Obelisk

by Stephen Baxter

  Barry took the box of bottled beer from the boot of his car and strolled up to the abbey. Neville Wilson was on his hands and knees tinkering with the TV’s tuning and its battery pack. He had brought blankets, a hamper of sandwiches, flasks – a regular picnic. Barry had brought nothing but beer. He dumped his bottles on the floor. ‘I can’t believe you actually brought that bloody set up here, you mad bugger.’

  Neville got to his feet, awkward and shy-looking as ever, and wiped his hands on his corduroy trousers. ‘Wotcher, Barry. Or should I say – peace and love?’

  ‘Shut up and have a beer.’ Barry sat on a blanket, threw Neville a bottle, and used the flat of his hand and the edge of a tumbled stone to open a bottle for himself. He took a long pull; the beer was warm after the drive up from his mum’s home in Cardiff.

  The ‘Our World’ show had already started, Barry saw. This was, he had been surprised to learn, a broadcasting stunt dreamed up by the staid old BBC. For the first time twenty-four countries, something like two hundred million people, were to share a single live show with contributions from each of the individual countries. Right now, rather bafflingly, jolly Swedes were showing off their canoeing skills. ‘Is that what they spent all those millions of quid on comsats for? Canoeing?’

  Neville grinned. ‘Wait until the Beatles come on. You’re looking tanned, as far as I can tell under all that facial hair.’

  ‘Ah, that Californian sun. You can’t beat it …’

  But while Barry dressed like a West Coast American, Neville wore pale-brown cords and a crumpled white shirt, and his eyes were hidden behind big Roy Orbison glasses, as if he had been deep-frozen since the fifties. Barry was struck by how much the two of them had grown apart. After their first degrees, while Barry had gone into the private sector, Neville had stayed on at Cambridge to do an astronomy PhD. Not surprising they looked so different, then.

  Barry felt like winding him up. ‘What a season. The Summer of Star Love, they’re calling it now. Out in ’Frisco those hippy chicks just fall over with a bit of banter about peace and love. And a British accent.’

  ‘That’s all it means to you, is it? Getting inside the knickers of some spaced-out teenage bird? I wonder what they’d think if they knew you work at a weapons lab like Livermore.’

  ‘Make no difference probably. It’s all bollocks, man, all of it. While one end of America is handing out flowers, the other is using helicopter gunships to strafe straw huts in Vietnam. You take what you can grab, just like always.’

  ‘Well, not everybody thinks that way.’ Neville pointed at the beacon. ‘And besides, that’s not bollocks, is it?’

  ‘Ah.’ Barry stood, beer in hand, and looked hard at the sunlight beacon. He felt a prickle of scientific curiosity, and envy, for Neville had managed to get involved with the global effort to study the new star. ‘Repeating the flickering pattern, is it?’

  ‘Yes. The beam lengths are running through the Fibonacci sequence, as far as we can tell. The SETI boys in America – the search for extraterrestrial intelligence, searching for radio signals from the stars – always thought the aliens would send us a sequence of prime numbers. But if you’re going to communicate in mathematics, the Fibonacci series is even more obvious. I mean, it’s there in nature, embedded in the spiral shape of the galaxies for instance …’

  ‘And it’s definitely coming from Altair.’

  ‘Oh, yes. Seventeen light years away. If we had more time we might be able to get a parallax and prove it for sure, but that depends on the signal lasting longer than nine days – time for the Earth to move significantly in its orbit.’ Neville held to a controversial view that there had been previous sightings of the beacon, perhaps in the thirteenth century – there was supposedly a note left by a monk of this very abbey to that effect. That sighting had lasted no longer than nine days; maybe this apparition would cut short too.

  ‘But the light we see,’ Barry said, ‘has nothing to do with Altair.’

  ‘No way. It’s pretty much monochromatic.’

  ‘A laser, then.’

  ‘We think so. Very narrow beam. Pointed right at us. And tuned to the peak wavelength of our own sunlight. Not only that, it’s got an almost identical apparent magnitude as Sirius, the brightest star in our sky.’

