第1章 迷失在宇宙中 Lost in the Cosmos · 第4讲S6

1. 老师，讲稿里提到的'critical density'（临界密度）和小孩学语言的'critical period'（关键期）里的'critical'意思一样吗？都是指'关键的'吗？
2. 老师，讲稿里用'Goldilocks effect'（金发姑娘效应）来比喻宇宙引力刚刚好，这个比喻具体是指哪方面像金发姑娘的故事呢？
3. 老师，'closed universe'（闭合宇宙）和'open universe'（开放宇宙）在密度和引力上到底有啥区别？为啥一个会缩回去一个会一直远离？
4. 老师，为啥讲稿里说'flat universe'（平坦宇宙）是'just right'？它的密度和临界密度是啥关系？
5. 老师，最后提到的'Martin Rees'认为我们只是众多宇宙中的一个，那'flat universe'这种'刚刚好'的情况，是不是在所有宇宙里都很少见？

1. Teacher, does 'critical' in 'critical density' mean the same thing as in 'critical period' for language learning? Is it always 'crucial'?
2. Teacher, how exactly does the 'Goldilocks effect' metaphor relate to the universe's gravity being 'just right'?
3. Teacher, what's the actual difference between a 'closed universe' and an 'open universe' in terms of density and gravity? Why does one shrink and the other expand forever?
4. Teacher, why is the 'flat universe' considered 'just right'? What's its relationship with the critical density?
5. Teacher, since Martin Rees thinks we're just one of many universes, is a 'flat universe' (the 'just right' scenario) actually very rare across all possible universes?

