Skylake

Note on numbering

LAKE-000 is not a finding. It is the thing we make findings with. It takes zero because every other entry's depth is measured against it.

Observation conditions

The lake and a radius of 1.2 km are closed under the cover of a forestry fire-watch station. Tie-off posts stand at 40 m intervals along the shore. Personnel within 5 m of the waterline work on a line, and never alone.

All observation is through a linear polariser. The angle between the filter axis and the surface normal must stay clear of 45° ± 2°. Do not look directly at the surface anywhere near that angle.

Shore work stops when wind speed falls below 0.5 m/s and resumes when the surface is disturbed again. A still surface carries no ripples, and without ripples there is no way to tell which side of the interface an image belongs to.

Anything crossing the surface is recorded as unrecoverable. No retrieval is to be attempted. Since incident 000-██ this station has held no diving or descent equipment.

Observation record

Skylake is an alpine lake of roughly 0.7 km² at an elevation of 2,4██ m. Shoreline ecology and the historical hydrological record are unremarkable.

Skylake holds no water. The medium below the surface matches surface atmosphere in composition, temperature, and pressure gradient, with a slightly higher refractive index. The surface is a discontinuity in refractive index rather than an air–water boundary.

The earliest anomalous measurement is a polarimetry run from 20██: Brewster's angle at the surface reads 45.03°, against 53.1° for water. The run was repeated eleven times with the same result.

What stands on the surface is not a reflection. With surface reflection cancelled by a polariser, an observer sees the far side of the interface directly. Along the bearing of least Δn, that side holds a downward sky, a shoreline, and a set of buildings matching this station in outline and reversed left to right.

Objects put into the surface do not sink. Past the interface they enter free fall at 9.8 m/s² directed away from it, and continue until they pass the limit of optical resolution. Multi-band sonar returns nothing. No object introduced has ever come back.

Figures seen below the shore move in step with the personnel above them. As of this revision there are ██ recorded departures from step, the longest lasting 0.4 s. During a departure the lower figure performs an action that the corresponding person did not complete and had not planned.

Inference

Below the interface there is not one world but a series of them, ordered by refractive index, not adjoining one another, sharing only the single face turned toward us. This station calls that ordering the strata; criteria and drafting conventions are in the Standing Orders.

One qualification. Fixing the Δn of LAKE-000 at zero is a convention, not a measurement. We do not know our own position in the series. We took ourselves as the origin because there is nowhere else to stand.