Dr. Dan Czarnecki arrives at the lecture theatre thirty seconds after the lecture was supposed to begin and stalks down to the front through a noisy cloud of conversations-in-progress. He throws his leather briefcase at a chair, grabs a marker pen from the nearest shelf and begins scrawling a board-wide equation on the far left whiteboard. His handwriting is appalling, even worse on the board than it is on the heavily photocopied notes he sometimes remembers to hand out. Today, the marker pen is running out. Czarnecki realises this halfway through the equation, glares at what he's written, glares at the pen, caps it and hurls it overarm into the waste paper bin at the other end of the wide, mainly circular stage. The bin is metal, and there's a sharp and satisfying tang as it catches the pen. Czarnecki finishes the equation with a different colour. Only then does he turn around and start removing his gloves, hat and coat. This is also the point at which he will start speaking, regardless of how many people in the room haven't managed to shut up yet. But they've shut up by now, because at the speed Czarnecki works, not listening for more than half a minute is a recipe for irreversible, eternal confusion.

"If you have the slightest recollection of what's happened to you in the last five-and-a-half weeks you'll recognise this as Vidyasagar's First Incomplete Field Equation, which I showed you on the first day of the course. You will also remember that when I showed it to you, I told you it has three errors in it. I corrected the first error right away. Can somebody tell me what that was?"

Czarnecki's tone of voice indicates that he wants this answer fast.

"Pi should be two pi," shouts a voice from the mid-left of the theatre.

Czarnecki adds a "2" to the equation. "Reflectivity," he clarifies. "Full-blown fully-accounted 5D thaumic flow is self-interfering. Good good. Vidyasagar's First Incomplete Field Equation was derived correctly, but derived from partial observations and inaccurate assumptions. When it was shown to disagree with the first 'real' uum casts, Rajesh Vidyasagar corrected one of his assumptions and revised his work. Good. This equation was for some years known as Vidyasagar's Completed Field Equation.

"The word 'Completed' was dropped and replaced with the words 'Second Incomplete' as a result of the Shelburne-Sharma experiment, which you duplicated in microcosm in the laboratory last Friday afternoon. At that time, all we gathered was raw data. Partially that was due to a shortage of time, but mostly that was to give you a chance to collate the data and draw a conclusion. Does anybody have a conclusion? Does somebody want to put their hand up and admit to having done some work last weekend? A vague stab will do. A guess?" Czarnecki starts snapping his fingers rapidly. He paces around the stage. "Come on. Come on, come on, come on! Not you."

Czarnecki's class is attentive and blank, but he singles out one girl at the front on the right. Czarnecki makes a deliberate habit of calling everybody "you" even though he has picked up just over a third of the sixty-five or so names. In his view, it is fairer if he pretends to not know any of them. But everybody knows Laura Ferno.

"Okay. Will somebody whose Veblen arbitrator didn't bleed out on Friday, and who therefore at least collected good data, and who has since had access to graph paper or an electronic substitute thereof, please summarise their observations for the benefit of the class? Come on. Who actually made graphs? Anybody? Yes! So what did you see? You?"

Czarnecki seizes on a student at the back of the class who has hesitantly raised his graphs in the air. From this distance the graphs look good: for one thing, at least five different plots are visible.

"They disagree," says the student, whose name is Mathis Schröter.

"What disagrees with what?"

"The measurements predicted by... Vidyasagar's Second Incomplete Field Equation... and the actual measurements don't match onto one another properly. There's a difference between them. But--"

"Characterise that difference for me."

"I... I don't know how. It's a five-dimensional vector field embedded in three-dimensional space, I can't visualise it. I couldn't slice it right."

Student Mathis Schröter is evidently in the dark. Czarnecki relents and calls on Laura. "You. Go."

"What, me?"

"Always you, who else?"

"I didn't actually have my hand up."

"Why not?"

"Because I don't know the answer."

