Durations ... and what this puzzle's circles literally represent

Usage examples of timeframes.

The closer the waves came to one another, the smaller the time distortion became among the different timeframes, and Jake saw that in two hours and two minutes, all the different rates of temporal flow would become identical-at the exact same moment as the temporal pressure between the two wormhole fragments equalized and all time stopped.

Three timeframes gradually coming into phase, only a few seconds off right now.

The latter—facilities to terminate pregnancies—imply that humans often change their minds over timeframes as short as a few months.