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This isn't possible without a huge uptick in technology. You certainly can't go back in time, because that would violate, among other things, causality. Also, going back in time wouldn't help, beca...
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#1: Attribution notice removed
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System
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2020-06-01T14:13:41Z (over 4 years ago)
Source: https://worldbuilding.stackexchange.com/a/5161 License name: CC BY-SA 3.0 License URL: https://creativecommons.org/licenses/by-sa/3.0/