Hopper Cuts 11.8-Inch Wire to Map Computing Delays, Curb Code Waste

funbury

Physical models of light speed measuring 11.8 inches for a nanosecond and 984 feet for a microsecond are required to stop programmers from squandering machine cycles and to prove satellite latency to military leadership.

AI-assisted summary of Admiral Grace Hopper Explains the Nanosecond — original source. Check the original for full context.

Source published: 2012-03-01

Key ideas

Admiral Grace Hopper translated abstract computing time into physical reality by calculating a nanosecond as an 11.8-inch piece of wire, representing the maximum distance light travels in a vacuum in one billionth of a second. (0:46)
To provide perspective on processing efficiency, Hopper commissioned a physical microsecond, which measures 984 feet of wire. (1:03)
Physical models of time serve as vital educational tools to explain computational latency, such as satellite transmission lag, to non-technical leaders. (1:36)

Detailed notes

## Background Published on YouTube by funbury on March 1, 2012, this clip features computing pioneer Admiral Grace Hopper—one of the first programmers of the Harvard Mark I and creator of the first compiler. According to the page description, Hopper uses this presentation to explain the concept of a nanosecond to an audience of learners.

## TL;DR Admiral Grace Hopper recounts her frustration with abstract technical jargon, explaining how she asked engineers for physical models to help visualize minuscule fractions of time. She introduces an 11.8-inch piece of wire as a nanosecond—the maximum distance light travels in a billionth of a second—and contrasts it with a massive 984-foot coil representing a microsecond, suggesting programmers should wear it as a reminder not to waste processing time. Hopper concludes by demonstrating how these tangible visual aids demystify complex computing limits, recalling how she used them to explain satellite communication delays to high-ranking military leadership.

## Atmosphere & style Hopper delivers her lesson with an engaging blend of folksy charm, sharp wit, and unassailable authority, playfully ribbing both downtown businessmen and admirals who throw around terminology without understanding it. The presentation feels intimate and lively, driven by her dry humor and hands-on showmanship as she physically displays lengths of wire. Watching her speak turns abstract physics and engineering into something immediately graspable, creating a masterclass in clear, accessible technical communication.

## Bulletin - [00:46](https://www.youtube.com/watch?v=9eyFDBPk4Yw&t=46s) Admiral Grace Hopper translated abstract computing time into physical reality by calculating a nanosecond as an 11.8-inch piece of wire, representing the maximum distance light travels in a vacuum in one billionth of a second. - [01:03](https://www.youtube.com/watch?v=9eyFDBPk4Yw&t=63s) To provide perspective on processing efficiency, Hopper commissioned a physical microsecond, which measures 984 feet of wire. - [01:36](https://www.youtube.com/watch?v=9eyFDBPk4Yw&t=96s) Physical models of time serve as vital educational tools to explain computational latency, such as satellite transmission lag, to non-technical leaders.

## Key takeaways - [00:01](https://www.youtube.com/watch?v=9eyFDBPk4Yw&t=1s) Abstract hardware metrics like nanoseconds (billionths of a second) were conceptually difficult to grasp without an intuitive reference for what a billion represents. - [00:18](https://www.youtube.com/watch?v=9eyFDBPk4Yw&t=18s) Hopper resolved conceptual frustration by requesting the engineering team physically cut off a 'nanosecond' and deliver it to her. - [00:30](https://www.youtube.com/watch?v=9eyFDBPk4Yw&t=30s) The physical nanosecond was conceived as the maximum limiting distance electricity or light can travel in one billionth of a second. - [00:46](https://www.youtube.com/watch?v=9eyFDBPk4Yw&t=46s) Using the velocity of light in space, computer calculations reveal that a nanosecond measures precisely 11.8 inches. - [01:03](https://www.youtube.com/watch?v=9eyFDBPk4Yw&t=63s) To establish a tangible scale of comparison, Hopper requested a microsecond, which equates to 984 feet of wire. - [01:17](https://www.youtube.com/watch?v=9eyFDBPk4Yw&t=77s) Hopper suggested hanging a 984-foot microsecond around programmers' desks or necks to remind them of the physical cost of wasting machine cycles. - [01:28](https://www.youtube.com/watch?v=9eyFDBPk4Yw&t=88s) Physical representations of time bridge communication gaps between technical personnel and non-technical stakeholders, including family and military leaders. - [01:36](https://www.youtube.com/watch?v=9eyFDBPk4Yw&t=96s) Satellite communication delays can be intuitively demystified to high-ranking officials by demonstrating the vast number of 11.8-inch nanoseconds between Earth and space.

