I generally like the BBC for news about the world, but I’m less impressed by their science articles. This one particularly me. The basic gist of the article is that a new physics model allows a person to travel back in time, but you would be prevented (some how) from changing anything that affects the present.
First, the article never really explains what the new model is, it just rehashes the argument that you can’t change the past, only be part of it (think Donny Darko and not Marty McFly). This is not new, it’s been a staple of time travel theory for years.
Secondly, the they state:
Clearly, the present never is changed by mischievous time-travellers: people don’t suddenly fade into the ether because a rerun of events has prevented their births – that much is obvious.
This is a Marty McFly approach to time travel. If you prevent your parents first kiss, your brothers and sisters will slowly fade away in front of your eyes, wiped from existence, but your memories of them would still exist as though they existed before just not now. If I were to travel back in time and prevent my parents from conceiving my sister (eww!), I’d have no memory of her because she never existed, hence the paradox because then I wouldn’t travel back in time to her from being conceived (double eww!), repeat as necessary.
Time travel is hard to explain. Hollywood hasn’t exactly helped the situation. So let me explain it. Time travel is one of the following:
- Impossible. We are traveling forward at a fixed rate and can only go in one direction. This is probably what is happening.
- Possible, but we are part of the time stream and any action we do has already occured (this is what the article rehashes). This plays havoc with the concept of free will because now we are just all cogs in some time loop.
- Possible, but any changes we make creates a new time line that we now can travel through, but we might not be able to get back to our original time line (read “A Sound of Thunder” by Ray Bradbury). This allows us to have free will and travel back in time and offers the best source of fictional material (read “The Man Who Folded Himself” for a really trippy version).
That’s it. There are no other possibilities. You won’t fade from existence if your parents are murdered in their childhood because you would have never existed. You couldn’t kill Hitler and return to find your everything the exact same, just with millions of more Jewish families. Doctor Who can’t travel through a ball of wibbly wobbly time-y wimey stuff. Time travel is a fun idea to play with, a grown up version of “What If”, but that’s about it. Time viewers on the other hand…