CHAPTER 31

65 mil ion years BC, jungle

‘You can do what?’ said Liam.

Becks hefted the log up in her taut arms and held it steady as Liam lashed it in place with a hand-woven length of rope made from the species of vine they’d found dangling from virtual y every tree around the clearing.

‘I believe it is possible for me to calculate when in time we are with a very high degree of accuracy.’

He wrapped the rope tightly round the log, tugging it hard so that it shu ed up against its neighbour. The palisade wal so far stretched only a dozen feet: about twenty logs, each just under eight inches in diameter and al roughly about nine feet tal . When they were done, they’d have a circular enclosure about four yards across –

large enough for al sixteen of them to huddle inside should something nasty nd its way on to their island and they needed somewhere to retreat to.

‘How?’ asked Liam.

‘I have a detailed record of al the variables during the time of the explosion.’

‘Variables?’

‘Data. Speci cal y, directly after we arrived here. The particle decay rate.’

particle decay rate.’

Liam cocked an eyebrow. ‘I haven’t a clue what that means, Becks.’

She walked over to a dwindling pile of logs and e ortlessly picked up another. They were going to need more. Across the clearing he could see Whitmore and several of the students carrying one between them, stumbling across the lumpy ground towards them. She slammed one end of the log down into the soft soil with a heavy thud, next to the last log, and Liam began to lash it into their wal .

‘I have a detailed record of the explosion. The number and density of tachyon particles that we were exposed to in 2015 and the number and density of tachyon particles that emerged here alongside ourselves.’

Liam looked at her and shrugged. ‘Assume I’m a child that knows nothing, Becks.’

She looked at him and he thought he caught her rol ing her eyes at his stupidity: a gesture the AI must have learned from Sal back when it was computer-bound and its visual world was what it picked up from the one webcam.

‘Tachyon particles decay at a constant rate. That is why it takes greater amounts of energy to beam a signal further into the past.’

Liam tugged hard on the vine rope, cinching the knot tightly. ‘I get that. So, if these particles die out at a steady rate, that means …?’

‘I am able to calculate how many particles decayed and, from that, determine how far in time we were sent.’

from that, determine how far in time we were sent.’

He grinned. ‘Real y? You can do that?’

Becks looked up and tried mimicking his uneven smile.

‘I have the processing power to do this.’

‘And we’l know exactly when we are?’

‘To an accuracy level of one thousandth of a per cent.’

Liam shook his head in wonder. ‘Jay-zus, that metal brain of yours is a bloody marvel, so it is!’

She seemed pleased with that. ‘Is that a compliment, Liam O’Connor?’

He punched her arm lightly. ‘Of course it is! Don’t know what I’d do without you.’

Her gaze drifted o across the clearing for a moment then back at him. ‘Thank you.’

He nished lashing the log and waited for her to pick up another and slam it down heavily beside the last one.

‘So what? We’l actual y know what day we arrived in the past? Even what time?’

‘Negative. I am unable to give that precise a calculation.

’ ‘OK. We’l know to the nearest week or something?’

She shook her head.

‘The nearest month?’

‘Negative.’

‘Year?’

‘I can calculate to the nearest thousand years.’

‘What?’

‘I can calculate our current time down to the nearest –’

He cut her o . ‘I heard you the rst time. But … but He cut her o . ‘I heard you the rst time. But … but that’s no good to us, is it? I mean, even if we could somehow get a message to the future and tel them which thousandth year we’re in, nding us here would be like trying to nd a needle in a haystack!’ He slumped down against the wal . ‘If they tried opening a window at the same time every day for every year for a thousand years that’d be … that’d be …’

‘Three hundred and sixty-ve thousand at empts,’ said Becks. ‘Add another two hundred and fty at empts for leap years.’

‘Right! That many. Jeeeez, they’d never nd us!’

She squat ed down on her haunches beside him. ‘You are correct. It is extremely unlikely,’ she con rmed.

‘So that’s it, then?’ he said, sagging. The moment of believing they might have the beginnings of a way out was gone now, leaving him feeling even more hopeless than before. ‘We’re stuck here.’

‘Until my six-month mission timer reaches –’

‘Yes, yes … I know. Then you’ve got to do what you’ve got to do.’

A hand reached out and gently grasped his arm. ‘I am sorry, Liam O’Connor. It does not make me happy to think of terminating these humans. Particularly you.’

He sighed. ‘Wel … I s’pose that counts for something,’

he mut ered. ‘Thanks.’

They watched as the others nal y arrived with the log, and between them heaved it on to the ground. Whitmore wiped sweat from his forehead and recovered his breath. wiped sweat from his forehead and recovered his breath.

‘Good God, I’m beat. Roughly how many more of these logs do you think you’re going to need to nish that?’

Becks turned and eyed the wal for a moment. ‘Seventynine.’

He pu ed out his cheeks. ‘Seventy-nine? You sure?’

She nodded. ‘I am sure.’

‘Right,’ Whitmore pu ed. ‘Right, come on then, you lot,’

he said to the others. ‘Back to work.’

Liam and Becks watched them go. ‘It would be possible for the eld o ce to narrow down the number of candidate windows,’ said Becks.

‘What?’

‘They do not need to try opening three hundred and sixty-ve thousand, two hundred and fty windows. I am certain the AI back in the eld o ce would make the same recommendation.’

‘Same recommendation? What?’

‘A density probe. They could at empt a brief scan of each day. Any scans that returned a varying density signal warning would indicate movement of some object at that location. It is possible they would consider density warning signals as best-case candidates.’

He looked at her. She was right. A routine protocol before opening a window, to make sure they weren’t going to get mangled up with somebody else. ‘Do you remember exactly where we appeared on this clearing?’

She nodded. ‘I have the exact geo-coordinates logged in my database.’ She pointed across the ground towards a my database.’ She pointed across the ground towards a cluster of ferns. ‘You appeared there. Fifty-one feet, seven and three-quarter inches from this location.’

‘Then –’ Liam looked at the spot – ‘we’d need to stand someone right there … apping their arms around or something, right?’

‘Correct. But it is unlikely the eld o ce wil be making probe sweeps this far back in time.’

Liam felt himself sagging again. Another dashed ray of hope. He bal ed a st with frustration. ‘This time-travel stu is nonsense. Would it be so hard for the agency to come up with some beamy signal thing we could send back to them?’

‘In theory it would be possible. But it would require an enormous amount of energy and of course time displacement machinery, and a sophisticated enough computer system to target where to aim a –’

He raised a hand to shush her. ‘Becks?’

Her grey eyes locked on him obediently.

‘Please, shut up.’

‘A rmative.’

He stood, stretching an aching back. ‘Ah, sod this!’ Then he suddenly snapped, slamming his st against the log wal . The palisade vibrated slightly with the soft creak of stretched vine-rope.

‘Ouch!’ he mut ered, and sucked on grazed knuckles.

‘That hurt.’

She tilted her head, curious. ‘Then why did you do that?

’

’ ‘Ugh … wil you not be quiet?’