Source: https://guthlabs.ai/docs/instruments/unit-converter-physics-quantities/mechanism/

instrument mechanism / verified-clean

# Unit Converter — Physics Quantities mechanism

The inspectable method record for Unit Converter — Physics Quantities, kept separate from implementation and qualification.

Status: **VERIFIED_CLEAN**Lifecycle: **verified-clean**

## Model scope

The stated algorithm is standard for compatible, multiplicative physics units, but the specification is not sufficiently precise to certify the instrument. Supply a versioned factor table, define all unit conventions and significant-digit/rounding behavior, and specify rejection behavior for incompatible, offset, and logarithmic units.

- Linear scale-factor multiplication is correct for conversions between compatible linear units, but the specification does not provide the actual conversion-factor table needed for verification.

- The converter must enforce dimensional compatibility; converting between incompatible quantity types must be rejected rather than applying an arbitrary factor.

- The specification does not define conventions for ambiguous units such as calorie, light-year, parsec, and amu, nor the precision and rounding policy for returned values.

- A purely linear model does not cover offset units such as degrees Celsius/Fahrenheit or logarithmic units such as decibels; these must be explicitly excluded or handled separately.

## Units and conventions

- eV uses the exact SI elementary-charge relation: 1 eV = 1.602176634e-19 J.

- 1 J = 1e7 erg exactly by the SI-to-cgs definition.

- 1 AU = 149597870700 m exactly (IAU nominal astronomical unit).

- 1 pc = (648000/pi) AU, using the IAU parsec definition and pi = 3.141592653589793.

- The zero-calorie test is independent of the calorie convention; nonzero calorie conversions require an explicit choice such as thermochemical calorie, 1 cal_th = 4.184 J.

- The amu, if supported, should mean the unified atomic mass unit (dalton), not an alternative historical atomic-mass convention.

## Inspectable vector

One of 4 source-bound review vectors:

````
{
  "inputs": {
    "quantity_type": "energy",
    "value": 0,
    "from_unit": "cal",
    "to_unit": "J",
    "calorie_convention": "thermochemical"
  },
  "expected_outputs": {
    "value": 0,
    "unit": "J"
  },
  "working": "1. Apply the linear conversion: J = cal × 4.184 J/cal. 2. J = 0 × 4.184 = 0 J. This is an edge case and gives the same result for any calorie convention."
}
````

## Failure boundary

**BREAK_CLAIMED** · SELF_FLAGGED

An extreme but representable input value, 1e308 J, converts mathematically to approximately 6.241509074460763e326 eV and overflows a JavaScript IEEE-754 Number to Infinity. The calorie probe also exposes a convention-dependent result if the lookup table does not specify the calorie definition.

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/unit-converter-physics-quantities/>)[03**Implementation**](<https://guthlabs.ai/docs/instruments/unit-converter-physics-quantities/implementation/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/unit-converter-physics-quantities/qualification/>)

## Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

- `VERIFIED_LEDGER.json`

- `evidence-tranche6/tranche6-results.json`

- `BOUNDARY_HAZARD_CATALOG.json`