The Beginning of Infinity - By David Deutsch Page 0,22

so long that many generations of passengers live out their lives in transit. This has been proposed as a means of colonizing other star systems. In the Spaceship Earth idea, that generation ship is a metaphor for the biosphere – the system of all living things on Earth and the regions they inhabit. Its passengers represent all humans on Earth. Outside the spaceship, the universe is implacably hostile, but the interior is a vastly complex life-support system, capable of providing everything that the passengers need to thrive. Like the spaceship, the biosphere recycles all waste and, using its capacious nuclear power plant (the sun), it is completely self-sufficient.

Just as the spaceship’s life-support system is designed to sustain its passengers, so the biosphere has the ‘appearance of design’: it seems highly adapted to sustaining us (claims the metaphor) because we were adapted to it by evolution. But its capacity is finite: if we overload it, either by our sheer numbers or by adopting lifestyles too different from those that we evolved to live (the ones that it is ‘designed’ to support), it will break down. And, like the passengers on that spaceship, we get no second chances: if our lifestyle becomes too careless or profligate and we ruin our life-support system, we have nowhere else to go.

The Spaceship Earth metaphor and the Principle of Mediocrity have both gained wide acceptance among scientifically minded people – to the extent of becoming truisms. This is despite the fact that, on the face of it, they argue in somewhat opposite directions: the Principle of Mediocrity stresses how typical the Earth and its chemical scum are (in the sense of being unremarkable), while Spaceship Earth stresses how untypical they are (in the sense of being uniquely suited to each other). But when the two ideas are interpreted in broad, philosophical ways, as they usually are, they can easily converge. Both see themselves as correcting much the same parochial misconceptions, namely that our experience of life on Earth is representative of the universe, and that the Earth is vast, fixed and permanent. They both stress instead that it is tiny and ephemeral. Both oppose arrogance: the Principle of Mediocrity opposes the pre-Enlightenment arrogance of believing ourselves significant in the world; the Spaceship Earth metaphor opposes the Enlightenment arrogance of aspiring to control the world. Both have a moral element: we should not consider ourselves significant, they assert; we should not expect the world to submit indefinitely to our depredations.

Thus the two ideas generate a rich conceptual framework that can inform an entire world view. Yet, as I shall explain, they are both false, even in the straightforward factual sense. And in the broader sense they are so misleading that, if you were seeking maxims worth being carved in stone and recited each morning before breakfast, you could do a lot worse than to use their negations. That is to say, the truth is that

People are significant in the cosmic scheme of things; and

The Earth’s biosphere is incapable of supporting human life.

Consider Hawking’s remark again. It is true that we are on a (somewhat) typical planet of a typical star in a typical galaxy. But we are far from typical of the matter in the universe. For one thing, about 80 per cent of that matter is thought to be invisible ‘dark matter’, which can neither emit nor absorb light. We currently detect it only through its indirect gravitational effects on galaxies. Only the remaining 20 per cent is matter of the type that we parochially call ‘ordinary matter’. It is characterized by glowing continuously. We do not usually think of ourselves as glowing, but that is another parochial misconception, due to the limitations of our senses: we emit radiant heat, which is infra-red light, and also light in the visible range, too faint for our eyes to detect.

Concentrations of matter as dense as ourselves and our planet and star, though numerous, are not exactly typical either. They are isolated, uncommon phenomena. The universe is mostly vacuum (plus radiation and dark matter). Ordinary matter is familiar to us only because we are made of it, and because of our untypical location near large concentrations of it.

Moreover, we are an uncommon form of ordinary matter. The commonest form is plasma (atoms dissociated into their electrically charged components), which typically emits bright, visible light because it is in stars, which are rather hot. We scums are mainly infra-red emitters because we contain liquids and complex chemicals which can exist