The big daddy of all travel concepts: moving through time as well as space in a controlled manner, typically by manipulating the geometry of spacetime itself via General Relativity. This isn't just going fast (relativistic travel), which only goes forward in time. This is about creating closed timelike curves—wormholes, warp drives, cosmic strings—to theoretically hop to the past or distant future without waiting. It's engineering the universe's roadmap to include shortcuts and loops.
Example: The Alcubierre "warp drive" concept is spacetime travel. It doesn't move the ship through space faster than light; instead, it contracts spacetime in front of the ship and expands it behind, effectively surfing on a wave of distorted geometry. The ship sits in a "warp bubble" not subject to relativistic effects. You arrive at your destination quickly without any time dilation mess. Another example is using a traversable wormhole: one mouth is accelerated to near light-speed and brought back, creating a time machine where entering one end exits the other in the past.
by Abzugal January 24, 2026
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