Chalmers Smith, 1867
And then I wander back twenty-six centuries to Lao Tzu and the first chapter of the Tao Te Ching:
The Tao that can be told is not the eternal
The name that can be named is not the eternal
The nameless is the beginning of heaven and
The named is the mother of ten thousand
Ever desireless, one can see the mystery.
Ever desiring, one sees the manifestations.
These two spring from the same source but
differ in name; this appears as darkness.
Darkness within darkness.
The gate to all mystery.
Posted July 8, 2005
An excellent reading experience that feels congruent with what I experience in my own explorations.Though I doubt that Wendell Berry would appreciate the comparison, Dr. Goodenough¿s essays remind me of poems and essays by Professor Berry.
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Posted May 23, 2011
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