Rendezvous With Rama - Arthur C. Clarke [14]
'Yes, Mr. Ambassador, I think I have some information of interest. What we have here is undoubtedly a "Space Ark". It's an old idea in the astronautical literature; I've been able to trace it back to the British physicist J. D. Bernal, who proposed this method of interstellar colonization in a book published in 1929—yes, two hundred years ago. And the great Russian pioneer Tsiolkovski put forward somewhat similar proposals even earlier.'
'If you want to go from one star system to another you have a number of choices. Assuming that the speed of light is an absolute limit—and that's still not completely settled, despite anything you may have heard to the contrary'—there was an indignant sniff, but no formal protest from Professor Davidson—'you can make a fast trip in a small vessel, or a slow journey in a giant one.'
'There seems no technical reason why spacecraft cannot reach ninety per cent, or more, of the speed of light. That would mean a travel time of five to ten years between neighbouring stars—tedious, perhaps, but not impracticable, especially for creatures whose life spans might be measured in centuries. One can imagine voyages of this duration, carried out in ships not much larger than ours.'
'But perhaps such speeds are impossible, with reasonable payloads; remember, you have to carry the fuel to slow down at the end of the voyage, even if you're on a one-way trip. So it may make more sense to take your time—ten thousand, a hundred thousand years . . .'
'Bernal and others thought this could be done with mobile worldlets a few kilometres across, carrying thousands of passengers on journeys that would last for generations. Naturally, the system would have to be rigidly closed, recycling all food, air and other expendables. But, of course, that's just how the Earth operates—on a slightly larger scale.'
'Some writers suggested that these Space Arks should be built in the form of concentric spheres; others proposed hollow, spinning cylinders so that centrifugal force could provide artificial gravity—exactly what we've found in Rama—'
Professor Davidson could not tolerate this sloppy talk. 'No such thing as centrifugal force. It's an engineer's phantom. There's only inertia.'
'You're quite right, of course,' admitted Perera, 'though it might be hard to convince a man who'd just been slung off a carousel. But mathematical rigour seems unnecessary—'
'Hear, hear,' interjected Dr. Bose, with some exasperation. 'We all know what you mean, or think we do. Please don't destroy our illusions.'
'Well, I was merely pointing out that there's nothing conceptually novel about Rama, though its size is startling. Men have imagined such things for two hundred years.'
'Now I'd like to address myself to another question. Exactly how long has Rama been travelling through space?'
'We now have a very precise determination of its orbit and its velocity. Assuming that it's made no navigational changes, we can trace its position back for millions of years. We expected that it would be coming from the direction of a nearby star—but that isn't the case at all.'
'It's more than two hundred thousand years since Rama passed near any star, and that particular one turns out to be an irregular variable—about the most unsuitable sun you could imagine for an inhabited solar system. It has a brightness range of over fifty to one; any planets would be alternately baked and frozen every few years.'
'A suggestion,' put in Dr. Price. 'Perhaps that explains everything. Maybe this was once a normal sun and became unstable. That's why the Ramans had to find a new one.'
Dr. Perera admired the old