If you attempt to make a disc out of rectangular blocks -whether their proportions are 1:4:9 or any other – it cannot possibly have a smooth edge. Of course, you can make it as near a perfect circle as you like, by using smaller and smaller blocks. Yet why go to that trouble, if you merely wanted to build a screen large enough to eclipse a sun?
The Mayor was right; the eclipse was indeed temporary. But its ending was the precise opposite of a solar one.
First light broke through at the exact centre, not in the usual necklace of Bailey's Beads along the very edge. Jagged lines radiated from a dazzling pinhole – and now, under the highest magnification, the structure of the disc was being revealed. It was composed of millions of identical rectangles, perhaps the same size as the Great Wall of Europa. And now they were splitting apart: it was as if a gigantic jigsaw puzzle was being dismantled.
Its perpetual, but now briefly interrupted, daylight was slowly returning to Ganymede, as the disc fragmented and the rays of Lucifer poured through the widening gaps. Now the components themselves were evaporating, almost as if they needed the reinforcement of each other's contact to maintain reality.
Although it seemed like hours to the anxious watchers in Anubis City, the whole event lasted for less than fifteen minutes. Not until it was all over did anyone pay attention to Europa itself.
The Great Wall was gone: and it was almost an hour before the news came from Earth, Mars and Moon that the Sun itself had appeared to flicker for a few seconds, before resuming business as usual.
It had been a highly selective set of eclipses, obviously targeted at humankind. Nowhere else in the Solar System would anything have been noticed.
In the general excitement, it was a little longer before the world realized that TMA ZERO and TMA ONE had both vanished, leaving only their four-million-year-old imprints on Tycho and Africa.
It was the first time the Europs could ever have met humans, but they seemed neither alarmed nor surprised by the huge creatures moving among them at such lightning speed. Of course, it was not too easy to interpret the emotional state of something that looked like a small, leafless bush, with no obvious sense organs or means of communication. But if they were frightened by the arrival of Alcyone, and the emergence of its passengers, they would surely have remained hiding in their igloos.
As Frank Poole, slightly encumbered by his protective suit and the gift of shining copper wire he was carrying, walked into the untidy suburbs of Tsienville, he wondered what the Europs thought of recent events. For them, there had been no eclipse of Lucifer, but the disappearance of the Great Wall must surely have been a shock. It had stood there for a thousand years, as a shield and doubtless much more; then, abruptly, it was gone, as if it had never been...
The petabyte tablet was waiting for him, with a group of Europs standing around it, demonstrating the first sign of curiosity that Poole had ever observed in them. He wondered if Halman had somehow told them to watch over this gift from space, until he came to collect it.
And to take it back, since it now contained not only a sleeping friend but terrors which some future age might exorcise, to the only place where it could be safely stored.
40 – Midnight: Pico
It would be hard, Poole thought, to imagine a more peaceful scene – especially after the trauma of the last weeks. The slanting rays of a nearly full Earth revealed all the subtle details of the waterless Sea of Rains – not obliterating them, as the incandescent fury of the Sun would do.
The small convoy of mooncars was arranged in a semicircle a hundred metres from the inconspicuous opening at the base of Pico that was the entrance to the Vault. From this viewpoint, Poole could see that the mountain did not live up to the name that the early astronomers, misled by its pointed shadow, had given to it. It was more like a rounded hill than a sharp peak, and he could well believe that one of the local pastimes was bicycle-riding to the summit. Until now, none of those sportsmen and women could have guessed at the secret hidden beneath their wheels: he hoped that the sinister knowledge would not discourage their healthy exercise.
An hour ago, with a sense of mingled sadness and triumph, he had handed over the tablet he had brought -never letting it out of his sight – from Ganymede directly to the Moon.
'Good-bye, old friends,' he had murmured. 'You've done well. Perhaps some future generation will reawaken you. But on the whole – I rather hope not.'
