The Light Between Us

by Katie Khan

  Ayo’s baby starts to cry, and she pats him gently on the back, lifting the blanket and saying ‘Beebo!’ in a mangled game of peekaboo to distract him from his tears. A gurgle emanates from beneath the blanket, and after a minute he settles.

  ‘What about your breakthrough?’ Urvisha says, walking over to the sink but stopping to finger Isaac’s pin badge on his coat lapel. ‘Looks like you had a busy day … sightseeing?’

  ‘You can’t even begin to imagine,’ Isaac says.

  Thea indicates for Urvisha to sit down at the table. ‘Please – tell us what you know.’

  Isaac blinks at Thea’s choice of words, noticing Ayo twig the phrasing too, but she doesn’t question it.

  ‘Come on, then,’ Ayo says, gesturing for them all to sit. ‘Urvisha and I have been running some numbers. We’ve been going back through the science, taking a closer look at the glass house and the laser.’

  Thea nods. ‘Go on …’

  ‘We also reviewed the theory,’ Ayo says tentatively, holding Thea’s gaze.

  Thea nods again, not enjoying the idea of her work being checked. ‘And?’

  ‘We found something really quite interesting.’ Ayo gets up slowly, her left hand cradling the baby’s head, and she puts him down in a portable cot next to her on the bench, shushing him as he snuffles and grumbles. ‘Go to sleep, little one, that’s right,’ she croons.

  The old-fashioned copper kettle whistles loudly on the hob, making them all jump; the baby stirs but doesn’t cry. Isaac stands to make the tea. He pours out four mugs of chamomile, thinking they could all do with some calming, their nerves are so fraught.

  ‘Ayo,’ Thea says, her hand shaking slightly as Isaac hands her the mug, ‘what did you find?’

  ‘We solved it,’ Urvisha says bluntly, parking her suitcase next to the table and throwing herself down onto a backwards chair, straddling it and using its back as an armrest.

  ‘Seriously?’ Isaac says. ‘You can’t sit like that.’

  ‘I’m being edgy,’ she says, scowling at him.

  ‘Well, you’re setting us all on edge, so why don’t you turn around and sit like a normal person?’

  ‘You solved it?’ Thea echoes, ignoring Isaac and Urvisha.

  ‘We solved it.’ Ayo’s face is kind. ‘Your physics was brilliant – extraordinary. But when we examined the laser and the logbook, all your research notebooks and reference texts—’

  ‘You read my notebooks?’

  ‘—We realized it is quite possible for somebody to jump and come back.’

  Isaac and Thea avoid meeting eyes as Isaac takes a sip of calming chamomile, then changes his mind and reaches for Thea’s hand. They’re both about to speak, when—

  ‘Guess what?’ Urvisha says, tapping incessantly on the table, making them wince. ‘We were wrong.’

  Thea sits forward, Isaac’s hand still on hers; it’s time to confess. ‘You weren’t wrong—’

  ‘It’s not a time machine, Thea,’ Ayo says gently. ‘That second compartment you built? That was a clue. And your theory of spacetime … Just because it’s happening in space, it doesn’t mean it’s happening in time.’

  ‘It is – it does. We have the proof,’ Thea says, reaching for the Portrait Gallery postcard.

  ‘It’s not a time machine,’ Urvisha repeats. ‘We’re certain.’

  ‘Then what is it?’ Isaac asks quietly, rubbing the tiredness from his eyes.

  Urvisha’s eyes take on a gleam. ‘It’s a portal.’

  Eighteen

  ‘A portal?’ Thea says.

  ‘What type of portal?’ Isaac asks, grimacing slightly as he recognizes he’s back in the land of scientific explanations requiring simplification for his benefit. ‘Or should I say, a portal to what?’

  ‘Not what. Not when.’ Urvisha’s the cat that got the cream. ‘But where.’

  Thea sits back in a daze, a frown upon her face. She leaves the Portrait Gallery postcard in her bag, waiting for further explanation.

  ‘We misunderstood the time crystals. And the theory of relativity,’ Urvisha says, grinning.

  ‘All the paradoxes of time travel,’ Ayo says to Thea, ‘all of the reasons it’s never been done before. Changing the past so that it affects the present. Killing your grandfather so you cannot be born. Would any of those be an issue if, say, instead of jumping to the past, you jumped to a parallel timeline, instead?’

