Welcome. Hope you spend more time here contributing with your expertise in the field than some of your colleagues have (giving side-eye to Phil Plait and Neil deGrasse Tyson).
Until I got a reliable self-setting timepiece (i.e. set the NTP setting on Windows in the late 1990’s) I still set my timepieces to “CBC Beep Time” which is still happening today. Indeed, I’ve run across a number of PC’s whose clock can lose a minute or more a week if not synchronized. Our house phone picks up the time from the caller ID info, so if there was a power failure or such, it doesn’t know the time until the next call comes through.
Alvin Toffler’s The Third Wave mentions that one of the main lessons of school for second-wave (industrial) civilization, is to teach students to become good factory workers by training them to follow the clock more precisely, with established start and stop times, recess and lunch and different periods, so as to impress on us the value of following the clock. Decades ago, one of the complaints with working in the (first wave) Third World that Toffler mentions is the lackadaisical attitude toward time, which drives clock-oriented first worlders crazy.
It is interesting that much of this thread discusses whether people even need to know the “exact” time. For those who needed it, even in antiquity there were time balls, water clocks, sundials, and so forth available, and later on increasingly sophisticated mechanical contraptions and time guns, time distribution via telegraph and radio, etc. The other side of all of this is the need for scientifically accurate time, which meant astronomical observations, chronometers, and atomic time.
When some of the physicists on here were born, these were two separate fields of study.
There’s an “eleven years late” joke in here somewhere but I can’t be bothered plus don’t want to be obnoxious to a new poster.
The Nelson Monument is a commemorative tower in honour of Vice Admiral Horatio Nelson, located in Edinburgh, Scotland. It is situated on top of Calton Hill and provides a dramatic termination to the vista along Princes Street from the west.
The monument was built between 1807 and 1816 to commemorate Nelson’s victory over the French and Spanish fleets at the Battle of Trafalgar in 1805, and his own death at the same battle.
In 1852 a mechanized time ball was added, as a time signal to shipping in Leith harbour. The time ball is synchronized with the One O’Clock Gun firing from Edinburgh Castle. The monument was restored in 2009.
When I was an undergraduate, my travels took me past a Shortt Synchronome clock resplendent in a glass fronted alcove half way down the stairs in the physics department. Long obsolete, it had spent a couple of decades as the most precise clock made. It was still operating. I would set my watch by it whenever I passed.
Sadly it has fallen in to disrepair and is no longer there. But it kept ridiculously good time for half a century. A claimed one second a year, it was, according to the link above, actually good to about one second every 12 years. That means over its 50 odd year life it was probably, at worst, 4 seconds out.
I disagree with this. Railroad timetables have been scheduled to a precision of a minute since the 19th century, and being correct within five minutes only is a surefire way of missing a lot of trains. In 1884, the international meridian conference was held in Washington to eliminate the problem of differences in the range of seconds between different nations’ telegraphic time signals, so apparently a pressing need for that degree of precision was felt back then already.
I just called it ands got a series of tones. Are you supposed to decode them?
Railroads had a lot to do with modern timekeeping, but their need for precision doesn’t really affect that many people. If you wanted to catch a train you’d have to plan to be at the station ahead of time and prepared to wait for delays. So the need for correct time was limited to railroad management. Extremely important some times, but most people did just fine using the sun, a town clock, or a siren blaring at noon every day.
I think that’s too pristine a view of what 19th century (say, late 19th century, when industrialisation was well under way) life was like. It may have been like that for the farming population, but city life was already governed by accurate timekeeping. Factory workers had to be on their shift in time, business appointments had to be kept, and trains reached. See here (pdf) for Curtis v March, a famous (in the history of timekeeping) 1858 court case in which the time difference between GMT and local mean time at Dorchester (Dorchester is 2.5 degrees west of Greenwich, so that time difference is about ten minutes in time) was held to be crucial.
I know this post is 11 years old, but this related anecdote is still relevant: in the New England town I live in, there is an old church with a spire on it that has a clock face on three of the four sides. The story goes that the town took up a collection in the mid-1800s to pay for the installation of the clocks, and the people who lived on the south side of town (the side with the missing clock face) didn’t chip in enough money so no clock face for them! 
We’re just talking about different time periods. Time wasn’t that sensitive before railroads. By the late 19th century there were not only time zones and train schedules, there were also stop watches and time/efficiency concerns that didn’t exist earlier. At some point the ‘time=money’ equation went into practice.
It probably worked 11 years ago when it was written.
OK, I missed that.
ETA: Update - For the U.S. Naval Observatory’s time- Dial 202-762-1401
Of course, you could just go to
Are the clocks on our cell phones “exact” time. Or are they off a tiny bit? [not that it matters to me, but this thread has made me curious]
I sure know our DVR (and certain shows on Hulu) aren’t exact. Either that, or networks regularly run their shows past their posted times (the bastards).
You should also look at the 1998 PBS Nova episode Lost at Sea: The Search for Longitude. John Harrison invents an accurate chronometer to help ships determine longitude, which is really hard to do at sea without an accurate clock.
Cell phones are synchronized to time servers, either directly over the Internet, or through the cell towers, which are themselves synchronized with Internet time servers.
That said, the clocks aren’t atomic clocks, and thus can drift a bit between synchronizations—which happen every time you turn on your phone, send or receive a call, as well as on a set schedule. (There may be other synchronizations that I left out.) The drift is rarely more than a couple seconds, however.
Crappy time sync protocols do exist, however: NITZ - Wikipedia