But did you ever wonder - where did telling time come from?

但你有沒有想過 查時間這檔事是從哪兒來的？

Why does it matter what time it is?

為什麼知道時間 是那麼重要呢？

Who determined the clock

時間是由誰定的？

and why in the world are there so many different time zones?

為什麼世界上 有這麼多不同的時區？

The first form of telling time was the sundial

第一種觀察時間的方式 是透過日晷

and the earliest sundials known from the archaeological record

根據考古記錄 我們得知，最早的日晷

are obelisks from nearly 5,000 years ago.

就是五千年前的方尖碑

Sundials indicate the time by casting a shadow

日晷透過投射於 地面上的陰影

onto a surface.

指出當下的時刻

The object that casts the shadow is a stick in the center known as a gnomon.

投射陰影的物件是一根 被稱為日規 (gnomon) 的棍子

A well-constructed sundial can measure time with remarkable accuracy,

製作一個完好的日晷 可以讓我們準確地測量時間

and sundials were used to monitor the performance of clocks until the modern era.

一直到現代來臨前 日晷被人們拿來檢測時鐘的性能

But sundials have their limitations too.

但日晷也有其局限

Obviously they require the sun to shine,

顯然地，它們需要陽光

so they don't work at all during the night when it's dark.

因此它們在漆黑的夜晚中無法工作

Many different devices have been used over the years to estimate the passage of time:

人們在許多年中使用了 多種不同的設備來測量時間的推移：

candles and sticks of incense that burn down at fairly predictable speeds

蠟燭、熏香枝和沙漏 以一種可預測的速度燃燒

have been used, along with the hourglass.

人們用它們來測量時間

Hourglasses are devices in which fine sand

沙漏是一種以細沙

pours through a tiny hole at a constant rate

流淌過一個小洞的設備 人們用它的恆定速率來測量時間

and indicates a predetermined passage of an arbitrary period of time.

它指出細沙在一段時間中 所流動的速率

The origin of the hourglass is uncertain,

我們不確定沙漏的起源為何

although beginning in the 14th century, the hourglass was used commonly,

雖然，自十四世紀開始 人們已經開始普遍地使用沙漏

especially on board ships.

特別是用在船上

The motion of the boat on the water did not affect the hourglass,

不同於其它測量時間的裝置

unlike other time-measuring devices.

船在水上的晃動 並不會影響沙漏

The mechanical clock was invented in the 13th century

十三世紀時 有人發明了機械時鐘

which sparked a big change in traditional timekeeping methods.

這個裝置引發了 傳統計時方法的大變化

This modern clock relied on the swing of a pendulum

這個現代時鐘仰賴一個鐘擺，或一個

or the vibration of a quartz crystal, which was far more accurate than sand

振動石英晶體的擺動而運作 它的準確率遠遠超過沙漏

or candles.

或蠟燭

Today, the basis for scientific time

今天，科學的時間是基於

is a continuous count of seconds

一串根據世上所有原子時鐘

based on atomic clocks all around the world, known as the international atomic time.

所連續運行的讀秒 它被稱為國際原子時間

Why does it matter that we keep track of time?

為什麼對時很重要呢？

Well, time regulates our daily lives

嗯，時間讓我們可以調整日常生活

and makes it possible to accurately communicate with people

讓我們能夠準確地

all over the world.

與世上所有人溝通

Without a time system, we would have many challenges in farming,

如果沒有時間系統 我們可能會在農耕、

social structures, communication, and business.

社會結構、 通信和商業 等層面上面臨許多挑戰

Take the American railroad system, for example.

以美國的鐵路系統為例

In the mid-19th century, each railroad used its own standard time

十九世紀中期，每條鐵路 使用它自己的標準時間

generally based on the local time of its headquarters,

它們通常是以 其總部的本地時間為準

and the railroad's train schedules were published using its own time.

鐵路公司用它自己的時間 發佈自己的火車時刻表

Some major railroad junctions

有一些主要的鐵路交匯口

served by several different railroads

由幾條不同的鐵路交錯而過

had a separate clock for each railroad, each showing a different time.

每一條鐵路有各自不同的時鐘 每個時鐘都顯示了不同的時刻

The distance between New York and Boston is about 2 degrees, or 8 minutes,

紐約和波士頓之間的距離 大約有兩度，或八分鐘

which can be the difference between making or missing your train connection.

這個小差距可以成為 你趕上或者錯過班車的關鍵

If the difference between New York and Boston

如果紐約和波士頓之間的時差

is 8 minutes, imagine the difference

是八分鐘，你可以想像

between Boston and Australia.

波士頓與澳大利亞之間的 差距該有多少呢？

The use of time zones irons out these differences

時區消除了這些差異

and makes communication significantly smoother.

讓溝通變得更流暢

A time zone is a region on earth

時區是地球上的一個

that has a uniform standard time.

統一了標準時間的區域

There are 40 time zones on land

因為地球上 最早和最晚的時區

because the earliest and latest time zones

相距了二十六個小時

are 26 hours apart.

所以我們有四十個時區

Any given calendar date exists at some point

所有日曆的日期 都多多少少地

on the globe for 50 hours.

存在了地球上的這五十個小時

So the next time someone asks you

所以下次有人問你：

"What time is it?"

「現在是幾點？」

Your answer may be a whole lot more complicated than it used to be.

你的回答也許會比之前的 還要更加複雜也說不定呢