Medoro was confused. ‘What has that got to do with some future rival stealing your glory?’

‘Complexity grows in a sequence of steps,’ Agata stressed. ‘So far, we’ve never seen it appear fully formed, and we have no reason to think that the messaging system could change that. If some future researcher did send me a theorem that made all my own efforts obsolete, it would enter the scientific culture and be passed down the generations – so whoever wrote the message would merely have heard the result during their own education: they wouldn’t be its discoverer.’

‘In which case . . . who would?’ Medoro struggled.

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.’