So, in my opinion, if time travel is ever going to become possible in the future, we'd know about it now.
This. I honestly believe if it were possible to travel backwards in time, someone, somewhere would turn it into a vacation of sorts. You'd see time travelers visiting key points in history to "be there" and witness it in person.
Hell,
I'd pony up the dough to do it. Wouldn't you like to have been there when the Declaration of Independence was signed? Or the Magna Carta, or the Treaty at Versailles? Witness a pyramid be built, see ancient Greece in all it's glory? Be at a safe distance when Mt. Vesuvius erupted?
And with all these vacation destinations available to future society, don't you think one of the morons they send back in time would screw up, would reveal that though they're dressed in a appropriate garb and trained to speak in a language or accent appropriate for the time period and place (or given a "babel fish" of some sort), that
one of them would give up the goat and pull out a future cell phone to take a picture for that future Facebook page?
And if
one idiot would do it, it stands to reason that thousands, maybe millions would as well.
No, time travel back in time is not possible. If it was, we'd know all about it because some idiot from the future would have let the secret slip out.