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科幻小说中最逼真的人造重力是什么?

What's the Most Realistic Artificial Gravity in Sci-Fi?

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人造重力 这在大多数科幻小说中
Artificial gravity, it’s an essential plot element
是一个至关重要的情节元素
in most science fiction stories.
但事实上这些故事
But do any of those stories actually
都需要人造重力吗?
get artificial gravity right?
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你是否意识到这一点
Whether you realize it or not, artificial gravity
人造重力对大部分科幻明星至关重要
is essential to most sci-fi stars.
让我们想一下
Think about it.
如果让吕克-皮卡德失去一些重力
Jean-Luc Picard loses some gravitas if he’s
他会像一个气球一样漂浮
floating around like a balloon.
更戏剧的是
And drama aside, the high cost of shooting
一些高成本的影视镜头
realistic zero-g scenes for TV and movies
像宇宙飞船上的零重力
is just another rationale for inventing
是发明人造重力机器
some kind of mechanism for artificial gravity
的原因
on spaceships.
这里强调的是发明
The emphasis here is on inventing.
大部分的人造重力都用在这里
Most artificial gravity that’s just there,
通过一些重力发生器
either through some kind of gravity generators
或者是与物理学有所冲突的虚构“重力保护层”
or fictitious “gravity plating” seems
像“星际大战”、“太空堡垒卡拉狄加”
to conflict with known physics. “Star Wars,” “Battlestar
“星际迷航”、“仙女座”
Galactica,” “Star Trek,” “Andromeda,”
雷德利·斯科特的“外星人”、“普罗米修斯”系列
the Ridley Scott “Alien,” “Prometheus” series, all
他们都用了这种比喻
of them use this trope.
但除了“星际迷航” 其他没有一个
But with the exception of “Star Trek,” none of them
给出了详细解释
even bother with a detailed explanation.
你是否在牛顿或爱因斯坦的基础上
Whether you want to think of gravity
再去思考关于
in the Newtonian or the Einsteinian sense,
重力仍存在的问题
the problem persists.
目前没有已知的方法能制造出
There’s simply no known way to produce the equivalent of 1
仅有一克引力 有着平滑表面
Earth g on stacked, flat surfaces, like decks of a ship,
的局部区域空间
in any localized region of space.
你需要大量的质量
You’d need either enormous amounts of mass,
大到你基本上能够制造一颗行星
so much that you’d basically have a planet and not
而不是一艘星际飞船
a starship.
或者你需要外来的东西 像负质量重力排斥
Or you need something exotic, like gravitationally repulsive
但是这也不存在
negative mass, which doesn’t exist.
因为技术原因
And no, for technical reason, I don’t
我不喜欢用暗能量来解决这个问题
think dark energy would be a solution to this problem.
在这一集中 我们坚持
In this episode, we’re going to stick to franchises
用一种具有真实感的方式
that use the only semi-realistic way we
来了解人造重力
know of to get artificial gravity,
即旋转你的飞船
namely rotating your spaceship.
好的 那么如何旋转来模拟重力?
All right, so how exactly does rotation simulate gravity?
想想嘉年华游乐设施
Think about carnival rides.
我想到有重力感的东西
I’m thinking of something called the Gravitron, maybe
像Starship 3000(游乐设施)
the Starship 3,000.
就是你进入一个封闭的圆形空间
Basically, you enter a closed, circular room,
然后开始高速角速率的旋转
which is then spun up to a high angular speed.
在这个过程中
And in the process, the wall starts
墙面会用力推你的背部
pushing hard against your back.
为什么会这样那?
Why does that happen?
从上面俯瞰就会发现
From an overhead perspective, your body
你的身体想飞出去而不是做圆周运动
wants to fly off in a tangent, not move in a circle.
就是这个原因墙推着你
And the reason the wall is pushing on you is to turn you,
让你去做圆周运动
i.e. to move you in a circle.
但从空间的中间看的话
But what do things look like from the perspective
事情是什么样子的那?
inside the rotating room?
