Navigation & Timekeeping · Recorded milestone
Atomic clock
Recorded year1955
Louis Essen and Jack Parry's caesium clock keeps time to a second in 300 years; such clocks later become the core of GPS.
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- Quantum mechanicsRecorded · 1925enables
- Quartz clockRecorded · 1927enables
- RadarRecorded · 1935enables
Led to
- Atomic secondRecorded · 1967enables
- Voyager probesRecorded · 1977requires
- Metre defined by lightRecorded · 1983requires
- Internet clock sync (NTP)Recorded · 1985enables
- Handheld GPS receiverRecorded · 1989enables
- Radio-controlled wristwatchRecorded · 1990enables
- GPSRecorded · 1995enables
- Mars roversRecorded · 1997requires
- Optical frequency combRecorded · 2000enables
- Chip-scale atomic clockRecorded · 2011enables
- Networked quantum sensorsRecorded · 2016enables
- Black-hole imageRecorded · 2019enables
- Deep Space Atomic ClockRecorded · 2019enables
- SI redefined on constantsRecorded · 2019enables
- Nuclear clock transitionRecorded · 2024enables
- Quantum navigation sensorsRecorded · 2025enables
- Low-orbit navigation satellitesForecast · ~2029requires
Sources & evidence
Dataset updated 2026-10-18. This individual record has not been separately re-reviewed.