Modeling Motion — Physics Simulations (2004)

This is original coursework from the Modeling Motion program at The Evergreen State College (2004). These are Python simulations I wrote modeling physics phenomena — springs, gravity, epidemics, numerical integration, 3D visualization — using the VPython library. I was learning physics and programming simultaneously, figuring out how to translate equations of motion into running code. Everything here is from that year of exploration.

The Rubik's Cube

The program I'm proudest of from this course is the Rubik's cube. It wasn't a class assignment — I built it entirely from scratch as an independent project. It renders a full 3D Rubik's cube using VPython and implements face rotations with correct piece tracking. The original/rubiks-cube/ directory contains every evolutionary stage of the project, from early experiments (get this box to grow!.py) to the final working versions (best_cube.py, cube_class.py). Each file is a snapshot of me figuring out 3D transformations one breakthrough at a time.

Simulations

Simulation	Files	Description
Spring Pendulum	original/assignments/spring.py, springsim.py	Damped spring-mass system modeled with Euler's method
Universe Simulation	original/assignments/universe.py, fountain.py	Gravitational interactions, bouncing balls, particle fountain
Collision Detection	original/assignments/collision.py	Billiard ball elastic collisions
SIR Epidemic Model	original/assignments/sir.py	Susceptible-infected-recovered disease spread simulation
Logistic Equation	original/assignments/logistic.py	Population growth with carrying capacity
Lissajous Figures	original/assignments/lissajous.py, lissa2.py	Parametric curves rendered in 3D
Riemann Sums	original/assignments/riemann.py	Numerical integration visualization
Rubik's Cube	original/rubiks-cube/	3D visualization and rotation of a Rubik's cube (independent project)
Assembly Simulator	original/extras/assembler.py, processor.py, simulator.py	Custom instruction set simulator with its own machine language

How to Run

Prerequisites

• Python 3.7+
• vpython and numpy:

pip install vpython numpy

Running Simulations

Set PYTHONPATH to include the compatibility shim so legacy from visual import * imports resolve correctly:

PowerShell:

$env:PYTHONPATH = ".\compat"
python original/assignments/springsim.py

Bash:

PYTHONPATH=./compat python original/assignments/springsim.py

Non-Visual Programs

Some programs don't require vpython and run directly:

python original/assignments/sir.py
python original/assignments/riemann.py
python original/assignments/logistic.py

Project Structure

modeling-motion/
├── original/                    # All original code from 2004
│   ├── rubiks-cube/             # Rubik's cube project (all versions)
│   ├── assignments/             # Course assignments (springs, gravity, etc.)
│   └── extras/                  # Supplementary programs (crypto, assembler, calculus)
├── compat/                      # Compatibility shim for legacy VPython imports
│   └── visual/                  # Maps `from visual import *` to modern vpython
├── references/                  # Third-party material (NOT my original work)
│   └── glowscript-examples/    # GlowScript/VPython example programs
├── docs/
│   ├── journal/                 # Weekly reflections and evaluations
│   │   ├── weeks/               # Journal Week 1–10
│   │   └── evaluations/         # Quarterly self-assessments
│   └── FUTURE_IDEAS.md          # Planned extensions and improvements
├── extensions/                  # Reserved for future new work (empty for now)
├── .gitignore
└── README.md                    # This file

Known Limitations

• Programs using frame (spring.py, springsim.py) may have visual positioning issues with modern vpython. The frame object was removed from vpython — the compatibility shim provides a workaround, but composite objects may not render identically to the 2004 originals.
• Assembly simulator programs (falling.py, .mm1 files) are source code for the custom CPU instruction set, not runnable Python scripts.
• Some programs were works-in-progress. LogisticEquation.py has incomplete methods. Several cube files are intermediate experiments that may not run cleanly.
• The cube programs have many evolutionary versions. best_cube.py and cube_class.py are the most complete and functional. The others document the journey.
• Window positioning (display(x=4000, y=500)) doesn't work in modern vpython since it now runs in a browser rather than a native window.

Journal & Learning Journey

The docs/journal/ directory contains weekly reflections and evaluation worksheets from the course. These document what I was learning each week, what I struggled with, and how my understanding of physics and programming evolved together. See the journal index for a chronological listing.

Future Plans

I have ideas for extending this work — adding RK4 integration, numpy optimizations, interactive parameter controls, and new simulation models. See docs/FUTURE_IDEAS.md for the full list. Any new code will live in the extensions/ directory, keeping the original coursework untouched.

Credits

• The Modeling Motion program at The Evergreen State College (2004)
• Barry Tolnas — instructor (credited in sir.py)
• The GlowScript examples in references/ are third-party material included for reference, not original work