在中间看 它不同于任何的旋转
In there, it doesn’t look like anything is spinning.
似乎有一些神秘的力量
Instead, it appears that there’s some mysterious force that
强迫的把你向外推
wants to hurl you outward.
墙推你的原因是防止你向外
And the reason the wall is pushing against you
这就有点类似于
is to prevent that outward fall, kind of like how
地球把土向外推到你的脚下
the ground here on Earth pushes up
而你向着地球中心
on your feet to keep you from falling inward toward Earth’s
下落
center.
基本论点就是从空间的角度来看
So bottom line, from the perspective of the room,
好像有一个直接向外的
it’s as though there’s a radially outward directed
“重力”
“gravity.”
现在假如你在太空 那么地球的重力
Now, if you were out in space, Earth’s real gravity,
也只会把你向下拉 而不会像图中把你向外推
which also pulls you down, wouldn’t be in the picture.
墙给你的这个向外的力
And this force from the wall on you
是给你的唯一的力
would be the only force on you.
现在把你的脚对着墙面 然后站直 哇!
Put your feet up against a wall, stand up straight, boom,
人造重力
artificial gravity.
事实上 有一个简单的公式
It turns out that there’s a simple formula
可以计算出这个旋转结构
for how big the effective surface gravity produced
产生了多大的表面有效重力
by this rotating structure would be.
也就是旋转结构的半径
It’s just the radius of the rotating structure multiplied
加上其角速度的平方
by the square of its rotational speed in radians per second.
如果你调整空间的半径和转速
If you adjust the radius and rotation rate of the room,
你的脚从墙上获得的力量
you can make that force from the wall on your feet
将和在地面上获得的力量一样大
just as big as the force from the ground
现在 在你的脚上模拟
currently on your feet and thus simulate
地球表面1克的重力
Earth’s 1 g of surface gravity.
记住这一切都建立在物理的基础上
Now, keep all this in mind as we gut check the physics
下面的科幻例子-“2001”、“环形”
of the following sci-fi examples– “2001,” “Ringworld,”
“光环”、“巴比伦5号”-都将通过旋转引出
“Halo,” and “Babylon 5”– all which use rotation-induced
人造重力
artificial gravity.
我知道这个列表并不详尽
I know this list is not exhaustive.
我只举了些著名的科幻小说系列
I’m just focusing on well-known sci-fi franchises
提供一些人造重力显著的例子
that offer salient examples of artificial gravity in action.
我们先从标志性的场景开始
Let’s start with the iconic scene
弗兰克·普尔在“2001:太空漫游”中绕着
of Frank Poole jogging around the rotating command module
旋转命令模块慢跑
in “2001: A Space Odyssey.”
普尔的身高是一米八
Poole’s height is 1.8 meters.
用他作为标准 那他绕着跑的
Using him as a ruler, the radius of the module he’s running in
模块的半径大约是8米
looks to be about 8 meters, give or take.
才能在表面产生1克有效重力
To produce 1 Earth g of effective gravity
或者10米的每秒平方
at its surface or 10 meters per second squared,
我们的公式告诉我们
our earlier formula says the ring
这个圆形需要每秒旋转1.1个弧度
would need to rotate at 1.1 radians per second.
这个弧度有点超过57度
Since a radian is a little more than 57 degrees,
所以每分钟转10.5圈
that’s about 10.5 revolutions per minute or 10.5 RPM.
不幸的是 在现实中
Unfortunately, in real life, even a few RPMs
即使误差很小的转速也会产生
in such a small craft would create a lot of weird effects
“2001”这样不可思议的效果
that “2001” overlooks.
为了更好的理解 打个比方
An analogy will help you see what I mean here.
你和朋友在旋转木马上
Say you and a friend are on a merry-go-round
从上空俯瞰 是逆时针在旋转
that spins counterclockwise as viewed from above.
你扔了个球给朋友
Say you throw a ball to your friend.
