Who "started the clock" for standardized time? Some reference clock had to start at a predetermined moment.

Question

Who started it and when?

Answer 1

The reference, as it happens, is not some clock in a vault somewhere. The reference for standard time is the moment when the sun is at its zenith at 0 deg longitude on one of the equinoxes. That is defined as Noon. Standardized time zones and time keeping are calibrated from there, which process has been greatly simplified by the invention of atomic clocks.

Answer 2

The original clock was the sun, and the time standard was local noon, corrected for the equation of time (the amount that the time of noon varies over the year). In the US, standard time zones were established in 1883. The need for standard time came about because of the increased rapidity of transportation and communication brought by railroads and telegraph. Greenwich Mean Time was formally accepted as the international reference standard in 1884. It had been in widespread use for some time because of the astronomical and nautical almanacs published by the Royal Observatory there, but other references, such as the Paris meridian, were also used in the past.

The modern time standard, Universal Coordinated Time (UTC) is kept by atomic clocks at standards bureaus around the world, and managed by international agreement by the International Bureau of Weights and Measures or Bureau international des poids et mesures (BIPM). In the US, The National Institute of Standards and Technology (NIST) and the US Naval Observatory (USNO) each maintain an atomic time standard.

Answer 3

I assume you are talking about the time zones?

The time zones are all based off of the time in Greenwich, England, thus Greenwich Mean Time.

You can see this also in the denoting of a particular time zone, such as the Pacific Time Zone: it has the denotion of -8, that is 8 hours before Greenwich Mean Time (0).

You can see this on your computer's clock.