## Detailed walkthrough ### [00:01](https://www.youtube.com/watch?v=9eyFDBPk4Yw&t=1s) Visualizing the Nanosecond with a Piece of Wire

Admiral Grace Hopper recounts the frustration she felt when people first started talking about computer circuits operating in nanoseconds—billionths of a second. As she dryly observes, she did not even know what a billion was at the time, adding with a laugh that she did not think most of the men downtown understood what a billion was either. That confusion led to a fundamental conceptual problem: if one does not know what a billion is, it is impossible to genuinely comprehend what a billionth is. After fussing and fuming over the abstract terminology, she reached a point of complete exasperation and decided to take a physical approach. She called over to the engineering building with an unusual request: “Please cut off a nanosecond and send it over to me.”

Having brought several of these physical nanoseconds to distribute to the audience, Hopper explains the exact physics behind the object. What she wanted was a piece of wire cut to represent the maximum limiting distance that electricity could travel in a billionth of a second. She clarifies the technical caveat that electricity would not actually move that fast through a copper wire; rather, the calculation is based on the velocity of light moving through space. Running the calculation through a computer reveals that a nanosecond measures precisely 11.8 inches long, establishing a tangible, visual benchmark for an otherwise unimaginable fraction of time.

- **Definition of a nanosecond**: One billionth of a second. - **Physical length of a nanosecond**: 11.8 inches, representing the maximum distance light travels in a vacuum during that billionth of a second.

---

[01:03](https://www.youtube.com/watch?v=9eyFDBPk4Yw&t=63s) The 984-Foot Microsecond and Explaining Delays to Admirals

