Light Travel Time

Inspectable records

Ledger state

The current ledger marks this instrument verified clean within the source-bound verification corpus.

Area

Earth & Space (astronomy, orbital mechanics, meteorology, geology, geodesy, oceanography)

Tranche

tranche-4

Evidence ID

t4-077

Ledger rows

1

No ledger note is attached.

Review findings

Formula is valid for vacuum propagation over a specified path length, but the blank honest_label and missing physical/unit constraints require review. A more honest label is "Vacuum Light-Travel Time" with explicit supported units, exact conversion constants, Julian-year definition, and a warning that cosmological distance measures are not interchangeable with light-travel distance.

Formula and scope findings

• t = d/c is the standard formula for propagation time through vacuum when d is a path length and d and c use compatible units.
• The input description "distance (any astronomical unit)" is ambiguous: it does not specify the accepted unit set, whether "astronomical unit" means AU specifically or any astronomical distance unit, or how units are selected and converted.
• The formula assumes a static Euclidean distance and vacuum light speed; it is not generally the cosmological light-travel time for comoving, luminosity, or angular-diameter distances.
• The specification does not define the year convention for output; Julian year (365.25 days) should be explicitly required.

Unit assumptions

• c is the exact vacuum speed of light, 299792458 m/s.
• Distance and c must be converted to compatible units before division.
• 1 AU = 149597870700 m exactly.
• 1 light-year is defined using the Julian year: 1 ly = c × 31557600 s.
• Output years use 1 Julian year = 31557600 s.
• The distance is a nonnegative path length in vacuum.

Boundary hardening

BREAK_CLAIMED · SELF_FLAGGED

The specification does not define behavior for negative distances, creating a convention-dependent result: signed arithmetic returns a negative travel time, while physical distance semantics require rejection or magnitude normalization. The extreme finite input also exposes floating-point precision limits, although it does not overflow.

Errata and corrections

No applied erratum is attached to this unique-name record.

Inspectable example

4 review vectors are recorded. One source-bound sample is shown below.

{
  "inputs": {
    "distance": 299792458,
    "distance_unit": "m",
    "c": 299792458,
    "c_unit": "m/s"
  },
  "expected_outputs": {
    "time_s": 1,
    "time_min": 0.0166666666666667
  },
  "working": "t = d/c = 299792458 m ÷ 299792458 m/s = 1 s. Convert to minutes: 1 s ÷ 60 = 0.0166666666666667 min."
}

Related workflows

No source-defined multi-instrument workflow membership is recorded.

Sources and evidence

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

• VERIFIED_LEDGER.json · VERIFIED_CLEAN
• evidence-tranche4/tranche4-results.json
• BOUNDARY_HAZARD_CATALOG.json