Thread by @ErrataRob

Kids these days don't understand: when we grew up, we NEVER knew what time it was. Think it through: before the Internet, how would you know what time to set your clock to?

https://twitter.com/BraddrofliT/status/1489370877485469696

Big Ben (in London) is not the clock but the bell. People are confused about this today, but back in the day, it was obvious: people set their own clocks according to hearing Big Ben.

In the middle ages, the current time was a function of the church. They were the ones with bell towers that would ring at certain times. The current time is whatever they said it was.

Then time became a function of the railways, both because they had a telegraph to transmit it, but also because they had a schedule to keep.

Then, time became a function of the electric grid. The grid promised to produce 60 Hz signal (in America, 50 Hz in Europe), so a simple circuit would simply count the number of Hz of the alternating current.

The electric grid was speed up or slow down to keep clocks synchronized, so once you set them, they'd go for a long time before the grid drifted too far and they needed to be reset.

Then time became a function of space and GPS. Your location is calculated from the time it takes for the signal from a GPS satellite to reach you (many milliseconds due to speed-of-light delays)

Today, time is largely a function of the Internet. Most of our devices know time from the Network Time Protocol (NTP) and some server on the Internet. Windows gets it from Microsoft, by default.

One way we test whether election/voting computers have been connected to the Internet is by looking through their logs to see if they've synced time with the Internet.

Also note: election computer times are always a bit off, their clocks drift.

Clocks always drift, so they always showed different time. There was a joke:

A man with one watch knows what time it is, and a man with two watches could never be sure.

In movies, capers always started by the perps synchronizing their watches. Because of course, they all showed different times. Friends were late meeting at the bar because 15 minutes different wasn't unusual.

Today, tell Siri and Alexa to set an alarm at 8am. Both will go off within milliseconds of each other, even though the paths they choose to the official time can be quite different.

Where do Siri and Alexa get OFFICIAL time? One source of official time is the US Naval Observatory, where GPS gets its time.

Why the US Navy? Why not the Air Force? or Space Force??

Because ships used time to navigate. Location north/south could be determined by angle of objects in the sky, like the sun. Location east/west was difference in time between the clock and the sun.
cnmoc.usff.navy.mil/Organization/U…

so, synchronize your naval chronometer with the naval observatory (USNO or Greenwich), then travel east/west. If you clock says 1pm but the sun says noon, you know you've traveled 15 degrees longitude.

Clock accuracy was the critical innovation that allowed easy transport back and forth between Europe and the New World, so that navigators could know where they were.

Everyone knows "sextant", as this was the thing that measured angle of the stars or sun. But without a clock, it was powerless to calculate longitude (east/west), and was only able to calculate latitude (north/south).

So the Brits. Time was their thing. They had this vast overseas empire, where such clocks where integral into maintaining that empire, which is why we have "Greenwich Mean Time". It's a Navy thing.

When radio was invented, the BBC would broadcast a countdown of beeps so the entire empire could set their watches to London time.

https://twitter.com/RichardKeppler1/status/1489423923691282436

It's an integral part of BBC news today. It's their theme.

So as a kid, you get up in the morning to get ready for school. All the clocks in the house show slightly different time, because nobody is anal enough to constantly reset them. 5 minutes either way could mean missing the bus to school.

You can hear the synchronization BBC beeps going back to early recordings in the 1950s, for example.

Yea, this. Each city would have their own time, depending upon when it was noon in that town. Then railroad synchronized time across the country.
99percentinvisible.org/article/defini…

h/t

https://twitter.com/ryandotclair/status/1489433293791580163