The Astrophages
Extraterrestrial life that devours stars
Grace discovers he's on a spaceship traveling at interstellar speeds. In flashbacks, he examines the Petrova line organisms in the lab and discovers properties that defy known physics: they absorb all radiation, are invulnerable to heat, and store energy at E=mc² levels.
Acceleration = gravity: the Equivalence Principle
Grace sees on the control room display that he's traveling at ~11,872 km/s and decelerating at exactly 15 m/s², matching the "gravity" he measured.
The science behind it
If a ship accelerates (or decelerates) at 15 m/s², everything inside "falls" backward (or forward) with that force. It's indistinguishable from real gravity.
This is Einstein's Equivalence Principle: you cannot design any experiment that distinguishes between standing on a planet with gravity and being on a ship accelerating at the same rate.
11,872 km/s is 4% of the speed of light. For context: the escape velocity from the solar system is ~42 km/s. The Hail Mary travels 280 times faster than that.
Speed only makes sense relative to another object (relative velocity). Grace measures his speed relative to the star he sees on his instruments.
Key terms
Grace is not in the solar system
Grace measures the rotation speed of the star he sees using starspots. It spins 10 times faster than the Sun. It's not the Sun.
The science behind it
The Sun rotates once every ~25 days. Every star has its own rotation speed, like a fingerprint.
Sunspots are cooler, darker regions on a star's surface. By observing how they move, you can calculate how fast the star rotates.
Grace measures the apparent size of the stellar disk and the displacement of spots on his screen. With simple trigonometry, he calculates the real rotation speed.
Result: the star spins 10× faster than the Sun. Devastating conclusion: he's in another star system.
Key terms
Life doesn't need water (or does it?)
Grace is a science teacher and molecular biologist. His academic thesis argued that life doesn't require water.
The science behind it
The "habitable zone" (or Goldilocks zone) of a star is the band where a planet could have liquid water. Most astrobiologists consider water an indispensable requirement for life.
Grace argued otherwise: life only needs a medium where chemical reactions can copy the original catalyst (self-replication). Other solvents could work: ammonia, liquid methane, even sulfuric acid.
In reality, this is an open question in astrobiology. All life we know uses water, but that could be observational bias: we only know Earth.
Key terms
Astrophages in the lab: impossible properties
Grace examines samples in a quarantine lab with argon gas. He discovers astonishing properties that defy known physics.
The science behind it
Astrophages absorb ALL electromagnetic radiation: visible light, infrared, ultraviolet, X-rays, gamma rays. No known material does this. They're completely black dots.
They're invulnerable to temperatures up to 2,000°C. For context: steel melts at 1,500°C. The Sun's surface is 5,500°C.
They propel themselves by emitting infrared light at the Petrova frequency (25.984 μm). Light has momentum even though it has no mass: by emitting a photon, the astrophage pushes itself in the opposite direction. Same principle as solar sails.
Each astrophage weighs ~20 picograms (20 trillionths of a gram) and stores energy at E=mc² scale. This means a single gram of astrophages contains as much energy as 20 kilotons of TNT.
The lab uses argon gas (a noble gas, completely inert) to avoid contamination. Argon doesn't react with absolutely anything.