This is all rather fun, but, I don't think it takes into account the Observability of the Universe.
Basically, once something is observed, it stays observed, unchangeable, and indestructible as observed.
Thus, one could go "back in time", and save Lincoln, save Kennedy, save the dinosaurs, save Hiroshima, and alter events from your point of origin
frame of reference to all sorts of varying degrees, but change absolutely nothing at the point of origin frame of reference.
This is because the "alteration" of events in the "past" is in actuality creating an alternate bubble of dimensionality to an already observed event.
One could then revisit that moment in space time at its 'original' observation over and over without ever concern for altering point of origin events
as any changes affected create alternate bubbles off the existing already observed one.
In this respect, anyone and everyone alive today could go time traveling, if we had the technology, and basically create and live in their own private
universes at any point in time, even just seconds apart from each other, without ever a concern for overlapping interactions, or
destruction/alteration of the originating frame of reference.
In short, we'll see no evidence for time travellers unless an original primary root observation event was the result of, or had time travellers in
attendance such they could be detected.
edit on 1/3/2014 by AliceBleachWhite because: (no reason given)