Silent Worlds, Empty Worlds
6 July 2011
A Question of Absence:
A Meditation on SETI
At present I am listening to The Eerie Silence: Renewing Our Search for Alien Intelligence by Paul Davies. I’m only a little more than half way through the book so far, so while I have much more to say on the book, I’ll reserve more extensive remarks until I’ve gotten through more of it.
For the time being, I will content myself with some brief remarks on the central theme of the book. This theme is emptiness, silence, absence, lack, privation, nothingness…
Are we alone?
The eerie silence is the deafening nothingness that has greeted those SETI scientists listening among the stars for extraterrestrial radio signals. They haven’t heard anything in fifty years. Some in the discipline are having second thoughts, and these second thoughts have largely inspired this book. Davies describes the difference between “old” SETI and “new” SETI, the latter being an attempt to think through, and hopefully go beyond, the presuppositions of the original SETI program.
Davies’ book is fairly comprehensive, so he takes the reader through much familiar material, such as Fermi’s Paradox — which asks of any extraterrestrial intelligence, “Where are they?” — which leads immediately to the equally familiar refrain, absence of evidence is not evidence of absence.
Let us, for the moment, grant the SETI skeptics the argument, if only hypothetically, and ask what kind of galaxy we live in, if we live in it quite alone.
Suppose we are alone, or nearly alone. What then? Then the cosmos is filled with empty worlds, silent worlds. It is an odd feeling simply to know this. Our bustling planet is a loud place, filled with noises. Arthur Schopenhauer wrote a justly famous short essay, “On Noise” which begins with the following paragraph:
“Kant wrote a treatise on The Vital Powers. I should prefer to write a dirge for them. The superabundant display of vitality, which takes the form of knocking, hammering, and tumbling things about, has proved a daily torment to me all my life long. There are people, it is true — nay, a great many people — who smile at such things, because they are not sensitive to noise; but they are just the very people who are not sensitive to argument, or thought, or poetry, or art, in a word, to any kind of intellectual influence. The reason of it is that the tissue of their brains is of a very rough and coarse quality. On the other hand, noise is a torture to intellectual people. In the biographies of almost all great writers, or wherever else their personal utterances are recorded, I find complaints about it; in the case of Kant, for instance, Goethe, Lichtenberg, Jean Paul; and if it should happen that any writer has omitted to express himself on the matter, it is only for want of opportunity.”
Though Schopenhauer is remembered to philosophical history as a pessimist, he could be a very amusing writer, and this brief essay offers an excellent display of his wit and charm.
If the Milky Way is empty of intelligent life except for us, it is empty of that particular variety of noise that Schopenhauer protested. Schopenhauer specifically mentioned “knocking, hammering, and tumbling things about,” which is more or less synonymous with the activities of early industrial civilization. Schopenhauer quotes Thomas Hood as saying of the Germans, “For a musical nation, they are the most noisy I ever met with.” Schopenhauer attributes this to the obtuseness of mind of his people, but I think this is rather a universal, or nearly universal, condition of civilization, and a condition that is heightened by industrialization.
An empty universe would be a marvelous place for silent meditation and contemplation, interrupted by only the soothing sounds of nature in its various forms. How far would these forms of nature extend in a universe empty of intelligent life? This is perhaps more interesting and promising question than appears at first.
The rare earth hypothesis, upon which the empty universe is predicated, involves a suspension of the principle of mediocrity, which in some formulations is essentially the same thing as the Copernican Principle. If the kind of life, intelligence, and technological civilization that we have here on the earth is a rare event, and perhaps a unique event, then the earth and the civilization that it hosts is in no sense mediocre, but is the exception to many rules.
In several posts I have noted how our expanding knowledge of the universe has only pointed toward confirmation of the Copernican Principle. For example, in More Evidence for the Copernican Principle I argued that the discovery of extrasolar planets in the Helmi Stream extends the Copernican Principle to other galaxies, since the Helmi Stream associated with the Milky Way is the remnant of a captured galaxy once separate from the Milky Way.
