网友看到外星人入侵地球（龙腾网美版知乎）

网友看到外星人入侵地球（龙腾网美版知乎）Human beings have been around what 100 000 years? Yet that’s just one-billionth of the expected lifespan of the universe. We exist at a very tiny scale both in terms of time and distance.Just 10 billion years after the universe started we know life evolved on Earth. But the Earth has had intelligent life for just the past 1/30 000th of its existence. For aliens to find us they would have to ex

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Krister Sundelin UX Writer at HiQ G?teborg (2011-present)
If there are aliens why do they not invade Earth?
Any advanced alien species would come from at least 4.5 light-years away and probably a lot more. But let’s go for best case: 4.5 light-years. That’s the distance light travels in 4.5 years. Using our best rocket technology it takes us about 80 000 years. Using the best rocket technology we can imagine we could make the journey in 50 years.
So if they can get an invasion fleet here in any time for an invasion to be practical they’re ludicrously advanced. Possibly they have access to technology that we can barely imagine. Let’s imagine that they have something like an Alcubierre drive. They would have access to or knowledge to make matter with negative energy density and they would have all their practical energy needs satisfied.
如果有外星人，为什么他们不入侵地球？
任何先进的外星物种都至少来自4.5光年以外，或许更远，但让我们看看最好的情况： 4.5光年，这等于光传播4.5年所走过的距离。
使用我们最先进的火箭技术，我们需要8万年的时间，使用我们能想象到的最好的火箭技术，我们可以在50年内完成这一旅程。
因此，如果他们可以在任何时候在这样的距离部署入侵地球的舰队，那么他们就可以说是十分先进，也许他们能接触到我们几乎无法想象的技术。
我们想象一下，他们会有类似曲速驱动引擎的东西，他们有机会或相应知识制造负能量密度的物质，他们将满足所有实际的能源需求。

The point is: if you can traverse the depths of interstellar space with an invasion fleet you’re so advanced that you have no reason to invade a planet. Every need you might imagine for invading a planet can be easier solved in space with the resources that are there and uncontested.
Except perhaps if it is about religion.
关键是：如果你能用一支入侵舰队穿越广漠的星际深空，你已经非常先进了，没有理由去入侵一颗行星。
你能想象到每一个入侵行星的需求都可以在太空中更容易地解决，因为那里有无可争议的资源。
当然，如果涉及（外星人）宗教的话，情况可能会不一样。

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Christophe Meessen
This question is based on the assumption that an alien invasion of earth would be perceivable like the invasion of the American continent by Europeans. But one should keep in mind that aliens may have are or might invade earth in an non-perceivable way.
Any action made by any living entity is motivated by a benefit. There must be an advantage that outbalance the risk and consequences of a negative reaction.
ET reaching earth if any must have master the energy source to do so. So energy can’t be the motivation. Materials might also be mastered and there is plenty in space even water. ET have spaceships perfectly adapted for them and space travels. They can move escape and hide with a spaceship. They can’t do that on earth. We are currently vulnerable to a collision with asteroids or whatever they are not.
这个问题是基于这样一个假设，即外星人入侵地球会像欧洲人入侵美洲大陆一样可以被感知。
但是我们应该记住，外星人可能已经，正在，或者可能以一种不可察觉的方式入侵地球。
任何活着的实体所采取的任何行动都是出于利益，而且还必须存在某种优势能够抵消消极反应的风险和后果。
到达地球的外星人—— 如果存在的话——必须掌控能量源才能做到这一点，所以能源不可能是其动机。
还必须掌控材料，太空中有足够的空间，甚至水，外星人拥有完美适应他们的太空飞船和太空旅行，他们可以移动，逃跑，躲藏在宇宙飞船里，但他们在地球上不能这么做，我们现在很容易受到小行星撞击或者其他什么的影响，但他们不会。
The element of value we have on earth is our genetic material which is the product of billion years of evolution. That is what might interest ET and they don’t need to invade earth for that. They only need to collect samples and eventually create hybrids in their spaceships if they consider it of value.
We currently don’t know if there are plenty ET civilization more advanced than us and if they have full liberty of movement. It could be that there is a fundamental law of life among them that is to respect the development of any life form. Any civilization that would not respect this law would represent a threat to the others. This is what is more or less happening between countries on earth.
There may be other reasons which we are not aware of yet.
对外星人来说，地球上拥有的最具价值元素可能是是我的遗传物质，它是亿万年进化的产物，这一点到是可能会引起外星人的兴趣，但他们不需要为此入侵地球啊，如果他们认为它有价值，他们只需要收集样本，在他们的太空船就能创造出相应的混血儿。
我们目前不知道是否有很多比我们更先进的外星文明，也不知道他们是否有充分的行动自由。
可能在他们之中有一个基本的生命法则，那就是尊重任何生命形式的发展。
任何不遵守这一规则的文明都将对其他文明构成威胁——地球上的国家之间或多或少存在这样的规则。