  Barry thought that over. ‘They intended it for us, then. The Altaireans. They could see us, see the Earth. They designed it, knowing what our sunlight is like, how bright our brightest star must be. Jesus.’

  Neville was grinning. ‘It’s scary, or thrilling, depending how you look at it. We’ve actually been able to dig out a lot more information. There are slight Doppler shifts on two periodic cycles, one of a few days, the other of years. We think their transmitting station is on a planet. We’re seeing the station move towards and away from us, as the planet turns, and travels around its sun.’

  ‘You’ve worked out their day and year.’

  ‘Yeah. Altair is maybe eleven times as bright as the sun. We think their planet is a big one, turning slowly, about three times as far from Altair as Earth is from the sun.’

  ‘Cool enough for liquid water?’

  ‘We think so.’

  ‘All that from Doppler shifts.’ Barry sat again, finished his beer and cracked another bottle. ‘I think I’m more interested in the reaction down here on Earth.’

  He had seen some of it for himself. For the few days of its patient signalling the sunlight beacon had been a wonder in the press, even crowding Vietnam and the aftermath of Israel’s Six Day War off the front pages. The scientists were crowing. The Pope had made an earnest statement about sending the Altaireans evidence of Christ’s incarnation. Wernher von Braun had declared, ‘With the right funding we’ll be at Altair in fifty years.’ The UFOlogists said it was a government hoax designed to distract attention from the truth about aliens.

  And all over the western world a generation of young people, already blissed out on drugs and music and sunshine, had kicked off a kind of global party. Barry had bluffed his way into one of them, a ‘star happening’, just a few days ago, at the feet of the Golden Gate Bridge. The drugs and sex had been on tap.

  ‘I suppose the hysteria will wear off,’ he said. ‘I mean, as far as alien life is concerned the beacon is only a proof of existence, as old Prof Morton would have said at Cambridge. I figure most people believed in aliens anyhow, and half of them think they’ve met them.’

  ‘I don’t know,’ Neville said thoughtfully, pushing his heavy glasses up his thin nose. ‘Yes, it will pass out of the headlines. But even a proof of existence represents a philosophical upheaval – like Copernicus, like Darwin. From now on, we can still theologise if we like, but we’re going to have to separate religion from the knowledge that we really do share the universe with a higher power. They might even be here soon; seventeen light years isn’t all that far.’

  ‘Um.’ Barry swigged his beer and watched the TV. ‘Speaking of God …’ The screen had filled up with an image of John Lennon in a flowery shirt, strumming a guitar and chewing gum.

  Neville turned the volume up. He had always been a Beatles fan.

  The Beatles were singing in a flower-strewn studio with a string orchestra and acolytes sitting at their feet. Barry recognised Mick Jagger, Donovan, Keith Moon. The song was slow, dreamlike, littered with what sounded like sitars, and very beautiful.

  Barry said flatly, ‘I see they’ve all dressed up again. What are they singing?’

  ‘A new song by George. “Eagle Song” – for Aquila, see. Apparently they were going to do something by Lennon, but scrapped it when the sunlight beacon lit up.’

  ‘I hope the Altaireans enjoy this when they get to hear it in seventeen years.’ He eyed Neville. ‘And this is why they are speaking to us, right? They detected our first radio broadcasts, and now they’re flashing their beacon to show they know we’re here.’

  Nevill
e shook his head. ‘That’s the consensus. You know I don’t agree. I’m convinced they’ve been signalling since long before the radio age.’ Hastily, he ran over the evidence for previous sightings of the beacon. ‘Those Chinese were good astronomers; we know they made accurate sightings of novas whose relics we can see. And there’s a pattern to the dates …’ He picked up a pad and scribbled: 1967 AD, 1238 AD, 949 BC. ‘Look at the intervals. Going back in time, seven hundred and twenty-nine years, then two thousand, one hundred and eighty-seven years – which is precisely three times the previous interval. I’m willing to bet there was a previous event another threefold years before then.’

  Barry could never resist a puzzle. ‘Three times twenty-one eighty-seven is six thousand, five hundred and sixty-one. Add that to your oldest date …’ He wrote the result on Neville’s list: 7510 BC. ‘That’s back in the Mesolithic.’

