That's a valid point. But then again we don't know how the time machine affects on the person going to past, does that person remain as they are, be younger or appear as something else like the opposite sex or perhaps a cat? A rat? Or a bird! There were so much more birds in the times gone, they could have all been time travelers! And yes, I totally believe your Greek fire deduction. So many things can be explained if time machine is true.