Li shrugged. 'OK, whatever. But what now?'

'We'll stop transmitting our message. That'll signal to them that we've picked up their transmission. We'll know soon enough if they've been using our code. They'll have tried to make it easy to decipher. Whether we're smart enough to grasp what they're telling us is another matter.'

JOINT INTELLIGENCE CENTER

Weaver was attempting the impossible. She was trying to disregard all the existing research about the evolution of intelligent life – and, at the same time, confirm its findings.

Crowe had explained that every theory on the existence of alien civilisations hinged on the same set of questions, including: how big or small could intelligent life-forms be? In SETI circles, where the focus was on interstellar communication, people were busy hypothesising about beings whose gaze was turned towards the skies – extra-terrestrials who had entertained the possibility of other worlds and had decided to make contact. Such beings would almost certainly live on dry land, so there were clear limitations governing their size.

Astronomers and exobiologists had recently come to believe that a planet would have to possess no less than 85 per cent and no more than 133 per cent of the Earth's mass to generate surface temperatures conducive to the development of intelligent life within one to two billion years. The dimensions of this hypothetical planet had implications for its gravitational field, which in turn allowed certain conclusions to be drawn about the anatomy of any beings that might live there. Theoretically a living creature could grow infinitely large on an Earthlike planet. In practice, though, it would be limited by the ability of the body to bear its own weight. Dinosaurs, of course, had developed extraordinarily large bones, but their brains had failed to keep up. They were designed for lumbering, eating and not much else. Accordingly, there was a rough rule of thumb: intelligent non-stationary life-forms were unlikely to grow more than ten metres tall.

The more interesting question was how small they could be. Could ants develop intelligence? And how about bacteria? Or viruses?

SETI researchers and exobiologists had good reason to want to find out: it was almost certain that the Earth's corner of the galaxy was free from other humanoid civilisations, at least within its own solar system, which left scientists clinging to the hope that Mars or one of Jupiter's moons would be home to a few stray spores or some single-cell organisms. They started to search for the smallest viable unit of life, which inevitably led them to complex organic molecules – the smallest self-contained units capable of storing and using information. But could a molecule like that develop intelligence?

The answer was a decisive no.

But the individual neurons of a human brain weren't intelligent either. For humans to attain the brain-to-body ratio that made them intelligent, it took one hundred billion neurons each. It was conceivable that an intelligent organism smaller than a human could make do with fewer cells, but there was no altering the size of the molecules of which the neurons were composed – and without a critical mass of neurons, there could be no intelligent spark. That was the limiting factor for ants, who seemed to possess non-conscious intelligence but whose brains could never attain a higher neural capacity because they lacked sufficient cells. In fact, since ants didn't breathe through lungs but absorbed oxygen through their body surface, their growth was inherently restricted. Their respiratory system would fail if they exceeded a certain size, so their brains had no chance to develop any further. In evolutionary terms, ants and their fellow insects had reached a dead end. Scientists had therefore concluded that the smallest possible size for an intelligent life-form was roughly ten centimetres, which meant the chances of encountering a scuttling Aristotle were practically nil. Single-cell intelligence seemed out of the question.

All that was at the back of Weaver's mind as she sat down to program the computer to link mental capacity and single-cell organisms in a meaningful combination.

In the hours following the discovery in the lab, the general mood was one of scepticism. Could the jelly really be intelligent? Single-cell organisms weren't capable of creativity and couldn't develop self-awareness. No one contested that a sizeable number of single-cell organisms theoretically corresponded to a brain or a body. The blue cloud filmed by the URA near Vancouver Island had evidently consisted of billions of cells – but did that mean it could think? And even if it could, how was it supposed to learn? How would the cells communicate? What had to happen for a conglomerate of cells to become a higher entity?

How had it worked for humanity?

Either the jelly substance was nothing more than insentient goo, or there was a trick to it.

The jelly had steered whales and crabs.

Computer programs developed by Kurzweil Technologies used billions of bits to simulate neurons that worked together as a brain. Artificial intelligence of one kind or another was already being used throughout the globe. AI systems were capable of learning, and there was even a sense in which they used their own creativity to further their development. None of the AI researchers claimed to have created consciousness, but their work already posed the question as to when a mass of tiny identical parts could be classed as alive – and whether life could be generated artificially in that way.

Weaver was now in possession of one of the latest generation of artificial brains, having approached its inventor Ray Kurzweil directly. Her first move was to save a backup copy. Then she set about dismantling the original into its individual electronic components, breaking down the bridges and turning it into an unstructured swarm of tiny units. She tried to imagine breaking down a human brain. What would she have to do to get the cells to come back together and re-create the thinking whole? Billions of electronic neurons were swarming all over her computer, tiny bits of data with nothing to bind them together.

She tried to imagine that they were single-cell organisms.

Billions of single-cell organisms.

She thought through the next steps. It would be best to stick as closely as possible to the facts as she knew them. After some reflection, she constructed a three-dimensional space and gave it the physical characteristics of water. What did single-cell organisms look like? They came in all kinds of different shapes – rods, triangles, stars, sometimes with irregular outlines, sometimes with flagella – but it made sense to settle for the simplest. She decided on spheres.

Step by step the computer became an ocean. Weaver's virtual organisms rolled and spun through their electronic world. Maybe she should add currents, so that the virtual space mirrored the deep-sea environment. No, that could wait. First there were some major questions to address.

So many units. How could they give rise to an intelligent being? There weren't any limitations on maximum size. None of SETI's assumptions about size was relevant to water-dwelling organisms, since the forces affecting bodyweight were different under water. An intelligent marine-based life-form could be incomparably bigger than any land-dwelling organism. SETI's scenarios barely accounted for water-based civilisations, because any such civilisation would be beyond the reach of radio waves. Besides, it seemed unlikely that an underwater species would be interested in space or other planets – unless it was planning to cross the universe in a travelling aquarium. But a water-based scenario was what she needed now.

When Anawak arrived in the JIC thirty minutes later, she was staring at the screen, forehead knitted. She was cheered when she saw him. Since his return from Nunavut, they'd talked a lot about themselves to each other, and Anawak seemed more confident and self-assured. The dejected Inuk whom she'd found in the hotel bar had vanished in the Arctic.