"I thought you knew everything."

"My results were garbage."

Czarnecki strides forward, picks up Laura's results and skims the raw data for a moment. He is surprised.

"Garbage. Fine." He hands the paper back and returns to the board. He writes "+ S t ; τ " on the end of his equation. Then he moves to the next board and essays a complete definition of S , a lengthy triple integral. While writing, he narrates: "The missing term is called the Sharma transduction tensor, also known as the thaumic flow transduction potential: the amount of nearby matter and energy which is enchanted and/or arranged in a mystically significant way. Flowing electrical lines will contribute to this factor. So will static or charmed magic rings, static or charmed staffs, electromagnetic waves, large electrically neutral masses and, in the smallest quantities, all other mass-energy in the universe out to an infinite range, give or take the inverse square law. It counts anything which could affect thaumic flow at that point in space or which could in turn be affected by that flow. The S -tensor is a statement of two critical facts: firstly, that magic can be created, shaped, collected, stored, transmitted and released using real, physical equipment; secondly, that magic can in turn be used to apply real, measurable effects to the physical world. The necessity of the S -tensor is the proof that magic is an interacting component of the real universe, whatever the real universe is, and not constrained to a co-located 'bare' universe of magic matter and magic energy. In short, magic is real. Precise measurement of this tensor led to the creation of the first reliable magical machinery and spelling. Congratulations, after five-and-a-half weeks of tensor algebra you have been handed on a platter what it took Indian physicists six years to derive from scratch. Welcome to thaumic physics, you are almost ready to begin.

"The third error took longer to find. Why?"

There's a pause, because this is a puzzle. While he waits, Czarnecki starts putting his staff together. His staff is split into six pieces of varying sizes, enabling him to construct any of two dozen different lengths using different combinations, but today he screws all six together for a total length of exactly two metres.

"Because it was a lot smaller?" somebody guesses.

"So how much magic do you think it takes to demonstrate that error under laboratory conditions?"

"A lot," says the same person.

"You, you and you, well volunteered," Czarnecki says, picking out three students in a row from the front. One is a gangly fellow with large glasses and long, scraggly hair. One is a broad-shouldered man wearing a scruffy blue shirt. The other is Laura - shortish, dark-haired, uninspiring. None of them had volunteered. "Come on. Come up here, come on. How are your mana levels? Good? Good."

The stage is larger than most, big enough to embed a seven-metre E-class magic ring in the floor. Czarnecki wheels a piece of machinery out of a corner and kicks the power switch on at the wall. The machine is a Veblen pump. It has the dimensions of a pair of upright pianos placed back to back, but it looks more like an enormous tower PC case, with the side missing and the interior filled with small magic rings and runes and tubes instead of circuitry and disk drives. Specifically, it looks like the old kind of tower - manufactured an optimistic white, but now faded to a depressing creamy beige after a few decades of use. It's a little beaten up, and could really use replacing, but as long as it continues to serve the fairly menial purpose that it needs to serve, that will never happen. On the side of the machine are some rolls of hose with more magic rings tying off the ends. Czarnecki unwinds a few turns of hose for three of the rings and hands them out to the students. He directs the gangly student to stand at twelve o'clock on the rim of the magic ring in the floor, the shorter one at eight o'clock and Laura at four. The three of them trail long hoses over the floor ring's interior.

Czarnecki invokes a few presets just to get the machine started. Then, "Mister Noon, would you provide me with a continuous steady flow of zeta-formatted mana, please?"

It's a moment before the tall student realises he's being spoken to. "My name's Jeremy," he says.

"Zeta load. Ring. As much as you feel you can part with while leaving your brain stable. Thank you in advance for your cooperation. Don't worry about overspill, I'm acting as buffer. Mister Eight O'Clock, the same amount of iota-class. Shout if you need reserves and we can work something out." As the stockier man starts his spell up, Czarnecki interrupts him with a clarification: "When I say 'the same amount', I mean tap into Noon's link and make a stabilising connector first."

