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本视频由Audible公司赞助
Get one audiobook and two Audible originals for free
在简介的链接里可免费获得
at the link in the description.
一份有声读物和两份有声原版书
So let’s say you want to lose weight.
假如你想减肥
You have some options.
可以这样做
You could join Weight Watchers, you could stop eating carbs,
加入减肥机构 戒掉碳水化合物
you could train for a marathon,
进行马拉松训练
you could cut off an appendage,
切下一条胳膊或腿
or you could just move to the Hudson Bay region of Canada.
抑或搬到加拿大的哈德逊湾地区
Why?
为什么？
Because the Hudson Bay is missing gravity.
因为哈德逊湾是失重地区
If you weigh 200 kilo-pounds normally,
如果你的正常体重是200公斤
by moving to Hudson Bay, you will, in an instant,
搬到哈德逊湾的话 你可以在一瞬间
automatically weigh 0.01 pounds or kilograms less—
自动减重0.01磅或公斤
and you don’t even have to stop eating pasta.
甚至都不需要你戒掉意大利面
You see, back in the 1960s,
你也看到了 在20世纪60年代
scientists were mapping the Earth’s global gravitational
科学家们在绘制全球重力场图
fields to make a thing that looks like this,
这样一个东西
and if you look here,
如果你看这里
you’ll notice that
就会注意到
it’s a different color from the not-here parts.
这部分颜色与其他部分不同
This is Canada’s Hudson Bay and this means
这就是加拿大的哈德逊湾
that there is literally less gravity here
这也就意味着 这里的重力
than everywhere else on earth.
比地球上其他地方要小
Based off science stuff, this should not have been the case.
从科学层面来讲 不应该是这样的
The scientists looked everywhere for the missing gravity—the cupboard,
科学家们到处寻找失重的地方：橱柜
their pants pockets,
裤子口袋
all the usual places—but they couldn’t find it anywhere.
所有这些比较常见的地方 但还是找不到
Over time, two major theories have developed
随着时间的推移 出现了两种主要的理论
to try to solve the mystery of Hudson Bay’s missing gravity.
来解释哈德逊湾失重之谜
But before we go into them, a quick primer on how gravity works.
但在开始之前 先快速引入一下重力的工作原理
Gravity, of course,
当然《Gravity》
was a 2006 song written by John Mayer as the third single off his album Continuum.
是2006年John Mayer创作的第三支单曲
It works by following a basic chord progression in the key of C
它遵循基本的C调和弦
and combining that with lyrics that are just vague enough
再结合含糊不清的歌词
to mean whatever you want them—
表达出想怎么样就怎么样的感觉
oh you know what, this is the wrong gravity.
噢 你知道了 这不是我要的“重力”
I should really stop having the AI write my scripts.
我真的不该让AI写脚本
Gravity is, put as simply as possible,
简单地说 重力
an attraction that relies on mass and distance
是基于质量和距离而产生的吸引力
and then there’s the Higgs-boson field and Higgs-boson particles and Higgs-boson…bosenhiggs
然后还有希格斯玻色子场 希格斯玻色子粒子 希格斯玻色子等
or whatever…you know what, for the purposes of this video,
或是你所知道的其他什么 出于本视频考虑
we’re going to oversimplify—
我们要极度简化一下——
not because I don’t understand it, or anything,
不是因为我不懂 或其他什么原因
but because I don’t wan na explain.
而是因为我不想解释
The basic idea you need to understand is
你要理解的基本思想是
that gravity is proportional to mass and to distance.
重力与质量和距离成正比
The more mass, the more gravity.
质量越大 重力越大
The more distance, the less gravity.
距离越远 重力越小
The reason that if you slip on a banana peel,
如果你踩到香蕉皮
you fall on the ground, is that you are pulled
在地板上滑倒 原因就是
down to earth by the Earth’s mass.
你被地球的质量拉到地面上
If the earth was twice as massive,
如果地球的质量是两倍
assuming it was the same size,
假设其大小不变
then we would experience twice as much gravity.
那么我们感受到的就是双倍的重力
Basically, the more mass below you,
基本上 支撑你的东西质量越大
the more gravity you experience,
你所感受到的重力也就越大
but the further you are from something, the less its gravity pulls you.
但是你离某物越远 所受的引力也就越小
That’s why, if you get far enough from the earth,
这就是 如果你离地球足够远
and you slip on a banana peel,
踩在香蕉皮上滑倒了
you will no longer be pulled down to the ground,
也不再会被拉倒在地的原因
you’ll just float around in space which
你只是漂浮在宇宙中
is way cooler than falling down
这比滑倒在地还要酷
on earth and then having all the kids in the 7th grade
然后所有七年级的孩子都嘲笑你
laugh at you and then getting called banana man Sam
在你的余生里
for the rest of your life.
都被人叫做香蕉人山姆
Not that that ever happened to me.
这种事情可不会发生在我身上
So, here are the two theories
有两个理论
on why the Hudson Bay is missing gravity.
阐述了哈德逊湾失重的原因
The first has to do with what’s called convection.
第一个与所谓的对流有关
Basically, something like 60ish miles or 100ish kilometers beneath the ground is the earth’s mantle
基本上 地下60英里或100千米左右的地方是地幔
and this mantle is full of super-hot magma.
地幔中充满了超热的岩浆
But the magma doesn’t stay still—it
但是岩浆并非静止不动的
swirls and whirls and twirls and churls and flurls.
而是旋转 旋转 旋转 搅拌 旋转
The reason that magma is in motion is because of convection.
岩浆运动的原因是对流
There’s heat coming from the Earth’s core and that heats up magma at the bottom.
来自地核的热量加热了底部的岩浆
That magma then expands, because it’s hot.