After living with her piece of wire for about a week, Hopper realized she needed a point of comparison to put the nanosecond into proper perspective. She called the engineering building back and asked for a microsecond. Because of its sheer size, she explains that she only owns a single microsecond and cannot hand one out to everyone: stretched out, a microsecond measures a massive 984 feet. Looking at the unwieldy bundle of wire, she reflects on the casual disregard software developers often have for machine efficiency, remarking on the discipline it could instill: “I sometimes think we ought to hang one over every programmer's desk (or around their neck) so they know what they're throwing away when they throw away microseconds.”

```mermaid flowchart LR accTitle: Physical Representations of Processing Time accDescr: Visualizing the length of a nanosecond compared to a microsecond. subgraph Nano ["Nanosecond (1 Billionth of a Sec)"] N["11.8 Inches of Wire"] end subgraph Micro ["Microsecond (1 Millionth of a Sec)"] M["984 Feet of Coil"] end Nano -. "x 1,000".-> Micro ```

Hopper encourages everyone in the audience to get their own nanoseconds, noting how exceptionally effective they are as communication tools. They work wonders for explaining technical limitations to spouses, children, and especially high-ranking military leadership. She shares an anecdote about an Admiral who demanded to know why sending a transmission via satellite took so long; rather than diving into abstract signal degradation or high-level physics, she simply pointed out that between the earth station and the satellite, there were an enormous number of those 11.8-inch nanoseconds to traverse. Having a physical model demystifies the delay immediately, proving that having a physical nanosecond on hand makes explaining complex computing constraints remarkably easy.

- **Length of a microsecond**: 984 feet (representing one millionth of a second). - **Communication utility**: Helps bridge understanding with non-technical stakeholders, including family members, generals, and admirals puzzled by satellite communication latency.

## Mentioned Grace Hopper, Harvard Mark I

## Video description Admiral Grace Hopper was one of the first programmers of the Harvard Mark I computer. She developed the first compiler for a computer programming language. Here she explains a nanosecond to a room of learners.

Transcript:

They started talking about circuits that acted in nanoseconds. Billionths of a second. Well, I didn't know what a billion was (I don't think most of those men downtown knew what a billion is either). And uh .. if you don't know what a billion is, how on Earth do you know what a billionth is? I fussed and fumed. Finally one morning, in total desperation, I called over to the engineering building and I said: "Please cut off a nanosecond and send it over to me." And I brought you some today. Now, what I wanted when I asked for a nanosecond was: I wanted a piece of wire which would represent the maximum distance that electricity could travel in a billionth of a second. Now, of course, it wouldn't really be through wire. It'd