Mister Eight, whose name is Benj, constructs and recites a rather longer mantra than Noon's. He mis-speaks a few times and has to stop himself, erase syllables from the floating stack and resume from mid-word. Perfect diction is desirable in a mage, as it gives an impression of professionalism and competence to observers, but it's totally unnecessary. In practice, one can get away with anything short of a genuine speech impediment. Constructing an industrial spell invariably takes a hundred times longer than speaking it, and unmatched floating syllables will hang around for the best part of half an hour before dissolving. So every mage learns up front to be methodical rather than reckless; nobody cares if the last and least important step in the process takes a few attempts to get right.

There's a hum now, something of a discordant buzz. Magic is silent, but the machine isn't. "And Four: mu."

"Same amount?" asks Laura.

"Yes, but you'll probably find yourself forced to synchronise with the others whatever you do."

Laura says a series of words which, in sequence: identify her simplest collector-spell, written years ago but still in regular use; prime it to slurp up a certain blend of ambient mana from the invisible clouds that surround her (and every mage, and every other human); associate the collector with her True Name and assigned mu band; and kick it off, like opening a keg tap. She feels her reserves ripple and start to spiral out of her. The mana emerges from her skull into air, seeks out the magic ring in her hands and bolts down into the machine with the rest. Harmonic effects from the two other flows interfere with hers until they settle down into synch, amplitude-modulated at a natural rate of a few kilohertz. Zoontch goes the machine as it spins up a gear.

So far so standard. These are the three most common "brands" of mana and this triple-phased feed is typical of the type used to power heavy chemical engineering equipment in industry. Three mages is two more than a real employer would be prepared to employ for this job, but these are the early days for this class and that kind of multi-tasking takes practice. Even the quantity is short. Laura softly adds some modifiers to her collector which widen its metaphorical maw by a fifth, letting more mana through. After all, the experiment calls for a lot of raw mana, right?

Thanks to symmetry, Eight and Noon's feeds increase correspondingly in lockstep with hers. Eight and Noon feel the feedback and look at her quizzically; Czarnecki doesn't appear to pick up on the change. Laura shoots a look back at them which says "We can do better than this," and applies the same modifiers a second time.

Unperturbed, Czarnecki strolls into the magic circle and installs a small but heavy metal bracket in the circular slot that exists at the centre. Into the bracket, he plants his staff vertically like a flag pole. He says a few magic words of his own, which add the staff to the half-built thaumic system and turn it into the core of a real live "lightning machine", an almost purely thaumic machine designed solely to vent/waste raw mana in a safe way. "Magic effects wash over you," he explains. "You're all feeling this by now. Those of you at the back of the room feel less than those at the front. There's a mild physical equipment response if you know what to look for and there's a mental reaction if you know how to think. These are S -tensor effects. But the reaction is fuzzy. It's like trying to figure out where the Sun is in the sky with your eyes closed, just by feeling which half of your body is warm. I count at least ten conventional senses. And this eleventh sense will indeed allow you to perceive things which cannot be perceived with the conventional ten. However..."

He leaves the fragment hanging, strolls back to the corner where the equipment is stacked up and picks up one last piece of equipment. This is a magic ring as wide as a hula hoop, but substantially heavier and ornately machined. He adds more words to the standing spell, these words completely new to the watching class. This charms the ring. Then he holds it up, pointing it at the class as if it were the frame of an invisible painting. In the empty frame, behind the frame, as if the window were augmenting reality with its own version of events, there is now visible evidence of flowing magic: sharpened streams of white mana linking the core staff with the rings at Noon, Four and Eight, creating what, from above, would take the form of a brilliant magnesium Y. Smaller light effects appear in the gaps between the streams, fluctuating in the air like shock diamonds. Czarnecki moves around the stage, pointing the magic window in different directions, making sure that everybody gets a look.

