Maciej Rząsa's wroclove.rb 2024 single-speaker talk. Opens with the frustrations of bugs that 'work on your computer', 'hero-complex' colleagues dropping 1,000 lines of code, and 'hot-potato' reassignments. Uses the Michelson–Morley experiment and Einstein's special relativity (describing reality instead of yelling at it) as a parable for how physicists proposed hypotheses, designed experiments, and published results. Proposes 'hypothesis-driven development' as a mindset for debugging and illustrates it with three Chattermill war stories: (1) a cucumber integration-test suite failing because a graphql-preloading gem appeared broken — the real cause was a before_filter temporarily changing a configuration constant while Puma had threading enabled; confirmed by a Ruby script manually interleaving the before/after filters with business logic, and fixed by reverting the race-condition-introducing PR. (2) A distributed docker-compose setup intermittently failing CI with read-timeouts (not open-timeouts) — found via Google that excessive logging plus a Docker Compose bug could freeze containers; disabling health-check logging fixed the problem and gave a precise ask to the infra team. (3) Recurring production 502s every 30 minutes on single nodes: hypotheses included DB load balancers, slow clients, memory leaks, and application-level crons; by taking copious notes in Slack, correlating Grafana passenger-queue charts, and adding metrics for process spawn events, an Argentinian teammate picked up the investigation across time zones and spotted Passenger entering deployment-error mode because bootsnap's cache had grown to 10–16 GB (a six-month-old minor bootsnap upgrade changed the cache directory but the deployment script never cleared the old one) — making Passenger time out on worker startup. Closes with lessons on scaling debugging: work in parallel on multiple hypotheses, collaborate across time zones by publishing small observations, use the Socratic method with juniors, take notes during interruptions (rebutting the 'flow state' dogma), balance time in the 'lab' with time in the 'library', communicate out loud, and transfer knowledge to retain it. Q&A covers post-mortems (useful only in a healthy culture; heavy long-term fixes are not always worth it) and whether to write a paper on the method.