He hoped that Clara would not be disappointed.

THIRTEEN

EARTH, 2034 AD

Lucas and Jacqui trailed Gus and her friend Ives into the Mexican restaurant. At a table just inside the door, a stocky, grizzled, bearded man was telling his grey-haired female companion: ‘A galaxy is like an M&M. The sugary coating is a dark matter halo.’

‘And the central black hole,’ the woman asked, ‘is the chocolate centre?’

Jacqui looked at Lucas and winked.

‘No, see, there’s a hundred billion stars, order-of-magnitude approximation’ – the man might look like a lumberjack, but he answered much as Lucas might have – ‘making up the whole of the visible galaxy. All of that is your chocolate centre.’

‘But I thought there was a—’

‘You’ve then got ten per cent of the stars comprising the bright bit in the middle, your actual galactic core. That would be like a tiny lump inside the M&M, at the centre of the chocolate. And the black hole would be microscopic. Smaller, in fact.’

Only in Pasadena.

Actually, come to think of it, any university town.

As the four of them were shown to their table, Jacqui said, ‘Seems like your kind of place, Lucas,’ and Ives smiled at them both. He was very tall, elegant in a tweed jacket with an honest-to-goodness bow tie whose spots were tiny spiral galaxies. He was also Gus’s oldest, closest friend.

Once they were seated, the waiter came over for their drinks order. Ives stared up into the young man’s eyes while discussing his choice in soft Spanish. After the waiter had left, Gus said: ‘He’s too young for you, darling,’ prompting Ives to answer that he knew as much, darling Augusta, but the truth was that she was jealous.

‘I hate it when you’re right,’ she told him.

Ives was a mathematician, a topologist with a sideline in topoi logics, a very different field, whose work on knots had once threatened to revolutionise both string theory and M-theory, by taking a traditional approach to analysing knots – focusing on their context, known as not-knots, and who says mathematicians have no sense of humour? – and applying it to the hyperdimensional twists known as Calabi-Yau manifolds. As a visiting lecturer in Oxford, during a sabbatical from MIT, he had befriended a precocious young student called Augusta ‘Gus’ Calzonni, and their collaboration produced both the computer game that kick-started Gus’s fortune – Fractal of the Beast – and her mu-space theory which, if mu-space turned out to be physically real instead of purely mathematical, might some day revolutionise humanity’s place in the universe.

Waving fingers, before his eyes, jolted Lucas back to Earth.

‘—images in your head,’ Gus was saying.

Holy crap.

His stomach rocked as his eyes refocused.

‘Eyeballs triangulate on a point in space,’ explained Ives, ‘when you’re strongly visualising. It’s a shock when some bad person’ – he patted Gus’s hand – ‘breaks up the virtual image like that.’

Gus smiled. ‘Sorry, Lucas. You were miles away, and I couldn’t resist.’

‘It’s because of the entorhinal cortex,’ said Ives, ‘And the neurons forming the spatiotemporal array inside it, which are geometrically quite fascinating.’

‘Feynman visualised colour-coded equations floating in front of a fuzzy picture of the phenomenon,’ said Lucas, referring to his science hero. ‘Like, I asked one of my PhD students to imagine electrons in a wire, and she saw a glowing white necklace moving along it. They wouldn’t really form an exact loop, but it highlights the mutual repulsion, right?’

‘Right, but no one teaches physics’ – Gus pointed an emphatic finger – ‘by teaching students to make visual hallucinations.’

‘Exactly,’ said Lucas.

‘Exactly,’ said Gus.

Ives looked at Jacqui.

‘Hobby horses,’ he told her.

‘And soap boxes.’

‘They really can’t help it.’

And that would have been that, a friendly meal spiced up with badinage and banter, a touch pretentious but balanced by self-mockery, had not a stranger approached their table: the grey-haired woman who had been sitting near the door. The stocky bearded man, still seated, looked furious.

‘Dr Woods?’ She addressed Lucas directly. ‘My name’s Amy, and I’m a medical researcher, and I’d really like to talk to you. Just for a moment.’

If her lumberjack friend caused trouble, Lucas hoped that Gus would deal with it – of everyone at the table, she was the one who knew how to fight. The lumberjack looked to be in his late fifties, one of those guys who got tougher as they aged.

‘This thing’ – the woman, Amy, held up a small silver device – ‘is a DNA sampler, online to a wide-array sequencer in the Cloud. It only takes seconds.’ She looked at the others, then back at Lucas. ‘I guarantee to destroy the results afterwards. Delete the data.’

The logical response was refusal, but the bearded man was approaching, looking about to intervene, and some devilry made Lucas hold out his hand and say, ‘What the hell. Why not?’

‘Lucas—’ began Jacqui.

There was a pinprick, and Amy nodded. ‘Thank you.’

‘Oh, for fuck’s sake,’ said the lumberjack.

He had been talking about dark matter and galaxies, hadn’t he?

‘If I left it up to you, Brody, we’d never find out.’ Amy held up the analyser. ‘Five more seconds, and we’ll know for sure.’

As if they had agreed to a countdown, everyone waited until Amy nodded, told this Brody that it was true, and turned the device so Lucas could see its small display. Two strips, labelled alleles #1 and alleles #2, contained clusters of dots. ‘The lower one is yours,’ she told him. ‘And look how similar they are.’

‘Very nice,’ said Lucas. ‘What the hell are you showing me?’

But Ives had slipped a qPad out of his jacket, and finger-gestured to transfer data from the analyser to his own device. He tapped away, and touched his collar to enable a throat mike, allowing subvocal commands.

‘Amy, grow up.’ The lumberjack was practically growling. ‘This is unnecessary. We gotta go.’

‘Maybe,’ said Amy, ‘you should introduce yourself.’

‘Sod off.’

You could hear it now: the man was English, underneath the Americanised accent.

‘Perhaps’ – Ives pushed his chair back, allowing him space to cross his legs – ‘I might be allowed to summarise the results. I’d like to introduce,’ he went on, gesturing toward the lumberjack, ‘Dr Brody Gould. And over here, Dr Lucas Woods.’

This Brody was frowning, and Lucas felt himself do likewise.

‘Bloody hell,’ said Gus, craning to see the qPad. ‘Lucas, you won’t—’

‘What is this?’ asked Brody. ‘A sodding soap opera?’

‘Your brother,’ Ives told Lucas.

My—?

He felt Jacqui take his hand, heard her telling him to breathe.

‘Half brother, to be precise.’ Ives directed his attention to Amy. ‘You’ve livened up everyone’s day, as I’m sure you’ve noticed.’

Then Gus took command, as was her privilege and habit.

‘Waiter? Two more chairs, please. Brody and Amy, you’ll join us.’

And so they did.

An hour later, Brody and Lucas had yet to shake hands. A big mitt like that could crush Lucas’s fingers. But it seemed Brody would never use his strength against Amy, which was how she had been able to go against his wishes. ‘High school sweethearts, is what we are,’ she told everyone at the table. ‘Met in London, when my Dad was working there. Brody got stuck with me then.’

Lucas rubbed his face.

‘Tell me again,’ he said to Brody. ‘How come you knew, and I didn’t.’

‘My dad – our dad – never married my mum. Sort of childhood sweethearts that didn’t work out, eventually. He was well out of the picture, as far as Mum was concerned, my mother, when he hitched up with yours.’

Brody was in his late fifties, older than Lucas by over two decades, old enough to be an uncle rather than a brother. Half-brother. But Dad was in his forties, thought Lucas, when he met Mum. She was a grad student at the time.