GURPS Infinite Worlds - ...And Time

...And Time

This chapter deals with the many theories of Temporal Physics both real and fictional that exist.

• Paradoxes (Assumes Fixed Time with one past, present, and future.)
  • The Grandfather Paradox
  • The Free Lunch Paradox (also known as the Ontological paradox The example is taken from The Eyre Affair and has the time traveler give Shakespeare a book detailing his plays which Shakespeare copies. The result is no one actually writes the plays!)

• Plastic Time (past can be changed but there are dangers to doing so)
  • Traveler at Risk (Example: Back to the Future)
  • World at Risk (Examples: Back to the Future II, and New Twilight Zone Episode "Portrait in Silver")
  • Past or Traveler at Risk (Combines Traveler at Risk and World at Risk)
  • Returned Blocked

• Chaotic Time (extreme version of Plastic Time where small changes can result in big alterations. Example: short story "A Sound of Thunder")

• Plastic Time with High Resistance (It is very hard to change history and the larger the event the more difficult it is to change. Examples: Twilight Zone episode "Back There", The Time Machine (2002 film)

• Paradox-Proof Time (Extreme version of Fixed Time where the past cannot be changed and any attempt to do so snaps you back to your present.)

• New Timelines

• Parallel Worlds (Time travel is really parallel universe travel. Examples: Timeline (novel), James P. Hogan's The Proteus Operation and the Parallels (Star Trek: The Next Generation) episode all use the Parallel Worlds mechanic for alternate timelines (Data calls them Quantum Realities).

There are some other ideas provided to make things either easier or more difficult for your intrepid travelers such as Linearity Principle, Oscillating Time, Recency Effect, and Temporal Exclusion as well how communication works.