But now, time travelers have read that paper, so they know how to cover their tracks! D'OH!
Worse - they read the paper before it was written and already have covered their tracks!
Haha it actually looks like someone invested quite a bit of time in that paper.
So what's the diff biff?
Time traveller from the future returns to the past to invest in the stock market on emerging high tech since he already knows which ones will make him rich.
Time traveller from the past comes to the future to see which stocks will make him rich, and returns to the past to do so.
Neither would be verifiable.
Separate names with a comma.