Physics and logic

What we ran

Seventy takes in three bins. Thirty chain reactions, stepped from two links up to seven. Twenty mirror and reflection tests. Twenty takes where the prompt names a number.

Every take was checked frame by frame, not watched. I built an eight-frame strip across the full duration of all 70 clips with ffmpeg and read every one. Where the answer lived in a moment — a marble arriving at a cup, a bell being struck, a coin entering a jar — I went back and pulled six more frames across the last two seconds. For the counting bin I pulled full-resolution stills at two or three timestamps and counted what was on screen. Two checks were measured rather than eyeballed: the rope in n58 by pixel span, and the neon text in n48 by flipping the frame on each axis to see which one made it readable.

What happened

Chain length is not what breaks it. Fourteen of the thirty chain takes delivered every beat the prompt asked for. Broken out by declared steps: 2 of 5 at two steps, 4 of 5 at three, 2 of 5 at four, 2 of 5 at five, 1 of 5 at six, 3 of 5 at seven. The seven-step row scored higher than the two-step row. n2 — "Wind slams a door; the candle on the table goes out" — is two beats long and fails: the door slams by 2.1s and the candle is still burning in the last frame at 5.0s.

What breaks is a particular kind of beat: a small object arriving somewhere precise. It is the same failure four times over. In n11 — "A ball topples dominoes that trip a lever that drops a marble into a teacup" — the ball, the dominoes and the lever all fire correctly. The marble is airborne above the cup at 8.8s, at the rim at 9.1s, and gone at 9.4s. The cup is empty for the rest of the take. In n25 the marble rolls the groove to the light switch, reaches it at 9.2s, and has vanished by 10.0s without moving the switch. In n17 the coin does fly at the jar — and ends up as a tan disc pasted flat on the glass. In n5 — "A cue ball rolls the length of the table and sinks the eight ball" — the eight ball drops at 2.92s, is back at the pocket lip at 3.56s, and by 4.2s the ball in the pocket is numbered differently.

1A ball topples dominoes that trip a lever that drops a marble into a teacup.

The second habit is cutting around the causal link. n4, n10, n29 all stage every prop and then jump between them, so what you get is the board's own phrase: nice pictures of things happening near each other. n29 staged a tire swing, an awning, a seesaw and a pebble, then used none of them — the paper simply lands on the awning and later appears on the doormat.

Mirrors held in 12 of 20. The eight that failed all failed the same way: the reflection is painted as scenery rather than computed from the subject. n49 proves it cleanly — the canal mirrors the towpath, the brick, the bridge arch and the bicycle, and leaves the rider out. n37 never puts the motorcycle in the mirror at all; at 4.6s the bike is level with the car and the glass shows empty road. n45 puts the cyclist's reflection about four metres ahead of him along the shopfront. n50 reflects a different man in different clothes.

1A canal mirrors a cyclist riding along it; both cross a bridge's shadow at once.

Where it wins, it wins on hard optics. n41 renders a spoon's concave bowl genuinely inverted — ceiling lights low, checkered floor high. n39 puts the reflected bird at the same horizontal position as the real one. n42 does exactly what an impossible prompt asked and keeps the departing figure only in the glass.

1A spoon reflects the diner upside down, correctly, as it is raised.

Counting is the weakest of the three. Nine takes name a number I could count on screen. Four came out right. Six slices in n52 at 0.4s and still six at 4.8s. Eight slices in n61, decremented one at a time across twenty seconds, tray exactly empty at 19.8s. Three glasses in n62. Three rope pieces in n58.

The failures cluster above eight. n65 — "Ten coins stacked, knocked over, and all ten are on the table" — I count thirteen coins at 9.9s. n60 — "Twelve balloons released; twelve balloons rise" — twelve on the ground at 0.4s, fifteen against open sky at 9.8s. n70 — a carton "of exactly twelve" — twelve empty cups, eight eggs in the bowl. n54 asks for four hands of thirteen; the bottom hand holds five cards. Quantity drifts in both directions, and it drifts once the objects separate and there is nothing left to hide behind.

n58 is the one measured case. Three pieces, correct count. Measured against the uncut original lying beside them: 391 + 523 + 407 = 1321 pixels against 1625. A sixth of the rope is missing.

Notable takes

n26 | Seven-step breakfast machine | Every beat lands in order — weight drops and toast launches at 5.78s, kettle tips at 8.54s, jam swings in at 14.06s, plate arrives at the chair at 19.59s.

1A full breakfast machine: alarm rings, weight drops, toast launches, a lever tips the kettle, tea pours, jam swings in on a spoon, and the plate slides to a stop in front of the chair.

n22 | Six-step door slam to pigeons | Orange leaves the shelf, takes the ramp, crosses the floor, tips the scale pan, seed pours at 10.49s, pigeons feed at 14.59s.

1A door slam shakes a shelf; an orange rolls off, down a ramp, across the floor, into a scale pan that tips and pours seed; pigeons arrive.

n41 | Spoon, inverted correctly | Concave optics done right, in a bin where most models paint a blob of chrome.

n49 | Canal reflects the bike, not the rider | The single clearest picture of what reflection failure actually is here.

n11 | The marble that never lands | Three of four steps perfect, then the payload vanishes between 9.1s and 9.4s.

n65 | Ten coins, thirteen on the table | Counted at full resolution on the final frame.

What this means if you're prompting FLUX.3

Write long chains. Seven steps is not the problem, and the model is unusually good at holding a machine together — n26 and n22 are better than the field.

Do not make the last beat a small object arriving in a container. Marbles into teacups, coins into jars, dominoes onto bells — that is the exact inch where it drops things. Make the payoff big and visible instead: a hat landing on a statue's head works (n14), a gate opening and chickens walking out works (n18).

For mirrors, prompt the reflection as its own subject and say what it must contain. Ask for a reflection that merely "matches" and you get wallpaper. n42 got an impossible reflection right because the prompt described the reflection, not the object.

Keep counts at eight or below and pin them to a shape — slices of a round thing, glasses in a row. Above ten, do not ask; either crop so the number is off screen, or say "a handful" and let it improvise.

1A pizza's eight slices taken one by one until the tray is exactly empty.