Deceit

by Peter Darvill-Evans

  He stopped. Bernice was deeply suspicious. The twinkle in his eyes looked genuine enough. But how could you tell with a Time Lord? Had he conceived of a scheme to lead them out of the maze?

  ‘How about this,’ Bernice said. ‘In the transmat booth that brought me and Elaine from Beaufort to Landfall, I saw the logo of the Spinward Corporation.’

  The Doctor, thinking deeply, tapped his front teeth with the crook of his umbrella.

  ‘Well, that’s right,’ he said expansively, and started to stroll onwards along the corridor. ‘Of course. Arcadia was a Spinward colony planet for centuries. It’s all in the Matrix. Nothing wrong with that.’

  ‘And another thing –’

  ‘No,’ the Doctor interrupted, ‘but this is all wrong.’ He gestured dangerously with his brolly. ‘I suppose I created the Spinward Corporation, in a way. Helped it along, anyway. Back then.’

  ‘Back when?’ Bernice said, her archaeologist’s mind ever alert to any opportunity to pin down the Doctor to a specific date.

  ‘A few centuries before now. On Earth, of course.’

  ‘Go on.’

  ‘I put a spanner in the works of one of the companies that later merged to form Spinward. A very large spanner. A job well done, if I do say so myself.’

  ‘But?’

  ‘Oh, nothing. Well, perhaps I nudged things just a little too far. It’s so hard to be sure. Their research was very advanced for its time. I successfully blocked one of the main avenues they were exploring. But perhaps that only encouraged them to move faster elsewhere.’

  Bernice waited for the Doctor to continue, but he walked on and then glanced sideways at her as if expecting another question. Go for the jugular, she thought.

  ‘So what, exactly, do you think you’re up against now?’

  ‘I really don’t know – exactly,’ he said. ‘I don’t even know if I’m against it. I can sense something like a vast, artificial intelligence. It’s almost like a primitive version of parts of a TARDIS. And that’s quite impossible, you see. Mankind doesn’t have that level of knowledge. Not in the twenty-fifth century. Not for centuries to come.’

  ‘We’re in the twenty-fifth century?’ Bernice punched his shoulder. ‘Doctor, why didn’t you tell me? I’ve come home.’

  The Doctor looked bemused for a moment, and then his face broke into a sheepish grin. ‘Do you know, Benny, it had completely slipped my mind. Yes, this must be almost exactly your time. But not your place, of course: we’re a good four hundred light years from your usual stamping grounds. Not that you could meet yourself, anyway. I understand about three years have elapsed since you left.’

  Bernice fought a brief mental struggle with the concept of meeting herself, surrendered, and took refuge in observed facts. She pointed at the minutely-decorated walls.

  ‘These materials. The murals. They don’t look – I mean, there was, or I should say is, I suppose, nothing like this in the twenty-fifth century. Not of human origin. Not that I’ve seen. Is it alien?’

  ‘I don’t think so. But you’re right. It shouldn’t be here. Whatever created it is an aberration. A very interesting aberration.’

  ‘That’s one way of describing it,’ Bernice said, but she couldn’t be bothered to come up with other, less half-hearted quips. She was too busy grappling with the concepts behind the Doctor’s deceptively simple explanations.

  ‘If you, several centuries ago, diverted the route through time that the Spinward Corporation would have taken...’ she began.

  ‘Yes?’ the Doctor said; with an infuriating smile.

  ‘Well, surely the TARDIS would have known about it? I mean, the TARDIS predicts the future, doesn’t it? Or you and the TARDIS between you, somehow. Or you can read some source of information that predicts the future. I’m sure that’s what you’ve told me, anyway. And stop looking so damned superior.’

  ‘Prediction isn’t the right word. It’s too definite. It’s always a matter of assessing probabilities. Ticklish work. Requires vast talent, of course, and a frightening amount of computing power, as well as a sort of knack... The universe isn’t a predictable place, that’s the trouble. But perhaps it’s just as well.’

  ‘Is it?’

  ‘Of course, Benny. You wouldn’t want to start watching one of those awful old adventure films you like so much if you knew exactly what was going to happen, would you? Much more fun if the ending’s a surprise.’