从上面来看 球会笔直的朝着
Viewed from above, the ball will go straight as your friend
朋友转过的位置飞去
rotates away from where the ball was headed,
所以你没有扔中
so you miss your target.
但在旋转木马的中间来看
But viewed from the merry-go-round,
相同的场景却表现为
the same scenario manifests as the ball’s path
球无缘无故的向右飞去
curving to the right for no apparent reason.
这明显偏离直线运动
That apparent departure from straight line motion
在旋转坐标系中这称为科里奥利效应
in rotating reference frames is called the Coriolis effect.
一个物体的科里奥利加速度
An object’s Coriolis acceleration
与它速度成正比
will be proportional to its speed, relative to the rotating
与旋转框架和框架的旋转速度相对
frame and the rotation rate of the frame itself.
在这个情况中 我们讨论的是环形
In this case, we’re talking about the ring.
一分钟10.5圈的转速
At 10.5 RPMs, the effect is big enough
效果大到普尔挥出的手臂可以击中自己
that Poole’s arms would flail as he punched.
普尔以每秒2米的速度慢跑
Poole himself would feel 20% heavier at his leisurely 2
会感觉到有20%的力量
meters per second jogging speed and feel pressed down
把他的脚按在地上
into the ground.
如果他跑的方向与环转动的方向相反
If he’s actually running against the ring’s rotation,
他会感觉自己在向上漂浮短跑
he would tend to curve upward and could levitate just
而不是在地上慢跑
by sprinting, instead of jogging.
你可能会说
Now, you might say that this isn’t
这个我们看到的“2001”不一致
necessarily inconsistent with what we see in “2001.”
其实还有更奇妙的生理效应
But there are other more subtle physiological effects
我们会看到这种效应
whose effects we should see.
比如说 你从椅子上站起来
For example, any time you stand up from a chair,
你的头有一个向上的1米/秒的速度
your head has an upward speed of about 1 meter per second.
在旋转的飞船上
On the rotating ship, standing up
你站起来 你的头
would therefore make your head want
会沿着科里奥利曲线方向运动
to curve forward from the Coriolis effect,
然后敲到你
knocking you over.
甚至你的头会极快的从左到右
Even turning your head left to right too quickly
你会感到头晕
would make you dizzy because the fluid
这是因为曲线的移动方向
in the ear that moves forward and in the ear that moves back
与耳液的移动方向不一致
would curve in opposite directions,
耳朵的前庭系统产生紊乱
sending mixed signals to your vestibular system.
所以总的来说
So even though “2001” gets the overall concept
“2001”的人造重力是正确的
of artificial gravity correct, given its small radius
但是由于半径太小和极高转速
and high rotation rate, it ends up sweeping major Coriolis
忽略了地毯对科里奥利曲线的影响
effect under the rug, especially the part
特别是普尔在运动中的跌倒
where Poole would be constantly falling down while running.
但是记住之前的公式
But remember the formula from before.
可以用一个更大的圈减弱这些误差
You can minimize these problems with a bigger ring,
因为很小的转速就可以
since that’ll require less rotation to get the same 1
得到相同的1克表面重力
g of surface gravity.
现在我们来看一个极端的例子
So let’s look at an extreme example of a big ring,
一个巨大的圈 拉里·尼文的“环形”
Larry Niven’s “Ringworld.”
小说中 这个环是
The ring habitat in that novel has the same radius
地球绕着太阳运行的轨道
as Earth’s entire orbit around the sun, around 93
半径是9300万英里
million miles.
甚至有向心力墙面
And it even has radially inward-pointing walls
来维持空气
to hold in an atmosphere.
为了实现1克重力
To achieve 1 g, Ringworld’s rotational velocity
环形的旋转速度要很小
would be small enough that, just like on Earth,
而科里奥利效应只被用在高速运动中
Coriolis effects would only be noticeable at very high speeds.
尼文确信 他的环形中有飓风
And to Niven’s credit, he also correctly had hurricanes
会垂直的旋转
on Ringworld rotate vertically because the deflections
就像这样
would go like this.
