Instrument Drift

In Union Irish: Síobadh Ionstraimí — the drifting of instruments, as snow drifts

Physical Effects

Instrument drift is the phenomenon by which two correctly calibrated instruments produce different readings when placed at different positions within a boundary zone.

This is not a malfunction. The instruments are both accurate for their specific positions. The underlying cause is that local physical conditions — including the local rate of time — differ across the boundary. Each instrument is measuring its immediate environment correctly. The environment itself differs.

Example: At Threshold Station, the two wall chronometers in Dock Seven differ by forty seconds. This discrepancy has been stable for eleven years and cannot be resolved by recalibration: when recalibrated, the discrepancy returns within forty-eight hours. This indicates a stable oscillating boundary condition rather than simple drift.

Discussion