be out in space; the velocity of light. So, if you start with the velocity of light and use your friendly computer, you'll discover that a nanosecond is 11.8 inches long (the maximum limiting distance that electricity can travel in a billionth of a second). Finally, at the end of about a week, I called back and said: "I need something to compare this to. Could I please have a microsecond?" I've only got one microsecond (so I can't give you each one). Here's a microsecond: 984 feet. I sometimes think we ought to hang one over every programmer's desk (or around their neck) so they know what they're throwing away when they throw away microseconds. Now I hope you all get the nanoseconds. They're absolutely marvelous for explaining to wives and husbands and children and Admirals and Generals and people like that. An Admiral wanted to know why it took so damn long to send a message via satellite. And I had to point out that between here and the satellite there were a very large number of nanoseconds. You see -- you can explain these things. It's really very helpful, so be sure to get your nanoseconds.

[Source](https://www.youtube.com/watch?v=9eyFDBPk4Yw)

中文简报

霍珀剪下11.8英寸电线具象化计算延迟，遏制代码浪费代表纳秒的11.8英寸和代表微秒的984英尺的光速物理模型，是阻止程序员浪费机器周期并向军方领导层证明卫星延迟所必需的。格蕾丝·霍珀海军少将讲述了她对抽象技术术语的沮丧，并解释了自己为何要求工程师制作物理模型来帮助直观展示极微小的时间单位。她拿出一段11.8英寸长的电线作为“一纳秒”——即光在十亿分之一秒内传播的最大距离，并将其与代表一微秒的984英尺巨大线圈进行对比，建议程序员佩戴它以提醒自己不要浪费处理时间。霍珀最后演示了这些切实可见的辅助工具如何消除复杂计算限制的神秘感，并回忆了自己如何利用它们向军方高级领导层解释卫星通信延迟。格蕾丝·霍珀少将通过将一纳秒计算为一段11.8英寸长的电线，把抽象的计算时间转化为物理现实，它代表了光在真空中十亿分之一秒内传播的最大距离。 (0:46) 为了从宏观视角审视处理效率，霍珀定制了一个代表微秒的实体模型，其长度为984英尺的电线。 (1:03) 时间的物理模型是向非技术领域领导层解释计算延迟（如卫星传输延迟）的重要教学工具。 (1:36)

Reading summary

Admiral Grace Hopper argued that abstract computing timeframes become easily understandable when converted into physical distances, using lengths of wire based on the speed of light to represent nanoseconds and microseconds. Materializing the Nanosecond through Light Speed (0:01) Frustrated by the abstract concept of a nanosecond—defined as one billionth of a second—Hopper sought a tangible representation after realizing that neither she nor many of her peers truly conceptualized what a billion was. She asked engineers to cut a wire representing the maximum limiting distance electricity could travel in that interval. Visualizing Microseconds to Encourage Software Discipline (1:03) To establish perspective, Hopper requested a physical model of a microsecond (one millionth of a second), which resulted in an unwieldy 984-foot coil of wire. Comparing the two scales highlighted the disparity between single operations and larger cumulative timeframes. Hopper humorously suggested that coils of this length should be hung over programmers' desks or around their necks to visually demonstrate the scale of processing time squandered when microseconds are casually wasted. Bridging Communication Gaps with Physical Models (1:03) Hopper emphasized that holding physical nanoseconds serves as a powerful communication tool for clarifying technical constraints to non-technical stakeholders, including family members and military officials. She cited an instance where an Admiral