Module exact 

ExactBrightDate — bit-exact picosecond-precision time.

Whereas BrightDate uses f64 decimal days for ergonomic math and astronomy, ExactBrightDate uses a signed i128 count of picoseconds since J2000.0 to provide bit-for-bit round-trip fidelity with Unix milliseconds, Unix seconds, and other integer-based representations.

When to use which

Use case	Choose
Application timestamps, logs, scheduling, display	BrightDate
Astronomy, physics, fractional math	BrightDate
Distributed systems, GPS, interplanetary timing	BrightInstant
Blockchain consensus on raw Unix-ms values	ExactBrightDate
Long-term archival that must survive bit-for-bit	ExactBrightDate
Sub-picosecond precision at any magnitude	ExactBrightDate

Precision

• Internal unit: picoseconds (1e-12 s).
• Range: i128 covers ±~1.7e38 ps ≈ ±5.4e18 years. Comfortably beyond the age of the universe in either direction.
• Resolution: 1 picosecond, exactly, everywhere.

Algebraic laws

For any integer unix_ms in i64:

ExactBrightDate::from_unix_ms(unix_ms).to_unix_ms() == unix_ms       (bit-exact)

For any a: ExactBrightDate and n: i128 nanoseconds:

a.add_nanoseconds(n).subtract_nanoseconds(n) == a                    (bit-exact)

ExactBrightDate is immutable. All operations return new instances.

Structs

ExactBrightDate

An immutable, bit-exact time value stored as picoseconds since J2000.0.

Constants

J2000_UNIX_MS_I64

J2000.0 expressed as Unix milliseconds — the exact i64 form of crate::constants::J2000_UTC_UNIX_MS.

J2000_UNIX_PS

J2000.0 expressed as Unix picoseconds (UTC label).

PS_PER_DAY

Picoseconds per SI day (86 400 s).

PS_PER_MS

Picoseconds per millisecond.

PS_PER_NS

Picoseconds per nanosecond.

PS_PER_S

Picoseconds per SI second.

PS_PER_US

Picoseconds per microsecond.