‘I’ve met him. Before he became a recluse. Or so it’s said …’
Jha, and others of the crew, had been involved in another twain mission that had taken Black, in secret and at his own request, to a refuge much further away than either Bowring or Abrahams imagined, probably. She kept her counsel.
They came to the rough work station Bowring and his team had set up, in the shadow of the twain hovering above. Trestle tables were laden with tablets and heaps of paper, meteorological charts, maps; there were samples too of the local flora and fauna. All this was a pale imitation of the more extensive science suite up on the twain itself.
Bowring said now, ‘It’s certainly a pleasure to find you here, Dr Abrahams. Coming in cold to a situation like this, there’s only so much progress we can make in a fixed time. No offence to the people here; your neighbours seem a smart, decent, very fine bunch of people. But to have had a scientifically educated man on the spot for some years—’
‘I understand.’
‘Tell me about a “Dyson motor”.’
‘Do you have a map of the world? Or any kind of global view …’
The Navy crew had toured the continent in the twain, and had sent up sounding-rockets for a higher-altitude view. There was even a clutch of simple orbiting satellites, though they had yet to complete a full planetary survey. There were various ways of viewing the result; they had maps on paper, electronic images, photographic surveys. Jha’s favourite was a globe you could handle: a basketball borrowed from the crew on to which a projected photographic mosaic had been glued. It looked pretty much like a globe of any stepwise Earth, save for a peculiar local readjustment of the continents: that gap between South and North America, the global seaway that ran from the Atlantic coast through the Mediterranean and out through Arabia to the south. That and the ubiquitous green of forests that stretched all the way to the polar regions, north and south.
But on this globe there were also false-colour markings of anomalies. Lurid orange bands around the coasts of the continents showed tsunami damage. Peculiar fractures circled the Pacific, divided the Atlantic lengthways, and spanned the southern oceans from northeast Africa south and east towards Australasia: the planet looked like a cracked vase, Jha thought. The cracks were huge tectonic flaws, bands of volcanoes and quakes. And most striking of all were the spidery bands of silver that followed the equator, and the lines of latitude to north and south.
Abrahams picked up the basketball and traced the silver lines with a finger. ‘I have seen some of these. I took my own twain journey to the south; I saw enough for me to infer the rest. You’ll be able to look it up for yourself. Freeman Dyson was a twentieth-century engineer who thought big. He worked on Project Orion, on how to use military-specification H-bombs to drive a spacecraft. And he came up with at least one conceptual scheme of how to spin up a world.’ He pointed to the latitudinal bands. ‘You wrap the world in conducting straps, and run an electrical current through them to generate a shaped magnetic field around the planet, a field shaped like a toroid, a doughnut. You have another electric current running pole to pole through the planet, and you close the loop with an arc through the magnetosphere. That causes the auroras we’ve been seeing from the ground. And then you throw in a stream of spacecraft, starting in high orbits and spiralling down through the toroidal field.’
‘Spacecraft?’
‘They need only be simple. Massive, but simple. Lumps of moon rock, for example, wrapped in some kind of conducting blanket. On my own twain journey, we reached the equator. I saw such rocks in the sky. You must have too.’
‘Yes. We’ve also been observing the moon, from where projectiles of that type are evidently being launched.’
‘And have been for years – since my wife and I first arrived here. The physics is trivial. The flyby rocks come in, they are dragged by the Earth’s new magnetic field, and, thus coupled, they pull at the Earth. Each rock speeds up the planet’s spin, just by a fraction. Then, when they reach their lowest orbit, they start to push against the planet’s magnetic field to spiral back out of there again – and, again, they give the planet another minute shove. Theoretically, it’s as if the Earth has been made the armature of a huge electric motor.’ He looked at their faces, seeking understanding.
Jha said, ‘I think I get it. Metaphorically anyhow. I have a daughter. When she was little, in the park in our home town back on West 5, there was a roundabout, a simple thing, a wooden disc with hand rails spinning on a pivot. The kids liked to run by it; each one grabbed a rail and let it go, and with every tug the roundabout spun a little faster.’
‘That’s the idea.’
Bowring sucked his teeth. ‘So the world’s spinning faster. What about the conservation of momentum? Where’s the extra spin coming from?’
‘I don’t have the facilities to observe properly,’ Abrahams said. ‘Perhaps you do. It appears that the flyby objects stream off towards the sun. There they are probably deflected at closest approach by a gravitational assist – or maybe they use solar sails – and that way they harvest angular momentum from the sun, and return for another pass. It’s a slow process for an individual rock; it must take months or years to make a full orbit, from Earth to sun and back again. But with a stream of such rocks the accelerating effect becomes continuous.’
‘So let’s see if I’ve got this straight,’ Jha said. ‘The latitude bands, the magnetic field they create, are ways of coupling these flyby rocks to the Earth. But what’s really happening is that through the rock stream some of the sun’s spin is being transferred to the Earth.’
‘The sun’s angular momentum, yes. And its angular kinetic energy.’
‘Yeah. A hell of a lot of energy,’ Bowring said dubiously.
Abrahams smiled wistfully. ‘That depends on your perspective. Suppose you doubled this Earth’s spin rate – brought the day down to twelve hours. You’d need four times its original angular energy. But to top up the spin to that rate would take just thirty minutes of the sun’s total fusion-energy output. It’s a lot to us, but if you can tap a source as vast as the sun …’
Bowring said grimly, ‘Well, the damage is being done. Dr Abrahams, I’m sure you can imagine the kind of effects the spin-up is having on this world as a whole. Every Earth is essentially a ball of liquid: the iron core and the mantle. The solid crust is only a fine rind laid over that liquid interior. Under the continents the crust is maybe sixty miles thick, compared with the Earth’s radius of four thousand miles. It’s as if the Earth is a big round crème brûlée.
‘Because of its spin – I mean its regular, standard-issue twenty-four-hour spin – every Earth is deformed, flattened slightly, not quite a sphere, bulging at the equator. Normally this isn’t a problem. And the natural state of things is actually for the spin to be changing anyhow, slowing very gradually over geological time. The solid crust has the chance to adjust to the changes of deformation.
‘That’s not the case here. In the few years since the spin-up has begun, the crust’s deformation, at the equator at least, has increased by around eight miles. That might not sound much, but the ocean-floor crust is only about three miles thick. And so—’
Abrahams traced the jagged lines that spanned and circled the oceans on the basketball globe. ‘Fractures in the sea bed.’
‘I’m afraid so. There are natural faults where the sea floor is spreading, such as down the spine of the Atlantic, and where the oceanic tectonic plates butt up against the continents, such as around the coasts of the Pacific. Now these faults are cracking, opening up, and you get quakes and volcanism. If they’re underwater, you can get tremendous tsunamis that batter the coastal areas—’