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我们能把地球隐藏起来吗? – 译学馆
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我们能把地球隐藏起来吗?

Could We Hide The Earth?

宇宙已经存在超过137亿年
The universe has been around for more than 13.7 billion years, which seems like plenty
这么长的时间也可能使其他文明发展
of time for another civilization to develop.
但是我们没有发现任何生命存在的证据也没有人向我们说“你好”
But we haven’t found any evidence of life, and nobody’s said hello to us either.
这就是费尔米悖论
That’s the Fermi Paradox.
所以其他文明是可能不存在的
So maybe other civilizations don’t exist.
或者……他们藏起来了
Or maybe … they’re hiding.
因为 理论上我们只需要发射一些激光 就能从望远镜中
Because, theoretically, we could hide the Earth from faraway telescopes, just by shooting
隐藏地球
some lasers.
超过70%的已知外行星是用中天法发现的
Over 70% of the exoplanets we know of were found with the transit method.
当用望远镜指向一个恒星我们会看到它射向我们的光线
When we point a telescope at a star, we expect to see all the light that’s shining in our
这取决于恒星的温度 尺寸 还有它离多远
direction – which depends on the star’s temperature, size, and how far away it is.
但是有时候一个行星环绕恒星旋转 或者恰巧处在
But sometimes a planet is orbiting that star, and transits, or crosses exactly between the
恒星和望远镜之间
star and our telescope.
行星阻挡了一些光线在测量结果上出现一个视倾斜 称作
The planet blocks some of the light, creating a dip in the measurements called a transiting
光线曲径
light curve.
一个规律的视倾斜图案告诉我们这里可能存在一个星体
And a regular pattern of dips tells us that an exoplanet is probably there.
所以是不是有其他文明正在用中天法看着我们?
So what if another civilization was using the transit method to look for us?
两个来自哥伦比亚大学的天文学家认为我们也许可以隐藏地球
Two astronomers from Columbia University think that we could hide the Earth.
理论上 我们可以在正确的方向 在正确的时间
In theory, we could /cover up/ those light curve dips – by shooting the right amount
通过发射正确数量的光线到太空中来覆盖这些光曲线
of light into space, in the right direction, at the right time.
这听起来有些复杂
Which sounds kind of complicated.
但你不要指望藏整个行星有多么轻松
But you wouldn’t expect hiding a whole planet to be easy.
所以这个伪装设备只存在这一对天文学家的幻想中
So this theoretical cloaking device is based on a couple assumptions.
就像 首先 我们先假设有其他文明正在寻找地球
Like, first of all, we’d be assuming that another civilization was looking for the Earth.
并且他们使用中天法
And that they’re using the transit method.
这意味着我们必定在他们的行星与太阳之间
That means we’d have to cross between their planet and our Sun.
为了这种事件的发生 他们的行星也必须沿着
For that arrangement to happen, their planet would have to be lying somewhere along the
黄道面—地球运行的路径—绕着太阳
ecliptic plane, which is the path the Earth is travelling on, as it orbits the sun.
更何况 我们必须考虑他们探索天空用到的技术
Not to mention, we have to think about the technology they’re using to survey the sky.
看一下我们的老朋友开普勒它是一架通过中天法发现过上千星体的
Take our old friend Kepler, which is a spacecraft that has found thousands of exoplanets through
航天器
the transit method.
开普勒使用一个被称作宽带光度计的仪器 它收集
Kepler uses an instrument called a broadband photometer [fuh-tah-meh-tir], which collects
在一段选择波长范围内的尽可能多的光子
as many photons of light as possible in a chosen range of wavelengths.
大部分类日恒星散发的光芒波长在600纳米 在光谱
Most Sun-like stars emit their light at wavelengths of around 600 nanometers, in the orange part
的橙色范围内
of the visible spectrum.
所以利用相似科技隐藏我们自己我们需要发射一组
So to hide ourselves from similar technologies, we could shoot an array of lasers into space
波长为600纳米的激光到太空中 功率峰值约为30w
with a wavelength of 600 nanometers, and a peak power of about 30 megawatts.
大的 橙色的激光?
Big, orange lasers?
停一下
Check.
有时候星体探索使用光谱法代替光度法
