Stella's Word List

The list from the back of my planner. Every word I met that term that I didn’t know, and what it means, in my own words, because a definition in somebody else’s words hasn’t really been caught yet.

Activation energy

The hill between two valleys. Even when a reaction would end up lower, the molecules have to be knocked over a hill first, and most collisions aren’t hard enough.First met in Chapter 6, No Signal

Best guess

Ada’s third margin mark. It fits the evidence, but it hasn’t been properly tested yet, or there are rival explanations. Not the same as a wild guess. A best guess is where you look first. Press the mark wherever it appears for the evidence, and why it isn’t settled yet.

Bolide

A meteor so big and bright it’s basically a fireball. Sometimes bits of it reach the ground. Ours did.

Carbonaceous chondrite

The most precious kind of meteorite: dark, crumbly, full of carbon compounds and hardly changed since before the Earth existed. Ruined by rain. Never touch one with your hands.First met in Chapter 8, Rain at Two

Catalyst

Something that makes a reaction go faster without getting used up, by holding the molecules close together and the right way round. Every enzyme in you is one. Mr Pell says good librarians are one too, for reading.First met in Chapter 6, No Signal

Chloramines

The real cause of the “chlorine smell” at a swimming pool. Chlorine plus things people bring into the water. I wish I didn’t know this.First met in Chapter 2, The Pool

Chondrule

A tiny round grain inside some meteorites: a droplet that melted and froze in the dust cloud the Sun was born in, before there were planets. Also the name of Dr Catchpool’s dog.First met in Chapter 14, Gated

Code-switching

Changing from one way of talking to another depending on who you’re with. Dr Okafor swearing and then sounding like the news, a few minutes apart.First met in Chapter 16, Like, Literally

Complementary

Fitting something the way a key fits a lock, or a footprint fits a foot. Copy the copy and you get the original back.First met in Chapter 9, The Impossible Number

Covert prestige

The status nobody admits they’re after: sounding rough-edged and local on purpose, because that’s what counts with your friends.First met in Chapter 16, Like, Literally

Derivative

How fast something is changing at one exact instant: the slope of its curve right there. Speed is the derivative of position. Found by taking shorter and shorter time slices, which is a limit.First met in Chapter 17, The Shape of Falling

Drag

The water pushing back. Goes up with speed squared, so trying harder is the most expensive way to go faster.First met in Before You Begin

Emergent

True at one scale and invisible at the scale below. You’d never find natural selection by staring at one molecule, or who won a race by listing every atom in the pool.First met in Chapter 5, The First Lie

Endotherm

An animal that burns fuel to keep itself warm all the time: mammals and birds. Expensive. Worth it on frosty nights.First met in Chapter 14, Gated

Entropy

A count of how many ways a thing can be arranged. Things end up where there are the most ways to be, which is why blueberries end up all over the table.First met in Chapter 5, The First Lie

Epigenetics

Small chemical marks on genes that life can leave, and that are sometimes passed on. Real in some plants and worms, argued about in humans, and nothing like inheriting your mum’s swimming training.First met in Chapter 18, The Counties

Equilibrium

When everything’s still moving but nothing’s changing. Like the Year 7 common room.First met in Chapter 6, No Signal

Eukaryote

A big cell with a nucleus and little power stations inside, like mine. Every plant, animal and mushroom is made of them.First met in Chapter 15, A Pound Owed

Filler

A sound that holds your turn while you think: um, er, like. Everybody uses them, and a few even help. Too many, and nobody else can get a word in, and the word you were getting to is buried. Thirty-one in two minutes is too many. Count your own.First met in Chapter 16, Like, Literally

Gated

Confined to school grounds, which at Stanbury also means signing in with Mrs Ashdown every two hours, like a prisoner on parole. The first definition I have ever not enjoyed writing.First met in Chapter 14, Gated

Integral

Adding up infinitely many infinitely thin slices: the area under a curve. The integral of speed over time is the distance travelled. The long S is for sum.First met in Chapter 17, The Shape of Falling

Limit

The number something gets closer and closer to, as you push something else further and further, without it ever having to get there. (1 + 1/n)ⁿ has the limit e.

Literally

Not a figure of speech: it actually happened. “She literally fell asleep in the exam.” The test is to take it out: if the sentence is still obviously a figure of speech, the word was only taking up room. It’s the only word we have for this, so it’s worth not wearing out.

LUCA

The Last Universal Common Ancestor: the most recent population of cells that everything alive today descends from. Not the first life. Just the last one everybody shares.First met in Chapter 12, The Minibus

Meteorwrong

A stone somebody thought was a meteorite, which isn’t. Most of them. Ours was kiln rubbish from 150 years ago. Finding one out is still finding something out.First met in Chapter 19, The Letter

Mitochondria

The power stations in your cells. They used to be bacteria, two billion years ago, and they still have their own DNA to prove it. Training makes you grow more.First met in Chapter 12, The Minibus

Momentum

Mass times speed. To get the same push through the water, move a lot of water slowly, not a little bit quickly: same momentum, half the wasted energy.First met in Chapter 2, The Pool

Nucleus

The tiny centre of an atom, made of protons and neutrons, tens of thousands of times smaller across than the atom but holding nearly all its weight. The number of protons in it decides which element the atom is: six for carbon, eight for oxygen. (Cells have a nucleus too, a different thing with the same name, meaning ‘kernel’.)First met in Chapter 5, The First Lie

PB

Personal best. The fastest you have ever swum that race. Better than a medal, some days.First met in Chapter 18, The Counties

Quantum mechanics

The description of how very small things, like electrons in atoms, behave, worked out in the 1920s. Its equations give where an electron is likely to be found and which energies it can have: only certain ones, like the notes a guitar string can ring at. Those allowed energies are why one proton more or less can change an element completely.First met in Chapter 5, The First Lie

Received Pronunciation

The posh accent. Only a few people in every hundred in Britain actually speak it. Not the same thing as Standard English.First met in Chapter 16, Like, Literally

Register

One of the different ways you talk: to friends, to teachers, to a dog. Not the attendance kind.

Seen

Ada’s first margin mark. Somebody has observed or measured it directly, and other people have done it again and got the same answer. Press the mark wherever it appears to see who saw it, how, and where.

Standard English

Grammar and words, not an accent. “I was”, not “I were”. You can speak it in any accent there is.First met in Chapter 16, Like, Literally

Streamline

Arms squeezed behind your head, hands stacked, head between your arms, doing nothing. The fastest you’ll go all length is right after you push off in one.First met in Chapter 2, The Pool

Terminal velocity

The speed a falling thing ends up at, when the air pushing up is as strong as its weight pulling down, so it stops speeding up. About 110 km/h for a stone the size of a walnut.First met in Chapter 11, Sixteen

Torpor

What hummingbirds do at night: let their body temperature drop a long way, so they don’t burn all their fuel before morning.First met in Chapter 14, Gated

Vesicle

A tiny hollow bubble made by fatty acids in water, all by themselves, because it’s the most likely way for them to end up.First met in Chapter 8, Rain at Two

Wave drag

The energy you waste making waves when you swim on the surface. Half a metre down, it disappears. That’s why the fifteen-metre line exists.First met in Chapter 18, The Counties

Worked out

Ada’s second margin mark. Calculated or inferred from things that were measured, but nobody watched it happen. Not second best: nobody watched the Earth form, but its age is pinned down anyway, because lots of different clocks agree. Press the mark wherever it appears to see what was measured and how the rest was worked out.