The ethics of multiple universes

My friend and host, Tucker, her son and I watched Source Code the other night.  Starring Jake Gyllenhaal and Vera Farmiga, it's one of those thrillers with a sci-fi twist that manages not to be sci-fi.  It's a fun watch, which is probably why nobody liked my constant philosophizing.

Spoilers follow (don't worry, you don't care).

So the premise of the movie is that a terrorist attack has destroyed a commuter train in Chicago, killing dozens of people.  Authorities suspect that it is a precursor to a much larger attack, so they need to find out who's behind it.

Luckily, there's Source Code, a top-secret military project that is able to take the consciousness out of an almost-dead blown-up helicopter pilot (Gyllenhaal) and put it into the body of someone on the train, hours earlier.  They can do it for eight minutes at a time, and the goal of each eight-minute mission is to find the identity of the bomber so they can catch him in the present.

But he's not a mere observer.  He can get up, go places and find information that his host didn't know.  He can even deactivate the bomb or get the pretty girl across from him off the train--though he's told that this doesn't actually change anything.  If it does have an effect, it's on a different reality than his own.  This would fall under the many-worlds interpretation of quantum mechanics: every time he changes something in the past, a new universe is created in which those events occurred.  If we assume this is the case, it's not a great leap to assume a new universe is created every time he goes back, since all he has to do is breathe in a slightly different pattern or say one word differently to create a new reality--even if it's practically identical to one that was already created.

We do eventually get confirmation that this is what is happening, because after he completes his mission and allows the people running him to capture the bomber, he insists on going back one last time to try what he has so far failed to do: save every person on the train.  He knows it doesn't mean anything; he just wants to do it.  At the end of this mission, Vera Farmiga agrees, his mutilated body will be taken off life support.

Naturally, Gyllenhaal rocks it.  He disarms the bomb (both detonators this time), apprehends the bomber, and calls in the authorities.  He also sends a quick e-mail and calls his father, who already thinks him dead, to speak with him one last time.  He asks the pretty girl out, and at the end of the eight minutes, just as Farmiga is taking him off life support, kisses her passionately.

And then... he keeps kissing her.  Apparently when his body finally dies in his reality, his consciousness doesn't snap back.  He gets to remain in his new body with his new identity.  He teaches everybody on the train a valuable lesson about enjoying life by paying a grumpy guy $100 to do a stand-up routine, then skips work and goes to Millennium Park.

Meanwhile, the Vera Farmiga of that reality is just starting her day when she gets an e-mail.  It's from Gyllenhaal.  "You should be seeing a story about a thwarted terrorist attack.  You and I stopped it together, and Source Code works better than you ever imagined."  See, while in his reality he only managed to stop the second attack, in this new reality, he stopped the first one, too.  This is how we know it's the multiple universes thing and not just a meaningless eight-minute simulation.

Still with me?

There are some ethical concerns here.  Firstly, what happened to the guy whose body he took over?  Has his consciousness been permanently replaced by Gyllenhaal's?

But the real question I was left with was, is his use of time-travel ethical?

With the exception of the last instance, every time Gyllenhaal goes back, the train is destroyed.  So every time he is creating another universe in which the terrorist attack--and the much larger second attack, which supposedly destroys downtown Chicago--occurs, all in the name of stopping one of the attacks in the reality he's from.  He is ensuring the bigger attack happens a half-dozen more times, across all realities, in the name of stopping it from happening once in his reality.

The question is, do people in other realities have standing?

My friend Sam, a philosophy major I met here in California, suggested that another consequence of considering the moral standing of people in other realities is that it can serve to de-value the suffering in our own reality.  If there are infinite realities with infinite people suffering infinitely, does one person suffering here even matter?  If such de-valuation is a danger, should that be used as a point of argument for caring only about our own reality?  Or should we have a "prime directive" that forbids interfering with other realities (and would essentially outlaw Source Code, since it does just that)?

Steve?