From: Phil Goetz (philgoetz@yahoo.com)
Date: Sat Aug 27 2005 - 15:19:09 MDT
--- Michael Wilson <mwdestinystar@yahoo.co.uk> wrote:
> Phil Goetz wrote:
> > In Newtonian physics, different objects have different speeds.
> > Say you represent them with floating point. A low-speed object
> > might move at 1.2345*10^-10 m/s. Its speed is known to within
> > 10^-14 m/s. A high-speed object might move at 1.2345*10^8 m/s.
> > Its speed is known to within 10^4 m/s. Suppose you're simulating
> > a high-speed spaceships travelling thru the universe. You only
> > know its speed, and the speed of everyone in the spaceship,
> > to within 10^4 m/s or so. You're unable to simulate
> > what's happening on board the spaceship.
>
> If you're using variables that have insufficient dynamic range to
> encompass the entire co-ordinate space, then by definition you
> must be using some kind of system for nesting reference frames.
Huh?
> If you're using true absolute co-ordinates, i.e. every particle
> or similar ontological primitive has a position in quanta relative
> to the universe itself, then your variables must have enough
> range to allow speeds from 1 distance quanta/time quanta up to
> 1 universe diameter/time quanta without any loss of precision.
In a Newtonian universe. Which is why it's a bad approach
for a universe-simulator.
> If
> relativity really did simplify anything, all non-trivial physical
> simulation programs would be using it, whereas of course in
> reality very few do.
Those that involve things moving at relativistic speeds, do.
I didn't say it simplified things; it reduces the storage
and computational requirements.
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