  ‘A parallel timeline,’ Thea repeats.

  ‘No paradoxes. No conflicts. Wouldn’t that be the simpler explanation?’

  ‘Occam’s razor,’ Isaac says. ‘The simplest explanation is usually the right one.’

  Ayo nods. ‘Precisely.’

  Thea snaps to attention. ‘But – going back in time …’

  ‘We thought about that, too,’ Urvisha says. ‘If you can jump to another timeline, then theoretically you could jump to a different marker on that timeline, such as a different year. Seemingly moving back in time.’

  ‘But the key part is that, whether you’ve gone back in time or not, you’ve jumped onto a parallel timeline,’ Ayo finishes. ‘In a different universe.’

  Isaac stays very quiet as he tries to digest what the team is describing. He watches as Thea takes out a notebook, bending the spine as she starts writing notes – ever the diligent scientist.

  ‘So the portal you’re describing,’ Isaac says at last, ‘it’s the glass house?’

  Ayo checks her baby is sleeping soundly on the bench next to her. ‘Yes,’ she says simply.

  ‘The glass house is the trap. It’s a conductor. And it’s also a shield,’ Thea says without looking up.

  ‘And it’s also a portal,’ Urvisha says, emphasizing the last word.

  Thea doodles her endless pattern of interlocking diamonds and prisms in her notebook for a moment, her brow wrinkled in concentration. ‘What you’re saying,’ she says, ‘is that it’s not time crystal theory – nor special relativity. It’s not even about wormholes. What we’re dealing with here is the many-worlds interpretation.’

  Isaac groans. ‘Of course there’s another theory. Quick, get the salt and pepper pots out – I am going to need some demonstrations to understand anything after the day we’ve just had.’

  ‘You’re not going to keep up,’ Urvisha says rudely. ‘You can’t learn this stuff through a quick demonstration with Thea’s crusty salt shaker.’

  ‘Try me,’ he says, folding his arms.

  ‘Fine.’ Urvisha squares her jaw, both physically and mentally. ‘Schrödinger’s cat.’

  ‘I know that one!’ he says. ‘It’s about a cat being alive and dead at the same time.’

  Urvisha wrinkles her nose. ‘An entanglement paradox – a thought experiment illustrating the problem of quantum mechanics applied to everyday objects, such as a cat. According to quantum superposition, the cat may be simultaneously both alive and dead.’

  ‘I hear the word quantum and I’m lost.’ Isaac throws up his hands. ‘I tune out.’

  Thea pats him on the shoulder. ‘Don’t worry. What you need to know is that one of the first multiverse references was made by Schrödinger. In a lecture, he joked that his Nobel equations seemed to describe different histories that weren’t alternative histories, but were really happening simultaneously.’ She looks up at Ayo and Urvisha. ‘Isn’t that right?’

  Urvisha folds her arms. ‘Sure. Of course you know everything. But what you didn’t look at in detail, when you were putting your theories together for time travel, was quantum mechanics.’

  Isaac yawns. ‘I don’t think I can take quantum mechanics tonight. You said it’s possible to jump and come back?’

  ‘Yes,’ Urvisha says, picking up her cooling mug of chamomile. ‘It’s perfectly possible, now we know what we’re dealing with.’

  ‘So we’ll be able to retrieve Rosy?’ Isaac doesn’t mention the Portrait of an Unknown Woman. He can’t muddy the waters, there’s too much going on. But he thumbs the pages of Thea’s bank statements and Ad
miral Coleman’s sales docket, quickly flicking open his phone to make sure the document photos he took are saved safely.

  ‘Hang on, Isaac. I want to know what I missed,’ Thea says, though her voice is so quiet the three others sit forward, straining to hear. ‘I want to know how I was wrong.’

  Urvisha takes a sip of the tea. ‘Quantum decoherence.’

  Isaac stands, picking up the paperwork. ‘I don’t know what you’re all talking about,’ he declares. ‘You said it wasn’t a time machine, but now you’re talking about quantum this and quantum that and I can’t follow.’ He looks at them expectantly. ‘Keep it simple, stupid.’

  Thea flashes a taut smile at her friend, sensing his frustration. ‘All right. I’ll take quantum-everything out of it and explain MWI – the many-worlds interpretation – like they would have done in our Philosophy class, rather than Physics. Okay?’

