ANN Nine Ball with Spin (English)

[Jim Hurley]

>
>Message: 17
>Date: Sat, 2 Apr 2005 08:45:25 -0800 (PST)
>From: Alejandro Tejada <capellan2000 at yahoo.com>
>Subject: Re: ANN Nine Ball with Spin (English)
>To: use-revolution at lists.runrev.com
>Message-ID: <20050402164525.4129.qmail at web40511.mail.yahoo.com>
>Content-Type: text/plain; charset=us-ascii
>
>Hi Jim,
>
>Your have make better an already excellent stack!
>Greetings!!! :-)
>
>Like everyone, i have my wish list for your
>stack. ;-)
>
>This is my wish list for future versions of
>Nine Ball:
>
>1- An undo command to place all the balls in
>their previous position after a shot.
>In real life this an impossible feature,
>but in the computer this is possible, by
>storing the loc of all the balls before
>a shot.
>
>2- A floating console (or substack) that shows the
>numerical quantities of the variables that player
>is applying in a shot... this does not sound like
>much fun, but permits (with the undo option) to
>learn eventually how works forces in movement.
>
>3- A pool Genie. This is a feature that suggest a
>shot to the player, with previews of outcomes
>of diverses shots. Yes, i know what you are
>thinking but this is not cheating. Consider this
>like a player in the computer...


Al,

Whew! Great ideas, but not right now.

Actually, I stumbled into Nine Ball by accident--isn't that always 
the way. I had set out to do a Statistical Mechanics simulation, an 
illustration of the Second law of Thermodynamics, demonstrating that 
a thermodynamic system assumes the most disordered state compatible 
with the constraints.

It is easy to see this in physical space. Set a number of balls 
moving in a frictionless environment and they become randomly 
distributed in space. But the randomization takes place not only in 
geometric space but in velocity space as well. There was a popular 
misconception that if and when the universe began to contract that 
time would begin to move backward. Stephen Hawkings was one of the 
early advocates for this position. You can find a discussion of this 
in his "Short History of Time"

The thing that Hawkings neglected was that a contracting universe is 
not becoming ordered, the entropy is not decreasing. One has to 
consider not just the decrease in geometric states available in the 
contracting space, but also the increase in velocity states made 
available in the contraction--gravitational energy converted to 
kinetic energy. The increase in disorder associated with the velocity 
states exceeds the loss in position states. The total disorder 
increases and all is right with the second law.

So I wanted to show that if one had a large number of objects (pool 
balls) initially all moving with the same speed in the same direction 
(highly order velocities) that, if you introduced collisions, the 
velocities would randomize and eventually assume the 
Maxwell-Boltzmann distribution, i.e. a bell curve.

But, alas, Run Rev was not quite up  to  the task. Couldn't get 
enough balls to make for good statistics.

In any event, I didn't want to waste the collision routines, so I got 
caught up in Nine Ball.

But I am off to something else right now--using Run Rev to create a 
simulation contrasting global warming on Venus, Earth and Mars. 
(Right now I need a tool for making circular arcs--like the Run Rev 
pie shaped circular segments, but without the radial lines. May be a 
job for Turtle Graphics.)

Long winded way of saying, I'll have to pocket Nine Ball for the time being.

Jim