Human beings have been around what 100 000 years? Yet that’s just one-billionth of the expected lifespan of the universe. We exist at a very tiny scale both in terms of time and distance.
Just 10 billion years after the universe started we know life evolved on Earth. But the Earth has had intelligent life for just the past 1/30 000th of its existence. For aliens to find us they would have to exist in the same teeny blip of time we occupy.
Spacefaring civilizations may pass each other like trains in the night with trillions of miles and hundreds of millions of years separating them. Not only are their planets incredibly far apart but they don’t even coexist in anywhere near the same time frx.
人类大概有10万年的历史了吧？ 然而，这仅仅是宇宙预期寿命的十亿分之一，我们存在于一个非常微小的尺度，无论是时间还是距离。
在宇宙诞生100亿年后，地球上的生命进化了，但是地球在过去的三万分之一的时间里都有智慧生命，要让外星人找到我们，他们必须和我们生活在同一点的时间里。
太空文明可能会像夜间的火车一样彼此擦肩而过，相隔数万亿英里、数亿年，他们的行星不仅相距遥远，而且他们甚至不能在同一时间段内共存。
小行星撞击地球造成大规模物种灭绝的可能性要大得多。
Kevin Stern B.S. Computer Information Systems (1997)
Why would they? We pose no threat to any civilization advanced enough to travel the stars. Especially being basically grounded. We’re in a lonely arm in the Galaxy. Not much strategic means there. We have little to offer an advanced civilization because we’re primitive to them.
Food/ i doubt any species will travel the universe abducting various creatures to test for how edible nutricous or delicious they are. And really can you imagine going through all that trouble of invading killing being killed just for a Happy Meal? I doubt we’d make good slaves and if they study our media they’d know we don’t take kindly to slavery (least of all white people who insist on being the slavers). Again an awful lot of trouble to round up some slaves that will revolt the first chance they get. Resources? Again why risk destruction in a war?
It really makes little sens to be invading other worlds considering the time technology danger and various other reasons. Sure it could happen but it sure hasn’t happened in our collective history. In fact if you want to believe the ancient aliens theory any alien contact has been rather peaceful.
他们为什么要这么做？ 我们对任何足够先进到可以星际旅行的文明都不构成威胁。
尤其是我们基本上形同被“禁足”，我们生活在银河系的孤独的臂膀里，这里没有多少战略意义。
我们几乎没有一个足够先进的文明，我们对他们来说是原始的。
为了食物？ 我怀疑是否会有物种会在宇宙中旅行，无聊到绑架各种各样的生物来测试它们的食用性、营养性或美味程度。
说真的，你能想象为了一顿开心乐园餐而费尽周折地入侵、杀戮吗？
奴隶？ 我怀疑我们是否能成为好的奴隶，如果他们研究我们的媒体，他们就会知道我们对奴隶制并不友好 ( 尤其是坚持要当奴隶贩子的白人)，为了围捕那些一有机会就会反抗的奴隶，实在不值得，也会有很多麻烦。
资源？ 有必要在战争中冒着毁灭的危险去获得资源？
考虑到时间、技术、危险和其他各种各样的原因，入侵其他世界确实毫无意义。
当然，这种情况有可能发生，但在我们的集体历史中肯定没有发生过，事实上，如果你相信《远古外星人的》理论，任何外星人的接触都是相当和平的。
Rebecca Harbison General purpose nerd
There’s a lot of steps between premise A and B that might prevent it.
Alien doesn’t necessarily mean intelligent or technological. If we find microbes on Enceladus they aren’t invading anything.
(Aside: if we find microbes in the solar system the glib answer is ‘they may already have’. There is a reason NASA has a whole office devoted to making sure our space probes (especially landers especially anything heading to Mars or an icy satellite with a sub-ice ocean) are squeaky clean. Microbes are a lot better at surviving hostile conditions than us big multi-cellular organisms )
We don’t know what aliens are like. Maybe most intelligent species live on places like Enceladus and think planets with open skies are creepy. Heck maybe they live on places like Titan and see us as weird creatures based on molten ice.
在前提 a 和前提 b 之间有很多步骤可能阻止它。
外星人并不一定意味着智能或技术，如果我们在土卫二上发现微生物，它们不会入侵任何东西。
( 除此之外：如果我们在太阳系中发现了微生物，那么一个简单的答案是“他们可能已经发现了”。NASA有一整个办公室致力于确保我们的太空探测器 ( 特别是着陆器，尤其是任何前往火星或冰层以下海洋的卫星 ) 是洁净无瑕的，这是有原因的，微生物比我们这些大型多细胞有机体在恶劣条件下生存得更好。)
我们不知道外星人是什么样的。
也许大多数智能物种生活在像土卫二这样的地方，并认为拥有太空旅行能力的行星是令人毛骨悚然的，见鬼，也许他们生活在土卫六这样的地方，把我们看成是基于基于熔融冰的怪异生物。
Space travel is hard. Humans still couldn’t invade anything off Earth and we’ve actually been to space. We haven’t even sent people past the Moon. But we’ve existed as a species for hundreds of thousands of years. So that’s a tiny proportion of time for us to be space invaders even if we land people on Mars tomorrow.
No seriously space travel is hard. Currently it would take us generations to get to the nearest place that might have a habitable planet. Which we haven’t identified yet — we just know the planets in our solar system are pretty hostile for life like us. And that is a limit as far as we know: nothing can travel at or above the speed of light that starts slower than light. That also means you need to dedicate an invasion and colonizing force at once as by the time you get the news it is way too late to send reinforcements.
They have better things to do with their time. If aliens could live in space for decades or centuries enough to get to Earth and send a whole army/support/colony staff why bother taking over someone else’s planet at all?