"Magic is lossy," he says. "Mana transferral and transduction are lossy. These waste emissions are in the chi-band. You have been told two facts in total about chi-band thaumic emissions, what are they?"

"There aren't any," somebody says.

"They don't do anything," somebody else adds.

"You were told that chi-band mana will cheerfully waft through a few metres of solid lead. You were also informed that chi mana is extremely rare. The logical consequence of which, is what? Come on." Czarnecki lays the ring down. "Why is that useful?"

"It means you can--" Laura begins, then stops when Czarnecki whirls around to face her. But he glances back at the class, sees that nobody else is about to jump in, then gestures for her to carry on. "It means you can use a Kovachev oracle like that one to see inside a machine," she says. "While it's running. And you can see how it's working and whether it's working, which means you can diagnose and debug a thaumic system."

The doctor turns back to the audience. "Chi emissions exist almost exclusively as waste products from magic expenditure. Up until now you have been measuring thaumic effects using gut feeling, inertial reactions in Kaprekar linkers and odd bits of old-fashioned, low-accuracy, manual, mechanical devices. Your results have been usable. But the instruments you've used are from a generation now thankfully past and no longer suitable for the needs of modern magic. An oracle scoops up chi particles, transduces them into photons as they pass the mouth and multiplies the photons to make an effective virtual retina. We can now render magical activity into hard numbers at great distances, through solid rock and metal, quickly and reliably and repeatably. You've been sitting there for nearly six weeks thinking 'When is he going to get to--?', well, here we are. Diagnostic power.

"Divination is the core skill of a mage. Oracular spells are numerous, complex and powerful. It's possible to waste arbitrary amounts of time refining them, up to and including your entire professional career. Right." A minor alarm has gone off in Czarnecki's head: whole minutes have now passed without him writing something on the board. He kills power to the oracle ring and props it against the wall. He scribbles out the third correction and its definition on the whiteboard above. "This is now Vidyasagar's Third Incomplete Field Equation. This is a name coming from modesty and cynicism. There is no third error yet, but historical trends suggest we're due. This year or next."

The three trainee mages are still happily running their machine. Czarnecki stares at them for a moment, while still writing. "Are none of you going to speak unless spoken to or are you all in trances? Nobody wants to sit down and take these critically important notes?" That gets a tiny bit of a laugh from the class, but no reaction at all from the 'volunteers'. Czarnecki frowns. He rolls the ring out again, crouches and powers it up while looking through it. He sees the same brilliant white triple flow: stable, minimal harmonics. " Kzarn oppol we xa oerin xa ," he says, switching it over to a different mode which could be called 'Is there something wrong?'

Then he stands up, strides into the magic circle--

*

It's the freezing cold wind which wakes Laura up, not the approaching footsteps. She breathes in once, still lying on her side on the dark glassy ground, then rolls upright and stands. The world is deep glass, a horizontal featureless plane. Not some purified fibre optic blend, transparent to a mile depth, not volcanic obsidian, just regular glass: dirty, and deep black at a metre's thickness. Only the faintest red colouration is detectable. It's a land designed to shatter underfoot and slice your footwear and feet with the pieces, unless you tread softly or wear fat boots which distribute your weight. Or you can just fly. It's night. There's a full Moon and a glittering three-pointed Milky Way, both of which reflect dully off the ground.

The wind is so cold it's razor-sharp. Laura is wearing... well, just clothes, suitable for a temperate to cool climate; indoor clothes and an indoorsy sort of shoes. But she can do better so she moves through an ill-defined blur which summons something warmer, something in the vein of heavily layered robes, with gloves and a hood.

She moves around vaguely, in blips; now she is a mile away to get a different look, now she is back in place, now she is a mile up. She can't go any higher. It is still all glass. The air is still icy on her face. There's faint yellow glow all around the horizon but she knows she could wait and wait and the Sun wouldn't rise. She could try to wait, anyway.

