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The Threshold
A universe of books. An unreasonable number of rabbit holes.
Search 1,194 entries across 26 subjects, or step through into the Star Chart to explore a selection by subject and publication year.
The door's rings are engraved with digits of π, the primes and the Fibonacci numbers, all computed in your browser. Background stars are decorative, not a sky map.
The Star Chart
Books from Ash's catalogue as stars. Journeys as constellations you can check.
Every position means something: the angle is an editorial region grouped from the catalogue's own categories, and the distance from the centre is the year recorded in the catalogue (rings from 800 BCE to 2000; recent centuries are stretched). The brass constellation is one proposed journey through seven catalogued books.
Keyboard: Tab to the chart, then use the arrow keys to move from star to star; Home and End jump to the first and last star; Enter or Space opens a book; Escape closes it. Zoom with + and − (0 resets) or the buttons above; when zoomed, drag to pan, and a focused star is always brought into view.
| Title | Author (as recorded) | Year (as recorded) | Category (as recorded) | Chart region (editorial) | Journey | Action |
|---|
The Observatory
An orrery that computes where the planets are.
Heliocentric positions from JPL's published Keplerian elements (Table 1, valid 1800–2050), solved with Kepler's equation in your browser. What is simulated and what is decoration are labelled separately.
Top-down view of the J2000 ecliptic plane; the x-axis points to the J2000 equinox. The table beside the orrery lists the same positions as numbers.
Outside 1800–2050: the Table 1 elements are not valid here.
| Body | λ longitude ° | β latitude ° | r au | JPL nominal λ error |
|---|
Accuracy check (one date, 2026-09-26): against JPL Horizons, 7 of 8 bodies were within JPL's nominal errors for this method. Neptune was outside: 32.3″ in longitude against a nominal 10″ (about 0.009°, too small to see here). This orrery is an approximation, not a high-precision ephemeris.
Assumptions and limits
- Two-body Keplerian ellipses with JPL's best-fit linear element rates; no perturbation terms from Table 2b.
- Valid 1800–2050 AD only. JPL's nominal errors are listed in the table (for example 600″ ≈ 0.17° for Saturn).
- "Earth" is the Earth–Moon barycentre, as in JPL's table.
- Dates are treated as UTC; TT−UTC (about 69 s) is ignored.
- Heliocentric (Sun-centred) and geometric: no light-time, no aberration, not what you would see from Earth.
- Latitude β is computed but the drawing is a top-down projection onto the ecliptic plane.
Parameters: JPL Table 1 at J2000 and rates per century
| Body | a au | e | I ° | L ° | ϖ ° | Ω ° |
|---|
Source: E. M. Standish, "Approximate Positions of the Planets", JPL Solar System Dynamics (ssd.jpl.nasa.gov/planets/approx_pos.html). Second line of each row: rate per Julian century.
The Mind Lab · plan only
Perception experiments with the arguments left in.
Educational exhibits beside real books, each with sources, competing interpretations and limits. No quizzes that diagnose, no scores about the visitor, and no reading of Ash's mind from the shelves.
One image, two readings
An original ambiguous figure; the visitor switches interpretations and reads why researchers disagree about what the switching shows.
The felt present
A timing exhibit on how long "now" feels, placed beside related catalogue books once they are chosen and reviewed.
How colour is inferred
Identical swatches on different surrounds, with the physics of light kept separate from the psychology of seeing.
The Captain's Log · empty until Ash writes it
Entries appear here only in Ash's own words.
Nothing is inferred from a catalogue entry: no reading status, no reactions, no notes unless Ash supplies them. The layout below is an example shape with no content.
Example layout
[Entry title]
[Date written by Ash] · [Books linked by Ash] · [Trail, if any]