Can you solve the unstoppable blob riddle? - Dan Finkel

7,908,531 views ・ 2019-03-18

TED-Ed


请双击下面的英文字幕来播放视频。

翻译人员: 진영 윤 校对人员: Lipeng Chen
00:07
A shooting star crashes on Earth,
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一颗流星撞上了地球,
00:10
and a hideous blob emerges.
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出现了一只可怕的粘液怪物。
00:13
It creeps and leaps, it glides and slides.
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它会爬行、会跳跃; 它会滑动、会滑行。
00:17
It’s also unstoppable:
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它也所向无敌:
00:19
weapons, fire, extreme temperatures…
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武器、火、极端温度……
00:21
no matter what you throw at it,
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不论你用什么方式攻击它,
00:23
it just regrows and continues its rampage.
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它总会再生并继续制造暴乱。
00:27
Its expansion is breathtaking;
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它的扩展能力十分惊人;
00:29
it doubles in size every hour.
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每小时,它的大小就会增大一倍。
00:32
But there’s one opportunity:
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但有一个机会:
00:34
after each hour, it goes to sleep,
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每小时之后,它就会进入睡眠,
00:37
forming itself into a flat triangle
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让它自己的形状变成扁平三角形,
00:39
and resting for a few minutes
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休息几分钟,
00:41
before it begins eating and growing again.
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接着又会开始吃东西成长。
00:45
Your only chance to save the planet
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你只有一个机会能拯救地球,
00:47
involves a satellite-mounted nano-fission ray that can cut through the blob.
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要用到装在卫星上的 纳米分裂光束来将它切成两半。
00:53
When the blog is active
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当怪物在活动时,
00:54
it heals itself within seconds.
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只要几秒钟时间它就会愈合。
00:57
However, when you break the sleeping blob into two triangles,
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然而,当你把在睡觉中的 怪物切成两个三角形时,
01:00
you make a critical discovery.
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你有了重大的发现。
01:03
The acute triangle portion,
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锐角三角形的部分
01:05
with all angles less than 90 degrees, is inert.
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也就是所有角都小于90°的 三角形,不再有生命力
01:09
It never “wakes up.”
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它不再醒来
01:11
The obtuse triangle,
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至于钝角三角形,
01:12
which has an angle greater than 90 degrees,
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也就是有一个角大于90°的三角形,
01:15
wakes up as usual and keeps growing.
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还是一样会醒来并继续成长。
01:18
Similar experiments show that all shapes other than acute triangles,
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类似的实验结果显示, 除了锐角三角形之外的所有形状,
01:22
including right triangles, will also wake up.
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包括直角三角形,都还是会醒来。
01:26
For the next few minutes,
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接下来的几分钟,
01:27
the blob is sleeping in its obtuse triangle form.
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怪物会以扁平三角形的 形式进入睡眠。
01:31
You can make clean, straight-line cuts
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你可以针对三角形上 或三角形内指定的任两个点
01:34
between any two points on or inside the triangle.
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做到精确的直线分割。
01:37
But you’ll only have time to make 7 cuts while the satellite is above you.
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但当卫星在你上方可以 进行切割的时间只够你切七次。
01:42
By the time it completes its orbit and returns,
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当卫星完成绕行再回来时,
01:45
the blob will have consumed the entire world,
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就已经来不及阻止怪物 把整个世界吞噬了,
01:48
if even a single portion that will wake up remains.
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即使只剩下怪物的一小部分也是如此。
01:52
How can you cut the blob entirely into acute triangles
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你要如何把怪物切割成锐角三角形,
01:56
and stop it from destroying the planet?
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阻止它摧毁地球?
01:59
Pause the video now to figure out for yourself
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如果你希望自己 尝试解题,请在此暂停。
02:01
Answer in 3
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答案即将公布:3
02:02
Answer in 2
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答案即将公布:2
02:05
Answer in 1
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答案即将公布:1
02:07
While this seems doable at first,
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虽然一开始会觉得这个方法可行
02:09
there’s a hidden difficulty when it comes to avoiding obtuse and right angles.
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其实若想避免钝角和直角三角形, 会碰到一个隐藏的困难处。
02:14
Every time you make a cut that reaches an edge,
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每当你做的切割有接触到边缘,
02:17
it either makes an acute and an obtuse angle, or two right angles.
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就会制造出一个锐角三角形和一个钝角三角形, 不然就是两个直角三角形。
02:22
That makes it seems like you’re doomed to keep creating obtuse angles.
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看起来似乎你注定会 一直制造出钝角三角形。
02:27
But as with so many of life’s problems,
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但是,就像许多人生难题一样,
02:30
we can look to pizza for inspiration.
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我们都能从披萨上找到灵感。
02:33
Imagine squaring off the outside of a pizza,
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想象一下,把披萨的外缘切平,
02:36
so that instead of a circle, it’s an octagon.
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披萨现在变成八角形,不再是个圆。
02:39
When we cut it into slices,
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当我们把它切片,
02:41
each of the eight triangles is acute.
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这8个三角形都是锐角三角形
02:44
This works with larger polygons too.
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对于边数更多的多边形, 这招也一样可以。
02:46
Importantly, it also works for some polygons with fewer sides,
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重要的是,对于边数 更少的多边形仍然可行,
02:51
including heptagons, hexagons, and pentagons.
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包括七角形,六角形,五角形。
02:55
That’s good news,
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那是好消息,
02:56
because if you cut off the sharp corners of the blob triangle,
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因为如果你把怪物 三角形的尖角切除,
03:00
a pentagon is exactly what you’ll be left with.
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你就会得到一个五角形。
03:04
And just like a pizza,
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就像披萨一样,
03:06
you can cut the blob pentagon into five acute triangles.
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你可以把怪物五角形 切成五个锐角三角形。
03:10
That’s 7 cuts, and it renders the blob completely inert.
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一共要切七次,结果是 怪物完全不再有生命。
03:15
You’ve saved the day!
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你拯救了世界!
03:17
Now you just need to figure out what to do
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现在,你只要想办法处理
03:19
with all of these giant, practically indestructible triangles.
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这些巨大且刀枪不入的三角形了。
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