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人类文明能遍布银河系吗
Could human civilization eventually spread across the whole Milky Way galaxy?
我们能在这个小小的蓝色星球之外的
Could we move beyond our small blue planet
广袤星系建立殖民地吗
to establish colonies in the multitude of star systems out there?
这个问题还挺吓人的
This question’s a pretty daunting one.
银河系有3000亿颗恒星左右
There are around 300 billion stars in the galaxy,
从一边到另一边的距离是160000光年
which is about 160,000 light-years across.
现在为止我们就发送了一艘宇宙飞船到太阳系外
So far we’ve sent a single spacecraft outside our solar system,
以0.006%光速缓慢前行
trudging along at 0.006% of the speed of light.
以那个速度 得花不止25亿年
At that rate, it would take over 2.5 billion years
才能横跨一个星系
just to get from one end of the galaxy to the other.
然后就有了这个人类生存的问题
And then there’s the question of human survival.
恒星间的距离简直大无边际
The gulf between stars is simply enormous.
在多数星球上我们都不能持续生存
We couldn’t live sustainably on most planets,
而且我们需要很多资源才能存活下来
and we require a lot of resources to stay alive.
然而几十年前 学者发现从理论角度
And yet, decades ago, scholars found that it’s theoretically possible
在银河系传播人类文明不仅是可行的
to not just spread human civilization across the galaxy,
而且还能很快实现
but to do so quite quickly,
还不违背现有的物理定律
without breaking any known laws of physics.
这个想法源于一名叫约翰·冯·诺依曼的数学家的研究
Their idea is based on the work of a mathematician named John von Neumann,
他在纸上设计了一台能进行自动复制和创造新一代的机器
who designed on paper machines that could self-replicate
他在纸上设计了一台能进行自动复制和创造新一代的机器
and create new generations of themselves.
后来这些机器被称为冯·诺依曼机器
These would later come to be known as von Neumann machines.
在太空探索的背景下
In the context of space exploration,
冯·诺依曼机器可以建在地球上
von Neumann machines could be built on Earth
然后发射进太空太空中
and launched into space.
这种自给机器会在遥远的星球着陆
There, the self-sufficient machines would land on distant planets.
然后开采可用资源、
They would then mine the available resources and harvest energy,
搜集能量进行自我复制
build replicas of 
themselves,
把复制的机器发射到最近的星球
launch those to the nearest planets,
然后不断循环这个过程
and continue the cycle.
最后结果就是无数探测器
The result is the creation of millions of probes
像水里的一点墨水一样不断向外在宇宙中蔓延
spreading outwards into the universe like a drop of ink in a fishbowl.
学者进行计算之后发现 一台冯·诺依曼机器
Scholars crunched the numbers and found that a single von Neumann machine
以5%光速飞行
traveling at 5% of the speed of light
要花400万年才能通过不断复制穿越银河系
should be able to replicate throughout our galaxy in 4 million years or less.
听起来时间很长
That may sound like a long time,
但想到140亿岁高龄的宇宙
but when you consider that our universe is 14 billion years old,
从宇宙尺度看来已经非常快了
on a cosmic scale, it’s incredibly fast –
也就是一整年里的两个半小时
the equivalent of about 2.5 hours in an entire year.
造一台冯·诺依曼机器需要几项目前没有的新技术
Creating von Neumann machines would require a few technologies
造一台冯·诺依曼机器需要几项目前没有的新技术
we don’t have yet,
包括先进的人工智能
including advanced artificial intelligence,
微型化科技
miniaturization,
更好的推进系统
and better propulsion systems.
如果想运用这些技术把人类送进银河系
If we wanted to use them to spread actual humans throughout the galaxy,
我们还得需要另一项技术性飞跃
we would need yet another technological leap –
通过原始元素和基因信息来人为造出生物有机体和生物机体
the ability to artificially grow biological organisms and bodies
通过原始元素和基因信息来人为造出生物有机体和生物机体
using raw elements and genetic information.
不管怎么说 如果过去10亿年间
Regardless, if in the last billion years
有外星文明造出了类似的机器
an alien civilization created such a machine
通过不断复制的方式向我们驶来
and set it multiplying its way toward us,
我们的银河系应该已经到处都是这些机器了
our galaxy would be swarming with them by now.
但是那些机器在哪儿呢
So then where are all these machines?
一些天文学家 比如卡尔·萨根
Some astronomers, like Carl 
Sagan,
说聪明的外星人不可能建造自我复制机器
say that intelligent aliens wouldn’t build self-replicating machines at all.
这些机器会在横冲直撞后失去控制
They might hurtle out of control,
为了实现自我复制把星球洗劫一空
scavenging planets to their cores in order to keep replicating.
另外一些人认为这种机器不存在是因为
Others take the machines absence as proof
根本不存在智慧的外星文明
that intelligent alien civilizations don’t exist,
或者在他们发展出必要科技前就已经灭绝了
or that they go extinct before they can develop the necessary technologies.
但这些想法并不妨碍人类想象 如果存在外星文明
But all this hasn’t stopped people from imagining what it would be like
将是怎样一番景象
if they were out there.
科幻小说作家大卫·布林
Science fiction author David Brin
描写了一个存在许多不同的冯·诺依曼机器并同时扩散的宇宙
writes about a universe in which many different von Neumann machines exist
描写了一个存在许多不同的冯·诺依曼机器并同时扩散的宇宙
and proliferate simultaneously.
一些机器跟年轻文明打招呼
Some are designed 
to greet young civilizations,
另一些则定位年轻文明 并且在年轻文明成为威胁前将其摧毁实际上
others to locate and destroy them before they become a threat.
布林的小说“Lungfish”里面
In fact, in Brin’s story “Lungfish,”
一些冯·诺依曼机器正密切关注着地球
some von Neumann machines are keeping a close watch over the Earth right now,
等我们成熟到一定阶段后
waiting for us to reach a certain level of sophistication
他们才采取行动目前
before they make their move.
我们有的只是好奇心和理论
For now, all we have is curiosity and theory.
但下次你仰望夜空时
But the next time you look at the night sky,
想象无数自我复制的机器
consider that billions of self-replicating machines
正在银河系的恒星间穿梭
could be advancing between stars in our galaxy right now.
如果它们存在 最后一定会降临地球
If they exist, one of them will eventually land on Earth,
也许 它们已经到地球
or maybe, just maybe, they’re already here.
