10 Its Time To Learn About Time

CHAPTER 1 What Time Is It? TODAY, THE RIGHT TIME IS IMPORTANT FOR ALL OF US. BUT WAS IT ALWAYS LIKE THAT? What is time? Is it always the same? It goes slowly when we're bored and fast when we're having fun. Many older people feel that years go very quickly for them. Time is different for each of us. Centuries ago, it wasn't so important to know the right time. Many people were farmers. Farmers don't need to know the time to the minute. They must know the season and if the weather will be rainy or sunny, cold or hot. But when people began to travel a lot at sea, sailors needed to know the right time. So clockmakers made new, better clocks. Then came trains. Now minutes were important. If the clock in one station showed 10:15 and the clock in another station showed 10:00, people were late for their train. So clocks had to show the same time in every station. Today, we need to know the right time to catch planes, meet friends, and get to school on time. We look at time differently now.

第一章几点了？ 今天，合适的时机对我们所有人都很重要。 但一直都是这样吗？ 时间是什么？总是一样的吗？ 当我们感到无聊时，它走得很慢，当我们开心时，它走得很快。 许多老年人觉得岁月对他们来说过得很快。 时间对我们每个人来说都不一样。 几个世纪以前，知道正确的时间并不那么重要。 许多人是农民。农民不需要知道时间到分钟。 他们必须知道季节，知道天气是晴还是雨，是冷还是热。 但是当人们开始在海上旅行时，水手们需要知道正确的时间。 于是钟表匠们制造了更新更好的钟。 然后火车来了。现在分钟很重要。 如果一个车站的时钟显示10点15分，而另一个车站的时钟显示10点，那么人们就赶不上火车了。 所以每个车站的时钟都必须显示相同的时间。 今天，我们需要知道正确的时间去赶飞机，见朋友，准时到达学校。 我们现在看待时间的方式不同了。

CHAPTER 2 Calendars A LONG TIME AGO, PEOPLE IN DIFFERENT PLACES MADE DIFFERENT CALENDARS. Calendars are things we use to measure months, weeks, and years. A year is the time the Earth takes to go around the Sun. —A lunar month is the time the Moon takes to go around the Earth. —A calendar month is part of a year. But the Moon goes around the Earth 12.4 times each year, not 12 times. So to make a year, we have different numbers of days in our 12 calendar months. In Roman times, more than 2,000 years ago, Julius Caesar saw that the year was 365.25 days long, not 365. So he said that every four years there must be one more day, to make a leap year of 366 days. This became the Julian calendar. Now our leap day is February 29. But now we use the Gregorian calendar. About 1,600 years after Julius Caesar, Pope Gregory XIII saw that the year was really a little shorter than 365.25 days. So he made a new calendar to make the dates right. He said that the day after October 4, 1582, was October 15! Many people were unhappy. They thought this made their lives 10 days shorter! But now all the dates on our calendar are right.

很久以前，不同地方的人们制定不同的日历。 日历是我们用来计算月、周、年的东西。 一年是地球绕太阳一周的时间。 -阴历月是月球绕地球一周的时间。 -日历月是一年的一部分。 但是月球每年绕地球转12.4圈，而不是12圈。 因此，为了构成一年，我们在12个日历月中有不同的天数。 在两千多年前的罗马时代，凯撒大帝认为一年是365.25天，而不是365天。 所以他说每四年必须再多一天，这样闰年才有366天。 这就是儒略历。 现在我们的闰日是2月29日。 但现在我们使用公历。 大约在凯撒大帝1600年之后，教皇格里高利十三世发现一年实际上比365.25天短了一点。 所以他做了一个新的日历，以使日期正确。 他说1582年10月4日之后的第二天就是10月15日！许多人不高兴。 他们认为这会让他们的寿命缩短10天！但是现在我们日历上所有的日期都是对的。

In most of the world today, we use the Gregorian calendar. But there are many others. The Gregorian year 2014 is the year 4711, 4651, or 4712, in different Chinese calendars. For Muslims, it is 1435. The Muslim calendar is lunar: it uses the Moon and not the Sun. So seasons start on different dates each year. But after 32.5 years, the seasons come back to the same date. India, one of the biggest countries in the world, uses the Gregorian calendar. But it also has a Hindu calendar. The year 2014 is also the year 1936 in the Hindu calendar! In 1792, France became a republic: a country with no king. It also chose a new calendar. Weeks were ten days long. People didn't like this. Before, they worked six days and had one day off, one day when they didn't work. Now they had only one day off in ten! So the old calendar came back in 1806. The Mayans, a group of people in Central America, made a calendar a long time ago. Some people thought their calendar showed the end of the world on 12/ 21/ 12— December 21, 2012. They were wrong!

在当今世界的大部分地区，我们使用公历。 但是还有很多其他的。 在不同的中国历法中，公历年是4711年、4651年或4712年。 对穆斯林来说，是1435年。穆斯林的历法是阴历：它使用月亮而不是太阳。 所以每年的季节开始的日期都不一样。 但在32.5年后，季节又回到了同一日期。 印度是世界上最大的国家之一，使用公历。 但它也有印度教历法。 2014年也是印度历法中的1936年！1792年，法国成为共和国：一个没有国王的国家。 它还选择了一个新的日历。 一星期是十天。人们不喜欢这样。 以前，他们工作六天，休息一天，一天不工作。 现在他们每10天才休息一天！所以旧历法在1806年恢复了。 玛雅人，中美洲的一群人，很久以前就制定了日历。 有些人认为他们的日历显示2012年12月21日- 12月21日是世界末日。 他们错了！

