RE: Re: re: Accuracy and Precision

*To*: mathgroup at smc.vnet.net*Subject*: [mg37221] RE: Re: re: Accuracy and Precision*From*: "DrBob" <drbob at bigfoot.com>*Date*: Thu, 17 Oct 2002 00:08:49 -0400 (EDT)*Reply-to*: <drbob at bigfoot.com>*Sender*: owner-wri-mathgroup at wolfram.com

Sorry, but that's not as profound as it sounds. The speed of light is indeed a very specific number, but that doesn't mean we can measure it precisely. Instead, like E or Pi or 2 or Sqrt[7], it's a defined constant and -- unlike E or Pi or Sqrt[7] -- the definition doesn't allow us to compute it with arbitrary precision. Yes, it's defined now so that it can pretend to unlimited precision -- but that only means meters (or seconds, take your pick) aren't defined precisely. For anything we can measure (or even COUNT, in the real world), I suspect 16-digit machine precision is more than enough. Bobby -----Original Message----- From: Kevin J. McCann [mailto:kjm@KevinMcCann] To: mathgroup at smc.vnet.net Subject: [mg37221] Re: re: Accuracy and Precision In the "real world" of physics there are several subatomic level processes which can only be distinguished by small changes in the n-th decimal place. But there is one example which is fairly easy to comprehend, and that is the constancy of the speed of light in a vacuum regardless of reference frame, as proposed in Einstein's special theory of relativity. If this were true "only" to the 9th or 10th decimal place, or, for that matter, to the 50th place, then whoever managed to show that it was not really a constant would certainly be in Nobel Prize territory, and much of modern physics would need a rewrite. Kevin > "Mark Coleman" <mark at markscoleman.com> wrote in message > news:aobg22$hrn$1 at smc.vnet.net... > > Greetings, > > > > I have read with great interest this lively debate on numerical prcesion > and > > accuracy. As I work in the fields of finance and economics, where we feel > > ourselves blessed if we get three digits of accuracy, I'm curious as to > what > > scientific endeavors require 50+ digits of precision? As I recall there > are > > some areas, such as high energy physics and some elements of astronomy, > that > > might require so many digits in some circumstances. Are there others? > > > > Thanks > > > > -Mark

**Follow-Ups**:**Re: RE: Re: re: Accuracy and Precision***From:*"Marko Vojinovic" <vojinovi@panet.co.yu>