  ‘But I like to watch them more than once.’

  ‘Several times more than once,’ the Doctor said, the tone of his voice reflecting the numerous occasions on which Bernice had dragged him into the flea-pit cinema she’d found in the TARDIS and insisted that he pay attention to the noir motifs and the semiotics of Double Indemnity. ‘But the universe is like that, too.’

  ‘Black and white?’ Bernice suggested.

  ‘Far from it. No, I mean that it comes as a surprise when you first experience it, and then after that you can’t change the course of events. Rick always sends Elsa to the aeroplane with her husband, no matter how many times you watch Casablanca.’

  Bernice was becoming confused. ‘But I thought... You’ve always said – or at least implied – that the things you do have an effect. You said you interfered with the development of the Spinward Corporation. For instance.’

  The Doctor sniffed. ‘Really, Benny. You know how much I dislike that word. Yes: I can help to write the script for movies yet to be made. We all do that, although I must admit the TARDIS gives me a wider range of opportunities than most people have. But I can’t alter a film that’s – what’s the expression – already in the can. Have you heard of a type of problem known as NP-complete?’

  ‘Are you changing the subject?’

  ‘Absolutely not.’

  ‘Why did you turn left at that last corridor?’

  ‘Ah-ha!’

  ‘Yes, I’ve heard of NP-complete problems. But I can’t quite remember...’

  The Doctor waited until Bernice had abandoned all hope of recalling her long-forgotten theoretical mathematics.

  ‘What’s the quickest way to solve a puzzle?’ he said.

  ‘Give it to a computer,’ Bernice replied immediately. ‘If the puzzle’s susceptible to analysis, the fuzzy logic will work out the principles involved. And if it’s just a matter of lots of calculations, any sort of processor will polish it off in next to no time.’

  ‘Unless?’

  ‘Unless it’s NP-complete?’

  ‘Precisely.’ The Doctor stopped again. They had reached the end of yet another corridor. Bernice glanced over her shoulder and was relieved to see that Francis and Elaine were only a few metres behind her.

  A passageway crossed left and right before her; a little way along the right-hand corridor she could see a wide opening in the wall, and through it the first few steps of a wide staircase leading upwards. The Doctor seemed uninterested in any of the alternative paths.

  ‘An NP-complete puzzle,’ he said, standing with his hands behind his back and his gaze wandering towards the ceiling, ‘is one in which the routes to the solution are so numerous that there is no single correct answer. Indeed, the number of possible routes increases exponentially as one explores them.’

  ‘Ah,’ Benny said. ‘Not unlike this maze of corridors, for instance?’

  ‘Exactly.’ the Doctor smiled indulgently. ‘The only way to find the way out of a single-exit maze consisting of mutually accessible junctions is to follow the paths until you find the way out. There are no short cuts. A robot, with no matter how powerful an artificial intelligence, would perform no better than a person.’

  ‘A robot would do it more quickly,’ Bernice said. ‘Metal legs don’t get tired.’

  ‘Of course, of course,’ the Doctor said. ‘I was speaking theoretically. If one imagines a machine that can travel from junction to junction almost instantaneously, finding a path to the exit would take only seconds. But what about adding a twist to the puzzle: the task is not merely to find
a way out, but to find the shortest route to the way out.’

  Bernice was beginning to have an inkling of the Doctor’s real subject. ‘The robot – the machine would have to explore every possible route. That would be the only way to establish which was the shortest. So in a maze with one four-way junction there would be four routes to explore and compare. With two junctions there would be four; plus three, that’s seven; eight; another three, that’s eleven – I can’t count them. There are quite a lot.’

  ‘A hundred and twelve,’ the Doctor said. ‘And that’s assuming the machine is programmed not to double back along the same path. A maze consisting of just three such junctions would have – well, hundred and hundreds of routes. You get the picture.’

  ‘Exponential numbers. You could give a computer quite a headache with an NP-complete puzzle.’

  ‘I’ve done so, on occasion. Now then: we were talking about predicting the future, I believe?’

  ‘Indeed we were, Doctor. And I take your point. The universe as NP-complete. Each beat of a butterfly’s wing – each division of each and every cell – seen as a junction in a maze.’

