The Dark Forest (Remembrance of Earth’s Past, #2)

by Liu Cixin

“The Low-Tech Level: Spacecraft speed achieves fifty times the third cosmic velocity10, or roughly eight hundred kilometers per second. Spacecraft are not equipped with life support. Under these conditions, the craft has a combat radius limited to the inner Solar System. That is, within Neptune’s orbit, or thirty AU from the sun. “The Mid-Tech Level: Spacecraft speed achieves three hundred times the third cosmic velocity, or forty-eight hundred kilometers per second. Spacecraft are equipped with partial life support. Under these conditions, the combat radius of the craft extends beyond the Kuiper Belt, and includes all space within one thousand AU of the sun. “The High-Tech Level: Spacecraft speed achieves one thousand times the third cosmic velocity, or sixteen thousand kilometers per second, which is five percent of the speed of light. Spacecraft are fully equipped with life support. Under these conditions, the combat radius extends to the Oort Cloud11, with preliminary interstellar navigation capabilities.