Reproducibility | Sebastian Spicker

2025

1 article

4 Dec 2025 Constraining the Coding Agent: The Ralph Loop and Why Determinism Matters In late 2025, agentic coding tools went from impressive demos to daily infrastructure. The problem nobody talked about enough: when an LLM agent has write access to a codebase and no formal constraints, reproducibility breaks down. The Ralph Loop is a story-driven harness intended to bound that variability through one model invocation per attempt, scoped writes, and atomic state. These constraints make runs easier to inspect; they do not make an unpinned model deterministic. agentic-codingautomationsoftware-engineering

2023

1 article

9 Oct 2023 LK-99: Six Weeks That Showed How Physics Works On July 22, 2023, a Korean preprint claimed that LK-99 — a copper-doped lead apatite — was a room-temperature, ambient-pressure superconductor. Within six weeks, converging null results and impurity studies had rejected the claim. The episode is more interesting for what it revealed about the sociology of science than for the compound itself: how a global community self-corrected at extraordinary speed, and how the media managed to fail at conveying uncertainty despite watching it happen in real time. physicssuperconductivitypreprints