Sometimes exoplanet surveys use spectroscopy [speck-TRAH-skuh-pee] instead of photometry,
虽然 用望远镜可以测量许多不同波长的光
though, with telescopes that measure light at lots of different wavelengths.
天文学家可以利用光谱法弄清楚一个星体的大气 因为
Astronomers can use spectroscopy to figure out what’s in an exoplanet atmosphere, because
不同的气体吸收和反射不同波长的光
different gases absorb and reflect different wavelengths of light.
所以如果我们像躲避这种类型的测量我们需要激光爆发
So if we wanted to hide from /these/ kinds of instruments, we’d need lasers blasting
一堆不同波长的光 这将更加复杂
light at a bunch of different wavelengths, which would get more complicated.
或者我们可以设置一对-像是氧气和臭氧的光信号 这意味着
Or we could pick a couple – like the light signatures of oxygen and ozone, which suggest
这里存在生命-使用激光去假装我们是简单的 无生命的
there’s life here – and use lasers to pretend that we’re just a simple, lifeless
石头
rock.
现在长时间发着这些激光听起来 真的 能量密集
Now, firing all these lasers for a long time sounds /really/ energy-intensive.
但是有一件事我们只需要它们像地球一样发送电波
But here’s the thing, we only need them as long as the Earth is transiting.
这取决于这个外星球相对于我们面向哪里怎么运动
That depends on how the alien planet is oriented and moving relative to ours.
但是至今这些假设都还很远天文学家估计一次发射要13小时
But by these assumptions so far, the astronomers estimated a transit of around 13 hours.
那意味着一组橙色激光需要每年维持13小时
Which means our array of orange lasers would need to be on for 13 hours, once per year.
它们可能会在地球表面但之后我们会思考地球如何
They /could/ be on the Earth’s surface, but then we’d have to consider how the Earth
凌日旋转以及大气存在的事实
rotates as it transits, and the fact that our atmosphere is in the way.
所以我们最好的赌注就是向太空发射一组激光
So our best bet might be launching this laser array into space.
一方面 我们需要用太阳能为其提供动力
On the plus side, we could capture energy from the Sun to power them.
但那也意味着要以载人航天任务把它们送往太空并组装
But that would also mean manned missions to get everything into space and put together,
这的确不便宜 也不容易
which isn’t exactly cheap or easy.
重要的是 我们可以用激光隐藏地球如果外星人存在 而且他们在寻找我们
Basically, we could hide the Earth with lasers if: aliens exist, they’re looking for us,
生活在黄道平面 并用开普勒勘探法常年收集数据
living in the ecliptic plane, using Kepler-like surveys, and recording data for multiple years.
如果这都是真的我们要不要藏起来?
Even if all that was true, would we want to hide?
如果我们不准备藏起来 天文学家也说他们的想法可以作为一种信号
If we don’t, the astronomers also mentioned that their idea could be used to /broadcast/
广播进入太空
a signal into space.
使用简单的激光我们可以扭曲光径使其看起来很古怪
Using similar lasers, we could /distort/ parts of our transiting light curve to look weirdly
以人为的方式 例如向太空发送蝙蝠信号任何人都想碰碰运气
artificial, kind of like sending a bat signal into space, on the off-chance that anyone
试一试
is looking.
但是现在 这种主意已从一些天文学家的广播延伸至我们的互联网
But for now, this idea from a couple astronomers remains broadcast across our internet … instead
而不是进入太空
of into space.
感谢收看SciShow Space视频辑当然也感谢
Thanks for watching this episode of SciShow Space, which was made thanks to the support
Patreon对我们的赞助支持
of our patrons on Patreon.
如果你想支持我们继续制作视频辑请前往patreon.com/scishow
If you want to help us keep making episodes like this, just go to patreon.com/scishow.
还有别忘了前往youtube.com/scishowpace订阅我们
And don’t forget to go to youtube.com/scishowspace and subscribe!

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视频概述

外星人是否存在?如果是,他们是否也在寻找着我们?我们应该如何把地球藏起来?

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收集自网络

翻译译者

逸生

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【MR】拾月

视频来源

https://www.youtube.com/watch?v=YhT29accDPI

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