物理与天文2020arxiv.org
能否在地质记录中探测到工业文明？
Would it be possible to detect an industrial civilization in geological record?
入门 · 约 45 分钟读完前置知识：地质学基础、碳同位素
导读
这篇论文探讨一个思想实验式的问题：如果地球历史上在人类之前存在过工业文明，我们能否从地质记录中检测到它。作者（天体物理学家 Gavin Schmidt 和 Adam Frank）分析了工业文明可能留下的地质信号，如碳同位素异常、合成材料、金属分布等，并指出这些痕迹在数百万年的地质过程中大多会被抹去，因此难以给出确定答案。
HN 关注点：这个'硅谷式天马行空'的问题触及了费米悖论、深时地质学和人类世标记等 HN 读者喜爱的话题，讨论焦点是：工业文明到底会不会留下无法抹去的痕迹。
HN 评论精选
这几条评论里：质疑 1 补充 3
补充先进技术可能超出认知框架，我们或许无法识别远古文明的痕迹
引用 Iain M. Banks《文明》系列的一个观点：技术进步更像攀岩而非爬梯子，充满意外与不可理解之处。我常想，宇宙参数空间如此浩瀚，如果古代先进技术远离我们当前的进步路径，我们可能根本认不出来。最喜欢的例子是：把存有维基百科和古腾堡计划的 SD 卡交给罗马皇帝，他只会对这块奇怪材料上的几何金属件略感兴趣；即使专家花多年说服学者它存有数百万份文献，要真正利用它也需要几代人的努力——不是那些人愚蠢，而是理解这个人工物所需的专业化知识远超他们的文化能力。我们凭什么认为自己的文化会有所不同？
filoeleven查看英文原文
One of my favorite quotes from Iain M. banks’ Culture series, paraphrased here since I don’t recall which book it’s in, is that technological progress is more like scaling a rock face than climbing a ladder. There is so much room for surprise and incomprehension. I sometimes think about how vast the parameter space of our physical universe is, and if that vastness means we wouldn’t be able to recognize ancient advanced technology if it’s far enough outside of our current mode of progress. My favorite example is handing an SD card with all of Wikipedia and the Gutenberg Project and maybe even the Wayback Machine on it to a Roman emperor. He’d look at it and might have a mild interest in the geometrical metal bits on an otherwise insignificant tiny flake of weird material. If the deliverer were to tell him that it contained millions of documents, he wouldn’t believe it. An expert in the field of storage media could, if for some reason permitted, spend years trying to explain it to the scholars of the time. Even if the expert succeeded in convincing them, it would take an unimaginable effort lasting lifetimes to ever make use of the thing. It would not succeed. Not because those people were stupid, but because the specialization that’s needed to understand the artifact is so far away from from their cultural knowledge and capabilities as to be unreachable. Why should we expect our culture be any different? The primary counter-argument to this is math and physics, and it’s a pretty strong one. It holds up quite well when dealing with past civilizations that are beneath or somewhere close to our current level of understanding. If you’ll permit another flight of fancy though, imagine an ancient society that figured out how to encode information in the irregularities of crystalline structures: every lame-ass quartz medallion we’ve unearthed could be the equivalent of a 10TB hard drive, and we’d never be the wiser. I think this is pretty unlikely, but it’s good to be humble and interrogate your assumptions.
质疑质疑：大规模工业文明必然留下可识别的地质痕迹
在地质时间尺度上，几乎所有东西都无法保存，文明的存续窗口在地质上可能基本不可见。但工业文明会制造大量耐久且明显是人造的东西，并散布全球。既然有保存超过 3 亿年的足迹和长达 40 亿年的化石，我很难想象一个大规模生产铝、钛、陶瓷的全球文明不会在所有可化石化的环境中留下可识别的东西——数百万个垃圾场、城市、工业设施、数百万英里的道路。更别提高轨道物体和月球表面了。你得假设一个非常有限的文明才能让我相信什么都不会留下。
jccooper查看英文原文
Yes, over geologic time, nearly anything has no chance of survival. And, yes, the lifetime of such a civilization may be a window that is, geologically, basically invisible. But an industrial civilization makes a LOT of stuff, and much of that is quite durable and easily recognizable as artificial, and is likely to be scattered all over the planet. Given that there are places that preserve tracks over 300 million years old, and fossils, well, up to 4 billion years old, I have a hard time imagining that a worldwide civilization that's producing and using aluminum and titanium and ceramics and all sorts of other stuff on a wide basis would not leave something recognizable in basically all the available fossilizing environments. We might not ever find fossils of the species, but are we really not going to find anything from the million refuse dumps and cities and industrial facilities and whatnot, or millions of miles of roads, or the multi-billions of accidental losses bound to be all over the world? Not to mention objects in high orbit or on the lunar surface, which is a whole other thing. You have to posit a really limited civilization before I believe it.
补充关键证据是缺失：易开采矿藏未被耗尽说明没有先前工业文明
换个角度看更有说服力：问题不是这样的文明会留下什么，而是它们会拿走什么。早期文明开采的是容易获取的锡、铜、金等矿藏，如果过去 1000 万年左右存在过另一个先进文明，这些易采矿藏早就该被耗尽了。
timoth3y查看英文原文
It more convincing to look at it the other way. It's not what such civilizations would have left, but what they would have taken. Our early civilizations found easily accessible deposits or tin, copper, gold, etc that would have been depleted if another advanced civilization had existed in the past 10 million years or so.
补充提供作者撰写的通俗版文章链接
论文作者在《大西洋月刊》上撰写的科普文章：https://www.theatlantic.com/science/archive/2018/04/are-we-earths-only-civilization/557180/
notional查看英文原文
Article by the authors of this paper, https://www.theatlantic.com/science/archive/2018/04/are-we-earths-only-civilization/557180/
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