I Wrote a NEW Story with Project Hail Mary Author

TL;DR

Andy Weir reveals his scientific world-building process by co-developing an original first-contact sci-fi story in real time.

Key Points

• 1.Andy Weir uses detailed spreadsheets to derive — not invent — story facts. For example, astrophage's operating temperature of 96.415°C was back-calculated from the kinetic energy needed to create two neutrinos moving in opposite directions.
• 2.The infection radius of astrophage (8 light-years) was mathematically derived, not chosen arbitrarily. Special relativity means astrophage only 'lives' a few months in its own reference frame but can travel up to 8 light-years due to time dilation.
• 3.Rocky's species was built by logical constraint from a real exoplanet candidate, 40 Eridani AB. Since discovered to not actually exist, but at the time it had ~8 Earth masses and a 46-day orbit, which drove all subsequent biological decisions.
• 4.Erid's 200°C liquid-water oceans required a thick ammonia atmosphere and a magnetic field 25x Earth's. The planet rotates in ~6 hours, creating a measurably oblate shape with centimeters-per-second gravity differences between equator and poles.
• 5.Eridians evolved echolocation instead of vision because no light reaches the surface through their dense atmosphere. Their entire carapace detects sound like touch, and they lack the brain structure humans use to memorize spatial environments.
• 6.All life in Project Hail Mary shares a single common ancestor originating at Tau Ceti. Primordial astrophage occasionally missed its star, causing panspermia events that seeded Earth and Erid — explaining shared cellular machinery like ribosomes and RNA transcription.
• 7.The new co-created story begins with a detected electromagnetic burst from a planet 20 light-years away. An amateur astronomer with a home observatory notices a visible-light anomaly; a second corroborating observer in Australia triggers official follow-up with the systemwide array.
• 8.Weir suggests detecting life by finding planets absorbing more radiation than they emit. A lifeless planet like Mercury reaches equilibrium; a planet storing energy in biological material (plants, algae) will show a measurable radiation deficit.
• 9.The story's central tension is that humanity detects aliens first — the aliens don't know we exist. Atmosphere analysis reveals oxygen, methane, and pollution signatures; the mysterious flash could be nuclear war, a new energy technology, or a natural planetary event.
• 10.Weir advocates for a single, well-defined technology that drives all plot consequences rather than stacking inventions. He also prefers protagonists who simply 'happened to notice' something over lone-genius heroes who are repeatedly vindicated, reflecting his broader optimistic view of ordinary human capability.**