English: "Illustration of the splicing procedure used to create a probe tuple for the physical concept of ‘unchangeableness’ as seen in Supplementary Fig. 4. Probe tuples consist of two possible videos and two impossible videos. The possible videos are created by running a physics engine with related initial conditions (for example, same objects but different positions). Importantly, videos are constructed so that they share a frame in common (centre image). The segments before this shared frame are called the ‘start segments’ (left) and the ones after are called the ‘end segments’ (right). Thus, to create any probe, we can gather frames from a start segment, add the common frame and add frames from an end segment. Possible probes (green arrows) are formed by starting and ending at corresponding start and end segments (for example, start segment A to end segment A). Impossible probes (red arrows) are formed by using a mismatched end segment (for example, start segment A to end segment B). This design ensures that the possible videos and impossible videos within a probe tuple are perfectly matched in terms of individual frames and pairs of frames."