Zhzzzzzz.

It's a fuzzy place, but this fuzziness is all normal. It's an unhappy place, but that's okay.

She still hears the footsteps.

"Laura, take my hand, this is--"

Familiarity. That's okay. But Laura doesn't remember where the familiarity is coming from. The memory of her asking him "How do I know you?" appears in both of their heads, without any sound having been transmitted.

The man is a fixed size, older and bearded. He wears dark brown trousers and a boring blue jumper and his dark brown hair in a dated style. Laura knows these colours even though there's no real light. This oddity passes her by. "What are you wearing?" he asks in return. Her clothes are shifting, inches thick and layered and elaborate. They would take an hour to don and remove if they existed, but they haven't actually been designed or put there. These are just the impressions he receives when he concentrates on her. The name of a thing is the same as the thing.

His name is Dan, Laura remembers. He is her... her... they know each other.

"Do you remember what happened?" he prompts her.

"I don't really know."

There's a buzzing, a locusty zhhrhzrrzrhzrhz as if from a very quiet badly-tuned radio.

Laura blips them across the country in mile bursts, which seems to startle the man. He stumbles around as the geography of the dark glass changes. First it's big glass cuboids with rounded corners, in neat stacks. Then they're in a valley with huge sharpened black glass peaks rising around them. There's a crunch as they land. Why does he stumble? Laura stands him up. Now triangular polygon surfaces, like crystal landscape from some antique videogame. Now a mosaic of tiny hexagonal glass tiles. Dan begins to find his mental footing and starts rippling between locations himself, but he doesn't quite know how he's doing it yet.

"We don't have a lot of time," he says. "Laura, two more people are stranded here. Can you find them? Kzarn eset ." Bright colours seem to pour out of his mouth as he speaks the magic words, but he frowns at the results and waves them away, like bad breath. They aren't what he wants to see. " Kzarn eset . Kzarn uum . This is loco." Now he has a staff in his hand and is trying more words. Elementary charging words, then collector spells and other simple things. The magical equivalent of Three Blind Mice. There are thumps and crackles and sparks. Laura watches and listens with interest. Bigger and more convoluted magical machines dance into existence, hook together and fade out over time. None of it seems to be giving him the results he wants.

"What are you doing?" she asks.

"Laura. Jeremy Willan is here somewhere. Can you find him?"

Saying things and doing things are the same thing, so now they have also found Jeremy. He was found because he was trying to be found. There was no flare, just something that he and Laura mutually made happen. Jeremy is in another part of the world on the glass shore of the glass ocean. He is young, about Laura's age, much taller. The glass is greener here, but the sky is still pitch dark and it is still cold and odd. The horizon is a fraction lighter and there is a faint hzzh on the wind.

"Are we okay? What is going on?" Jeremy asks. He's shivering.

"Why is he cold?" Laura wonders out loud.

"I'm cold," Jeremy says. "I don't know."

"Just be warm."

"I don't know how. I can't get anything to--"

Laura tries to make him be warm but it doesn't work.

I don't feel well, Jeremy has now said. He seems to be icing up.

Dan catches up with them both, out of breath from figurative running. "Do either of you know what happened to Kazuya Tanako?"

"That's not any of our names," Jeremy says, angry. "Why don't you bother to remember our names? Stop calling us 'you' all the time!"

"I do know your names," says Dan. " Dulaku , tolo , ennee ." Again, nothing.

"I'm so cold. We shouldn't be here."

"Kazuya Tanako isn't any of you. He was one of the greatest mages of all time. He died when he was just 25 and this is how. We need to locate Benj. Jeremy, do you remember what happened? Magic doesn't work here."

"Are we in trouble?" asks Jeremy, teeth chattering.

"Do you see shelter? Water? Food?" says Dan. "Do you feel welcome? No equipment, no rules. We need to locate Benj."

