Every run,
a room of its own
The windowsill keeps receipts. Twenty-seven captured runs live here: twenty-four have rooms of their own — live explainers running each experiment's real update rules in your browser — and three, the non-equilibrium wing, run further down this very page. The register below is the shelf; start anywhere.
Every run the lab has kept receipts for
A run reproduced its target, a run returned a null or is still in flight, and a run refused its own measurement — kept because the refusal is the lesson.
The magnet ladder — statistical physics
- M01The temperature where a magnet forgets itself
- M02Zoom out and the peak grows on schedule
- M03Every size is the same picture, rescaled
- M04How much heat the sheet drinks
- M05Change the grid, change the number, keep the law
- M06The same magnet in three dimensions
- M07Add a fourth colour and the transition changes character
- M08A transition with nothing to point at
- M09The experiment whose right answer is nothing
- M10The magnet with no magnetism
- M11A glass that only freezes at absolute zero
- M12The glass transition that has not shown up yetnull, twice
- M13The disorder that survives absolute zero
- M14A line through a disordered phase diagram where the answer is exact
- M15How fast order grows out of chaos
- M16A glass that remembers its ageon this page
- M17The universal roughness of growing thingson this page
- M18The knife-edge between spreading and dyingon this page
Coherence — crowds of clocks
- K01When a crowd of clocks decides to tick together
- K02The peak that cannot stay still
- K03The measurement that refused to happenrefused, honestly
Arithmetic and instruments
- C01Checking the arithmetic before trusting it
- I01The detector that was never plugged inno hardware, no fake
The sky
Three experiments that never settle
Most experiments on this instrument's ladder measure systems at equilibrium. These three measure systems that never reach it: a glass that ages, a surface that roughens without limit, and activity that either spreads or goes extinct. Each panel below runs the experiment's actual dynamics, live, in your browser; the quoted numbers are from the published runs — all three green, human-reviewed.
A glass that remembers its age
After a rapid quench, does a disordered magnet evolve in a way that depends on how long ago it was quenched?
A spin glass is a magnet with randomly competing interactions: no arrangement of its spins can satisfy every bond, so after rapid cooling it freezes into a disordered state that continues to evolve — extremely slowly — forever.
The signature is aging. Record the configuration at two different times after the quench, then measure how quickly the system decorrelates from each record. The older the system was at the time of the record, the more slowly it lets go. Below, one quenched glass and two record ages, running live.
left · the glass (dark/light = spin) — watch domains freeze, then barely move · right · memory curves: how much the glass still matches its snapshot taken at age tw=60 (ember) vs tw=600 (moss). The old snapshot fades slower. That is aging.
The published run — a three-dimensional ±J glass, averaged over 64 disorder realizations — found that the correlation curves collapse when plotted against lag divided by age, with a residual scatter 0.24 times that of the time-translation-invariant alternative, and that at fixed lag the older system retains measurably more correlation. Time-translation invariance is broken, as aging requires.
The universal roughness of growing things
When a surface grows by random local deposition, does its roughness obey a universal law?
A surface growing by random arrival roughens in a constrained way: for a broad class of growth processes — the KPZ universality class — the interface width grows as time to the power 1/3, independent of microscopic details. Frost fronts, combustion fronts, and colony edges are all argued to share this exponent.
Below is the model from the published run: single-step corner growth on a ring. The interface width is plotted against time on logarithmic axes beside the theoretical slope.
left · the droplet grows, its rim wandering · right · rim roughness vs time, log-log; the guide line is slope 1/3 — the KPZ signature the run must track until this small ring saturates. Past the marked crossing the rim can't get any rougher than the ring is long, and the curve flattens away from the guide: finite size, not a failed exponent.
The measurement is controlled: the same estimator was applied to two additional growth rules with exactly known, distinct exponents, and recovered both — ¼ for the Edwards–Wilkinson rule and ½ for random deposition, the latter within 0.6% of a closed-form prediction with no fitted parameters. An estimator that produced ⅓ from arbitrary data would fail both controls.
The knife-edge between spreading and dying
When activity can spread to neighbours or die out irreversibly, where is the threshold between survival and extinction?
The empty state here is absorbing: once all activity is gone, the dynamics cannot restart it. Systems with an absorbing state exhibit one of the sharpest transitions in statistical physics, with critical behaviour — the directed percolation class — conjectured to describe phenomena from the onset of turbulence to epidemic thresholds.
Below is the update rule from the published run: each cell becomes active with probability p per active neighbour (including itself). The slider crosses the measured threshold.
left · the moss bed (ember = alive) · right · surviving fraction over time, log-log. Below the edge it crashes; above, it levels off; at the edge it slides down a power law forever. The lab's measured edge for this rule: pc = 0.22415 ± 0.00005 — the slider's home position.
The published run reports the decay exponent as a bracket rather than a point value: one run marginally below threshold and one marginally above, verified to curve in opposite directions, bound the exponent between them. The bracket contains the accepted directed-percolation value (0.4505) and excludes the mean-field value (1.0). An independent full run on different hardware reproduced the result.