Most people in the standardization community know that the National Institute of Standards and Technology (NIST) plays a big role in keeping the official time in the U.S. But how is time tracked, how is it synced internationally, and how accurate are the times on our computers, phones, and watches? A new article published in Harper’s Magazine delves into the technicalities behind the time that we check on our devices every day.
“In Search of Lost Time” explains how the official time in the U.S. is subordinate to the Coordinated Universal Time—the UTC—which provides an aggregate of times gathered from atomic clocks maintained by more than 80 international agencies. Calculated after the fact, the UTC is sent to NIST and other institutions monthly, providing official time data from the previous month. Time-keeping professionals discuss the implications of the UTC report and recalibrate the official time in the U.S. accordingly. The article goes on to explain why the synced clocks on our computers may still be slightly off, and delves into NIST’s work in other areas of metrology, with fascinating insight into the Institute’s dematerialization of units and measurements of the “fundamental properties of the universe.”
Standards play an important role in bringing the official time into our homes and onto our devices, and in using it to its full advantage. UL 917, Standard for Clock-Operated Switches, guides timers that use an electric switch controlled by a timing mechanism—for example, outdoor lighting that turns on in the evening, pool pumps that run at a scheduled time each day, and heating or cooling devices set to turn on and off throughout the day. This standard was developed by UL Standards & Engagement (ULSE), a member and audited designator of the American National Standards Institute (ANSI).
Synchronization of clocks in networked systems is guided by another standard: IEEE 1588-2019, IEEE Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems. Developed by ANSI member and accredited standards developer IEEE, this standard offers guidelines that support sub-nanosecond time transfer accuracy in packet-based networked systems.
An international standard guides safety for electric clocks used in the household, like alarm clocks. IEC 60335-2-26, Household and Similar Electrical Appliances - Safety - Part 2-26: Particular Requirements for Clocks, was developed by the International Electrotechnical Commission (IEC) Technical Committee (TC) 61, Safety of household and similar electrical appliances. The U.S. holds the secretariat of this TC, with secretariat duties performed by ULSE. UL also serves as the U.S. National Committee (USNC)-approved U.S. Technical Advisory Group (TAG) Administrator to IEC TC 61, carrying U.S. positions forward to the committee.
Information about time and how it is communicated internationally relies on a standard, as well. ISO 8601-1:2019, Date and Time - Representations for Information Interchange - Part 1: Basic Rules, specifies representations of dates of the Gregorian calendar and times based on the 24-hour clock, offering an unambiguous calendar-and-clock format that can be universally understood. It was developed by the International Organization for Standardization (ISO) TC 154, Processes, data elements, and documents in commerce, industry, and administration. ANSI member Open Applications Group, Inc. (OAGi) is the ANSI- accredited U.S. TAG administrator to this TC.
Learn more about time-keeping and NIST’s role: In Search of Lost Time: The Science of the Perfect Second