  The Doctor looked extremely pleased with himself. ‘I’ll let you into a small secret,’ he said. ‘I haven’t met many humans who have understood the complexities of travelling in time as well as space.’

  ‘Hmm. I’ll take that as a compliment, I think.’

  ‘Of course, we don’t have to consider the whole of space-time. Some of the universe is pretty much cut and dried. All of the past, for instance. Although that’s still rather small, compared to the future. And there are long strands of fixed points, a bit like beads on long strings. Or like strands of lumpy noodle in the soup of probability. But there’s enough left to discombobulate even the biggest of predictive computers.’

  Bernice was fairly sure that if she asked whether she was, at that moment, on a lumpy excrescence on a strand of spaghetti stretching into the Doctor’s future and surrounded by a soup of probabilities, she wouldn’t like the answer. She decided that thinking in four dimensions was best left to the Doctor. ‘I remember now,’ she said. ‘I read somewhere that even if every atom in the universe could be made to function as a flipflop switch in a binary computer, it still wouldn’t be big enough to follow all the possible routes that the universe could create.’

  The Doctor thought for a moment, counting on his fingers. Bernice was sure he was bluffing. ‘Yes,’ he said slowly, as if he’d just completed a mental calculation, ‘that’s quite right. To predict the universe, you’d need a computer many times bigger than the universe.’

  ‘The TARDIS is big. Bigger than something very big indeed, I’d say.’

  ‘Very percipient, Benny. But I’m afraid even the TARDIS isn’t that enormous. The best she can do, even with the link to the Eye of Harmony and, the data stored in the Matrix, is to work in best estimates. Shall we see how she’s getting on?’

  ‘What?’ Bernice said. But the Doctor had turned on his heel and was almost skipping along the right-hand corridor.

  Bernice caught up with him as he veered towards the broad staircase. He didn’t take the stairs: he ducked under them and disappeared into the shadows. Bernice followed him, and found herself in a square space behind the staircase. It was empty but for the Doctor, looking very smug, and the TARDIS.

  Two weak cries of ‘Oh!’ broke the silence as Francis and Elaine arrived.

  ‘Before you ask, Benny –’

  ‘What makes you think I was going to?’

  ‘– I must confess that I have no idea what the TARDIS is doing here. Someone must have brought it here for a purpose, but I must admit it looks abandoned. Perhaps they’ve lost it. However –’

  ‘You can usually find the TARDIS.’

  ‘– I can usually find the TARDIS, if it’s nearby. And it’s in full working order.’

  ‘It never is!’

  ‘Well, not often, I’ll grant you. But she’s as well as can be expected. Now, where did I put the key?’ He patted his pockets for a few moments. His frown deepened, then transformed itself into a radiant grin. He plucked his hat from his head and extracted a key from the hatband.

  It was Francis who first realized the implication. ‘Doctor,’ he said accusingly, ‘the key to your blue box was in your hat. You left your hat in the maze. You might have lost it forever.’

  The Doctor looked disconcerted for the merest moment. ‘Ah, but I didn’t, did I? We found it again. By such infinitesimal chances are failure and success separated. Excuse me, won’t you? I shan’t be long.’

  He pushed open the TARDIS door.

  ‘Doctor!’ Bernice’s summons halted him in the doorway. ‘Would you, mind telling us what you’re doing? Are you going to leave us here? Because if you’re thinking of nipping back a century or two and uncreating this interesting aberration of yours, I think I’d rather be somewhere else at the moment of uncreation, if it’s all the same to you.’

  The Doctor beamed. ‘You haven’t been paying attention, Benny. I can’t rewrite the script, remember? Do you think I would have let the Master grow into the twisted megalomaniac he is if I could have prevented it? It’s not as simple as that. This is a piece of real space-time, and I can’t unmake it. I wish I’d understood that when I had to deal with that meddling Monk.’

  Bernice understood the rebuke, if not the particular examples, in the Doctor’s words. He kept glancing into the TARDIS as if anxious to perform his mysterious, self-appointed tasks. Bernice hadn’t finished with him yet.

  ‘So if you were to take the TARDIS a few hundred years back,’ she said, ‘what could you do?’

