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3 Mar 16th, 2017 at 8:08PMDo we have this? A person from the present goes back in time, and takes something which is common today but which doesn't exist in the past... a simple laser pointer, for example. They go back to a time before lasers were actually invented, and show off their amazing laser beam, and claim that they invented it themself. Bonus points if they understand it enough to build another one out of parts available to them in the past - then they can really claim to be the inventor of it.