Laura stops trying to heat Jeremy up, and instead shows Jeremy how to warm himself. Jeremy makes himself some clothes and now he is warm. This is good!

"Laura, where is Benj?"

Laura tries to point, but Benj doesn't want to be found and resists being pointed at directly. But that is a naive way to hide. By feeling the strength of repulsion, Laura can guess his direction. Blip blip blip.

It takes them a long time to reach sight of him, and then it feels like they're running on the spot while he runs on the spot too and runs away. They spend a long time looping around, running and not getting anywhere. Delays and delays.

Jeremy builds a new Benj instead, who just stands there with them, blank. That's better. "I get it now," Jeremy says. The real Benj keeps running away and soon is gone.

"No, he should be Benj," says Laura. "Not just look like Benj."

She does something and Benj wakes up inside the Benj body. "Hello?" he asks.

Jeremy wonders why Benj was running away. From what? Dan checks his wristwatch, but all he learns from it is that he is still wearing a wristwatch. The light on all horizons is brightening. He glances at the sky and does some brief trance work, muttering odd syllables which just drip onto the floor like paint, but which may possibly prepare his mind for a rough re-entry. "Did you ever see a man get hypnotised to forget the number seven exists, then try to count to ten?" he asks nobody in particular. "Derive the existence of seven from first principles and talk to me about thinking outside of the box. Let's try the falling reflex."

A cubic mile of glass below them disappears. They plummet into the chasm; then it slams closed, a tectonic movement of broken glass crushing them to shreds.

ZHRZHZZHRRRHRHRZZZZ

*

--kicks his staff out of the bracket and breaks the spell in half, scattering mana backwash over the three trainee mages like hot coffee.

All three of them fall, rings dropping out of their hands. The magic circle is too wide; Czarnecki can only catch the person nearest to him, who happens to be Jeremy. "Stay where you are," he advises them. "Don't get up, just sit down here and wait. You," - now he points at the student on the far left at the front row of the class - "go to that red telephone on the wall, dial eight zero four zero and ask for Dr Neal Marek to come down here. Everybody else, please stay in your seats for a second. You can all leave once Dr Marek has arrived, I don't want him struggling through all of you on the way in. We're finished for today."

Ten minutes later the lecture theatre is empty except for the five of them. Czarnecki has attached a segment of his staff to the Veblen pump and is flaring off the accumulated mana, prior to a proper shutdown. It's taking longer than it should. "This is a lot of energy," he says, partly to himself. "Three or four weeks' rent for a basic mage. At a guess."

Dr Neal Marek is about fifty-five, with a full grey beard and thin-rimmed varifocals. He is the deputy head of department. He has already had some words with Czarnecki, and he has already taken some notes in a fat A4 hardback notebook. Now he focuses on the three students, seated in the otherwise empty front row. They aren't actually in shock, but look like hell. "Tell me exactly," he says.

"I don't remember anything," Benj begins. "I just woke up falling on my face. Must have fallen into a trance while casting. I've got nothing."

"Laura committed us to too much mana," says Jeremy.

"Benj, how much mana do you have left right now? All bands."

"Nothing," says Benj.

"Running out that fast could easily have sent you to sleep. Basic exhaustion."

"I don't remember anything."

"That's normal, don't be concerned about it. Jeremy?"

"I'm tapped too," says Jeremy. "I can tell it's going to be a few days."

"And Laura?"

"I used a collection multiplier," says Laura, and recites the spell in regular words. Marek nods and takes some notes. "I used it several times."

"How many times?" Marek asks.

"I... don't remember."

"Do you mean you lost count?"

"...Yes." Laura slips a pair of thick grey rings off her right arm and hands them over to Marek. "I use storage. Most nights before bed I unwind all the mana I've got left into these rings. They're modified Montauk sinks. They're paired, like electrodes of a battery, so try not to touch them together too much. They'll take any type of mana. They're not as full as they have been historically. At one point I had to wear them on opposite wrists to keep them far enough apart. But I use a lot of mana for coursework and practice these days, so..."

