Watchers of the Sky
One of the problems of human knowledge is that the world which we see from the surface of this planet on a sunny day
bears almost no resemblance to the Universe at large. Our Earth is made of iron and rock, but the Universe as a whole is mostly
hydrogen. The actions which we see on the surface of this Earth run mostly on sunlight, but the Universe runs on gravity.
What we see here are continents, oceans, rivers and lakes, mountain ranges, forests, tundra and prairies. But the Universe
at large is mostly gas, partly condensed by gravity to galaxies and stars, and lightly sprinkled, here and there, with interstellar
dust. The dust is made from hydrogen in the bellies of stars, and is scattered through the galaxies by the explosions and
the stellar winds of stars much bigger and much hotter than our Sun. But the dust is scarce, and, like our bodies, the rock
on which we live is made of these dusts. It is a collector's item. The heavier elements, such as iron, have sunk to the
center, overlaid with rocks of the mantle and the crust and a thin veneer of water and gas. Since the age of this museum piece
is pushing five billion years, by now the water-soluble compounds of the surface rocks have leached into the water layer,
making the oceans salty. The saltiness of our blood is the saltiness of the ancient sea, some four hundred million years ago.
That is when our scaly ancestors, on stumpy fins, crawled out across the land in search of other water and the sight of other
fish. Descended as we are from them, we can think of our bodies, even now, as little bags of sea water, hung out on clotheslines
of bone, gulping oxygen directly from the gas layer above us, and shambling out across the rocks to gaze with starry eyes,
through the blackness of night, at the vast expanse of the Universe beyond.
Even the oxygen that we breathe is freed
by sunlight through the instrumentality of our photosynthetic relatives, first by the blue-green algae in the sea, and now
by the green leaves of the rain forest. Even the rain is driven by sunlight. But the Universe at large has a reducing atmosphere,
and it is without rain and without sunlight. It is very cold, very dark, and very lonely, trying desperately to fall together
by the seemingly inexplicable attraction of the particles for each other. Even the radiation of the Sun is driven by this
attraction which has pushed the central temperature of the Sun up to some fifteen million degrees Celsius. And it is only
because its gravitational collapse has been slowed by the nuclear fusion at its core that the Sun has bathed our Earth with
its warming rays for nearly five billion years. Only this delay has made possible our long genetic development till we were
able to climb out of the water and gaze in wonder at the starry sky of night. Although we, as living organisms, owe both our
existence and our long genetic development to the Sun, its dazzling brightness prevents us from seeing the Universe by day.
The blueness of the daytime sky is not the color of the air, but simply the shorter wavelengths scattered from the sunlight
by the gas layer above us. And that gas layer by night, unlit by the Sun, is sufficiently transparent so that through it we
may gaze into the far reaches of the Universe.
But seeing alone is not enough. It is only the beginning. We must also
understand what we see, and that has a history. Understanding rests on a foundation of concepts and information coming down
to us from the past, albeit not the very distant past. It is not from the first few hundred million years after we came ashore
in the swamps to look around, because in those distant days and nights the concepts which we framed, and the information which
we gained, could not be transmitted from generation to generation. We lacked a mechanism to transmit it. It is not transmitted
genetically and there were then no words. Written words, by which concepts and information are largely transmitted in what
we proudly think of as the Ã¢??Age of Science,Ã¢?? are only a few thousand years old. And vocal speech
itself is fairly new. It was probably forced upon us by the failure of our body language in the surf when we, as brachiating
primates, marooned on an island in northeast Africa, were driven by drought from the jungles to the beach, not more than ten
or fifteen million years ago. And even the body language common to the great apes, and easily understood by the orangs, the
gorillas, the chimps and ourselves, is less than fifty million years old. Our great gain in those earlier times was in our
genetically transmitted capabilities. By the early demise of those with poorer eyes, we gained our visual acuity, and by the
early demise of those with smaller brains, we improved our capacity to understand. It is that capacity which sets us apart
amongst the watchers of the skies.