历史与人物atlasobscura.com
一张著名照片：切尔诺贝利最危险的放射性物质
A Famous Photo of Chernobyl’s Most Dangerous Radioactive Material (2016)
2016 — 2019，它一次次回到首页
黑点是上首页（≥ 50 分）的那次投稿，空心点是没冲上去的投稿，点越大分数越高。
导读
这篇文章讲述切尔诺贝利“象脚”那张著名照片的来历，澄清它其实是用自拍方式拍下的，并介绍这种高放射性熔融物以及拍摄者所处的极端环境。文章把一张看似离奇的照片放回核灾难现场与清理行动的背景中理解。
为什么经久不衰：它把极端危险、核灾难历史和一张广为流传的照片背后的具体人物故事结合起来，而且关于照片如何拍成、辐射危害和熔融物行为的讨论至今仍有科普价值。
HN 评论精选
这更像用手电补光的长曝光记录照，而不是有意自拍。
我不觉得这算自拍……更像是他想拍一张“象脚”的照片。考虑到唯一光源是他的手电筒，他必须长时间曝光，同时把手电光扫过物体各部位以均匀照亮。如果他想摆姿势站在旁边并让自己可辨认，他也会在站着不动的那几秒把手电照到自己脸上。
geuszb查看英文原文
I don't think of it as a selfie... It looks more like he wanted to take a photograph of the "elephant's foot", and considering that the only available light was his flashlight, had to do a long take while he trained the flashlight onto various parts of the piece, trying to illuminate it evenly. If he'd wanted to pose next to it and be recognizable, he would have shone the light onto his face while standing still for a few seconds too
纪录片记录了“生物机器人”等清理行动，凸显现场辐射之致命。
有一部很棒的纪录片《切尔诺贝利之战》，包含大量事故现场和清理工作的影像。让我至今难忘的是：最初灭火的直升机飞行员在120—180摄氏度的高温中飞行，几乎都死于辐射。还有一段是机器人全部失灵后，人们用手捡起放射性材料扔出反应堆旁的屋顶；哪怕暴露一小时也足以致命，所以他们轮班作业，这些人被称为“生物机器人”。
owyn查看英文原文
There's an amazing documentary about this that contains a lot of footage of the actual incident and cleanup called the "Battle of Chernobyl". http://topdocumentaryfilms.com/the-battle-of-chernobyl/ Things that still haunt me: the helicopter pilots who put the initial fires out flew in 120-180C temperatures and pretty much all died of radiation. And the sequence that starts about here: https://youtu.be/ezohqY-vg4s?t=3430 Where they are picking up radioactive materials by hand and throwing it off the roof next to the reactor because the robots they were trying to use all break down. Even 1 hour of exposure was deadly so they rotated through shifts, and the guys who did it were called "Bio Robots"
“象脚”证明熔融堆芯会稀释、冷却并重新凝固，而非无止境向下熔穿。
“象脚”最有趣的地方是它否定了“中国综合征”假说。该假说认为失控熔毁会一直熔穿到中国（当然不可能穿过地核）。但“象脚”表明，熔融堆芯在熔化过程中会与材料混合、扩散，最终失去足够质量而进入次临界、重新凝固，到此为止。这就是为什么几乎所有西方反应堆都在安全壳下方铺有沙层：万一最坏情况发生，熔融物会熔进沙里变成玻璃。
ChuckMcM查看英文原文
The most interesting thing about the elephant's foot was that it disproved the "China Syndrome" hypothesis. That hypothesis of course was that an uncontrolled meltdown would simply melt down through to China (not that it could really go past the core :-) However, what the elephant's foot showed was that the melted core would diffuse into the material as it was melting, eventually it loses enough mass that it goes subcritical, re-freezes and that's that. That is why pretty much every western reactor has a reservoir of sand under the containment vehicle, if the worst of the worst happens, it melts into the sand which becomes glass.
关于只有切尔诺贝利熔融物突破安全壳的说法不准确，福岛2号机组情况仍有不确定性。
“在五处熔融堆芯物中，只有切尔诺贝利的逃出了安全壳。”这个说法过于绝对，因为福岛第一核电站2号机组的破损程度尚不清楚——μ子成像显示它很可能已经突破了主（钢制）安全壳。
caf查看英文原文
Of the five corium creations, only Cherobyl's has escaped its containment. This is statement is a bit too definitive, because it simply isn't known yet how bad the breach is at Fukushima Daiichi No. 2 - from muon radiography it certainly seems to have breached the primary (steel) containment.
历次讨论
同类还值得读
开发者无薪坚持完成 Mac 图形计算器：一个秘密项目的故事
Dev stays without pay to finish Mac Graphing Calculator as skunkworks project
苹果 Mac 图形计算器（Graphing Calculator）开发者的亲述：在项目被砍后，几位工程师在没有报酬、没有正式授权的情况下，以“地下项目”方式偷偷留在公司把软件做完…
历史与人物上首页 6 次 · 2009–2022pacifict.com理查德·费曼与 Connection Machine
Richard Feynman and the Connection Machine
长文回忆费曼晚年参与 Connection Machine 并行计算机项目的经历：他分析路由器、用自创的并行 Basic 编写 QCD 程序，也涉足细胞自动机等主题。
历史与人物上首页 5 次 · 2010–2021longnow.org编辑精选负 2000 行代码
-2000 Lines of Code
folklore.org 上 Andy Hertzfeld 记录的一则苹果 Macintosh 开发轶事：Bill Atkinson 被问到写了多少行代码时，回答“-2000 行…
历史与人物上首页 4 次 · 2014–2022folklore.org编辑精选Dennis Ritchie 的第一版 C 编译器（约 1972 年）
Dennis Ritchie’s first C compiler (c. 1972)
这个 GitHub 仓库保存了 Dennis Ritchie 约 1972 年编写的最早 C 编译器源码，是 C 语言和 Unix 早期历史的一手材料。
历史与人物上首页 4 次 · 2013–2025github.com一位破解赛马密码的赌徒
A Gambler Who Cracked the Horse-Racing Code (2018)
彭博社 2018 年的长篇特写，讲述数学家 Bill Benter 如何用统计模型和算法在赛马博彩中持续盈利、累计赢得近十亿美元的故事。
历史与人物上首页 4 次 · 2018–2024bloomberg.com