Chapter 9 · Section 3
Measuring the Device
The BPT law
BPT does not state this; it is a game method.
The established physics
None: a game method. It is the same idea as adaptive load control in real-time rendering, and the game already uses it in one place: the ring search, which times itself and grows by 15 % when a step takes under 4 ms and shrinks by 20 % over 8 ms (Chapter 3).
The game's math
Each system that does heavy work times its own step, t milliseconds for its current size n, and knows how its cost grows with n. Its ceiling V is the size that would just fill its share of the frame, the target τ:
| Cost grows as | Examples | Ceiling |
|---|---|---|
| n (one pass over the things) | bodies under mesh gravity, points, proto wells, ring sources | V = n · τ / t |
| side² (one pass over a square) | the grid, the gravity mesh | V_side = side · √(τ / t) |
| fixed by the screen | how many dots the eye can tell apart | V = field pixels ÷ pixels per thing |
For the screen, a Proto Well needs about 6 pixels across, core and ring, to read as its own well, so about 36 pixels of area: a phone's field of about 390 × 390 = 152,000 pixels gives V ≈ 4,000, and a desktop's of about 1,000,000 gives V ≈ 28,000.
V is smoothed so one slow frame does not swing it: each new measurement moves V a fraction of the way toward the new value. It starts from the device's own first measured step, not from its kind, so a strong phone and a weak desktop each find their own.
The targets are the one design choice the measurements need, proposed (30 October 2026) and to be confirmed:
- the drawn frame: 33 ms (30 frames a second);
- a physics flip: 1 s on a desktop, 2 s on a phone.
The scale model
V sets only what the device runs. The universe it stands for is the same on every device: a phone and a desktop running the same universe draw different numbers of things, each standing for a different share, and every total agrees.
Fixed numbers
| Number | Where | What it is | Kind |
|---|---|---|---|
| 33 ms | target | 30 frames a second | METHOD (proposed) |
| 1 s, 2 s | target | a physics flip, desktop and phone | METHOD (proposed) |
| 36 px | screen | the area one Proto Well needs to be seen as one | DISPLAY |