‘But this slowly developing community was disrupted by the freak emergence of one mutant world.

‘The human categorisation of complex creatures into “animal” or “vegetable” is too simple. Anthropocentric. Even on Per Ardua, the builders were animals that photosynthesised.

‘Well, then. Consider a world in which every complex organism, every plant and tree, every creature motile or not, is, if not sentient itself, then a sense organ for a larger mind. Every flower is like an eye or an ear on the world. Sensory impressions chatter down tendrils like nerves, and feed into root masses of huge complexity: aged vegetable brains. And these in turn, on this world, speak directly to the true minds of the planet, the Dreamers in their deep rocks. This world was called Alvega in some human cultures.’

Stef wondered how Earthshine could possibly know that.

‘All this came about because of a peculiar origin of life on this one particular world. On many worlds there can be several origin events; but on most worlds, like Earth or Per Ardua, a single design, a single DNA-like coding system controlling a single protein set – or the equivalent in different biospheres, like the Titans – emerges as dominant, and usually quite quickly, with small advantages rapidly becoming overwhelming. But not on Alvega. Here, two quite different and inimical biospheres battled down long ages for control, even after the emergence of complex life. When the war was won, the winner had become by necessity much more closely integrated than most worlds, with the complex surface florescence feeding directly into the Dreamer communities below.

‘On this world, then, the Dreamers were much more engaged with the external universe – and they had the means to achieve direct contact with others like themselves, for their complex partners on the planetary surface were, uniquely, entirely under the Dreamers’ control.

‘From Alvega a new wave of emissaries were sent out, in interstellar craft not unlike huge trees, their mission to link one world with another.

‘It took many hundreds of millions of years for the new living technology to spread across the galaxy. But, gradually, on one world after another, isolated Platonic Dreamers woke to the possibility of community, of deep and rapid communication with others of their kind.

‘There was a new urgency now – if you can ever call a billion-year-programme “urgent”. The value of complex life was seen for the first time, and panspermia of a new kind became intentional. Across the panspermia bubbles waves of modification were sent out, so that worlds that had not known photosynthesis were raised to that level, and then living complexity became possible on worlds suddenly rich with the energy provided by oxygen or methane, or other reactive chemicals. Creatures like plants, creatures like animals, new kingdoms of life blossomed on world after world—’

‘I knew it,’ the ColU breathed. ‘I found this, even on Per Ardua – the first world beyond the solar system reached by humans. The coincidences of timing. Photosynthesis appeared on Per Ardua two billion years before humans showed up, just as on Earth. And the first complex creatures appeared on both worlds with quite precise coincidences of timing: five hundred and forty-two million years before humanity on Earth, the same on Per Ardua. I measured this. I knew it! I remember speaking of this to your mother and father, Beth Eden Jones. Not that they understood the implications, not then. Well – nor did I. Not then.’

‘The coincidences were real,’ Earthshine said. ‘I have no detail on how this was done, what kind of agency they used to trigger a complexity explosion on Earth, say. I imagine farmers striding across the stars … But these events are indeed evidence of a deep, galaxy-wide bioengineering on multiple worlds, by communities of Dreamers who were becoming more knowledgeable, more communicative – and more willing to intervene in the destiny of life.

‘And as they grew in power and understanding, and as they learned more of the universe around them, so they developed a new urgency. Because—’

‘Because they became aware of the imminence of the End Time,’ Stef whispered.

‘Yes. Even the Dreamers, who, huddled in the deep rock, might survive even the supernova detonation of a parent sun, could not survive that.

‘And so they laid their plans.’

They might be a short-lived colony, but they were a busy colony.

They all had projects of one kind or another – well, Stef thought, there were so few of them there were always plenty of chores to do, ranging from stitching ripped clothing or fixing a leaking boot to supervising the synthesis of some new component by the clattering fabricators.

Meal times were the only occasions when they all gathered together, breakfast, lunch, supper. That included Earthshine, for they always sat around his spidery framework. The ColU too. Titus had mandated that from the beginning, once they had got over the loss of Ari and Inguill. They were too small a group to be able to afford to break up into cliques or factions. Stef supposed this was another relic of Titus’s field experience, presumably dating from when he had had to lead small isolated parties on long expeditions. She applauded his leadership.

It was unfortunate, though, that he always used language like ‘lancing boils’ or ‘spilling the pus’ to describe the process of talking out their problems. Especially when she was trying to force down the freeze-dried potato or fabricated slop that passed for food here.

And she tried not to let her dissatisfaction with the food distract her from listening to Earthshine’s long, complex account.

‘So. After the complexity waves. That was when they started to build the Hatches,’ Stef prompted.

‘That was when,’ Earthshine agreed. ‘I don’t know where, how, when the technology emerged. But a Hatch link is essentially a communications technology optimised to fit within the limits of the universe in which we find ourselves.’

‘Limits? What limits?’

‘To begin with, lightspeed. That seems to be a fundamental physical barrier – just as Einstein predicted all those years ago. And the other—’

‘The end of the universe,’ the ColU said.

‘A wall across the future. And very close in time, to such long-lived beings. There was never a sense that the minded worlds, or that any of the Dreamers – or any of us – could survive that final limit. But they felt the urgency to talk, to communicate – to share as much as they could, to make the most of the time available.

‘But here were these vast minds, dependent for their communication on the slow trajectories of crude starships, or on the still slower drift of rocks from star to star. It is as if Einstein and Newton, two tremendous intellects, both under sentence of imminent death, were able to communicate only by means of Morse code tapped out on a cell wall … They had to do better.’

‘And the Hatches were the way,’ Stef said.

‘Yes. The Hatches are something like wormholes, flaws in spacetime connecting one event to another. As you know, Stef, theoretically wormholes can even link different universes – different cosmoses drifting in the great hulk of the multiverse. Any transition would be limited by lightspeed—’

‘But with a Hatch one can step from Mercury to Per Ardua, say, four light years apart, in no more than four years.’

‘Exactly. It is the best one can do. But to build such engines, rips and twists in spacetime, requires huge amounts of energy, as you can imagine. Where is such energy to come from?’

‘The kernels,’ Stef said immediately. ‘Which are also like wormholes, through which energy pours. That was basically a lure – right? The cheese that baited the trap, into which we clever tool-making apes thrust our greedy paws. And all the time the true purpose was to get us to build those damn Hatches.’