You hold your smartphone in your right hand on a Sunday evening. You look at a screen that asks you for a specific number. You provide your current weight as a starting point. You provide a goal weight as a destination. You choose a target date in the future for a social event. The date is away. It is the anniversary party for your sister.
The software processes your data in a fraction of a second. It performs a calculation based on simple division. It produces a blue diagonal line that connects your two numbers. The line starts at the present moment and ends at the date of the party. This line represents a path of perfect progress. It suggests that change happens at a constant rate.
You feel a sense of relief when you see the graph. The image provides a sense of order. It makes the future look manageable. You believe that the line is a map of your upcoming experience. The software has taken your hope and turned it into a geometry. This geometry has the authority of a mathematical fact.
The line is an interpolation. Interpolation is the act of inserting intermediate values between two points. The software does not know how a body functions. It knows only how to divide a total into equal parts. It
