Harry Potter and the Methods of Rationality

She came to the classroom and her fingers slipped on the doorknob at first, too sweaty, she grabbed harder and the door opened -

- in a single flash of perception she saw Harry staring at a small pink rectangle on the table in front of him -

- as a few paces away the tiny black thread, almost invisible from this distance, supported all that weight -

'Harry get out of the classroom!'

Pure shock crossed Harry's face, and he stood up so fast he almost fell over, stopping only to grab the small pink rectangle from the table, and he tore out of the door, she'd already stepped aside, her wand was already in her hand coming up pointing at the thread -

'Finite Incantatem!'

And Hermione slammed the door shut again, just as the gigantic crash of a hundred kilograms of falling metal came from inside.

She was panting, gasping for air, she'd run all the way here without stopping, she was soaked in sweat and her legs and thighs burned like living flames, she couldn't have answered Harry's questions for all the Galleons in the world.

Hermione blinked, and realized that she had started to fall, and Harry had caught her, and was lowering her gently to sit on the floor.

'...healthy...' she managed to whisper.

'What?' said Harry, looking paler than she'd ever seen him.

'...are you, feeling, healthy...'

Harry started looking even more frightened as the question sank in. 'I, I don't think I have any symptoms -'

Hermione closed her eyes for a moment. 'Good,' she whispered. 'Catch, breath.'

That took a while. Harry was still looking scared. That was good too, maybe it would teach him a lesson.

Hermione reached into the pouch Harry had bought her, whispered 'water' through her parched throat, took out the bottle and drank in great huge gulps.

And then it was still a while before she could talk again.

'We broke the rules, Harry,' she said in a hoarse voice. 'We broke the rules.'

'I...' Harry swallowed. 'I still don't see how, I've been thinking but -'

'I asked if the Transfiguration was safe and you answered me!'

There was a pause.

'That's it?' Harry said.

She could have screamed.

'Harry, don't you get it?' she said. 'It's made out of tiny fibers, what if it unraveled, who knows what could go wrong, we didn't ask Professor McGonagall! Don't you see what we were doing? We were experimenting with Transfiguration. We were experimenting with Transfiguration!'

There was another pause.

'Right...' Harry said slowly. 'That's probably one of those things they don't even bother telling you not to do because it's too obvious. Don't test brilliant new ideas for Transfiguration by yourselves in an unused classroom without consulting any professors.'

'You could have gotten us killed, Harry!' Hermione knew it wasn't fair, she'd made the mistake too, but she still felt angry at him, he always sounded so confident and that had dragged her unthinkingly along in his wake. 'We could have spoiled Professor McGonagall's perfect record!'

'Yes,' said Harry, 'let's not tell her about this, shall we?'

'We have to stop,' Hermione said. 'We have to stop this or we're going to get hurt. We're too young, Harry, we can't do this, not yet.'

A weak grin crossed Harry's face. 'Um, you're sort of wrong about that.'

And he held out a small pink rectangle, a rubber eraser with a bright metal patch on it.

Hermione stared at it, puzzled.

'Quantum mechanics wasn't enough,' Harry said. 'I had to go all the way down to timeless physics before it took. Had to see the wand as enforcing a relation between separate past and future realities, instead of changing anything over time - but I did it, Hermione, I saw past the illusion of objects, and I bet there's not a single other wizard in the world who could have. Even if some Muggleborn knew about timeless formulations of quantum mechanics, it would just be a weird belief about strange distant quantum stuff, they wouldn't see that it was reality, accept that the world they knew was just a hallucination. I Transfigured part of the eraser without changing the whole thing.'

Hermione raised her wand again, pointed it at the eraser.

For a moment anger crossed Harry's face, but he didn't make any move to stop her.

'Finite Incantatem,' said Hermione. 'Check with Professor McGonagall before you try it again.'