第4章 万物的尺度 The Measure of Things · 第4讲S2

1. 老师，讲稿里说百慕大三角其实没那么邪乎，是作家为了写书博眼球编出来的。那为什么大家还是觉得它很危险，容易迷路呢？
2. 刚才听到说海里（nautical mile）的长度不固定，因为地球不是正圆的。那既然不精确，为什么航海的时候还要用它，而不是直接用公里或米呢？
3. 讲稿里详细讲了用‘千星板’测北极星高度来定纬度，那如果晚上阴天看不见星星，或者在赤道附近北极星看不到的时候，古人怎么知道自己在哪呢？
4. Norwood 这个人为什么要花大力气去计算‘一度经线’的具体长度？这跟解决百慕大难以定位的问题有啥直接关系吗？
5. 老师说一丁点的计算错误在海上会被放大，导致船只偏离目标。那除了算错距离，还有哪些因素会让船在茫茫大海上彻底迷路？

1. The transcript mentions that the Bermuda Triangle isn't actually that dangerous and that writers exaggerated it for their books. So why do people still believe it's so risky and hard to navigate?
2. I heard that a nautical mile isn't a fixed length because the Earth isn't a perfect sphere. Since it's not precise, why do sailors still use it instead of kilometers or meters?
3. The transcript explains how to use the 'quadrant' to measure latitude via the North Star. But what if it's cloudy at night, or you're near the equator where the North Star isn't visible? How did ancient sailors find their position then?
4. Why did Norwood bother to calculate the exact length of one degree of longitude? How does that directly help solve the problem of navigating small targets like Bermuda?
5. The teacher said that even a tiny calculation error gets magnified over the ocean, causing ships to miss their destination. Besides miscalculating distance, what other factors could cause a ship to get completely lost in the vast sea?

1 00:00:05,840 --> 00:00:07,940 In the early 17th century, 2 00:00:08,160 --> 00:00:11,840 Bermuda was well known among ship's captains for being 3 00:00:11,840 --> 00:00:13,140 hard to locate. 4 00:00:14,000 --> 00:00:18,260 hard to locate,locate 意思是定位, 5 00:00:18,440 --> 00:00:23,220 很难定位,也就是很难找到它准确的位置。 6 00:00:24,060 --> 00:00:26,500 Well,Bermuda is here on the map. 7 00:00:27,000 --> 00:00:30,480 You have probably heard of the Bermuda Triangle, 8 00:00:30,680 --> 00:00:35,340 or the Devil Triangle.大家可能听说过百慕大三角, 9 00:00:35,540 --> 00:00:37,400 又称为魔鬼三角。 10 00:00:37,640 --> 00:00:41,480 M any airplanes and ships are said to have mysteriously 11 00:00:41,480 --> 00:00:43,380 disappeared without a trace. 12 00:00:43,620 --> 00:00:47,160 They vanished into thin air or lost in deep waters. 