  ‘Okay,’ he says solemnly.

  Thea takes her notebook and draws a flat line across a blank page. ‘Here’s our reality. It’s always been viewed as a single unfolding history. Yes?’ At the very beginning of the line, she writes ‘Big Bang’. At the far end, she scrawls ‘Right Now’. And somewhere quite near that, for Isaac’s benefit, she adds a dark circle and writes ‘Nazis – Very Bad’.

  ‘Now, instead of this single unfolding history, imagine reality as a many-branched tree, where every possible outcome can be realized.’ She draws branches sprouting off from the line, running parallel in all lengths and sizes. ‘Every possible alternate history and future is real, each representing an actual universe. So in one universe, Hitler lived. In another, he was killed by a time traveller. And in another, he was never born at all. Do you see?’

  Isaac nods.

  Thea fractures each line into smaller branches, so that every one has multiple lines growing out of it at every point. ‘Each tiny, infinitesimal decision made by you or me, every choice faced by every single electron, causes a new branch to grow: a new timeline … an infinite number of timelines. A multiverse of parallel timelines, parallel universes.’

  ‘I see,’ Isaac breathes, looking at the tree she’s drawn, at how the branches radiate out, away from the central timeline, until there are many.

  ‘In one world, Schrödinger’s cat is dead, and in a parallel universe, the same cat is alive.’

  He looks up from Thea’s notebook. ‘So in a parallel world, I’m a millionaire?’

  ‘Sure.’ Thea nods. ‘Isaac Mendelsohn is walking down the street in downtown Manhattan. In this world, he’s late and hurries along without looking down. In another parallel world, he stops and finds a lottery ticket, becoming a multi-millionaire.’

  Isaac is quiet. ‘So in the many-worlds interpretation, there’s a parallel world out there where Rosy isn’t missing.’ His eyes graze Urvisha’s huge suitcase, and it breaks his concentration. ‘Going somewhere? It’s the middle of the night.’

  ‘I’m glad you asked,’ Urvisha says, standing, a fidget of excitement in her stance. ‘Now you’re caught up, we’re going to run the experiment again.’

  Thea and Isaac look at her, uncomprehending.

  ‘Let’s find out where the portal goes. That way we can find Rosy at the other end.’

  Ayo looks at her sleeping child, concerned. ‘Now?’

  ‘It was your idea,’ Urvisha says, pulling the suitcase over to the door, taking her coat down from the peg, then turning when none of them moves. ‘You said we could run it again when Thea and Isaac returned—’

  ‘I meant in the morning, but if you really can’t wait …’ Ayo says, getting to her feet, carrying her son in his portable crib. ‘But only if the baby monitor signal reaches to the barn.’

  Isaac’s curious. ‘Visha – what’s in the case?’

  Her expression is flat. ‘Everything I might need in another world. I’m going to go and get Rosy.’

  ‘We can’t—’ Thea begins, looking at her notes and doodles. ‘We need more time.’

  ‘Everything’s set up and ready to go,’ Urvisha says, opening the kitchen door so a freezing gust of wind wraps around the room, chilling them all.

  Isaac and Thea sit, stunned, at the kitchen table.

  ‘Coming?’

  They stand robotically, looking at one another from each side of the kitchen table. Thea moves to get her warmest coat as Isaac slides out the Portrait of an Unknown Woman postcard from its place tucked inside the sheath of papers, and puts it snugly into his back pocket. ‘I feel like my head is going to explode,’ Isaac says to Thea under his breath.

  ‘It’s a lot to take in, even for me,’ she says thoughtfully, as he helps her into the down-filled parka.

  ‘Come on!’ Urvisha strides out into the night.

  ‘This is ridiculous,’ Thea says, but she’s lost the upper hand.

  The group step out into the courtyard. The sudden darkness after the illuminated farmhouse makes them pause, and they let their eyes adjust before making their way to the kitchen garden with its untended vegetables growing wild and tall, past the paving stones – one, two, three – past the cylindrical dovecote, towards the outbuildings. The wheels of Urvisha’s suitcase grate against the quiet night, as she leads the way to the double-height black-timbered barn.

  ‘This is all happening so fast,’ Thea says to Isaac, as they hang back. ‘Do we even know if the glass house – the portal – can transport luggage along with a person?’

  ‘If your glass house truly is a portal, I think we’ve got bigger problems than its baggage allowance.’