He could imagine, all too clearly, one desperate reason why Halman's knowledge might be needed again. By now, surely, some message was on its way to that unknown control centre, bearing the news that its servant on Europa no longer existed. With reasonable luck, it would take 950 years, give or take a few, before any response could be expected.
Poole had often cursed Einstein in the past; now he blessed him. Even the powers behind the Monoliths, it now appeared certain, could not spread their influence faster than the speed of light. So the human race should have almost a millennium to prepare for the next encounter – if there was to be one. Perhaps by that time, it would be better prepared.
Something was emerging from the tunnel – the track-mounted, semi-humanoid robot that had carried the tablet into the Vault. It was almost comic to see a machine enclosed in the kind of isolation suit used as protection against deadly germs and here on the airless Moon! But no one was taking any chances, however unlikely they might seem. After all, the robot had moved among those carefully sequestered nightmares, and although according to its video cameras everything appeared in order, there was always a chance that some vial had leaked, or some canister's seal had broken. The Moon was a very stable environment, but during the centuries it had known many quakes and meteor impacts.
The robot came to a halt fifty metres outside the tunnel. Slowly, the massive plug that sealed the Vault swung back into place, and began to rotate in its threads, like a giant bolt being screwed into the mountain.
'All not wearing dark glasses, please close your eyes or look away from the robot!' said an urgent voice over the mooncar radio. Poole twisted round in his seat, just in time to see an explosion of light on the roof of the vehicle. When he turned back to look at Pico, all that was left of the robot was a heap of glowing slag; even to someone who had spent much of his life surrounded by vacuum, it seemed altogether wrong that tendrils of smoke were not slowly spiralling up from it.
'Sterilization completed,' said the voice of the Mission Controller. 'Thank you, everybody. Now returning to Plato City.'
How ironic – that the human race had been saved by the skilful deployment of its own insanities! What moral, Poole wondered, could one possibly draw from that?
He looked back at the beautiful blue Earth, huddling beneath its tattered blanket of clouds for protection against the cold of space. Up there, a few weeks from now, he hoped to cradle his first grandson in his arms.
Whatever godlike powers and principalities lurked beyond the stars, Poole reminded himself, for ordinary humans only two things were important – Love and Death.
His body had not yet aged a hundred years: he still had plenty of time for both.
EPILOGUE
'Their little universe is very young, and its god is still a child. But it is too soon to judge them; when We return in the Last Days, We will consider what should be saved.'
SOURCES AND ACKNOWLEDGEMENTS
SOURCES
Chapter 1: The Kuiper Belt
For a description of Captain Chandler's hunting ground, discovered as recently as 1992, see 'The Kuiper Belt' by Jane X. Luu and David C. Jewitt (Scientific American, May 1996)
Chapter 3: Rehabilitation
I believed that I had invented the palm-to-palm transfer of information, so it was mortifying to discover that Nicholas ("Being Digital") Negroponte (Hodder and Stoughton, 1995) and his MIT Media Lab have been working on the idea for years...
Chapter 4: Star City
The concept of a 'ring around the world' in the geostationary orbit (CEO), linked to the Earth by t
owers at the Equator, may seem utterly fantastic but in fact has a firm scientific basis. It is an obvious extension of the 'space elevator' invented by the St Petersburg engineer Yuri Artsutanov, whom I had the pleasure of meeting in 1982, when his city had a different name.
Yuri pointed out that it was theoretically possible to lay a cable between the Earth and a satellite hovering over the same spot on the Equator which it does when placed in the CEO, home of most of today's communications satellites. From this beginning, a space elevator (or in Yuri's picturesque phrase, 'cosmic funicular') could be established, and payloads could be carried up to the CEO purely by electrical energy. Rocket propulsion would be needed only for the remainder of the journey.