13 00:00:47,640 --> 00:00:49,420 Well,the facts,however, 14 00:00:49,640 --> 00:00:53,420 are quite far from what is generally believed to be 15 00:00:53,420 --> 00:00:53,700 true. 16 00:00:54,080 --> 00:00:57,620 The idea of the devil triangle was mostly the 17 00:00:57,620 --> 00:01:00,840 imagination of some writers trying to get attention to 18 00:01:00,840 --> 00:01:02,520 their books.In fact, 19 00:01:02,700 --> 00:01:05,900 people navigate the area every day without accidents. 20 00:01:06,240 --> 00:01:09,780 This area is not more dangerous than other waters. 21 00:01:10,440 --> 00:01:12,220 不过在 17 世纪, 22 00:01:12,300 --> 00:01:16,100 关于白木大三角的种种传说还没有兴起。 23 00:01:17,400 --> 00:01:20,660 The problem was that the ocean was big, 24 00:01:20,820 --> 00:01:21,840 but muter small, 25 00:01:22,160 --> 00:01:25,400 and the navigational tools for dealing with this 26 00:01:25,400 --> 00:01:27,760 disparity hopelessly inadequate. 27 00:01:28,540 --> 00:01:34,400 The problem 指的就是引起上面这种现象的原因也就是 28 00:01:34,400 --> 00:01:40,240 为什么百慕大是这么难以定位问题就在于大 29 00:01:40,270 --> 00:01:45,890 海是那么浩瀚无边而百慕大相形之下就显得很小 And 30 00:01:45,890 --> 00:01:47,050 the navigational tools 31 00:01:47,430 --> 00:01:51,770 航海工具 For dealing with this disparity D isparity 32 00:01:51,770 --> 00:01:52,550 means difference 33 00:01:52,930 --> 00:01:58,730 差距这个差距指的就是大海之大和百慕大之小这个差 34 00:01:58,730 --> 00:01:59,070 距 35 00:01:59,700 --> 00:02:04,680 hopelessly inadequate inadequate means not enough, 36 00:02:04,840 --> 00:02:06,720 not good enough 不足的, 37 00:02:06,760 --> 00:02:09,340 不够的,不够好当 38 00:02:09,730 --> 00:02:15,460 时的航海工具完全没法对付这种巨大的差距根本就不 39 00:02:15,460 --> 00:02:19,990 管用 there wasn't even yet an agreed length for a 40 00:02:19,990 --> 00:02:25,750 nautical mile Nautical 意思是跟海洋有关的当时甚至 41 00:02:25,750 --> 00:02:30,690 一海里有多长大家都还没有一个一致的意见海里到底 42 00:02:30,690 --> 00:02:37,160 是什么意思呢我们把这一圈看成是地球的经线那么这 43 00:02:37,160 --> 00:02:44,590 里的角度就是圆周角 360 度我们把 360 度平均分成 60 份 44 00:02:44,590 --> 00:02:46,970 就得到这么 45 00:02:47,060 --> 00:02:53,430 一个小小的角度这一角就是六度这六度呢就是一分我 46 00:02:53,430 --> 00:02:59,180 们把它称为一分分钟的那个分那这一分所对应的经线 47 00:02:59,180 --> 00:03:04,590 的长度也就是这么一点这就是海里一海里所以我们可 48 00:03:04,590 --> 00:03:11,700 以这样理解把一海里乘以六十其实就是地球的周长了 49 00:03:11,700 --> 00:03:16,840 就是经线的长度整个经线两条紧相对的这个经线的长 50 00:03:16,840 --> 00:03:23,220 度那为什么说海里没有一个固定的长度呢因为地球并 51 00:03:23,220 --> 00:03:28,720 不是这么圆形在这个地方的一海里跟在赤道附近的一 52 00:03:28,720 --> 00:03:33,880 海里长度是不同的那为什么要用海里这样不是那么精 53 00:03:33,880 --> 00:03:39,900 确的单位呢这是因为在一望无际的茫茫大海上测量航 54 00:03:39,900 --> 00:03:45,400 程的时候由于没有参照物再加上有时候是顺流有时候 55 00:03:45,400 --> 00:03:51,900 逆流有时候顺风有时候逆风人们无法判断自己运动的 56 00:03:51,900 --> 00:03:56,680 状态也就是无法判断自己的速度甚至是运动的方向无 