Lee, This is an astounding answer, I feel like I need to go eat another box of Captain Crunch!
John R. On Jan 28, 2005, at 8:57 AM, Lee Larson wrote: > On Jan 28, 2005, at 12:19 AM, Nelson Helm wrote: > >> I read that persons standing on the sidewalk below hear Big Ben, the >> bell at the Houses of Parlement, after Australian listeners to the >> BBC. Signal goes to Australia at speed of light, in less time than >> to sidewalk at speed of sound. > > Being my usual persnickety self, I checked the facts, and you're > right. (Google knows everything!) > > Big Ben is 106 m tall, so it takes the sound about 0.3 s to reach the > ground at 340 m/s. > > The mean circumference of the earth is 12,742 km and the speed of > light in a vacuum is 299,792,458 m/s. As a worst case, Australia is > halfway around the world, so use 6500 km as the distance from London > to Australia, giving 0.02 s as the time to get there. > > Light is quick, but not quick enough to help satellite broadband. A > satellite in geostationary orbit is 35,768 km above the equator. It > takes at least 0.12 s to get a signal there. Since we're talking > round-trip time, this is about a quarter second to squirt something up > there and get it back. > > I've tried satellite broadband. > > It works great for downloading big files because once the file starts > coming, it comes really fast. > > Using a terminal is pretty frustrating because the echo of what you've > typed takes at least a half second to appear. > > Complex Web pages are made up of dozens, or even hundreds of little > pieces. You can watch in slow motion as your computer requests them > and they arrive. The satellite broadband companies are fighting the > latency by caching commonly requested pages so they can send all the > pieces at once without waiting for the individual requests. > > Email is OK because you just get it all in one shot, so the half > second isn't noticeable. > > > > | The next meeting of the Louisville Computer Society will > | be January 25. The LCS Web page is <http://www.kymac.org>. > | List posting address: <mailto:macgroup at erdos.math.louisville.edu> > | List Web page: <http://erdos.math.louisville.edu/macgroup> > | The next meeting of the Louisville Computer Society will | be January 25. The LCS Web page is <http://www.kymac.org>. | List posting address: <mailto:macgroup at erdos.math.louisville.edu> | List Web page: <http://erdos.math.louisville.edu/macgroup>