  ∞

  The door to the barn is ajar, a crack of light seeping out. Urvisha hauls it open and Thea gazes at her experiment setup, familiar but somehow different. The photographic lamps aren’t on, and the glass house looms large in the dark, glistening and ominous.

  ‘The lamps weren’t important,’ Urvisha says, noticing her stare, but Thea’s in a daze, her mind working overtime. ‘It’s all about the laser.’

  ‘Are you all right?’ Isaac whispers to Thea, watching as Urvisha makes her way over to the laser.

  Thea turns on the three photographic lamps, looking out of the barn towards the dark line of trees behind the farm’s fences. ‘The many-worlds interpretation,’ Thea mumbles, to herself rather than to the others. ‘Every tiny, infinitesimal decision made by you or me, every choice faced by every single electron, causes a new branch to grow. So the question is …’ She trails off as Urvisha heaves the case over to the prismatic glass house.

  ‘What’s the logic there, Visha?’

  Urvisha rough-handles her luggage, leaving it just outside the door. ‘I’m hoping if I leave a suitcase with everything I need here, then in a parallel world there will be a suitcase with everything I need there.’

  Isaac wrinkles his forehead. ‘The worlds are like a mirror?’

  But nobody answers him.

  Ayo sets up the baby monitor, Thea’s camera and Urvisha’s laptop on the workbench, making small adjustments to ensure the perfect angle is captured between the laser and the booth.

  ‘Thea – you were saying something about a question?’ Isaac asks.

  Thea stares at the outline of the trees, their individual branches masked by the darkness and the distance. Concerned, Isaac peers out of the barn to spy what she’s looking at, but to no avail.

  ‘The thing about the many-worlds interpretation is that the worlds run in parallel until they split,’ she says at last. ‘Here, one decision is made, and there, the opposite decision is made.’ Thea rubs her neck, reasoning to herself. ‘The timeline splits at the exact point of decision. One goes left, one goes right.’

  ‘So it is like a mirror,’ Isaac says.

  ‘I need time to think this through,’ Thea says, almost like she’s talking to herself rather than Isaac. ‘There’s something about that split that’s bothering me.’ She puts her notebook on the workbench, drawing two parallel timelines like train tracks, diverting one left and one right in a Y-shape. ‘Two worlds running in parallel unt
il I leapt. They split, and now they’re different. So—’

  ‘What do you mean, you leapt?’ Urvisha stares at Thea from where she stands by the glass house, and Isaac shifts uncomfortably.

  ‘It’s theoretical,’ Thea says. ‘If there is an infinite number of timelines, a multiverse of parallel worlds that you can jump into, then which decision – which choice, which precise moment – split our two worlds?’

  Urvisha shrugs. ‘We know that. It was Rosy’s jump.’ She returns to the laser setup and control panel, not seeing Thea’s face and the uncertainty all over it.

  Isaac mouths a question, and Thea shakes her head.

  ‘Ayo?’ Urvisha says. ‘Can you help set the laser?’ Ayo walks across to the box and, checking against Thea’s notes, enters the same strength and brightness settings used for Rosy’s experiment, double- and triple-checking that they are correct.

  ‘Time for go or no go.’ Urvisha confirms the power to the barn is stable, then checks the recording devices are live. ‘Go.’

  ‘Why are we rushing this?’ Thea asks.

  ‘It does seem a bit soon,’ Isaac says.

  ‘Rosy’s been gone for days,’ Urvisha retorts. ‘It’s time one of us goes to retrieve her.’

  ‘Go,’ Ayo says, verifying all the doorways to the barn are clear, then standing next to the laser, ready to fire.

  Both Ayo and Urvisha look at Isaac and Thea. ‘Well?’ Urvisha says expectantly. ‘You want Rosy back, don’t you?’

  They can’t argue with that. ‘Where do you want me?’ Isaac sighs, pulling the heavy door closed and walking deeper into the barn.

  ‘You’re tech-savvy – you take over the computer, monitoring the National Grid. The program should run itself, so don’t worry. You only need to keep it running. I’ll get in the glass house.’ Urvisha walks to the prismatic glass, clambering past her oversized suitcase. ‘Thea?’ she says impatiently.

  ‘Yes,’ she says, at last.

  ‘Make sure you use the same prism in the door that you used for Rosy.’