Dr Marek tucks his notebook under an arm and inspects the two rings, pinging them thoughtfully.

"Because it's just a waste to leave mana ambient," says Laura, to fill the silence. "Every second it sits there, it's doing nothing. So I save it, why would anybody not save it?"

"Very interesting. I can't tell how much energy they contain without direct inspection," says Marek. "But this is the equivalent of a few tonnes of TNT."

"Tonnes?" says Benj.

Laura hurriedly interjects, "Sure, but, you see, it's impossible for all of that to be vented at once--"

"And that's now," Marek continues. "Not before."

"I don't-- I didn't do anything wrong. The demonstration needed a heavy concentration of mana. What happens when you run out of mana? You run out. The experiment stops! I didn't do anything! Why did we all end up in my dream?"

"I don't remember anything about a dream," Benj repeats.

"There was this big dark planet," says Jeremy, "like a big-- marble. I can't remember. We were all there."

"The more I think about it, the more detail slips away from me," says Laura.

"It wasn't a dream," says Marek. "For one thing, whether you remember it or not, you were all in it together. For another, I've had it before. Laura thinks it was her dream-- she's had it before. So have other mages. It has several different names. 'Tanako's world' is as good as any. As for what it actually is: we, mages collectively, do not know. To the extent that it's a dream, it's a bad one. To the extent that it's a world, it appears to be fictional. All we do know is that magic is incredibly complicated, magic heavily involves the human brain and the human brain is even more incredibly complicated. The best theories say it arises from training our brains the way we do. All of us do essentially the same meditation exercises, which means we have a lot of common mental ground. And so some sort of link occurs."

"But how come we've never heard about it?" Jeremy asks.

"Because you haven't been doing magic for long enough. You were going to hear about it in your third year. It's right here." He flicks through his notebook and produces a high-level schedule for the whole Thaumic Engineering syllabus, a 16-page paper booklet. He opens it to the relevant page and hands it over to Benj. "It's not a secret. Three years from now, I hope you'll all be qualified to help us pursue the question. Or, better yet, we'll have an answer before then."

Benj hands the syllabus to Jeremy. Jeremy reads it, and hands it to Laura. She reads it.

"Is it dangerous there?" she asks.

There is an unsettlingly long pause. Marek glances over his shoulder at Czarnecki. Czarnecki is completely expressionless.

"Yes," says Marek.

"Kazuya Tanako died of a stroke. Did he die... there?"

"Yes."

"So I'm having dreams that could kill me?"

"No. Not unless you're habitually sleeping inside a hundred-kilothaum Dehlavi lightning machine. And even then--"

"But he put us in a hundred-kilothaum Dehlavi lightning machine today!" cries Benj, pointing.

"Again, no."

"If he knew the experiment was dangerous why didn't he warn us beforehand?"

"Because Dr Czarnecki wasn't following procedure."

"What?" says Czarnecki. He looks up, suddenly angry and embarrassed.

"He should have made sure that none of his students had brought dangerous foreign objects into the system. He should have paid closer attention to his students while they were casting. He should have realised that something was wrong sooner and, yes, he should have warned you up front." Marek says all of this without even turning around.

"About what? What the hell, Neal? You're doing this in front of them?"

"There was more than one mistake made today, Dan. I want all of us to understand all of those mistakes."

"She got them into it! That ring-couple is close to undetectable! I don't have to listen to this."

"Actually, you do. That machine needs draining safely and it isn't going to do that by itself and it'll take a little while."

There's a heated pause.