这不会用到科里奥利效应
There would be no Coriolis effects sideways.
但环形的组成仍有问题
But Ringworld has a different problem, namely composition.
为维持1克重力
To sustain 1 g, the ring would need
环形转完一个地球轨道
to complete the equivalent of one Earth orbit
只能用九天
around the sun in only nine days.
和科里奥利相比 这很慢
That’s slow for Coriolis purposes,
但环形的机械应力
but it’s really fast in terms of mechanical stresses
会非常的大
in the ring.
任何一个普通原子都会被撕裂
So anything made out of ordinary atoms would be ripped apart.
你就需要使用
And once you have to use some kind
虚构的超强材料
of fictional, super strong material,
那么你就会失去 较为现实的
you’re not gonna win a most realistic artificial gravity
人造重力标题
title.
减少了科里奥利效应是很不错
So bigger is better for reducing the Coriolis effect.
但减少太多 机械应力
But if you go too big, the mechanical stresses
就会把你的环形摧毁
will destroy your ring.
所以制作任何的特许环形时
So do any franchises have a ring size
找到半径和速度之间的平衡
that finds a good balance between these two?
视频游戏“光环” 很有趣
Interestingly, yes, the video game “Halo.”
半径是5000公里 也就是地球半径的80%
At a radius of 5,000 kilometers or about 80% of Earth’s radius,
绝缘光环一天旋转19次
a halo insulation would need to rotate 19 times a day
或者一分钟0.015圈 产生1克重力
to produce 1 g or about 0.015 RPM.
这样的转速 让科里奥利效应
The Coriolis effect at such RPMs would
在日常生活中 不被察觉
be undetectable in ordinary human activity.
显然 这样的光环大小和转速
And apparently, a halo at that size and rotation
可以保持机械完好无损
could actually stay mechanically intact.
凯文曾经是NASA的行星科学家
Kevin Grazier, a planetary scientists formerly at NASA,
也是“太空堡垒卡拉狄加”的科学顾问
who was also the science adviser for “Battlestar Galactica”
为电影“引力”做了科学计算
and the movie “Gravity,” did the math.
他估计可以用钢
And he estimated that you could handle the stresses
这样一般的金属来处理压力
with a material as mundane as steel.
所以“光环”检测完成
So gravitationally, “Halo” checks out.
但其实很难去建立一个绝缘光环
But it’s hard to see how we’d ever build a halo insulation.
凯文也估计光环会
Grazier also estimated that each halo has as much mass
像小行星带一样聚集起来
as the entire asteroid belt. So new question,
所以关键是 任何的科学幻想都要建立在物理基础上
do any sci-fi franchises get all the physics right but
让它的理论足够正确
with a structure that’s compact enough that it’s not
而不是脱离现实的疯狂想象
entirely crazy to imagine humanity one day building it?
所以最接近这点的是
Well, the closest thing I could think of
“巴比伦5号空间站”
was the space station on “Babylon 5.”
“巴比伦5号”抛弃了环的形状
The key is that “Babylon 5” abandons the ring shape
采用了一个
altogether and makes a cylinder instead,
长8公里 半径半公里的圆柱体
one about 8 kilometers long and half a kilometer in radius
绕着纵轴旋转
spinning around its longitudinal axis.
为获得1克重力 圆柱本身转速是1.3圈/分钟
To get 1 g, that cylinder would need to rotate at 1.3 RPMs.
边缘的速度是60米/时
The show once quoted a rim speed of 60 miles an hour,
大概是0.5圈/分钟
which would only half an RPM.
但这只会给你一个月球引力
But that would only give you 1 moon g.
这是个愚蠢的错误
So it’s a boo-boo.
不管如何 1.3圈/分钟会使
Anyway, 1.3 RPMs, that would give you
这个科里奥利力比“2001”中的
Coriolis forces that are 10 times smaller than the ones
小了10倍
you see in “2001.”