CHAPTER 3 Clocks HOW DID WE BEGIN TO MEASURE TIME? The first clock was the sundial. As the Sun moved in the sky, the dark shadow on the sundial showed the change of time. Of course, sundials didn't work when there was no sun at night or on a cloudy day! Later, people used other clocks to tell the time. In a water clock, water went slowly down from one part to the other. When there was more water in the bottom, people knew it was later. With candle clocks, the candle got shorter, and the line on it showed the time. People on boats at sea needed clocks. If they could see the sun and knew the right time, they knew where they were. But pendulum clocks didn't work on boats because a boat moves too much. In 1714, Britain asked clockmakers to make a clock for boats. There was a prize of 20,000 that's like $4,500,000 today! Clockmakers worked on this for many years. Then, an Englishman called John Harrison made a new watch with a spring, not a pendulum. It showed the right time at sea. At first, people didn't think it was true. They thought it was impossible. But the watch worked, and Harrison got his prize money in the end!

第三章时钟我们是如何开始测量时间的？ 第一个时钟是日晷。 当太阳在天空中移动时，日晷上的黑影显示了时间的变化。 当然，当晚上没有太阳或阴天的时候，日晷就不起作用了！后来，人们使用其他时钟来显示时间。 在水钟里，水慢慢地从一部分流到另一部分。 当底部有更多的水时，人们就知道是晚了。 有了蜡烛钟，蜡烛变短了，上面的线显示时间。 在海上航行的人需要时钟。 如果他们能看到太阳，知道正确的时间，他们就知道自己在哪里。 但是摆钟在船上不起作用，因为船移动得太快了。 1714年，英国要求钟表匠为船上制造时钟。 本来有2万的奖金，今天是50万！钟表匠为此工作了很多年。 后来，一位名叫约翰·哈里森的英国人用弹簧而不是钟摆制造了一块新的手表。 它显示了海上的正确时间。 起初，人们不相信这是真的。 他们认为这是不可能的。 但手表起作用了，哈里森最终得到了奖金！

Most people use the 12-hour clock. They say "three o'clock in the afternoon" or "3 p.m." But soldiers really have to get the time right! So they use the 24-hour clock. They don't say "three o'clock." They say "fifteen hundred hours" (15:00). For 3:15 p.m., they say "fifteen-fifteen hours" (15:15). At twelve o'clock at night, the day starts again. So they say "zero zero hundred hours" (00:00), not "twenty-four hundred." Many countries use the 24-hour clock for things like trains and planes. For hundreds of years, the shortest time was a second. But today, we use shorter times. When athletes run, we need to measure the time to a hundredth (0.01) of a second. That can be the difference between best and second best. And scientists use even shorter times. Light travels one kilometer in 0.0000033 seconds! That really is a short time! So how short can time get? Is there a shortest possible time? Scientists say yes: 1043 seconds!

大多数人使用12小时制。 他们说“下午三点”或“下午三点”。 但是士兵们真的必须把握好时间！所以他们使用24小时制。 他们不说“三点”。 他们说“一千五百小时”（15:00）。 下午3点15分，他们说“15 - 15小时”（15:15）。 晚上12点，一天又开始了。 所以他们说“zero zero hundred hours”（00:00），而不是“2400 hours”。 许多国家使用24小时制，比如火车和飞机。 几百年来，最短的时间是一秒。 但是今天，我们使用更短的时间。 当运动员跑步时，我们需要测量到百分之一（0.01）秒的时间。 这就是最好和次好的区别。 科学家使用的时间甚至更短。 光传播一公里需要0.0000033秒！那真的是很短的时间！那么，时间到底能有多短呢？ 有没有最短的时间？ 科学家的答案是：1043秒！

CHAPTER 4 Time Zones TIME CHANGES AROUND THE WORLD. WHY AND HOW? When the sun comes up in Japan, it goes down in the USA. So we cannot have the same time in every country. Around the world, there are 24 different time zones. Each time you go from one time zone to another, the time is different. Big countries have more than one time zone. Russia has nine! So when people in different parts of Russia look at their watches, they see different times. Sometimes people who live very close together are in different time zones. Florida, USA, has two time zones. There's a river between them. You live in Bristol, and you have a friend in Blountstown on the other side of the river. You want to meet. But at what time? Bristol's 4 p.m. is Blountstown's 3 p.m. It's easy to get it wrong. You must say, "I'll see you at three o'clock your time." What about phoning people in other countries? If you are in Sydney, Australia, at 11 a.m., don't phone your friend in Johannesburg, South Africa. It's 3 a.m. there!

第四章时区世界各地的时间都在变化。 为什么？怎么做？当日本的太阳升起时，美国的太阳就下山了。 所以我们不可能在每个国家都有相同的时间。 世界上有24个不同的时区。 每次从一个时区到另一个时区，时间都不一样。 大国有不止一个时区。 俄罗斯有9个！所以当俄罗斯不同地区的人看手表时，他们看到的时间是不同的。 有时住得很近的人在不同的时区。 美国的佛罗里达州有两个时区。 他们之间有一条河。 你住在布里斯托尔，你有个朋友住在河对岸的布朗斯敦。 你想要见面。但是什么时候呢？ 布里斯托尔的下午4点是布朗斯敦的下午3点。 很容易出错。 你必须说：“我在你的时间三点见你。” 给其他国家的人打电话怎么样？ 如果你在澳大利亚悉尼，上午11点，不要给你在南非约翰内斯堡的朋友打电话。 那里现在是凌晨3点！