The photograph that settles a race is not a picture of the finish. It is a picture of the finish line, and nothing else, taken over and over.
A photo-finish camera does not see the track. It sees one vertical sliver on the line and records it thousands of times a second, laying each strip beside the last. It looks like a photograph because the eye wants it to be one. Left to right is not distance. It is time. Every runner in the frame is in the same place, at a different moment.
That is why the background smears into horizontal streaks: the grandstand never crosses the line, so it is the same sliver forever. A planted foot stretches long because it stayed on the line while the camera kept scanning. Fast is narrow and slow is wide. A runner who stopped on the line would fill the whole picture.
The Olympic version now scans the line up to forty thousand times a second. At the 2012 US trials, a camera running at three thousand had Allyson Felix and Jeneba Tarmoh crossing in 11.068 seconds each. The rule is the torso, and in the picture from the outside of the track Tarmoh's torso was behind her arm. The timing official offered an estimate from her bib and bicep. The referee refused it — an interpolation is not a fact. Dead heat. A run-off was arranged. Tarmoh withdrew.
The ordinary language is all about proximity. A nose ahead. Neck and neck. Side by side. In the one document that decides, nobody is beside anyone. Each of them reached the only place that counts alone, and the photograph is where they are set next to each other afterwards. A dead heat is not two bodies level. It is two bodies in the same column.