In addition to avoiding the danger, noise and environmental hazards of rocketry, the space elevator would make possible quite astonishing reductions in the cost of all space missions. Electricity is cheap, and it would require only about a hundred dollars' worth to take one person to orbit. And the round trip would cost about ten dollars, as most of the energy would be recovered on the downward journey! (Of course, catering and inflight movies would put up the price of the ticket. Would you believe a thousand dollars to CEO and back?)
The theory is impeccable: but does any material exist with sufficient tensile strength to hang all the way down to the Equator from an altitude of 36,000 kilometres, with enough margin left over to raise useful payloads? When Yuri wrote his paper, only one substance met these rather stringent specifications – crystalline carbon, better known as diamond. Unfortunately, the necessary megaton quantities are not readily available on the open market, though in "2061: Odyssey Three" I gave reasons for thinking that they might exist at the core of Jupiter. In "The Fountains of Paradise" I suggested a more accessible source – orbiting factories where diamonds might be grown under zero-gravity conditions.
The first 'small step' towards the space elevator was attempted in August 1992 on the Shuttle Atlantis, when one experiment involved the release – and retrieval – of a payload on a 21-kilometre-long tether. Unfortunately the playing-out mechanism jammed after only a few hundred metres.
I was very flattered when the Atlantis crew produced The Fountains of Paradise during their orbital press conference, and Mission Specialist Jeffrey Hoffman sent me the autographed copy on their return to Earth.
The second tether experiment, in February 1996, was slightly more successful: the payload was indeed deployed to its full distance, but during retrieval the cable was severed, owing to an electrical discharge caused by faulty insulation. This may have been a lucky accident – perhaps the equivalent of a blown fuse:
I cannot help recalling that some of Ben Franklin's contemporaries were killed when they attempted to repeat his famous – and risky – experiment of flying a kite during a thunderstorm.
Apart from possible dangers, playing-out tethered payloads from the Shuttle appears rather like fly-fishing: is not as easy as it looks. But eventually the final 'giant leap' will be made – all the way down to the Equator.
Meanwhile, the discovery of the third form of carbon, buckminsterfullerene (C60) has made the concept of the space elevator much more plausible. In 1990 a group of chemists at Rice University, Houston, produced a tubular form of C60 – which has far greater tensile strength than diamond. The group's leader, Dr Smalley, even went so far as to claim it was the strongest material that could ever exist – and added that it would make possible the construction of the space elevator.
(Stop Press News: I am delighted to know that Dr Smalley has shared the 1996 Nobel Prize in Chemistry for this work.)
And now for a truly amazing coincidence – one so eerie that it makes me wonder Who Is In Charge.
Buckminster Fuller died in 1983, so never lived to see the discovery of the 'buckyballs' and 'buckytubes' which have given him much greater posthumous fame. During one of the last of his many world trips, I had the pleasure of flying him and his wife Anne around Sri Lanka, and showed them some of the locations featured in The Fountains of Paradise. Shortly afterwards, I made a recording from the novel on a 12" (remember them?) LP record (Caedmon TC 1606) and Bucky was kind enough to write the sleeve notes. They ended with a surprising revelation, which may well have triggered my own thinking about 'Star City':
'In 1951 I designed a free-floating tensegrity ring-bridge to be installed way out from and around the Earth's equator. Within this "halo" bridge, the Earth would continue its spinning while the circular bridge would revolve at its own rate. I foresaw Earthian traffic vertically ascending to the bridge, revolving and descending at preferred Earth loci'
I have no doubt that, if the human race decides to make such an investment (a trivial one, according to some estimates of economic growth), 'Star City' could be constructed. In addition to providing new styles of living, and giving visitors from low-gravity worlds like Mars and the Moon better access to the Home Planet, it would eliminate all rocketry from the Earth's surface and relegate it to deep space, where it belongs (Though I hope there would be occasional anniversary re-enactments at Cape Kennedy, to bring back the excitement of the pioneering days.)
