Apart from that, however, there remains the fact that, if you do travel back in Time then you were really there then … and if you were there then, whatever you do is what you did … so you can’t actually make any difference to the Present by travelling to the Past.

Yeah, I know about causal loops. That is interesting to think about, in a way, because it assumes each loop is identical. Which it should be. But when has “should” ever stopped nature? The more complex a system becomes, the more likely it is for errors to slip in. For every billion times a déjà vu is ignored, one time it will give someone that split second longer pause. A temporal cancer, if you will.

the Squid People are going to be over-run by the Sea Otters

Oh crap! Not the otters! We have to do something now. Quick, throw out your jar of peanut butter! And your jam too, just to be on the safe side.