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A Century of Fast

Three short lessons on the Olympic 100 m freestyle since 1908: the winners on a chart, a straight line against a curve, and why every line says something silly about the year 2100.

Spark & Whetstone · sparkwhetstone.org/learn/a-century-of-fast · CC BY-NC-SA 4.0. Answers are at the end, so you can try each question first.

Lesson 1. The Olympic century

Twenty-seven Olympic Games have crowned a men’s 100 m freestyle winner since 1908. Charles Daniels won in 65.6 seconds; Pan Zhanle won in Paris in 46.40. Before 1972 times were kept only to the tenth, so the early points are a little rounded.

The early Games used open water, odd pools and no lane ropes, and 1896 (in the sea) and 1904 (in yards) are left out because they were not the same race. Any chart starts with choices like these.

Question. Between 1908 and 2024 the winning time fell from 65.6 to 46.40 seconds. By about how much?

  1. About 19 seconds
  2. About 46 seconds
  3. About 9 seconds

Say it back. In your own words: why were the 1896 and 1904 races left off the chart?

Lesson 2. Lines and curves

Draw a straight line through the 27 points and it falls about 0.15 of a second a year. It fits well — r² about 0.95.

A curve that drops and then levels off fits a little better, r² about 0.97, and levels near 37.4 seconds. Where it levels is the curve’s guess, not a fact: the data stop in 2024, and nobody knows where the floor is.

Question. The line falls about 0.15 of a second a year. Over the 16 years from 2008 to 2024, how much does the line say the winning time falls?

  1. About 16 seconds
  2. About 0.15 seconds
  3. About 2.4 seconds

Say it back. In your own words: why is the curve’s floor a guess and not a fact?

Lesson 3. The trouble with 2100

Carry the straight line forward and it says the 2100 winner swims about 33 seconds, and that the winning time reaches zero in 2317. Nobody can swim a hundred metres in no time, so the line stops being a good model long before then.

The curve says about 41.7 seconds in 2100 — kinder, but still a guess made from one century of numbers. A model is a short summary of the past. Use it to ask good questions about the next Games, not to promise an answer.

Question. The line and the curve each give a number for the 2100 winner. What is the most honest thing to say about those numbers?

  1. The line is the safer forecast, since straight trends usually hold for another century
  2. The curve is right, because it fits the past better
  3. Both are guesses from one century of numbers; neither is a forecast

Say it back. In your own words: what should you trust, and not trust, about a line drawn through the past?

At the table: Draw the century

Players: Two or more, 10 and up. You'll need: Graph paper, a ruler, a pencil, the list of 27 winning times (in the course guidebook or on SplitForge).

  1. Draw years across (1900 to 2040) and seconds up (40 to 70), and plot the 27 winners.
  2. Each person draws the line or curve they believe, and marks a guess for 2028.
  3. Say why you drew what you drew. Write the guesses down with today’s date.
  4. After the 2028 Games, take the paper out and see whose shape held up.

Answers

  1. About 19 seconds — 65.6 − 46.40 = 19.2 seconds over 116 years.
  2. About 2.4 seconds — 16 × 0.15 = 2.4 seconds. The real winners fell only 0.81 (47.21 to 46.40) — one reason a flattening curve fits the recent Games better.
  3. Both are guesses from one century of numbers; neither is a forecast — Both shapes summarise 1908 to 2024. A closer fit to the past makes the curve a better summary, not a promise about 2100.