Practice Tests
IELTS Reading (AC) Task 1 #77

A. Human societies have long relied on timekeeping to coordinate planting and harvesting, schedule trade, and navigate across oceans. Yet the history of measuring time is not merely a catalog of instruments; it is a story about the pursuit of precision. As communities grew larger and economies became more interconnected, the costs of being "out of sync"—missed ships, delayed trains, or conflicting market hours—increased. Each technological step toward better accuracy reshaped daily routines and, in turn, demanded even stricter standards.|Early devices such as sundials and water clocks marked the passage of hours, but they depended on sunlight or steady flow and were vulnerable to weather and wear. Medieval Europe''''s weight-driven mechanical clocks brought a measure of independence from natural cycles, but they drifted by minutes each day. The pendulum transformed this landscape. Inspired by Galileo''''s observations of isochronous oscillations and engineered by Christiaan Huygens in 1656, pendulum clocks cut errors dramatically. At sea, however, rolling decks rendered pendulums unreliable, and the pressing "longitude problem" persisted until John Harrison''''s marine chronometers in the 18th century kept sufficiently stable time for navigators to fix their east–west position.|Industrialization multiplied the social value of synchronization. Railways in the 19th century exposed the chaos of local solar times—noon could differ by minutes between towns. Telegraph lines enabled distant clocks to be set together, and time zones emerged as a practical solution. In 1884, delegates at the International Meridian Conference designated Greenwich as the prime meridian, laying the groundwork for standardized civil time. The shift was not merely administrative: factories, stock exchanges, and postal services reorganized around timetables that assumed a uniform clock.|The 20th century ushered in electronic oscillators and, eventually, atomic clocks. Quartz crystals improved stability, but atomic standards—using the microwave frequency associated with transitions in cesium-133—redefined precision. In 1967, the International System of Units defined the second by this atomic transition, freeing time measurement from astronomical irregularities. Modern cesium fountains and hydrogen masers achieve accuracies better than one part in a billion, enabling comparisons of clocks separated by continents—and even small differences in altitude.|Today''''s infrastructure depends on such fidelity. Global Navigation Satellite Systems compute positions by measuring signal travel times from synchronized satellite clocks, with adjustments for Einstein''''s relativistic effects. Financial markets timestamp trades to the microsecond; power grids and telecommunications rely on coordinated phase and packet timing. Yet Earth''''s rotation still drifts, leading to occasional leap seconds to keep Coordinated Universal Time aligned with astronomical time. Looking ahead, optical lattice clocks promise even finer resolution and may redefine the second once more, offering benefits for geodesy and fundamental physics while raising fresh questions about how societies will manage ever more exacting standards of time.