Why would anyone use time travel to commit murder? So you have everyone in the world with nano technology in their bodies that keeps track of their movements. When they die, the authorities know immediately where they are. But... why would time travel circumvent this? If a central computer is keeping tabs on everyone, as soon as they disappeared from the grid, there would be huge red flags. Anyone in the vicinity would be automatic suspects. Put another way, how would the outcomes differ between time travel and depositing someone in a huge Faraday cage and incinerating their body?
- The location tag only triggers upon death, not disappearance. To quote the director:
"Everybody in the movie has this nano technology tracking in their body and whenever there’s a death, a location tag is sent to the authorities from this tracking material. So they can’t kill people in the future. But if they send them back, that is not triggered."
- Yes, I read the director's interview prior to my headscratcher. It still doesn't make sense. The location tag is only triggered at death? Then, how do the authorities establish any suspects? Obviously their response time is lousy, because the only time a murder occurs in the future (Joe's wife), the mafia goons still had enough time to transport Old Joe to the time machine. So, you kill someone, and run away. Who are the police going to suspect? Under the director's scenario, the mafia goons' location tags weren't sent because they're not dead. All the authorities know is where a dead body is located. That's hardly an impossible obstacle for the mafia. Like I said before, you stick someone in a Faraday cage, kill them there. Or bury someone in a coffin deep underground with a limited air supply and wait for them to asphyxiate. No murder signals escape. There are plenty of ways to circumvent the nanotechnology without resorting to time travel.
- My guess is that the "death signal" is a constant signal, triggered upon death. It doesn't matter if you kill them in a Faraday cage, because as soon as the person dies, that "dead" switch kicks in and begins to broadcast their location (for up to two years after death). You would essentially have to keep the corpse in a Faraday cage for at least two years. If they die in the past, then the signal goes out but there's nothing to receive it. As for the why, the point isn't to allow the mafia to kill someone, it's to make someone "disappear", which is a similar but different goal. Sticking someone in a coffin underground? How do you know that would foil the advanced nanotechnology of the future?
- Quite right, we don't know how it works (or even exactly what it does - they only talk about it briefly). All they really tell us is that it is good enough to stop people getting away with murder in the future, and that fits the story as we see it.
- Also consider that having a body is a large step in having a successful case. Without a body, it's dramatically harder to prove murder. If nothing else, making it literally impossible to find the body means that even if the signal pops, there's a lot less the police can do because there's no evidence.