questioned the delay in satellite transmissions; rather than relying on abstract electronic concepts, Hopper explained the latency by illustrating the sheer volume of 11.8-inch segments a signal must traverse between an earth station and a satellite. By grounding invisible temporal fractions in physical space, Hopper demonstrated that tangible models can demystify complex engineering boundaries and bridge communication barriers across technical and executive divides.

精炼阅读摘要

计算机科学家 Grace Hopper 海军准将通过将不可见的微小时间尺度转化为具象的电线长度，把抽象的纳秒与微秒概念落地为直观的物理极限，用以促进技术沟通并倡导更严格的计算效率。将纳秒物化为11.8英寸电线 (0:01) 当计算机电路的运行速度开始以纳秒（十亿分之一秒）计量时，Hopper 因术语过于抽象而难以真正理解其含义。她认为如果无法具象化十亿，就更不可能切实理解十亿分之一。为了打破这种概念障碍，她要求工程部门制作一个实物化的纳秒模型，将电信号或光在极短时间内移动的极限距离实体化。经计算机测算，光在真空中于十亿分之一秒内所能传播的最大物理距离精确为11.8英寸。Hopper 借此向公众发放该长度的电线，同时特别澄清这属于光在真空中行进的理论极限，电信号在实际铜线中的传播速度并不会达到这一数值。 984英尺微秒线卷与编程效率 (1:03) 为了给纳秒建立鲜明对照，Hopper 随后测算并制作了微秒（百万分之一秒）的物理模型。微秒展开后的长度达到了庞大的984英尺，庞大到她只能持有一卷而无法向听众逐一分发。借助这一巨大的物理体量，Hopper 批评了部分软件开发人员对机器运行效率的漫不经心；她戏称应当把这条984英尺的线卷挂在每位程序员的桌子上方甚至脖子上，以此警示他们在编写低效程序时实际上浪费掉了多么庞大的物理尺度与处理资源。跨越专业门槛的技术沟通工具 (1:03) Hopper 强调具象化的时间线段是极具说服力的沟通工具，能够向非技术背景的家人、乃至高级军事将领清晰解释复杂的物理与工程限制。她举例指出，在面对一位对卫星通信为何存在延迟深感困惑的海军将领时，她并未阐述复杂的信号衰减或高阶物理公式，而是直接指出地面站与卫星之间相隔着数以亿计的11.8英寸纳秒线段。这种直观的物理参照物瞬间消解了技术延迟的神秘感，证明将抽象约束转化为具象模型是弥合认知鸿沟的极有效手段。 Hopper 通过直观的物理演示揭示了光速与物理距离对计算和通信速度构成的硬性约束，但该模型仅以真空中的光速为理想基准，未进一步细化电信号在真实硬件导线介质中传播时的额外物理衰减与阻抗延迟。

Detailed notes — zh

## Background 该视频由 YouTube 频道 funbury 于 2012 年 3 月 1 日发布。视频简介指出，哈佛马克一号（Harvard Mark I）计算机的最早程序员之一、首个编译器开发者格蕾丝·霍珀准将（Grace Hopper），在现场向学员们生动讲解了“纳秒”这一时间概念的物理意义。 ## TL;DR 格蕾丝·霍珀准将回忆了自己为了理解“十亿分之一秒”的抽象概念，让工程人员剪下一段代表光在真空一纳秒内行进极限距离的导线——长度正好为 11.8 英寸。为了形成鲜明对比，她还展示了一根长达 984 英尺的“微秒”实物线缆，幽默地告诫软件工程师切勿在编写代码时挥霍微秒。霍珀强调，通过将纳秒实体化为具体的物理长度，能够非常直观地向家庭成员、外行大众以及军队将领解释卫星通信等高科技领域的传输延迟机制。 ## Atmosphere & style 整段演讲洋溢着幽默机智与举重若轻的大师风范，霍珀准将以充满自嘲与调侃的叙事打破了前沿计算机理论的高冷门槛。她手持导线实物的讲述极为通俗接地气，逗趣中带着老牌科研人员的严谨与敏锐。观众在阵阵欢笑中不仅能感受到老将领的风趣魅力，更能真切体会到抽象物理尺度被具象化时所带来的认知震撼与顿悟感。 ## Bulletin - [00:01](https://www.youtube.com/watch?v=9eyFDBPk4Yw&t=1s) 格蕾丝·霍珀准将通过将光速在真空中行进的距离实物化，将抽象的“1纳秒”转化为一根长 11.8 英寸（约 30 厘米）的导线，直观呈现电信号在十亿分之一秒内的物理极限。 - [01:03](https://www.youtube.com/watch?v=9eyFDBPk4Yw&t=63s) 为形成鲜明对比，霍珀将“1微秒”对应折算为长达 984 英尺（约 300 米）的线缆，并呼吁程序员应时刻意识到浪费微秒所带来的巨大性能代价。 - [01:03](https://www.youtube.com/watch?v=9eyFDBPk4Yw&t=63s) 霍珀将这种“以物理距离表征时间”的模型应用于卫星通信延迟的科普，向军方将领通俗解释地表到卫星之间因空间跨度累积的海量纳秒延迟。 ## Key takeaways - [00:01](https://www.youtube.com/watch?v=9eyFDBPk4Yw&t=1s) 电路运作速度进入纳秒时代后，由于“十亿”概念过于抽象，使人难以直观理解“十亿分之一秒”的真实含义。 - [00:01](https://www.youtube.com/watch?v=9eyFDBPk4Yw&t=1s) 格蕾丝·霍珀提出用物理长度来具象化时间概念，向工程团队索要一段能代表时间流逝距离的实体“纳秒”。 - [00:01](https://www.youtube.com/watch?v=9eyFDBPk4Yw&t=1s) 以电磁波在真空中以光速传播为极限计算，一纳秒所对应的物理极限距离恰好约为 11.8 英寸（约 29.97 厘米）。 - [00:01](https://www.youtube.com/watch?v=9eyFDBPk4Yw&t=1s) 将抽象的纳秒转化为可握在手中的金属线模型，为非专业人士理解极短时间尺度提供了直观标尺。 - [01:03](https://www.youtube.com/watch?v=9eyFDBPk4Yw&t=63s) 为了提供对比参照物，霍珀进一步制作了一微秒（百万分之一秒）的物理模型，其长度达到 984 英尺（约 300 米）。 - [01:03](https://www.youtube.com/watch?v=9eyFDBPk4Yw&t=63s) 霍珀幽默建议应在程序员桌上或脖子上挂一根 984 英尺的微秒线，提醒开发者不可在代码中轻易挥霍计算性能。 - [01:03](https://www.youtube.com/watch?v=9eyFDBPk4Yw&t=63s) 当军方将领质疑卫星通信延迟过长时，霍珀运用“海量纳秒累加”的空间距离概念化解了复杂的物理理论解释。 - [01:03](https://www.youtube.com/watch?v=9eyFDBPk4Yw&t=63s) 将微观时间尺度与宏观空间尺度进行物理绑定的教学法，是向大众及决策层科普高深技术原理的极佳沟通范式。 ## Detailed walkthrough ### [00:01](https://www.youtube.com/watch?v=9eyFDBPk4Yw&t=1s) 实体化“纳秒”：从十亿分之一秒到11.8英寸的导线格蕾丝·霍珀准将（Grace Hopper）回忆起人们最初开始谈论那些以“纳秒”（十亿分之一秒）为单位运作的电路时的情景。当时她对这种过于抽象的概念感到非常困惑，她幽默地调侃道，自己根本不知道“十亿”（billion）究竟有多大，而且她觉得“市中心那帮大人物大多也不知道十亿到底是多少”。霍珀指出，如果一个人连“十亿”都没有概念，那究竟该如何去理解“十亿分之一”到底意味着什么？她为此感到坐立难安、烦躁不已，最终在某天清晨出于彻底的无可奈何，她直接打电话给工程楼提出了一个看似荒唐的要求。霍珀准将对工程人员说：“请帮我剪下一段‘纳秒’寄过来。”她今天把制作好的实物带到了现场。她解释道，自己当时索要“纳秒”时，其实是想要一根能够直观代表电在十亿分之一秒内所能传播的最大物理距离的金属线。严格来说，电信号在普通导线中的传播会有衰减，这里的物理上限应当是电磁波在真空中以光速传播的极限距离。如果以光速为基准，并在计算机上进行计算，就会发现一纳秒所对应的物理长度正好是 11.8 英寸（约合 29.97 厘米）。霍珀向听众强调了这一物理极限：“如果从光速开始算起，并借助身边的计算机，你会发现一纳秒有11.8英寸长（即电在十亿分之一秒内所能移动的最大极限距离）。” ```mermaid flowchart LR accTitle: 纳秒与微秒的物理距离折算 accDescr: 展示光速在真空中分别在纳秒和微秒内行进的物理距离换算 subgraph TimeConversion ["时间与物理距离换算（光速）"] A["1 纳秒 (10⁻⁹ 秒)"] -->|"光速传播极限"| B["11.8 英寸导线<br/>(约 30 厘米)"] C["1 微秒 (10⁻⁶ 秒)"] -->|"光速传播极限"| D["984 英尺导线<br/>(约 300 米)"] end ``` - **纳秒定义**：十亿分之一秒（$10^{-9}$ 秒）。 - **物理对应长度**：以真空光速计算，一纳秒对应传播距离为 11.8 英寸（约 29.97 厘米）。 --- ### [01:03](https://www.youtube.com/watch?v=9eyFDBPk4Yw&t=63s) 984英尺的微秒与卫星通信的“纳秒距离” 在随身携带了这段 11.8 英寸的“纳秒”大约一周后，霍珀准将发现自己还需要一个参考物来建立鲜明的对比，于是她再次打电话给工程团队，请求给他们剪一段“微秒”（百万分之一秒）。但霍珀表示自己今天手里只有这一根微秒线，因此无法给在场的每位听众都发一份。这根“微秒”实物长达 984 英尺（约合 300 米）。看着这根长长的线缆，霍珀语重心长又半开玩笑地谈到了软件工程师的效率意识，她感叹道：“我有时觉得我们应该在每位程序员的办公桌上方悬挂一根（或者套在他们的脖子上），好让他们看清楚自己在白白挥霍微秒时究竟扔掉了什么。” 霍珀准将希望今天在座的各位都能领到属于自己的“纳秒”导线。她指出，这种把抽象时间转化为具体长度的实物模型有着极佳的沟通效果，非常适合拿去向妻子、丈夫、孩子，甚至是军队里的海军上将和陆军将军们解释复杂的科学原理。霍珀分享了一个亲身经历的趣事：曾有一位海军上将十分恼火地质问她，为什么通过卫星发送一条信息要花费那么长的时间。霍珀准将面对质问，并没有搬出枯燥的理论公式，而是非常形象地告诉对方，从我们所处的地方到外太空的卫星之间，实际上隔着“极其庞大数量的纳秒距离”。她总结道，只要掌握了这种方法，任何人都能轻松解释清楚这些看似高深的概念，因此大家一定要随身带好自己的“纳秒”。 - **微秒定义与长度**：百万分之一秒（$10^{-6}$ 秒），对应光速距离为 984 英尺（约 299.9 米）。 - **现实应用场景**：利用长距离的纳秒累积效应，形象化解释高空卫星通信中不可避免的信号往返传播延迟。 ## Notable quotes > [00:01](https://www.youtube.com/watch?v=9eyFDBPk4Yw&t=1s) 如果从光速开始算起，并借助身边的计算机，你会发现一纳秒有11.8英寸长（即电在十亿分之一秒内所能移动的最大极限距离）。 — 格蕾丝·霍珀 ## Mentioned 格蕾丝·霍珀 (Grace Hopper), 哈佛马克一号计算机 (Harvard Mark I), 通信卫星 ## Video description Admiral Grace Hopper was one of the first programmers of the Harvard Mark I computer. She developed the first compiler for a computer programming language. Here she explains a nanosecond to a room of learners. Transcript: They started talking about circuits that acted in nanoseconds. Billionths of a second. Well, I didn't know what a billion was (I don't think most of those men downtown knew what a billion is either). And uh .. if you don't know what a billion is, how on Earth do you know what a billionth is? I fussed and fumed. Finally one morning, in total desperation, I called over to the engineering building and I said: "Please cut off a nanosecond and send it over to me." And I brought you some today. Now, what I wanted when I asked for a nanosecond was: I wanted a piece of wire which would represent the maximum distance that electricity could travel in a billionth of a second. Now, of course, it wouldn't really be through wire. It'd be out in space; the velocity of light. So, if you start with the velocity of light and use your friendly computer, you'll