Time itself is the subject of this closing episode in a four-part series hosted by physicist Michio Kaku, who spent the previous three installments tracing time through the body, the geological record, and now the cosmos. Kaku turns to the discoveries of atomic and cosmic physics that upended older assumptions about a fixed past and an orderly, predictable future. The episode asks what time actually is at the largest scales, whether the universe had a true beginning, and whether it could ever end. Kaku's own background in string theory shapes the questions he pursues, pushing past everyday clock-time toward the physics of cosmic origins and endpoints. As the finale of the series, it pulls the previous episodes' smaller-scale investigations of biological and geological time up to the scale of the universe itself, closing the four-part arc on the biggest version of the question it opened with.