funbury
5 HN recommenders · recommended in 10 months, 2020–2025
2:04 · 163K views · Mar 1, 2012
Admiral Grace Hopper holds up a length of wire to show how far light travels in a nanosecond, about 11.8 inches. She explains how she made the idea concrete to people who could not picture a billionth of a second.
HN uses it to illustrate physical latency limits and why performance and distance matter in computing.
12 comments from Hacker News
My favorite is more a small presentation than an image: Admiral Grace Hoper Explains a Nanosecond. this video For me it changed my mind on wasting time on less efficient algorithms.
Yes it is and no it isn't. Learn from Admiral Grace Hopper: this video The speed of light in fiber optic cable is about 2/3 the speed of light, which is why SpaceX's Starlink will have a potential latency advantage over oceanic fiber optics. It also gives good perspective on what's being thrown away when you add a single ms of latency through a router or a display. 186 miles at the speed of light. Many on HN don't get this, but this is why cloud gaming is perfectly feasible if we're running with low latency displays and inputs, low distance to the edge compute, and few routing hops.
Speaking as somebody who never stopped optimizing like its the 90s: there's definitely a learning curve, but when microbenchmarking becomes a reflex, you learn your language in depth and the burden drops quickly. It only seems esoteric to you because the industry has collectively decided that Grace Hopper is an old codger who doesn't need to be listened to. this video
> Light is slow, not exactly 1 foot per nanosecond but it's a reasonable mnemonic. "Admiral Grace Hopper Explains the Nanosecond" is a good illustration of this (segment is only 2m): * this video * [LINK] Full lecture: * [LINK]
> The nanosecond wire alone should be a compelling argument. For those that haven't seen it: this video (Of course, I expect that most here have, but xkcd 10,000 and all that.)