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How could somebody prove to you that they're from the future?
You come across a man. He appears to be roughly 30 years of age. He tells you that he has come to 2009 from 100 years in the future. He also says that due to complications, his time travel machine is gone. He has a slightly strange accent, and uses some different vocabulary and idioms.
Under what circumstances would you believe that he truly is from the year 2109?
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