也就是在日常活动中 这个力不明显
So that’s mostly unnoticeable in day-to-day activity,
除非你突然的冲刺
unless you sprinted or moved very, very abruptly.
实际上“巴比伦5号”有很多定性的东西
“Babylon 5” actually gets a lot of other qualitative things
比如感应旋转重力
right about rotation-induced gravity,
在星际狂人的战斗飞船中
like the way that its fighter ships, the Starfurys,
向外发射的静物或者是
launch just by dropping outward or the fact
发射在中心轴附近休息的人
that objects or people that are at rest
其实不会掉落到边缘
near the center of the central axis don’t fall toward the rim.
他们要采取措施
They get correct that you already
就是去旋转来感受人造重力
have to be rotating to feel the artificial gravity.
我很想说“巴比伦5号”
So I really want to say that “Babylon 5” has
是在科幻小说人造重力描述的最真实
the most realistic depiction of artificial gravity in sci-fi.
但确切的说 它仍存在一些错误
But to be fair, in light of some of its errors,
所以我把票投给“光环”
I gotta give my vote to “Halo.”
因为实际上我没法
Truth is I can’t actually find anything
在旋转人造重力中找到
that the game gets wrong per se in its rotational artificial
游戏的错误之处
gravity.
其实也可能是我忽视了“光环”的缺陷
But hey, maybe I overlooked some flaw in “Halo.”
我知道你们在评论中会提醒我
I’m sure you guys will let me know
投出你的票
in the comments, along with your own votes
你认为在科幻小说中最真实的人造重力
for what the most realistic artificial gravity in sci-fi
是哪个
is.
我知道这个话题仅仅是表面上的
I know that I just scratched the surface of the topic.
所以我留了白 你可以填写
So I’ll report any blanks that you all
在下一集的“时空”中会说到
fill in for us on the next episode of “Space Time.”
上周 我们说了时间和空间是不是错觉
Last week, we asked whether space and time are an illusion.
你们写了很多很好的评论和问题
You guys had great comments and questions.
我回答部分评论
I answered some individually in the comments.
奈特说让我在评论中回答
And yes, Michael-Luca Natt, it’s really me in the comments.
在这 我回答一些
But here, I’m gonna address them more in groups
类似的问题
because so many were very similar.
首先 一个公告 是观众的 不是我们的
But first, an announcement– a viewer, not us, started
制作了一个致力于我们节目的网站
a sub-Reddit dedicated to our program
作为节目讨论的另一个地方
as an alternate form for episode discussion.
我会写出链接
I’ll tweet the link.
请在推特上关注我们 记得添加描述
So follow us on Twitter, but also add it to the description.
好 现在开始评论
OK, now to the comments.
部分人要求更多的例子
Some of you asked for more concrete examples of things
对于不同的观点
like event disagreement.
我们是有一些 到为了时间不得不删减
We had some originally, but had to cut them for time.
在下周 我们会进行投票
Now, next week, we’re going to poll you
对于未来视频的话题
all about future episode topics.
如果大部分都赞成 那我们会做相对
And we can do one about basic relatively if enough of you
长一点的视频
vote for it.
但同时 请记住
But in the meantime, remember you’re not supposed
你不能仅仅为了自己
to get this stuff right away.
你要有群体的概念
You have to erect a bunch of conceptual
在个人之前
scaffolding your head first.
视频中说到的好的资源 可以去使用
Good resources for this are in the description, so use them.
寻找书籍去阅读
And also look for books and read.
这事可能花费几个月
This sort of thing takes months to sink in, not minutes.
尝试去做
That’s just how it works.
虽然时光漫漫 但一旦决定
I know it’s frustrating, but it’s worth it
这是值得的
once things finally click.
为什么我会认为空间和时间是错觉?
Why exactly am I concluding that space and time are illusions?
我不在这里赘述
I can’t redo the whole episode here,
我只强调重要的部分
but I’ll reiterate part of what I meant.
