EnigmA Amiga Run 1997 July/EnigmA AMIGA RUN 20 (1997)(G.R. Edizioni)(IT)[!][issue 1997-07 & 08][EAR-CD IV].iso/lightwave/lwmlist/95.lightwave-07/[e-mail]_Fri Jul 21 03:38:06 1995.msg

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Date: Wed, 19 Jul 1995 14:01:52 -0400 (EDT)
From: Ernie Wright <[e-mail]>
To: [e-mail]
Subject: Re: Scaling the universe
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> Say, then, I really don't care about tracking the accuracy of an
> object   to within 1 meter beyond 2/3 of an au (BTW: au=Astromomical
> Unit, the   distance from the Earth to the Sun, 150 billion km).
>
> So, I put these objects way out there... (just to make up a number)
> 5.5x10^100 (10 to the 100th power). Way out there.

I was going to ignore this (the reasoning is weak, so the numbers didn't
seem worth correcting), but since it's being repeated...

1 AU = 150 million, not billion, kilometers (or 150 billion meters, not
kilometers).

The largest distance in meters that a 15-digit number can represent with
an accuracy of 1 m is about 6700 AU, not .67 AU.  This is about 80 times
wider than Pluto's orbit, a distance it would take more than a month to
travel at the speed of light.

5.5 x 10^100 meters is larger than the visible universe by a factor of
about 10^75.  In fact, the universe is only 10^40 or so proton diameters
wide.  10^100 is a truly ridiculous number.  (The author was worried that
a camera motion of 300 km/s would completely disappear, since it's much
less than machine epsilon in a 10^100 m universe.  This is true, but to
fix the problem with increased floating-point precision would require at
least a 95-digit number.  It's not possible to measure position with any-
where near that much accuracy, even in principle.)

- Ernie

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Ernie Wright <[e-mail]> sent this message.
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