Almost certainly most of the City would be empty scaffolding, and only a very small fraction would be occupied or used for scientific or technological purposes. After all, each of the Towers would be the equivalent of a ten-million-floor skyscraper – and the circumference of the ring around the geostationary orbit would be more than half the distance to the Moon! Many times the entire population of the human race could be housed in such a volume of space, if it was all enclosed. (This would pose some interesting logistics problems, which I am content to leave as 'an exercise for the student'.)
Chapter 5: Education
I was astonished to read in a newspaper on 19 July 1996 that Dr Chris Winter, head of British Telecom's Artificial Life Team, believes that the information and storage device I described in this chapter could be developed within 30 years! (In my 1956 novel The City and the Stars I put it more than a billion years in the future... obviously a serious failure of imagination.) Dr Winter states that it would allow us to 'recreate a person physically, emotionally and spiritually', and estimates that the memory requirements would be about 10 terabytes (10e13 bytes), two orders of magnitude less than the petabyte (10e15 bytes) I suggest.
And I wish I'd thought of Dr Winter's name for this device, which will certainly start some fierce debates in ecclesiastical circles: the 'Soul Catcher'... For its application to interstellar travel, see following note on Chapter 9.
For an excellent history of the 'Beanstalk' concept (as well as many other even farther-out ideas such as anti-gravity and space-warps) see Robert L. Forward's "Indistinguishable From Magic" (Baen 1995).
Chapter 7: Infinite Energy
If the inconceivable energy of the Zero Point Field (sometimes referred to as 'quantum fluctuations' or 'vacuum energy') can ever be tapped, the impact upon our civilization will be incalculable. All present sources of power – oil, coal, nuclear, hydro, solar – would become obsolete, and so would many of our fears about environmental pollution. They would all be wrapped up in one big worry – heat pollution. All energy eventually degrades to heat, and if everyone had a few million kilowatts to play with, this planet would soon be heading the way of Venus – several hundred degrees in the shade.
However, there is a bright side to the picture: there may be no other way of averting the next Ice Age, which otherwise is inevitable ('Civilization is an interval between Ice Ages' – Will Durant: "The Story of Civilization", Fine Communications, US, 1993)
Even as I write this, many competent engineers, in laboratories all over the world, claim to be tapping this new energy source. Some idea of its magnitude is contained in a famous remark by the physicist Richard Feynman, to the effect that the energy in a coffee-mug's volume (any such volume, anywhere!) is enough to boil all the oceans of the world. This, surely, is a thought to give one pause. By comparison, nuclear energy looks as feeble as a damp match.
And how many supernovae, I wonder, really are industrial accidents?
Chapter 9: Skyland
One of the main problems of getting around in Star City would be caused by the sheer distances involved: if you wanted to visit a friend in the next Tower (and communications will never completely replace contact, despite all advances in Virtual Reality) it could be the equivalent of a trip to the Moon. Even with the fastest elevators this would involve days rather than hours, or else accelerations quite unacceptable to people who had adapted to low-gravity life.
The concept of an 'inertialess drive' – i.e. a propulsion system that acts on every atom of a body so that no strains are produced when it accelerates – was probably invented by the master of the 'Space Opera', E.E. Smith, in the 1930s. It is not as improbable as it sounds – because a gravitational field acts in precisely this manner.
If you fall freely near the Earth (neglecting the effects of air resistance) you will increase speed by just under ten metres per second, every second. Yet you will feel weightless – there will be no sense of acceleration, even though your velocity is increasing by one kilometre a second, every minute and a half!
And this would still be true if you were falling in Jupiter's gravity (just over two-and-a-half times Earth's) or even the enormously more powerful field of a white dwarf or neutron star (millions or billions of times greater). You would feel nothing, even if you had approached the velocity of light from a standing start in a matter of minutes. However, if you were foolish enough to get within a few radii of the attracting object, its field would no longer be uniform over the whole length of your body, and tidal forces would soon tear you to pieces. For further details, see my deplorable but accurately-titled short story 'Neutron Tide' (in "The Wind from the Sun").
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