Physics for simulated worlds — a kernel that knows nothing about any particular physics, and thirteen domains built on it that do: light, heat, motion, sound, electricity, electromagnetic fields, elastic deformation, incompressible flow, flow through a packed bed, matter one atom at a time, a quantum wavefunction in a well, and a drug distributing through a body. Two layers above them place a simulation in the world and draw it, and neither knows a domain either.

Dimensions live in the type system, so Length + Time does not compile. Conservation is audited rather than assumed, and a Violation names what went missing and where. Every result is reproducible bit for bit — across platforms, across optimisation levels, in WebAssembly, and under sixteen threads as readily as one.

Every claim is checked against a closed form or an independent computation, never against another implementation that might be wrong in the same direction. Where no closed form exists, EVIDENCE.md says so.

cargo run --release --example lens_spots -- lens.svg. Every figure here is the output of an example CI runs on every commit, and every example checks itself against a closed form.

cargo add pantometry     # one dependency, all nineteen published crates
pip install pantometry   # or from Python — see bindings/python

pantometry = "0.21"

In a clone of this repository:

cargo run --release --example melting            # a crystal melting, read off its own structure
cargo run --release --example beam_hot_spot      # a laser on a mirror, and the hot spot a lumped
                                                 # model misses
cargo test --workspace                           # the suite, all against closed forms

Add an output path to any example and it draws the result:

cargo run --release --example lens_spots -- lens.svg

Everything a person runs is one binary, in app/ — the CLI, the viewer, the editor and the GPU accelerator:

cd app
cargo run --release -- run    scene.json out.html   # run it and write an asset, by extension
cargo run --release -- verify scene.json --deep     # margins, determinism, sweeps, geometry
cargo run --release -- edit   scene.json            # the editor: check as you type, run, verify

pantometry edit with no file opens on a start screen: a new project, a scene to open, or one you had open before.

pantometry edit 29-a-designed-bracket-becomes-cells.json --run. An L-bracket designed as an STL, filled into 4 100 cells at 2 mm and cooling to still air. The scene is the text on the left and the picture is what running it produced — the readings, the colour bar and the frame transport are the run's, and the note in orange is the mesher saying what it did.

A laser on a mirror. The thin line is the lumped mean, which every curve has exactly — and the thick ones are what a lumped model cannot tell you: the peak is well above it.

There is one consumer, pantometry-world, and its first job was not to be a good application but to use the SDK the way a stranger would. app/pantometry-world/FRICTION.md is what it came back with: forty-eight findings, forty-three fixed and five argued down in writing. Not one of the library's own tests could have found any of them — a test is written by somebody who already knows the shape.

If this software contributes to work you publish, please cite it. CITATION.cff is beside this file and GitHub renders it as a Cite this repository button; the same content as BibTeX:

@software{park_pantometry,
  author  = {Park, Younghyeon},
  title   = {pantometry: physics for simulated worlds, checked against closed forms},
  version = {0.21.0},
  year    = {2026},
  doi     = {10.5281/zenodo.22233493},
  url     = {https://doi.org/10.5281/zenodo.22024817},
  note    = {ORCID: 0000-0002-4733-5049. The `doi` is 0.20.0's; the `url` is the concept DOI,
             which always resolves to the newest version. Both move with a release --
             this block named 0.16.0 through the whole of 0.17.0, and its `version`
             was left at 0.19.0 through the 0.20.0 bump because no list covered it},
  license = {MIT OR Apache-2.0}
}

It would be easy to write "please add me as an author" here, and it would be wrong on three counts.

It could not be required. MIT OR Apache-2.0 is already granted irrevocably, and a licence with an authorship condition attached would no longer be an open-source licence under the OSI definition — it would impose a restriction the two licences people already rely on do not have.

It is contrary to how authorship works. ICMJE and COPE both rest authorship on an intellectual contribution to the specific work being published. Supplying a tool is not that, however much work the tool was. Authorship asked for on those grounds is what the literature calls gift or honorary authorship, and an editor who saw it as a condition of use would strike it.

And it would cost the thing it was reaching for. A tool with a tax on it loses users, and users are where citations come from.

If you build something with this, I would like to hear about it — and if there is a question the library cannot answer yet, open an issue. Where that turns into real involvement in your work — a domain built for your problem, an analysis argued through together — a joint contribution is earned in the ordinary way, and I am glad to do it. That is an invitation and not a condition.

An acknowledgement, if the work does not warrant more, is always welcome and never expected.

Dual-licensed under either MIT or Apache-2.0 at your option — the Rust ecosystem's convention, and not indecision. Each covers a gap the other has. Apache-2.0 carries an explicit patent grant and MIT does not, which is the first thing a corporate legal review asks about. MIT is compatible with GPLv2 and Apache-2.0 is not, which matters here because the scientific-computing world has plenty of GPLv2 code. Offering both lets a consumer take whichever they need, so OR is strictly less restrictive than either alone.

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 licence, shall be dual-licensed as above, without any additional terms or conditions.

Every dependency is permissive too, and that is checked rather than remembered: deny.toml holds an allow-list and CI fails on anything outside it. Twelve external crates at the time of writing, of which three reach a published artifact — glam, serde and serde_core, all under the same MIT OR Apache-2.0. serde_json and its three transitive crates are a dev-dependency of four of the published crates, so they reach no artifact either. The rest are compile-time or test-only.

Two crates were added in 0.9.0 and the count did not move. pantometry-view has no dependency at all beyond pantometry-scene: SVG and HTML are text, so a renderer is a format! and a file write, and the alternative would have put a plotting stack into the tree of every consumer who wanted a picture.