Comments on: Three rules of thumb

By: Nick Brown

Nick Brown — Thu, 05 Jan 2012 18:31:22 +0000

It’s funny that both the speed of sound and speed of light can be so readily approximated by “1 foot per x” – 1 foot per millisecond is a very common rule of thumb in acoustics, sound recording (microphone arrays) and live sound (speaker arrays).

By: Ben Bradley

Ben Bradley — Thu, 05 Jan 2012 17:22:54 +0000

I just saw this page in a tweet from @CompSciFact
The video has been taken down, but a quick search brings up another copy:
http://www.youtube.com/watch?v=RZ0g5_NgRao

By: fernando

fernando — Thu, 05 Jan 2012 17:22:00 +0000

the video is not available anymore, its account has been removed due to copyright issues

By: Pi seconds equals one nanocentury — The Endeavour

Pi seconds equals one nanocentury — The Endeavour — Thu, 14 Oct 2010 12:16:35 +0000

[...] wrote briefly about Duff’s rule a while back in the post Three rules of thumb. That post also includes a great video of Grace Hopper explaining to David Letterman her rule of [...]

By: harrywwc

harrywwc — Tue, 07 Sep 2010 10:10:11 +0000

I know it’s “late”, but I suspect that Grace’s “nano-second” was actually 30cm long (0.3m) , rather than 12inches. There is a slight difference ;’) in which case, her nano-second is (by my reckoning) about 1/3 of 1% ‘off’.
My reasoning is that she was a Scientist, and she would have been familiar with the MKS (meters / kilograms / seconds) system. Indeed, the wikipedia article seems to back up this inference that she used 30cm (11.8in) rather than 1foot.
great site,
.h

By: Jared Updike

Jared Updike — Wed, 01 Jul 2009 20:56:32 +0000

Thanks Bill for sharing that video, and John for adding the link. Made my day.

By: Rick Regan

Rick Regan — Wed, 01 Jul 2009 18:23:13 +0000

Re: the video (at about 7:55): A picosecond is a trillionth, not quadrillionth of a second.

By: John

John — Wed, 01 Jul 2009 14:39:06 +0000

Thanks, Bill. I updated the post to include the interview you pointed out.

By: Bill the Lizard

Bill the Lizard — Wed, 01 Jul 2009 14:16:28 +0000

Grace Hopper gave a fun interview back in the early 1980's on David Letterman. She explains Hopper's rule, and even takes it a step further and shows Dave what a picosecond looks like.