‘If four-space is curved, though, that does the job for everything. Light waves and luxagen waves, it makes no difference: if they’re following the shortest path in four-space, they’ll arrive in phase. That’s enough to bend the beam, and enough to make a planet swing around in its orbit.’

Azelio pondered this, and found nothing he could object to. ‘It makes more sense than I thought,’ he admitted.

Agata was delighted. ‘So what’s your conclusion?’

‘My own prediction, now,’ he declared, ‘is that the light won’t bend at all. I can see why you think it would make things too complicated if you had to account for the bent paths of both light and matter, in flat space. So the simplest solution would be to keep space flat, but have light unaffected by gravity.’

Agata was on the verge of embarking on an account of how this would violate conservation of energy, but she stopped herself; she’d reached the point where it would be more economical to let the results speak for themselves. ‘Do you want to put two loaves on it?’ she suggested.

Azelio feigned shock. ‘The shape of the cosmos is at stake . . . and you want to swindle me out of my rations?’

‘Who’s swindling you? You can check all the data yourself. You can ask Ramiro to audit the software.’

Azelio considered the offer. ‘If the light goes straight, you pay me; if Lila’s predictions are confirmed, you win. Anything else – including Vittorio’s theory – is a draw.’

‘Agreed.’

‘Two loaves, then,’ Azelio confirmed. ‘You’re on.’

‘Is there something that needs monitoring while you’re waiting for the stars to align?’ Ramiro asked Agata. ‘I’m on watch all night – it wouldn’t be any trouble.’

‘There’s nothing like that,’ she replied.

‘Then why not get some rest?’

Agata looked up from her console. ‘I can’t just shut off my mind in the middle of this.’

Ramiro stretched his shoulders and swivelled around to face her. ‘The star trails will still be there when you wake. And we’ll be following the same orbit whether you’re sitting here fretting, or fast asleep in bed.’

‘That’s true.’

‘But . . . ?’

Agata said, ‘Why would I wait six years for the chance to do this, and then sleep through half of it?’

Ramiro buzzed. ‘Fair enough.’

‘I used to hold vigils outside the voting halls,’ Agata recalled. ‘I’d watch the people come and go, watch the tallies rising.’

He said, ‘So when you take something seriously, you try to make the most of it?’