Dorothy Rowe

The search for a suitable planet could take our lifetime, and our children's life time, or even longer, space being so unimaginably immense. How would we and our descendants cope with living in a cylinder, admittedly a cylinder much bigger than the ones we travel in today? Science fiction tells us that human beings are capable of travelling for huge lengths of time within a spaceship but is this really so?

This is the problem. We are children of the Earth, and we're more attached to Earth than we know.

Time, as we experience it, is not just a matter of setting our clocks so that they will tell us how much time has passed since we first set them. On Earth we always have marked the passing of time with the rising and setting of the sun and the passing of the seasons. However, we are more intimately connected with the passing of time than simply through what our eyes tell us about the passage of the Earth around the sun. In her delightful book Time, Eva Hoffman wrote, 'The adjustment of the diurnal cycle does not occur through anything as simple as sight, which would let an animal know whether it is day or night, or through any sensory signals from the environment. Rather, the periodicity of living creatures is governed endogenously, from within, by versions of that marvellous mechanism called the "biological clock".' The biological clock or circadian rhythms govern the complex biochemical and physiological processes in our body. As the scientists who work with astronauts know, interruptions to circadian rhythms have serious consequences. Circadian rhythms operate over a more or less 24 hour cycle. Just as the Earth does not take a precise 24 hours to circle the sun, neither do our circadian rhythms closely follow our man-made clocks.

Such is the way that we perceive what is around us that we measure ourselves and all that we see in relation to the Earth. We see everything in human sized terms. We see the world in relationship to our human size. When Captain Kirk and the Star Ship Enterprise travelled through the final frontier of space, all the worlds they encountered and all the sentient creatures they found they could see in the same way as they saw themselves and their planet Earth. Yet as far as we know, out there in the farthest reaches of space, there could be sentient beings that are the size of particles or the size of planets. In a world of particle-sized beings everything would appear to us to be travelling at the velocity of particles, while in a world of planet-sized beings everything would appear to us as travelling very slowly. Eva Hoffman wrote, 'We come into the world equipped with a certain mode of consciousness, so that we are predisposed to to understand reality in a certain way. At the same time we are inextricable part of the world we come into, so that we imagine or experience time and space as we do - as time and space - by virtue of being constituted as we are, and of coming into the world as it is.'

Inside the spaceship everything would relate back to us. The spaceship would have been been built and now run by us. We would have set the clocks, just as we would have built and programmed the computers. Yet this was not how we lived on Earth. There we had something outside ourselves that we could relate to in terms of ourselves but which operated independently of us. That was the kind of world in which we became ourselves. We learnt about the part of the world where we lived by interacting closely with it. On the DVD of the Disney-Pixar film Up there is a short film about the team who created Up. Central to the plot of the Up are the Tepuis. These are immense, table-topped upthrusts of ancient rock rising thousands of feet out of the jungle in Canaima National Park, Venezuela. Drawing the Tepius from photographs was not good enough for the team. They need to climb the Tepuis, stand on their surface, and be surprised and moved by what they discovered. Ricky Nierva, the art director, commented, 'You've got to smell it, you've got to taste it, you've got to be there to get the realness of it.'

This is how we as children learned about the realness of our part of the Earth. In learning this, we became part of the Earth, and the Earth became part of us. The sight, the smell, and the taste of our Earth are part of our body's memory and a vital part of our identity. Would the children born on the spaceship feel about the metallic surfaces of their world in the same way as we feel about the plants and insects, flowers and trees, the birds and animals, rivers, lakes and ponds, the sea, the wind and the sky that we saw from Earth? How terrible it would be to climb aboard a spaceship knowing that you could never go home again.