"One of the purposes of the experiment," Marek continues, "was to-- safely-- demonstrate, ah, 'low-energy high-energy magic', and introduce some of the safety concerns associated with it. If procedure had been followed, it would have been perfectly safe. As for what Dr Czarnecki did right: while he was setting up the experiment, he verified that all the raw mana held by everybody in the room combined couldn't have crossed the threshold of danger. That's by the book. When he did realise something was wrong, he quickly determined the problem and was decisive in resolving it. And he got all three you out of Tanako's world very quickly, which is a testament to his skill."

Czarnecki glowers.

"Benj, did you notice that you were running low?"

"I did. It happened fast, though--"

"Were you told to say something if that happened?"

"I-- yes."

"Then you should have said something," says Marek. "Jeremy, did you notice when Benj dropped out?"

"He didn't fall over or anything..."

"His eyes would have closed and he would have been visibly unsteadier on his feet. Like a sleepwalker. Also, Laura would have taken over his iota supply when it dropped."

"I didn't notice any of that."

"Then you should have paid closer attention. You also should have said something when Laura started using unwarranted collection multipliers."

Jeremy holds his hands up, the gesture that means "Fine".

"Laura--" Marek begins.

"I should have paid closer attention to Benj and Jeremy. I shouldn't have--"

"Shut up."

Laura shuts up.

"Laura, you know what you did wrong. What are these?"

"They're modified Montauk sinks--"

"Where did you get them?"

"My mother taught me how to manufacture them."

"Did she teach you how to use them?"

"...Apparently not," Laura concedes.

"Did she warn you about high energy magic? Did she warn you about Tanako's world or how to break out of it?"

"No."

"How often do you bring your own equipment to labs?"

Laura is silent, but Czarnecki speaks: "That must be why your results from Friday were gibberish. Equipment that advanced is designed to suppress exactly the kind of interference you were supposed to be measuring."

Marek summarises: "You brought foreign objects into a magic circle; you altered an experiment on the fly without consulting your teacher; you either didn't notice or ignored or were unable to help your fellow students when they got into trouble. You assumed you knew what you were doing, when in fact there are things you don't know."

"I'm done here," says Czarnecki, pulling the fragment of staff out of the machine and letting it switch itself off. Its background hum cuts out, leaving a conspicuous silence. He returns to the front of the stage.

"Accidents happen," says Marek, tossing the Montauk sinks back to Laura one at a time. "Almost every lab accident could result in fatalities if carried to its logical extreme, including this one, but in the vast majority of cases it's not a big deal, including this one. Accidents happen, they're part of the learning process. But so is learning from your mistakes." He nods at Benj and Jeremy, "You two can go. I think you've got the point. Laura: I want this lesson learned. You're going to come and see me first thing next Monday morning and pass a TES-3 practical exam."

"That's a third-year high-energy magic safety course," says Czarnecki. "She doesn't know how to pass it."

"Then you should both get to work," says Marek, making one final note. "I'll see you next week." He leaves.

There's an echoing clang from the door closing behind him, then silence. Czarnecki prowls around the theatre, putting equipment away, wiping the boards clean, and generally avoiding making eye contact with Laura. Eventually he loses it. "That was--"

"Unprofessional," Laura suggests.

He glares at her. Then he visibly relaxes, as if defused. It's disconcertingly sudden. "Thank you. I was going to say 'typical'. There's a story. I'm not going to tell it to you now. What's your university email ID?"

" ltf15 ."

"I'll book us some lab time and email you when I have a slot. It's going to be early in the morning. Go to the library and check out Parasara's Thaumic Engineering Safety. You already know section 1; read as much of 2 and 3 as you can before tomorrow."

"Understood." Laura collects her coat and bag and hurries for the door. "I'm sorry."

"No, you're just embarrassed," says Czarnecki. "You don't know how badly we're being punished for this. By Monday you'll be sorry."

"You've done TES-3?"

Czarnecki nods.

"What's wrong with it?"

"Have you ever found magic boring?"

Laura shakes her head.

Czarnecki smiles humourlessly. "You really do have a lot to learn. See you tomorrow."