  ‘They can see us. They know how long our year is, and used it as a unit of time.’

  ‘Why all the threes?’

  Neville waggled his hand. ‘Maybe they have three fingers.’

  ‘Or three cocks. How could they have known we were here in the Mesolithic? We weren’t using radios then.’

  ‘No, but we were changing the world already. The big forest clearances came with the farming revolution in the Neolithic, but even in the Mesolithic we were slashing and burning, starting to domesticate plants and animals. You can imagine viewing the composition of a remote planet’s atmosphere with some kind of spectroscope. Maybe you can see that kind of global change. It would be distinguishable from natural events like volcanoes or asteroid strikes, for instance by the characteristic timescale.’

  ‘And when they saw us starting to farm—’

  ‘They hit us with a beacon. They didn’t expect we had radio telescopes, but it was a good guess we had eyes that could see our own sun. God knows what they intended our ancestors to make of the signal, mind. Could have kick-started a Neolithic astronomical revolution, I guess. Pity we weren’t a bit smarter. I hope whoever saw it back then found some consolation. Which begs the question, what use will we make of this latest signal?’

  ‘Time will tell,’ Barry said.

  ‘I guess so. Anyhow, it’s a falsifiable hypothesis. If the pattern persists we can predict the next sighting, after a third of seven hundred and twenty-nine years.’ He added another date to the list: 2210 AD.

  ‘Well, you and I won’t be around to see it.’ Barry had drained another beer, and cracked a third. The Beatles were finishing their song with a long, repetitive coda. Neville stared at them wistfully, a true fan. On impulse Barry dug into his pocket and produced a couple of sugar lumps wrapped in tin foil. ‘Here. You ever tried this?’

  Neville took one dubiously. ‘LSD, right?’

  ‘Makes the world sparkle.’ He nibbled his own lump.

  ‘I can’t afford to pay you—’

  ‘In Cardiff it costs about a quid a tab. Forget about it. Listen, Neville. What you said about the Altaireans being a higher culture. How much power would you need to send a signal like the sunlight beacon?’

  Neville put down the lump and rubbed his nose. ‘Well, we’re not sure. The laser will cast a spot of some size across the solar system, like a searchlight. We don’t actually know how big the spot is, how far it extends beyond the Earth. NASA are trying to measure it using their Mariner deep-space probes. It depends how good their aim is, and how tight the beam is. I mean, you’d have to fire the laser to where Earth was going to be in seventeen years’ time … Across that target spot you need to maintain a flux equivalent to the light reaching us from Sirius.’

  ‘So how much power?’

  ‘In the terawatts. That’s surely beyond us for the near future, but a Kardashev Type II culture could manage it easily.’

  ‘A what?’

  The Kardashev types were a theoretical grading of alien civilisations based on the power they could muster: Type II controlled the entire output of a star, and Type III a galaxy. Humanity was somewhat less than a Type I, controlling a planet’s energy supply.

  Barry nibbled his sugar, thinking that over. ‘A terawatt laser would be a hell of a weapon.’

  Neville frowned. ‘Typical of you to think that way. Anything’s a weapon, potentially. I could choke you with flowers.’

  ‘I guess so.’ But Barry thought of himself as a realist. Tanks burned in the desert around Israel: that was the truth of the world, and maybe the universe. His thinking loosened by the booze and the drugs, he let ideas run around in his head. The Altaireans had offered evidence of the possibility of a pretty powerful technology … Hell, more than that. The demonstration of a working model, evidence of its performance parameters. And knowing that, you could back-fit a design. He began to run over proposals he could make back at Livermore.

  Neville handed back the sugar cube. ‘Sorry, man. Not for me.’

  ‘Forget it.’

  The Beatles had gone now, to be replaced by a feature on trams in Australia. Neville turned the set off and they sat in the dark, gazing up at the beacon. Barry was content with the silence, as he waited for the drug to kick in.

  2210 AD

  By the time he had finished his walk to the weapons installation in the shade of the Giant’s Stone crag, Owen Wilson was out of breath. At sixty-eight he was too old for this, too old to be sneaking around in the dark.