有无数种自恰的方式
There are an infinite number of self-consistent ways
去安排何时何地做事
to arrange events according to when and where they happen.
不同的安排
And in those different arrangements,
不同的事件安排在不同的顺序中
not all events occur in the same sequence.
你只是知道“过去”
Once you accept that phrases like “the past”
“现在”“未来”这几个词语 却缺乏了乐观意义
now and “the future” simply lack objective meaning.
时间顺序不是一成不变的
Temporal order is not a universal fact
也不是“熟悉”就能解释的
and neither are other “familiar” aspects of time.
所以 时间是错觉吗?
So is time an illusion?
我认为这是一个语义问题
I think that’s a matter of semantic taste,
但绝对不是你认为的
but it certainly isn’t what you think it is.
所以如果我们不理解事件的秩序
So how can we agree about causality
那怎么理解因果关系那?
if we disagree about order of events?
有一些时间
Well, for certain event pairs, we
让我们理解这个秩序
do all agree about the order.
那证明一下
Those turn out to be event pairs for which
假如一个单独的问题
a single piece of matter or light
或者同时出现的两个事件
could have been present at both events, which corresponds
哪个符合零或负时空间隔
to a zero or negative space time interval between those events.
有限的情况下
So in those limited cases where we
我们同意两个事件的秩序时
agree about the sequence of two events,
我们赞同一个事件
we’re really agreeing about whether one of them
能够影响另一个事件
had the capacity to influence the other.
当我们不同意秩序时
And when we disagree about sequence,
我们就同意时空
we’re really agreeing that the space time
事件间隔是正的
interval between them is positive
一个事件不影响另一个事件
and that neither event could have influenced the other.
时间不允许我在这个视频中解释这个情节
I did not address the direction of time in this episode.
没事
That’s true.
讨论很许许多多可以涉及的
And it’s because that discussion is way more involved,
尤其在相对论的背景下
especially in the context of relativity.
大家都是婴儿学步
Baby steps, people.
也许是未来的事件
Maybe a future episode.
自由意志在哪儿?
Is there no free will?
这是一个未完的哲学问题
That’s a loaded, philosophical question.
狭义相对论表明
But yes, I happen to think that special relativity suggests
自由意志是一种错觉
that free will is an illusion.
量子力学带来了自由意志吗?
Does quantum mechanics bring back free will
它充满了不可预知的随机性
since it attaches some inherent randomness to the future.
记住 没有“未来”
Well, remember that there is no “the future.”
除此之外 我的回答仍然是否定的
But that aside, I happen to think the answer is still no.
快速的做了一些解释
This is also too involved to explain quickly.
但首先 阅读是背景
But for starters, do some background reading
有一些事情叫“退相干理论”
on something called “decoherence.”
有一点注意
On a related note, DreamsOfMorpheus
DreamsOfMorpheus问是否大部分的科学家支持
asks whether most physicists hold this view
未来已经存在这一观点
that the future already exists, knowing that Brian Greene has
要知道布莱恩·格林就说过类似的话
said similar things.
我正好知道布莱恩
I happen to know Brian.
在研究生院时他教过我
He taught me in grad school.
我问过他 他认为大部分人都相信
So I asked him what he thinks most people believe.
我觉得他和我在同一个立场
I think he and I on the same page.
但你可以逐字逐句的阅读他下面回答
But you can pause and read his verbatim response to me below.
亚历山大告诉我 我要去
Finally, Aleksander Stepien said I should get a guest spot
芝麻街接人
on “Sesame Street.”
听到了吗?
Hear that, Big Bird?
有人要见我
The people want me.
现在让这件事发生
So let’s make it happen.
给我发推特消息
Tweet @PBS to bring me on the show
用#PUTGABEONSESAMESTREET#
with #PUTGABEONSESAMESTREET.
每个人都有关于物理的潜在的疑问
Everyone could use a good physics-related existential
包括六岁的孩子
crisis, even six-year-olds.
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