Volume 1, Issue 2 · December 2024

Winter 2025

Things spreading through a lattice, a network, a coastline and a forest. A universal constant measured overnight on a laptop, the decade-long hunt for whatever killed five billion sea stars, and an honest look at whether early warning signals give any warning worth having.

6 articles, in the order the club meant them to be read.

1. 1

   ReplicationWinter 2025

   Measuring a Universal Constant on a Laptop: The Site Percolation Threshold

   Fill the cells of a square grid at random. Each cell is occupied with probability (p), independently. Below a certain density the cells form scattered islands. Above it, one cluster reaches from top edge to bottom. That density, on an infinite grid, is the site percolation threshold. The square lattice has no closed form for it, so the constant has to be measured. We measured it. Our experiment is a computation, an

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2. 2

   Original ResearchWinter 2025

   The Same Disease on Four Different Networks

   Give four populations the same disease and the same average number of contacts each, then change nothing but the shape of the contact network. Nobody was infected, contacted or observed. The computation is the experiment. It ran on a school laptop, and a rerun finishes in minutes. We simulated stochastic SIR epidemics on four graphs of 10,000 nodes with mean degree fixed at 6 , a triangular lattice, an Erds-Rnyi rand

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3. 3

   Original ResearchWinter 2025

   When Most People Infect Nobody: What Overdispersion Does to an Outbreak

   An outbreak's average reproduction number, (R), does not say how that transmission is shared out. We fixed (R = 2.5) and swept the negative binomial dispersion parameter (k) across seventeen values from 0.01 (extreme superspreading) to 10,000 (indistinguishable from Poisson, no superspreading at all), running 40,000 independent branching-process replicates per value and checking every simulated extinction proba

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4. 4

   Paper AnalysisDisease Ecology

   Solving a Ten-Year Marine Murder Case: What Actually Killed Five Billion Sea Stars

   Sea star wasting disease began in 2013. It emptied the Pacific coast of North America of sunflower sea stars. Roughly 3,000 km of coast. The prime suspect for ten years was a virus. Wrong suspect. In August 2025 a team led by Melanie Prentice named the killer: Vibrio pectenicida strain FHCF-3, cultured from the coelomic fluid of a diseased star, able to reproduce the disease in healthy animals and recoverable from th

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5. 5

   Original ResearchWinter 2025

   Why Small Fires Are Common and Big Fires Are Not Rare Enough

   Trees grow at random, lightning falls at random, and whatever connected patch the bolt lands in burns. Those two rules make the Drossel-Schwabl forest fire model, which the literature quotes everywhere as a clean case of self-organised criticality, complete with a power-law distribution of fire sizes. We tested the claim rather than repeating it. The club wrote the model and ran it on a laptop, and since no forest wa

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6. 6

   Original ResearchWinter 2025

   Can You Tell a System Is About to Tip Before It Does

   A system approaching a fold bifurcation recovers from disturbance more and more slowly, and that slowing is supposed to be readable in ordinary noisy measurements before anything visible happens. The club has no laboratory, so we tested the claim by simulation, which is in any case the only place where the control can be run. In 38,600 simulated trajectories of a cusp normal form driven slowly toward its fold under p

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