Harry Potter and the Methods of Rationality

Aurors on fast racing broomsticks angled out of the sky, diving straight down toward them, faint sparks of light already blazing downward as the first shots were fired.

Listen up!

'Protego Maximus!' shouted Bellatrix in a mighty, cracked voice, followed by a cackling laugh as a shimmering blue field surrounded them.

You see this?

From the decaying pit in the center of Azkaban, over a hundred Dementors rose into the air, appearing to some as a great mass of corpses, a flying graveyard; appearing to another as a conglomerate of absences that seemed to form one vast rip in the world as they slid upward.

This...

The voice of an ancient and powerful wizard bellowed a terrible incantation, and a great blast of white-golden fire shot out of the hole in Azkaban's wall, shapeless for only a moment before it began to form wings.

Is...

And the Aurors activated the Anti-Anti-Gravity Jinx that had been built into the wards of Azkaban, disabling all flying spells whose enchantment had not been cast with the recently changed passphrase.

The lift on Harry's broom switched off.

Gravity, on the other hand, stayed on.

Their broom's upward rise slowed, started to decelerate, began the process of turning into a fall.

My...

But the enchantments that kept the broom pointed in a direction and allowed steering, the enchantments that kept the riders attached and somewhat protected them from acceleration, those enchantments were still functioning.

BROOMSTICK!

Harry hit the ignition switch on the General Technics made, model Berserker PFRC, N-class, ammonium perchlorate composite propellant, solid-fuel rocket that had been mated to his Nimbus X200 two-person broomstick.

And there was noise.

Chapter 59: TSPE, Curiosity, Pt 9

Broomsticks had been invented during what a Muggle would have called the Dark Ages, supposedly by a legendary witch named Celestria Relevo, allegedly the great-great-granddaughter of Merlin.

Celestria Relevo, or whichever person or group had really invented those enchantments, hadn't known a darned thing about Newtonian mechanics.

Broomsticks, therefore, worked by Aristotelian physics.

They went where you pointed them.

If you wanted to move straight forward, you pointed them straight forward; you didn't worry about keeping some of the thrust going downward to cancel out the effect of gravity.

If you turned a broomstick, all of its new velocity was in the new direction of pointing, it didn't go sideways based on its old momentum.

Broomsticks had maximum speeds, not maximum accelerations. Not because of anything to do with air resistance, but because a broomstick had some maximum Aristotelian impetus its enchantments could exert.

Harry had never explicitly noticed that before, despite being dextrous enough to get the best grades in flying class. Broomsticks worked so much like the human mind instinctively expected them to work that his brain had managed to entirely overlook their physical absurdity. Harry, on his first Thursday of broomstick lessons, had been distracted by more interesting-seeming phenomena, words written on paper and a glowing red ball. So his brain had simply suspended its disbelief, marked the reality of broomsticks as accepted, and proceeded to have its fun, without ever once thinking of the question whose answer would have been obvious. For it is a sad fact that we only ever think about a tiny fraction of all the phenomena we encounter...

That is the story of how Harry James Potter-Evans-Verres was almost killed by his own lack of curiosity.

Because rockets did not work by Aristotelian physics.

Rockets did not work like a human mind instinctively thought a flying thing should work.

A rocket-assisted broomstick, therefore, did not move like the magical broomsticks upon which Harry was such a very good flyer.

None of this actually went through Harry's mind at the time.

For one thing, the loudest noise he'd ever heard in his life was preventing him from hearing himself think.

For another thing, accelerating upward at four gravities meant that he had around two and a half seconds, total, to go from the bottom to the top of Azkaban.

And even if they were two and a half of the longest seconds in the history of Time, that wasn't enough room to do much thinking.

There was time only to see the lights of the Aurors' curses arrowing down at him, slightly angle the broomstick to avoid them, realize that the broomstick was simply continuing on with mostly the same momentum instead of going in the direction he pointed it, and activate the wordless concepts