Getting from A to B at a high enough velocity that Einstein's Special Relativity stops being a math problem and becomes your travel agent. The key feature is time dilation: for the travelers moving at a substantial fraction of light speed, time passes slower than for the people they left behind. You can cross the galaxy within a human lifetime... but you'll return to a future where everyone you know is dust.
*Example: The classic Twin Paradox. One twin blasts off on a round-trip to a star 10 light-years away at 99% light speed. For her, the journey might take 15 years. She comes home only 15 years older. But on Earth, over 20 years have passed. Her stay-at-home brother is now older than her. This isn't sci-fi magic; it's a direct prediction of tested physics. Relativistic travel is the ultimate "you can't go home again" scenario, because home exists thousands of years in your future.*
by Abzugal January 24, 2026
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