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MathGroup Archive 2002

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RE: Re: re: Accuracy and Precision

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

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.


-----Original Message-----
From: Kevin J. McCann [mailto:kjm@KevinMcCann] 
To: mathgroup at
Subject: [mg37221]  Re: re: Accuracy and Precision

In the "real world" of physics there are several subatomic level
which can only be distinguished by small changes in the n-th decimal
But there is one example which is fairly easy to comprehend, and that is
constancy of the speed of light in a vacuum regardless of reference
as proposed in Einstein's special theory of relativity. If this were
"only" to the 9th or 10th decimal place, or, for that matter, to the
place, then whoever managed to show that it was not really a constant
certainly be in Nobel Prize territory, and much of modern physics would
a rewrite.


> "Mark Coleman" <mark at> wrote in message
> news:aobg22$hrn$1 at
> > Greetings,
> >
> > I have read with great interest this lively debate on numerical
> and
> > accuracy. As I work in the fields of finance and economics, where we
> > ourselves blessed if we get three digits of accuracy, I'm curious as
> what
> > scientific endeavors require 50+ digits of precision? As I recall
> are
> > some areas, such as high energy physics and some elements of
> that
> > might require so many digits in some circumstances. Are there
> >
> > Thanks
> >
> > -Mark

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