The history of keeping time - Karen Mensing

人类计时史 —— 凯伦·门生

翻译人员: Yixiong Zhu 校对人员: Sherry Chen

We check the time every day, all day long.

我们无时无刻不在看时间。

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

但你有没有想过，计时是怎么开始的？

Why does it matter what time it is?

为什么要知道现在是什么时间？

Who determined the clock

谁规定了时间，

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

为什么世界上有这么多时区？

The first form of telling time was the sundial

最早的报时方法，是使用日晷。

and the earliest sundials known from the archaeological record

考古学发现的最早日晷，

are obelisks from nearly 5,000 years ago.

是将近5000年前的方尖碑。

Sundials indicate the time by casting a shadow

日晷通过将阴影投射在一个平面上

onto a surface.

来进行报时。

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

产生阴影的尖状物体叫做指时针。

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

做工良好的日晷能够相当精确地衡量时间。

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

直到现代社会，日晷一直都被用于评估钟表的准确度。

But sundials have their limitations too.

但日晷也有局限性。

Obviously they require the sun to shine,

很显然，他们需要太阳的阳光，

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

所以他们晚上天黑时是无法工作的。

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

多年来，很多仪器都被用于衡量时间的流逝：

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

能够以比较稳定的速度燃烧的蜡烛和香，

have been used, along with the hourglass.

还有沙漏。

Hourglasses are devices in which fine sand

沙漏让细砂以恒定速度

pours through a tiny hole at a constant rate

穿过一个小孔，

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

从而测量预先设定好的一段时间。

The origin of the hourglass is uncertain,

沙漏的起源并不确定，

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

尽管在14世纪初，沙漏已经有广泛的应用了，

especially on board ships.

尤其是在船舶上。

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

船在水中的移动不会影响沙漏，

unlike other time-measuring devices.

这点其他衡量时间的仪器做不到。

The mechanical clock was invented in the 13th century

机械钟发明于13世纪

which sparked a big change in traditional timekeeping methods.

传统计时方式因此发生了很大变化。

This modern clock relied on the swing of a pendulum

这座现代钟运用钟摆的摆动，

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

还有石英石的振动。这比砂子和蜡烛

or candles.

要准确得多。

Today, the basis for scientific time

如今，科学计时

is a continuous count of seconds

基于不间断的秒数，

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

由世界各地的原子钟来计算。 这被称作国际原子能时间。

Why does it matter that we keep track of time?

为什么计时很重要？

Well, time regulates our daily lives

时间规范我们的日常生活，

and makes it possible to accurately communicate with people

让我们能够准确地跟世界各地的人们

all over the world.

进行沟通。

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

没有时间体系，人类的农业活动，

social structures, communication, and business.

社会结构，通讯，商业，都将受到挑战。

Take the American railroad system, for example.

以美国铁路为例，

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

19世纪中叶，每条铁路都有自己的标准时间，

generally based on the local time of its headquarters,

这些时间通常是总部的当地时间。

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

铁路时刻表也是以自己的时间来标注的。

Some major railroad junctions

很多大型铁路枢纽

served by several different railroads

同时有多条铁路，

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

就要为每条铁路都配备一个时钟，分别计时。

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

纽约和波士顿之间有2度的经度差，也就是8分钟的时差，

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

而这可能就是赶上和错过火车的差别。

If the difference between New York and Boston

如果纽约和波士顿的时差

is 8 minutes, imagine the difference

是8分钟，那想象一下

between Boston and Australia.

波士顿和澳大利亚会怎样。

The use of time zones irons out these differences

时区的使用剔除了这些差别，

and makes communication significantly smoother.

让人们的沟通更加顺畅。

A time zone is a region on earth

时区是地球上的拥有相同标准时间的

that has a uniform standard time.

一个区域。

There are 40 time zones on land

地面上有40个时区，

because the earliest and latest time zones

最早和最晚的时区之间相差

are 26 hours apart.

26个小时。

Any given calendar date exists at some point

任何一天，在地球上都将

on the globe for 50 hours.

存在50个小时。

So the next time someone asks you

所以如果下一次有人问你

"What time is it?"

“现在几点了？”

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

你的回答可能比之前以为的要复杂许多。