The Arrows of Time

Agata buzzed. ‘Nobody! And there’d be no contradiction in that, but it’s as unlikely for the cosmos to contain such an isolated loop of unexplained complexity as it would be for the same idea to have popped into my mind all by itself this morning, with no prompting from any future informant.’

Medoro thought it over. ‘Suppose I take your word for all that. You’ve still only told me what you think won’t happen – you’ve given me an unlikely scenario. So what’s the alternative? What’s the likely story?’

Agata said, ‘There’ll have to be some self-censorship of the messages. People won’t pass back ideas that would entail the creation of complexity out of nothing.’

Medoro hummed with frustration. ‘Now you’ve introduced some magic cosmic censor?’

‘It’s not magic,’ Agata insisted. ‘It’s not some extra premise or some new constraint. If the messaging system can be built at all and the cosmos is self-consistent, the less improbable scenario – by far – is the one that contains some limits on the content of the messages, not the one that allows whole new sciences to come into existence without a day’s toil by anyone.’

Medoro plucked at the rope, dissatisfied. ‘What if someone in the future decides to break this rule?’

‘They can’t, they don’t,’ Agata said flatly. ‘Or to be precise: it’s prodigiously unlikely. The fact that ordinarily such an act would be unexceptional is beside the point: the messaging system will put them in a situation where the prerequisite for such a disclosure is that they have something massively improbable to disclose in the first place.’

Medoro wasn’t placated. ‘What happened to the freedom the engine tests gave us?’ he demanded.

Agata said, ‘That’s just the freedom to send messages in general, not some open-ended guarantee that the usual range of actions will always be possible. You didn’t complain about our lack of freedom to ignore an outbreak of crop disease, if we get a message spelling out everything we will have done to contain it.’

‘No,’ Medoro admitted. He buzzed wryly, finally reconciling himself to the strangeness of it. ‘Maybe you should stay clear of this in the debate. It might make people feel a bit… trammelled.’

‘If Ramiro doesn’t raise it, I’ll have no reason to bring it up.’ Agata felt much happier about the whole subject after arguing it out with Medoro, but she wasn’t going to spread anxiety needlessly just to prove to people that she had the cure. ‘It’s going to be hard enough as it is.’

‘You’ll be fine,’ Medoro assured her.

‘Will I?’ Agata pictured herself at the front of the packed meeting room, ready to follow in Lila’s footsteps. Or possibly her brother’s.

‘I’d offer you an eyewitness report of your success,’ Medoro said. ‘But we can’t quite pull that off yet.’

9

Tarquinia reached across and squeezed Ramiro’s shoulder. Her hand made contact roughly, imperfectly controlled in the near-weightlessness, but that only gave the gesture more force.

‘Good luck,’ she whispered. Ramiro kept his rear gaze on her as he dragged himself away along the guide rope towards the stage.

The meeting room was full, and brightly lit by the beams from a dozen coherers bounced diffusely off the ceiling. People were still talking among themselves as Ramiro approached the front of the stage and reached over to start the timer. He waited a pause or two for the echoing ping to grab their attention, but he knew it would only waste time if he held out for complete silence.

‘My job,’ he began, ‘is to automate things. There are many tasks where we already know exactly what we want to achieve, but find it too arduous to supervise the execution of our plans in detail. If I do my job well, though, the results are easy to foresee: you tell me what you want some machine to do for the next five stints, and I make that happen.

‘So I’m familiar with the advantages of control and predictability, and I can understand why the Council aspires to bring those qualities to as many aspects of the running of the Peerless as possible. If we could receive a message from the future assuring us that the mountain had reached the home world safely, and this message was accompanied by a list of the actions we’d need to take – or in the sender’s view, had already taken – to sidestep a host of potential calamities, then I’d have no complaint about that at all.’

Ramiro let himself scan a few faces in the audience; so far, he didn’t seem to have offended anyone.