One of Bear's favorite themes is how observers effect or create reality. In "Blood Music" reality becomes unstable as the number of observers–trillions of intelligent single-cell organisms–gets higher and higher. Both "Anvil of Stars"–a sequel to "The Forge of God"–and "Moving Mars" propose a physics based on information exchange between particles, capable of being altered at the "bit level." (Bear has credited the inspiration for this idea to Frederick Kantor's 1967 treatise, "Information Mechanics.") In "Moving Mars" this knowledge is used to remove Mars from the solar system and transfer it to an orbit around a distant star.