  He knew he didn’t have much time before he was detected. But he gave himself one minute to rest. Leaning against a bit of surviving wall of the old abbey, he took a swig of his water, and a deep breath of the hot, smoky air. There actually wasn’t much left of the ruined abbey, whose stones had been ground up to make the concrete base of the weapon.

  He got on with it.

  He stepped forward towards the installation, his way illuminated by a torch strapped to his forehead; the sky was a lid of smog. The Morgan laser was surrounded by an electrified fence and monitored by a surveillance system, but Owen had used a microgrenade to knock out the fence’s juice, and smart viruses were already at work in the Unitary Authority’s data processing systems to make him invisible to these electronic eyes. He just snipped through the wire and walked in.

  He soon reached the weapon.

  It looked like a cannon, its metres-wide snout poking stubbornly at the obscured sky. He had studied its design carefully, and knew just which maintenance hatch to open, just where to plug in the software patch he had prepared. In only minutes, with a grind of massive servomotors, the laser prepared to move, obeying his commands. Owen allowed himself to punch the air.

  And yet his triumph was muted. He looked up into the sky. It was midsummer day – not that you’d know it any more, every day was as murky and warm as the rest, right through the year. And today, somewhere above the obscured sky, he was sure, the sunlight beacon from Altair was once again pinging Earth with its hopeful Fibonacci sequence. The story of many-times-great-grandfather Neville, who had witnessed the last apparition back in the twentieth century, had been passed down as a family legend. As Owen had grown up, in between his work in the big offshore food factory in Cardiff Bay, he had been able to verify the old story with a bit of data mining. And he had been thrilled to discover that his long-dead ancestor had predicted that the next apparition from Altair would come in Owen’s lifetime.

  But he would see nothing of it. The sky was entirely shrouded, and deliberately so, to protect Britain, Russia, North America and the rest of the Unitary Authority commonwealth from the Chinese laser mounts on the moon. Make the air opaque with aerosols and endless fires and you could scatter the light of the most intense laser weapon, even the big Chinese petawatt monsters; the laser war continued between the space platforms, but at least the planet itself had some degree of protection.

  And then there was political control. With the sky covered you could make the sunlight beacon invisible for the first time in its ten-tho
usand-year history of interaction with mankind. The citizens of the Authority need never be troubled by the existence of another world, another civilisation – or by the idea that other possibilities might exist, a destiny other than a war that had now ground on for a century.

  But tonight, Owen believed, the air might clear enough, if not for him to see the sunlight beacon for himself, at least enough to give this big old beast a shot at replying, on behalf of mankind. The Morgan was antiquated by comparison with the latest Chinese weapons, capable of no more than a few megawatts, and much of its brightness would be lost even before the signal got out of the murky atmosphere of Earth, let alone began its seventeen-year journey to Altair. But Owen was confident the Altaireans would be able to pick up the signal, and to read the message he intended to encode into it: ‘SOS’ in Morse code, easy to decipher for a culture that had surely been monitoring human radio broadcasts since Marconi. A weapon used to send a cry for help.

  Help us – that was all he wanted to say. Help us, for we have misused your gift and your example; we used the idea of your beacon and turned it into a weapon. Neville Wilson had long ago calculated that if the beacon continued to recur at intervals reducing by a factor of three every time – after another eighty-one years, twenty-seven, nine, three, one – the ten-thousand-year sequence would come to an end in 2331, not much more than a century away. What would happen then? Would the Altaireans’ mighty ships slide into the solar system?

  But Owen was by no means sure mankind would still be around on that date. So he needed to send his reply today. Help us now—

  The shot’s noise was soft, from a silenced gun, but the round ricocheted noisily off the barrel of the repositioning laser.

  Owen turned off his torch and stood stock-still. In the murky light he couldn’t even see who was shooting at him or how many there were. There were no voices, no sounds of footsteps, only that single shot. With a grind of seized-up bearings the laser began to tilt up. He crept round towards its muzzle. His programme might yet be completed, his signal sent—