Earlier, in Other Worlds, I wrote the following:
“…claims to cosmic uniqueness are being disproved as soon as the technological means are available to disprove them. For example, there is a large and growing body of evidence on extrasolar planets. We now know for a fact that there are planetary systems other than our own. Since we already know that planetary atmospheres are not unique (from the example of Mars, Venus, and several planetary moons), and we know from the moons of Jupiter that volcanic activity is not unique to the earth, it would be foolish to suppose that these extrasolar planets are all without atmospheres, and if they are small, rocky planets, they will be, like Mars, places not unlike the earth. And among these places not unlike the earth, there will be very interesting places, beautiful places, places unique in their own way, and well worth seeing. It is entirely reasonable to want to see such places quite apart from the question of whether there is life or whether such places are inhabited by sentient creatures or civilizations.”
These worlds upon which I speculated would not be silent, but they would not have noise in the Schopenhauerian sense. What sounds would they have? As near to us as Mars, if we could listen through the suits that would be necessary to survive on the surface, we could hear the Martian wind whistling among the dead rocks and stones on the Martian desert. The shifting sands of Mars might also produce the phenomenon of “singing sands” known on earth, though these would be the singing sands of Mars — plaintive, alien sounds of an alien world.
Farther afield than Mars, since we now can prove that there are extrasolar planets, and recent technological improvements have yielded smallish, rocky planets within the habitable zones of stars, there may be alien worlds with water, perhaps even entire oceans. Water in lakes, ponds, streams, waterfalls and oceans would make sounds. A waterfall can be nearly deafening if you are close to it, as can the tide washing upon the shore.
This last example, the sound of the tide, points to the interesting fact that the earth has one large moon. If we had no moon, the oceans would be attracted by the gravity of more distant celestial bodies, but this would not likely be sufficient to create the tides we know. If the earth had several moons, or much smaller moons, again we would not have the familiar tides. The sound of the tides would vary according to the gravitational environment of the ocean in question. It would be a definitely odd experience to stand on the shore of an alien ocean moved by no tides at all. In fact, the effect might be so dramatic that a person might want to travel there simply to experience this uniquely contemplative environment.
If we add into the picture further elements, in line with the principle of mediocrity but not fully violating the rare earth hypothesis that leaves us stranded alone in the Milky Way, there may be worlds — empty worlds, nearly silent worlds — in which the only sound to be heard is the wind in the grasses and the trees. Or, if there is animal life as well, the sounds of wings, and the clicks and chirps of insects. If you have ever been in the Amazon at night, you know that the ambient sound is almost as deafening as a waterfall, a torrent of white noise produced by countless organisms going about the ordinary business of life, but once again this is not Schopenhauerian noise.
If you had the leisure to listen long enough in any of these environments, you would hear periodicities in the ambient sound — diurnal periods, seasonal periods, annual periods, and perhaps also periodicities governed by unique forms of life.
These silent, empty worlds would only be silent and empty in so far as we identify meaningful sounds with human acitivity, which seems to me to be the antithesis of the spirit of SETI. No natural scientist would suppose for a moment that a world without “noise” would be a world without interest. One of the most surprising claims I found in Davies’ book was this:
“If there is somebody at the destination planet already, then why bother to make the trip? If the purpose of space travel is exploration, well, the aliens can send us the content of their latest DVD. On the other hand, if it is conquest, then the fact that the target planet already has a far more advanced civilization ensconced would constitute a pretty strong deterrent. All in all, it would make more sense for the newcomer civilization to stay put and simply join the Galactic Club.”
Paul Davies, The Eerie Silence: Renewing Our Search for Alien Intelligence, pp. 119-120
In this context, Davies doesn’t even consider the kind of motivations that inspire people to climb mountains, though just a few pages after this quote he considers these motivations in a different context.
Exploration is about much more than knowing what it out there. It is also about experiencing what is out there, and even touching what is out there. While there will always be some people content to know, just as there are always some people content with ignorance, there will also always be people who want to go and see for themselves, and this motivation will not be dampened by the possibility that there are no other technological civilizations in the Milky Way. The Cosmic wilderness awaits us.
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