The universe is 13.7 billion years old and, according to the film, may be living on borrowed time, its ultimate fate hinging on whether Stephen Hawking's theories about its end prove correct. The film moves from the human scale to the cosmic one: global life expectancy has climbed to 65 years from around 20 in the Stone Age, yet the whole of human history barely registers against deep time. It tracks the clocks we actually use to measure change, from radioactive decay to the Earth's rotation, noting that a day is really 23 hours, 56 minutes, 4.1 seconds by the stars, and that tidal drag from the Moon means dinosaurs lived through 370-day years and we now add leap seconds every 18 months. Milankovitch cycles bend Earth's axis every 23,000 to 41,000 years and get blamed for ice ages, while ocean currents run in loops lasting centuries. Circadian rhythms, melatonin, and the carbon cycle round out the case that time operates in nested, discoverable rhythms, not just a single arrow toward an end.