1 00:00:05,780 --> 00:00:09,380 The third option is that gravity is just right, 2 00:00:09,620 --> 00:00:13,880 critical density is the cosmologist's term for it, 3 00:00:13,980 --> 00:00:16,860 and that it will hold the universe together, 4 00:00:17,060 --> 00:00:18,760 adjust the right dimensions, 5 00:00:19,040 --> 00:00:21,760 to allow things to go on inde finitely. 6 00:00:23,920 --> 00:00:27,580 第三种情况,第三种选择 option, 7 00:00:27,580 --> 00:00:30,020 指的是选择选项, 8 00:00:30,140 --> 00:00:34,860 那就是宇宙的引力是刚刚好。 9 00:00:34,860 --> 00:00:41,680 Critical Density 这个词 Critical 是临界值临界密度 10 00:00:42,360 --> 00:00:44,680 临界这个概念指的是 11 00:00:45,240 --> 00:00:50,140 在这个范围之内它是不会产生变化的如果超出了这个 12 00:00:50,140 --> 00:00:52,950 临界值的话就会产生变化 13 00:00:54,060 --> 00:00:55,120 比如说这个 14 00:00:55,700 --> 00:01:00,780 这里讲的 Critical Density 临界密度如果在这个临界 15 00:01:00,780 --> 00:01:03,080 密度之内那就没有问题 16 00:01:03,690 --> 00:01:08,510 而超出的话的话宇宙恐怕就不成其为现在我们所知的 17 00:01:08,510 --> 00:01:09,210 这个宇宙了 18 00:01:10,020 --> 00:01:13,980 我们还可以说小孩在学语言的过程中他会有一个 19 00:01:13,980 --> 00:01:15,100 critical period 20 00:01:16,790 --> 00:01:18,430 就是一个关键期 21 00:01:19,050 --> 00:01:23,750 如果过了这个关键期呢他恐怕就无法自然地习得语言 22 00:01:23,750 --> 00:01:24,810 了后 23 00:01:25,640 --> 00:01:29,560 面这个 that 引导的从句跟前面的 that 从句是并列的有 24 00:01:29,560 --> 00:01:34,820 and 连接 The third option is that and that 这样 25 00:01:35,560 --> 00:01:42,940 由于重力也就是引力刚刚好它就可以让这个宇宙维持 26 00:01:42,940 --> 00:01:50,400 在一种恰如其分的恰到好处的尺寸上它的尺寸就不会 27 00:01:50,400 --> 00:01:56,140 太小不会像引力太大的情况那就会变得越来越小它缩 28 00:01:56,140 --> 00:01:59,940 成一个起点也不会太大越 29 00:02:00,190 --> 00:02:04,950 来越大越来越大然后什么都不会发生它会刚刚好然后 30 00:02:04,950 --> 00:02:08,850 allow things to go on indefinitely 那这个宇宙就可以 31 00:02:08,850 --> 00:02:10,490 一直存在下去 32 00:02:11,940 --> 00:02:16,820 cosmologists in their lighter momentssometimes call 33 00:02:16,820 --> 00:02:21,720 this the Goldilocks effectlighter moments 指的是心 34 00:02:21,720 --> 00:02:27,060 情比较轻松的时候因为天文学家嘛科学家他们一般来 35 00:02:27,060 --> 00:02:32,840 说解文章的时候要比较严肃的但是在轻松的时候有时 36 00:02:32,840 --> 00:02:34,860 候他们会把这种情况叫做 37 00:02:38,950 --> 00:02:39,430 金 38 00:02:39,520 --> 00:02:45,080 发姑娘不知道大家有没有听过金发姑娘和三只小熊的 39 00:02:45,080 --> 00:02:47,920 故事呢金发姑娘到了森林里边 40 00:02:48,800 --> 00:02:50,120 到了小熊的家 41 00:02:51,030 --> 00:02:53,630 她看到熊爸爸的椅子太硬 42 00:02:54,480 --> 00:02:58,560 熊妈妈的椅子太软小熊的椅子刚刚好 43 00:02:59,610 --> 00:03:05,730 熊爸爸的那碗粥太烫熊妈妈的太凉小熊的粥刚刚好他 44 00:03:05,730 --> 00:03:10,790 就吃完了所以这 Goldilocks effect 指的就是这种恰到 45 00:03:10,790 --> 00:03:12,030 好处的情况 46 00:03:15,400 --> 00:03:19,180 Well,cosmologists sometimes call this the 47 00:03:19,180 --> 00:03:23,640 Goldilocks effect that everything is just right 这个 48 00:03:23,640 --> 00:03:24,040 that, 49 00:03:24,300 --> 00:03:28,500 everything is just right 其实就是解释这个 50 00:03:28,500 --> 00:03:33,940 Goldilocks effect 也就是所有的东西都是刚刚好 For 51 00:03:33,980 --> 00:03:34,540 the record, 52 00:03:34,820 --> 00:03:38,360 these three possible universes are known 53 00:03:38,360 --> 00:03:40,840 respectively as closed, 54 00:03:41,160 --> 00:03:41,700 open, 55 00:03:41,880 --> 00:03:48,850 and flatrespectively 的意思是各自分别的比如 56 00:03:48,850 --> 00:03:53,010 successful in their respective fields 在他们各自的 57 00:03:53,010 --> 00:03:55,890 领域都取得成功这是形容词, 58 00:03:56,010 --> 00:03:58,190 而我们这个是副词指 59 00:03:58,290 --> 00:04:05,010 的是前面说到的三种可能的宇宙模型也就是宇宙未来 60 00:04:05,010 --> 00:04:09,290 的三种可能的命运分别可以叫做 61 00:04:09,960 --> 00:04:14,940 闭合型开放型平坦型这 62 00:04:16,790 --> 00:04:20,650 页的内容并不是我们书本上的内容但是它可以帮助我 63 00:04:20,650 --> 00:04:27,620 们理解这三种宇宙模型闭合型也就是它的 density 64 00:04:28,840 --> 00:04:36,640 就是密度是大于临界密度它的引力非常大所有的东西 65 00:04:36,640 --> 00:04:42,580 它就会 curves back on itself 都会回到自身然后整个宇 66 00:04:42,580 --> 00:04:44,780 宙就会越缩越小而 67 00:04:44,940 --> 00:04:51,140 开放型宇宙呢它的 density 也就是密度是小于临界密 68 00:04:51,140 --> 00:04:52,280 度它的 69 00:04:52,820 --> 00:05:00,280 引力很小所以所有的东西就会不断地离开相互地远离 70 00:05:00,280 --> 00:05:04,160 一直永远在不断地远离而 71 00:05:05,600 --> 00:05:07,480 这个 sorry 平 72 00:05:07,870 --> 00:05:12,790 坦型宇宙它就没有这种弯曲的现象它的 73 00:05:12,850 --> 00:05:18,350 密度是刚刚好等于零件密度而它的引力也就是刚好的 74 00:05:18,900 --> 00:05:23,920 那 Diverging lines remain at a constant anglewith 75 00:05:23,920 --> 00:05:28,740 respect to each other 这里的一切是不会变的这个宇宙 76 00:05:28,740 --> 00:05:31,460 就会永久地存续下去 77 00:05:34,150 --> 00:05:34,670 Well, 78 00:05:34,870 --> 00:05:37,790 now let's have a quick review of what we have covered 79 00:05:37,790 --> 00:05:38,610 today The 80 00:05:39,000 --> 00:05:43,380 universe is just right for us with exactly the right 81 00:05:43,380 --> 00:05:44,900 gravity But why? 82 00:05:46,210 --> 00:05:49,630 Some experts believe that there may have been many 83 00:05:49,630 --> 00:05:50,610 other big bands 84 00:05:51,190 --> 00:05:56,370 也就是说以前存在过很多很多的大爆炸出现过很多很 85 00:05:56,370 --> 00:05:59,150 多的宇宙那些都不合适好了 86 00:05:59,250 --> 00:06:03,990 终于有一个恰到好处的宇宙出现了 Mart 87 00:06:04,240 --> 00:06:08,840 in Rees believes that we are in one of many universes 他 88 00:06:08,840 --> 00:06:10,220 认为同 89 00:06:10,380 --> 00:06:16,180 时存在着很多的宇宙很多不同的宇宙在同时存在那么 90 00:06:16,180 --> 00:06:22,450 这么多总有一个合适的我们正好就存在我们正好就生 91 00:06:22,450 --> 00:06:26,660 活在那个正合适的那个宇宙里面他 92 00:06:27,200 --> 00:06:30,280 还说 We have just the right values that govern our 93 00:06:30,280 --> 00:06:30,820 universe 94 00:06:31,400 --> 00:06:37,240 有六个基本有六个特别的数字主宰着我们的宇宙举 95 00:06:37,720 --> 00:06:43,260 了一个例子也就是氢和氦的转换率千分之七那个最 96 00:06:44,290 --> 00:06:49,870 后作者还提到我们的宇宙的未来会是什么样的呢他 97 00:06:50,410 --> 00:06:53,910 说有 three possible outcomes 也就是 closed, 98 00:06:53,990 --> 00:06:55,930 open and flat 99 00:06:57,250 --> 00:06:58,450 Well,like usual, 100 00:06:58,710 --> 00:07:03,240 we'll have a question for our next session 101 00:07:04,080 --> 00:07:09,120 下一次的问题就是 What is it like to travel to the edge 102 00:07:09,120 --> 00:07:09,980 of the universe? 103 00:07:09,980 --> 00:07:11,260 拜拜