  ‘Oh, the usual. Resist oppression, lighten the burden of the underdog, spread understanding and reason. You know the sort of thing. But I can’t unmake this piece of space-time. It would be difficult to make any long-term difference to the development of the Spinward Corporation, because this moment exists and must fit into Spinward’s development. I could go back and leave myself some notes, a bit of helpful advice; but as I don’t know yet what I’m dealing with, I can’t leave myself anything useful. And I haven’t come across any notes from me to me, so obviously I’m not going to go back into the past and leave anything for me to discover in the future, which is the present. I hope that’s clear? Now I really must –’

  ‘What if you destroyed Arcadia? Before it was colonized, I mean, in the past. Wouldn’t that prevent this happening?’

  ‘Not necessarily, Benny. There are other planets that would have served just as well, I imagine, in Spinward’s schemes. And before you suggest that I should consider annihilating this entire sector of the galaxy –’

  ‘I wouldn’t suggest that,’ Bernice said quietly. Countless faces, silently screaming, thronged her mind. The Destruction of the Seven Planets would live with her forever.

  ‘No,’ the Doctor said. ‘No, of course not. I was merely going to say that it is possible to alter the past to such an extent that subsequent events are incompatible with it. The results are, as you might have guessed, violently unpredictable. Now I really must attend to the TARDIS.’ He disappeared into the dark interior. The door closed.

  Seconds later the door opened again. The Doctor hopped out, and re-locked it.

  ‘Is that it?’ Bernice said.

  ‘Yes, all done,’ the Doctor said, and made for the bottom of the stairs.

  ‘Doctor,’ Bernice almost wailed, ‘can’t we at least use the TARDIS to get out of this maze? Let’s go somewhere else. Somewhere comparatively interesting. What about Lubellin, the Mud Planet. I always thought I’d like to be stuck there for a dirty weekend.’

  ‘Out of the question, Professor,’ the Doctor admonished. ‘First, if we leave now I won’t find out what’s going on, and as you know I don’t like to leave anywhere until I know what’s going on. Something always is.’

  Bernice peered questioningly at the Doctor. As he talked, he was staring fixedly at her. Francis and Elaine, clutching each other’s hands, were also g
azing at her with wide eyes.

  ‘Second,’ the Doctor continued, ‘we don’t have to use the TARDIS to escape from the maze. We have found a way out.’

  ‘We have?’

  The Doctor, Francis and Elaine spoke in unison: ‘Behind you!’

  ‘Third,’ the Doctor said, as Bernice whirled to see an open doorway where only seconds earlier there had been a flat wall, ‘I imagine those androids would prefer us not to attempt to escape, in the TARDIS or in any other way. The usual procedure in this sort of situation is to act like prisoners and let the guards take us to their leader. And not before time, in my opinion.’

  Six androids were standing in the doorway. Bernice hadn’t seen them at first: their black silk cloaks merged into the darkness beyond the doorway, and only the jerky movements of the red-painted muzzles of their stubby blasters revealed their location.

  ‘These are the three humans and the humanoid paradox,’ spluttered one of them. ‘They have been attracted to the box paradox. We will load them all on the transporter. Also re-load the box.’

  Five of the androids limped into the space between the doorway and the staircase, surrounding their captives. The sixth disappeared into the darkness beyond the doorway, and shortly afterwards the whirr of a motor started and became louder. A goods transporter – little more than a metal platform hovering a few centimetres above the floor – edged through the doorway, with the sixth android at the controls. It inched forward until the front of the platform nudged the base of the TARDIS. ‘They’ll have to tip it on to its side,’ Bernice whispered.

  ‘I know,’ the Doctor said. ‘Did I remember to set the internal stabilizers? I can’t remember.’

  Four of the androids exerted all of their considerable strength against one side of the TARDIS. It teetered on one edge of its base, and toppled on to the platform with surprisingly little noise but with enough force for Bernice to feel the floor move beneath her feet and a blast of displaced air brush against her face.

  My specimens, she thought. The script discs from Sakkrat. The Heavenite porcelain. My collection of beer glasses. If he’s forgotten the stabilizers...