Synchronizing our watches : synchronizing hardware and software clocks in a distributed environment

This lecture is directly linked to the lecture given on December 11, 2013 by Edward Lee (UV Berkeley) and entitled " Cyber-Physical Systems: A Fundamental Intellectual Challenge ".

It is advisable to view this lecture before the lecture.

Abstract

Keeping time and synchronizing with others has long been a difficult problem. The visible rhythms of the sun and moon are not regular, and the various instruments invented over the ages were not very accurate: clepsydra, hourglasses, spring or pendulum clocks, etc. The first truly accurate watch (a few seconds on an Atlantic crossing) was designed by John Harrisson in 1773. The first truly accurate watch (a few seconds on an Atlantic crossing) was designed by John Harrisson in 1773, to win the British Admiralty competition opened following the sinking of part of the English fleet in the Isles of Scilly in 1714. This sinking was a direct result of poor weather measurement, leading to an inaccurate estimate of longitude. Later, with the arrival of the train, mistimings led to serious rail collisions. The situation only really improved in the second half of the ^20th century, with the widespread use of the telegraph, which harmonized local times and created time zones. Today, much greater precision can be achieved thanks to the atomic clocks embedded in GPS satellites, for example, and the computer protocols that synchronize the clocks of computers and computerized objects of all kinds.