Time change

So if you really did discover a time portal to 35 billion years ago, wouldn't that screw up the parallel time of the future? Like, wouldn't dinosaurs get used to humans, humans to dinosaurs and then humans and cro magnons would have a war of their own? An unmatched war, of course. And then what if humans and cro mags mated? Would the future alter as the past was? Or would there just be a parallel future? Or would past and future blend later or before?

Time is tricky territory and truthfully, I don't entirely understand it. According to Einstein (or better yet, according to my limited understanding of Einstein's theories), we can never travel backward in time but only forward. And in the novel, Einstein's Dreams, we are given thirty different vignettes of how time could change subtly and not so subtly. 

All of this crosses my mind while watching the (relatively problematic, colonialist, racist and also ridiculously over budgeted) tv series, Terra Nova, which depicts the first possibility described above (humans from 2149 who leave their desperate, filthy world for earth some 85 billion years beforehand). There are as many problems with the show as there are dinosaurs in it (thanks, Stevie!), but it does raise the interesting question of time travel and of course, it pits the nerdy (though buff) scientist realm against the cro magnon (pun intended) militaristic realm in hopes of offering hope/escapism in an era of environmental and political crisis and exploring the time-honored (once again, pun intended) tradition of time travel and its possibilities. I'm not sure why I watch it other than for the purposes of procrastination (and to see how well I can identify dinosaurs, which fascinated me as a child; my favorite was the ankylosaurus because he could really knock out an opponent with that tail club), but it does occasionally lead me to ponder some questions out of the norm of my everyday life. Sigh.