use-relativity

Small special relativity scalar helpers for RustUse.

Install

[dependencies]
use-relativity = "0.0.1"

Foundation

use-relativity provides small special relativity scalar helpers for Lorentz factor, time dilation, length contraction, mass-energy relations, relativistic momentum, rapidity, velocity addition, and simple longitudinal Doppler calculations.

Inputs are expected to be SI-style numeric values:

• meters per second for speed and velocity
• seconds for time
• meters for length
• kilograms for mass
• joules for energy
• kilogram meters per second for momentum
• hertz for frequency

Positive beta in the Doppler helpers means the source is approaching the observer.

This crate keeps SPEED_OF_LIGHT locally for convenience. Broader physical constants belong in the top-level use-constants set.

Unit abstractions belong in the top-level use-units set.

Example

use use_relativity::{RelativisticBody, SPEED_OF_LIGHT, beta, dilated_time, velocity_addition};

assert_eq!(beta(SPEED_OF_LIGHT * 0.5), Some(0.5));
assert!((dilated_time(10.0, SPEED_OF_LIGHT * 0.6).unwrap() - 12.5).abs() < 1.0e-12);
assert!((velocity_addition(SPEED_OF_LIGHT * 0.5, SPEED_OF_LIGHT * 0.5).unwrap()
    - (SPEED_OF_LIGHT * 0.8))
    .abs()
    < 1.0e-3);

let body = RelativisticBody::new(1.0, SPEED_OF_LIGHT * 0.6).unwrap();

assert!(body.total_energy().unwrap() > body.rest_energy().unwrap());

When to use directly

Choose use-relativity when you need small scalar special relativity helpers without a full unit, geometry, or simulation system.

Scope

• APIs stay f64-first and focus on scalar special relativity helpers.
• General relativity, tensor calculus, curved spacetime, and numerical simulation are out of scope.
• Full constants systems and unit abstractions belong in use-constants and use-units.

Status

use-relativity is a pre-1.0 crate with a deliberately small API.