57 00:03:56,680 --> 00:03:58,680 法直观地测量出距离 58 00:03:59,220 --> 00:04:03,800 陆地上的单位固然很准确但是对于测量航程没有任何 59 00:04:03,800 --> 00:04:09,640 意义人们聪明地想到用经纬度来表示因为在海上测量 60 00:04:09,640 --> 00:04:14,040 经纬度还比直接测量距离更简单些那 61 00:04:14,110 --> 00:04:17,890 他们如何知道自己所在的纬度呢基本 62 00:04:18,620 --> 00:04:27,580 上就是靠在晴朗的夜晚测量眼睛跟北极星连线和水平 63 00:04:27,580 --> 00:04:30,960 面组成的夹角我在 64 00:04:31,220 --> 00:04:36,380 福建泉州的古船博物馆看到了一件展品就叫千星板 65 00:04:37,150 --> 00:04:43,530 千星板共有 12 块最大的一块边长 24 厘米最 66 00:04:44,650 --> 00:04:47,490 小的边长 2 厘米板 67 00:04:48,580 --> 00:04:55,540 的中心穿着一根 72 厘米长的绳子使用的时候呢左 68 00:04:55,730 --> 00:04:57,170 手拿 69 00:04:57,300 --> 00:05:04,520 着木板右手牵着那根拉直的小绳子眼睛向木板上看去 70 00:05:04,520 --> 00:05:12,420 使得这个木板的上边缘对准北极星下边缘对准水平面 71 00:05:12,420 --> 00:05:18,000 对准海面如果你用的板不合适太大了把北极星和海平 72 00:05:18,000 --> 00:05:22,700 面都挡住了那就换一块小的直到找到一块差不多合适 73 00:05:22,700 --> 00:05:26,120 的板这个三角形里边呢这 74 00:05:28,560 --> 00:05:31,400 条边就是那个绳子的距离已经知道了 75 00:05:31,860 --> 00:05:37,460 这条边就这个三角形的高也已经知道了而且这里这个 76 00:05:37,460 --> 00:05:41,400 角是直角那这样我们就很容易可以算出 77 00:05:42,300 --> 00:05:46,800 这个角的角度当然再乘以 2 就是 78 00:05:47,670 --> 00:05:53,030 这个假角的角度这个角我们就把它叫做北极星的高度 79 00:05:53,030 --> 00:05:53,350 角 80 00:05:53,970 --> 00:06:00,530 这个角的度数呢正好就是你所处的纬度比如说你看到 81 00:06:00,530 --> 00:06:06,950 的这个时候这是 30 度那其实你所在的纬度也就是 30 度 82 00:06:06,950 --> 00:06:08,690 北纬 30 度 83 00:06:09,240 --> 00:06:15,380 因为从赤道上看北极星北极星就在水面上就是零度到 84 00:06:15,380 --> 00:06:22,360 了北极它就在你的头顶正中跟海平面的夹角是 90 度那 85 00:06:22,360 --> 00:06:26,320 不正好跟纬度一致了吗因为在北极点的时候你的纬度 86 00:06:26,320 --> 00:06:29,720 也是 90 度在赤道的时候你的纬度也就是零度 87 00:06:30,710 --> 00:06:35,670 航行了一段时间后再次测量北极星的高度角就可以测 88 00:06:35,670 --> 00:06:37,590 量出自己纬度的变化 89 00:06:38,720 --> 00:06:43,530 但是这到底是多长的距离呢但我机智的表示不用算到 90 00:06:43,530 --> 00:06:47,890 底多长了大家知道我们刚才说过圆周角是 360 度它可 91 00:06:47,890 --> 00:06:53,020 以分为 60 份每份就是 6 度这就叫做一分那直接就把一 92 00:06:53,020 --> 00:06:57,380 分定义为一海里就好了把海里换算成公里那是后来的 93 00:06:57,380 --> 00:06:57,980 事情了 94 00:06:58,600 --> 00:07:03,600 我刚才介绍的是几百年前海上测量自身纬度位置的方 95 00:07:03,600 --> 00:07:03,880 法 96 00:07:04,440 --> 00:07:06,820 现在当然有更先进的定位系统 97 00:07:07,340 --> 00:07:08,680 另外需要说明的是 98 00:07:09,120 --> 00:07:14,040 中国古代的人不知道地球是圆的当然不会有纬度以及 99 00:07:14,040 --> 00:07:19,260 海里的概念但它们的确也是通过北极星的高度来测量 100 00:07:19,260 --> 00:07:21,500 自己在海面上的相对位置的 101 00:07:22,950 --> 00:07:28,410 现在好奇的同学又有问题了纬度的测量知道了那它们 102 00:07:28,410 --> 00:07:33,130 怎么测量自己的经度位置呢我们没有时间再去讲这个 103 00:07: ……（后略，完整文稿见视频页字幕）