Francesco Maddalena Msc. Nanoscience / PhD Physics
Well why should they in the first place?
In any case there are several reasons:
They do not exist (not anywhere in our galaxy or galaxy cluster at least)
They don’t have the technology to reach us or mount an invasion. I mean imagine we discovered Mars was inhabited by little green men with similar tech level as us. We would be NOWHERE near mounting an invasion. We are not even ready to send a few people there!
They are too far. Perhaps physics prevents all to travel faster than light. This would basically forbid any Alien civilization to conquer us unless they were willing to spend hundreds of years in space… Still even so logistically it would be nearly impossible
They don’t care about us (why should they really? Is Earth the only piece of prime real estate in the galaxy?)
They do not want to interfere with us (like Prime Directive in Star Trek)
They have very low technological level (we might as well be the most advanced in the galaxy as far as it goes)
There is no sentient life (near enough to us) except for us
那么，首先，他们为什么要这样做呢？
无论如何，有以下几个原因：
它们不存在 ( 至少在我们的星系或星系团中不存在 )
他们没有技术来接近我们或发动入侵。
我的意思是，想象一下，我们发现火星上居住着和我们技术水平相当的小绿人，我们根本不可能发动入侵，我们甚至还没准备好派几个人去那里！
他们太远了。
也许物理学阻止了一切超光速的运动，这将基本上禁止任何外星文明征服我们，除非他们愿意在太空中度过数百年...... 尽管如此，从逻辑上讲，这几乎是不可能的。
他们不关心我们 ( 他们为什么要关心我们？ 地球是银河系中唯一的黄金地段吗? )
他们不想干涉我们 ( 正像《星际迷航》中的《最高指令》所述 )
它们的技术水平非常低 ( 就目前而言，我们可能是银河系中最先进的 )
除了我们之外，没有任何有知觉的生命 ( 离我们足够近 )
Bill Hitchens Logical and Critical Thinking University of Auckland
The Earth is an unremarkable planet out in the middle of nowhere.
Even if they can see the planet it’s unlikely that they can see anything about us. They might be able to tell there’s life but that’s about it.
Space travel is expensive and hard. You need to make sure you’re doing it for a worthwhile cause.
Invading Earth doesn’t get you anything you can’t find elsewhere.
You want diamonds? There are planets made of diamond.
You want slaves? Robots are far more efficient than people could ever be.
Whatever technology the aliens might use to get here would be better used to get them what they actually want.
在茫茫荒野中，地球是一颗不起眼的行星。
即使他们能看到地球，他们也不可能看到我们的任何东西，他们也许能分辨出生命的存在，但仅此而已。
太空旅行既昂贵又困难， 你需要确保你是为了一个有价值的事业而做这件事。
入侵地球不会给你带来任何你在别处找不到的东西。
你要钻石？有些行星是由钻石构成的。
你要奴隶？机器人远比人类更有效率。
无论外星人可能使用什么技术来到达这里，都比他们真正想要的东西要好。
Andrew Wrigley Earth is neither flat nor round. It bulges at the middle.
Why on Earth would aliens invade Earth when it is jam packed with the kind of seriously aggressive and destructive beings that are humans hell bent into the bargain on destroying Earth and quite capable of doing it without any help from outer space?
Never mind trying to get here across the intractable vastness of space?
Or being greeted by Donald Trump who has just invaded the UK because Jeremy Corbyn is a loser who has refused to nuke the incoming aliens?
I think you get my drift but just in case:
If these aliens are so bloody intelligent that they can not only get here but also invade us then this is the last shit hole in the local cluster they will bother to visit.
Or invade.
地球上挤满了极具侵略性和破坏性的生物，人类拼命摧毁地球，而且完全有能力在没有外太空帮助的情况下摧毁地球，为什么外星人还要入侵地球？还尝试着穿越这难以驾驭的浩瀚太空来入侵地球？
还是为了受到唐纳德 · 特朗普的欢迎，他刚刚入侵英国，因为杰里米 · 科尔宾是一个拒绝用核武器攻击外星人的失败者？
我想你明白我的意思，但以防万一我说清楚点：
如果这些外星人是如此的聪明，他们不仅可以到达这里，而且还可以入侵我们，那么这里就是他们最不愿意来的地方。