Here comes another topic from baralbion‘s philosophical questions
Travel to the furthest imaginable star. Look back across the vast areas of space and time at the earth. What is then the significance of the earth and all that’s on it?
There could be different answers to this question, depending on the viewpoint that we choose. The first, the one I think the question implies, is what might be called the “Grain of Dust” viewpoint. What this is might best be explained by a parable:
I get off the bus in Oxford Street, still clutching my bus ticket which is a small thin piece of paper. Looking around, I see here and there the big black litter bins that decorate London streets. Here and there, too, are notices asking us to keep the city clean and to put our litter in the bin. Absentmindedly, I drop my ticket on the ground and walk on.
Have I done any harm by dropping my ticket on the ground? Technically, yes. I have contributed my metaphorical grain of dust to the huge mass of rubbish that London struggles to clear from its streets. Technically. In reality, my little ticket hardly counts. It’s too small to be noticed or accounted for. It doesn’t matter whether I drop it or not. What does matter is that I am one of millions of people travelling about London. If we all dropped our bus tickets on the ground then it would soon be noticed. One will not.
According to the Grain of Dust viewpoint, our planet and even the entire solar system is of no importance whatsoever in the universe as a whole. It is less to the universe than the bus ticket is to Oxford Street, vanishingly small, infinitesimally small. The solar system could pop out of existence in an instant and hardly be noticed apart from an ever expanding and ever weakening pulse of gravity waves. In a word: we wouldn’t be missed.
But there is an alternative view. Cosmologists researching the history of the universe and trying to predict its future have produced a number of models. For the purposes of the discussion let us consider the group of theories that suggest that the universe, its physical laws, its evolution, in fact its entire history were all determined at the moment of the Big Bang. Had any of the details of the Big Bang been slightly different, there would have been a very different universe; a universe, perhaps, with different constitution, different physical laws and a different history.
Suppose now that the earth, instead of coming into existence and (hypothetically) being destroyed, had never existed at all. Where does that leave the universe? We cannot say, of course, but a reasonable speculation is that a universe in which the earth did not come into being would have had to be rather different at the moment of its Big Bang from the one we know. In that case, the consequences might be huge.
Of course, in a universe in which the earth does not come into existence we cannot logically ask how significant the earth is. Nor can we say that the absence of the earth causes the hypothetical universe to be different. Its differences, including the absence of our planet, are all symptoms, not causes, of what happened at the Big Bang. Nonetheless, we can still turn the argument on its head and say that a universe without planet earth would probably be very different and in that sense, the presence or absence of earth matters greatly indeed.
There is yet another viewpoint, of course. To us it is the important one. It is the human point of view. There may or may not be other intelligences in the universe but the only intelligent view of the universe that we know is our own. In one sense, when we say “the universe” we mean “the universe as seen from the human viewpoint”. In this, the sole viewpoint that we can know, planet earth and its environs, are of supreme importance. No earth, no human viewpoint. It’s hard to imagine how the earth could have a greater importance (at least to us) than that.