岩浆受热膨胀
Once it’s expanded, it’s lighter, so it floats up
一旦膨胀 就会变轻而浮起
and when it floats up, it pushes colder magma down.
当它浮起的时候 就往下推较冷的岩浆
Eventually that magma heats up, and does the same thing,
最终岩浆会升温 同理
and the cycle repeats over and over and over.
循环往复 周而复始
So it creates a current, that looks like this,
所以它会产生对流 像这样
that goes around and around and around like
一圈一圈的
a giant, terrifying, hot magma merry-go-round.
就像一个巨大的 可怕的 滚烫的岩浆式旋转木马
The convection current can pull down the Earth’s tectonic plates.
对流可以把地球的构造板块向下拉
If the tectonic plates are pulled down in an area,
如果一个地区的构造板块被下拉
like Hudson Bay, there’s less mass below you, and therefore less gravity.
支撑你的东西质量就变小 因此重力也就变小 就像哈德逊湾一样
The second theory has to do with something called the Laurentide Ice Sheet.
第二种理论与劳伦泰德冰盖有关
Back in the Ice Age,
在冰河时代
there was this giant sheet of ice that covered most of where Canada
这片巨大的冰盖覆盖了
and the northern US are now.
加拿大和美国北部的大部分地区
It was like an ice skating rink,
它就像一个溜冰场
except 2.5 million square miles across, and about 2 miles or 3.2 kilometers thick,
只是有250万平方英里宽 2英里或3.2公里厚
so actually, not like an ice skating rink at all, and in two places in Hudson Bay,
而它压根就不像一个溜冰场 哈德逊湾有两个地方
it was even thicker—closer to 2.3 miles or 3.7 kilometers.
甚至更厚：接近2.3英里或3.7公里
About 10,000 years ago, the ice melted,
大约一万年前 冰融化了
and it left behind a massive dent in the earth.
在地球上留下了一个巨大的凹陷
That dent pushed a bunch of earth to the sides.
那个凹陷把这一块挤到边上去
So now, if you stand in that dent,
那么现在 如果你站在凹陷处
there’s less mass below you.
支撑你的东西质量就更小
And like we said before—less mass equals less gravity.
就像我们之前说的 质量越小 重力越小
The earth is slowly rebounding from the dent,
地球慢慢地从凹陷处反弹回来
but at a rate of half an inch or one and a quarter centimeters a year,
但反弹速度是每年0.5英寸或者1.25厘米
so it’s going to take a while for things to get back to normal,
所以需要一段时间地球才能恢复正常
and therefore until then, there’s less gravity in the area.
因此在那之前 这个区域的重力会较小
Now it’s important to note that
需要注意的是
when you’re in the dent,
当处于凹陷处
you’re also closer to the center of the Earth’s gravity,
你更接近地球的引力中心
which makes gravity stronger.
引力也就越强
After all, the closer you are to something, the stronger the gravity,
毕竟 你离得越近 重力也就越强
but in this theory,
但在这个理论中
the loss of gravity caused by the reduction in mass below you
因支撑你的东西质量减少而造成的失重
is more than the gain in gravity resulting from being closer to the Earth’ center.
比因离地球中心更近而增加的重力更大
So which theory is right?
那么哪种理论是正确的呢?
Well, as a certain taco ad once wisely said:
嗯 就像一个墨西哥卷饼广告曾经明智地说:
“ Por qué no los dos? ”
“为什么不能两者兼得?”
As it turns out, both theories were right.
事实证明 这两种理论都是正确的
Geophysicists at the Harvard-Smithsonian Center
哈佛-史密森中心的地球物理学家
for Astrophysics satellite data from the Gravity Recovery and Climate Experiment,
根据重力恢复与气候试验（GRACE）的天文卫星数据
or GRACE, were finally able to calculate that that rebounding
终于计算出
ice sheet and the swirling magma are each causing
反弹的冰盖和旋转的岩浆
about half of the missing gravity,
对失重现象的产生 各起一半作用
and so, the mystery solved.
于是谜底揭开了
And just to think,
想想看
gravity might have gotten away with it if it weren’t for those pesky geophysicists.
要不是那些讨厌的地球物理学家 重力可能就侥幸逃脱了
Now, there is one other type of gravity
现在 还有另一种重力
that I’m not sure you understand—the gravity of this situation.
我不确定你是否明白这种重力
Audible is offering you, yes you, Michael,
就是你 迈克尔 或其他什么人 Audible为你提供
or whatever your name is, one free audiobook,
一份免费的有声读物
one free Audible original,
一份免费有声原版书
and another free Audible original by signing up for a 30-day
另一份有声原版书
free trial at audible.com/HAI and using the promo code, “HAI.”
要在audible.com/HAI注册即可免费试用30天 也可以使用优惠券“HAI.”
You can use that to listen to all 48 glorious hours of the Stand,
也可以用来听48小时的精彩的《The Stand》
which is objectively the best Stephen King book, for free.
客观地说 史蒂芬·金最好的书也是免费的
Just think of all the dishwasher unloading sessions, dog walks, and work commutes
想想洗碗时 溜狗散步 工作通勤所有这些放松过程中
you’ll be entertained for with this one audiobook.
听听这些有声读物 会很开心的
There’s no better place to get audiobooks than Audible
这么庞大的图书馆 如此棒的移动app
given their enormous library and fantastic mobile app
没有比Audible更好的获得有声书的地方了
and of course, once again,
必须再强调一下
by going to audible.com/HAI and using the code, “ HAI, ” or texting, “ HAI,” to 500-500,
登陆audible.com/HAI使用代码” HAI, ” 或发短信” HAI, “到500-500
you will get one audiobook and two audible originals for free.
你可以免费得到一份有声读物和两份有声原版书