discover that a nanosecond is 11.8 inches long (the maximum limiting distance that electricity can travel in a billionth of a second). Finally, at the end of about a week, I called back and said: "I need something to compare this to. Could I please have a microsecond?" I've only got one microsecond (so I can't give you each one). Here's a microsecond: 984 feet. I sometimes think we ought to hang one over every programmer's desk (or around their neck) so they know what they're throwing away when they throw away microseconds. Now I hope you all get the nanoseconds. They're absolutely marvelous for explaining to wives and husbands and children and Admirals and Generals and people like that. An Admiral wanted to know why it took so damn long to send a message via satellite. And I had to point out that between here and the satellite there were a very large number of nanoseconds. You see -- you can explain these things. It's really very helpful, so be sure to get your nanoseconds. [Source](https://www.youtube.com/watch?v=9eyFDBPk4Yw)

Source quotes

[0:01] 格蕾丝·霍珀: 如果从光速开始算起，并借助身边的计算机，你会发现一纳秒有11.8英寸长（即电在十亿分之一秒内所能移动的最大极限距离）。

Original transcript

[0:01] They started talking about circuits that acted in nanoseconds. Billionths of a second. [0:07] Well, I didn't know what a billion was (I don't think most of those men downtown knew what a billion is either). [0:15] And uh .. if you don't know what a billion is, how on Earth do you know what a billionth is? [0:20] I fussed and fumed. Finally one morning, in total desperation, [0:24] I called over to the engineering building and I said: "Please cut off a nanosecond and send it over to me." [0:30] And I brought you some today. Now, what I wanted when I asked for a nanosecond was: I wanted a piece of wire [0:38] which would represent the maximum distance that electricity could travel in a billionth of a second. [0:45] Now, of course, it wouldn't really be through wire. It'd be out in space; the velocity of light. [0:50] So, if you start with the velocity of light and use your friendly computer, you'll discover that a nanosecond is 11.8 inches long [0:57] (the maximum limiting distance that electricity can travel in a billionth of a second) [1:03] Finally, at the end of about a week, I called back and said: "I need something to compare this to. Could I please have a microsecond?" [1:10] I've only got one microsecond (so I can't give you each one). [1:14] Here's a microsecond [1:19] 984 feet. I sometimes think we ought to hang one over every programmer's desk (or around their neck) so [1:27] they know what they're throwing away when they throw away [1:30] microseconds. [1:31] Now I hope you all get the nanoseconds. They're absolutely marvelous for explaining to wives and husbands and children and [1:40] Admirals and Generals [1:41] and people like that. An Admiral wanted to know why it took so damn long to send a message via satellite. [1:47] And I had to point out that between here and the satellite there were a very large number of nanoseconds. [1:56] You see -- you can explain these things. It's really very helpful, so be sure to get your nanoseconds.