Jim Kakalios of the University of Minnesota has achieved internet demi-fame — he has a YouTube video with over a million and a half views. It’s on the science of Watchmen, the movie based on Alan Moore’s graphic novel. Jim got that sweet gig because he wrote a great book called The Science of Superheroes — what better credentials could you ask for?
More recently Jim has written another book, The Amazing Story of Quantum Mechanics. But even without superheroes in the title, everything Jim thinks about ends up being relevant to movies before too long. The new movie Source Code features a twist at the end that involves — you guessed it — quantum mechanics. Jim has applied his physicist super-powers to unraveling what it all means, and was kind enough to share his thoughts with us in this guest post.
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There is an interesting discussion taking place on the internets concerning the ending of the newly released film SOURCE CODE, that suggests that the film concludes with a paradox. I believe that any such paradox can be resolved – with Physics!
This entire post is one big honkin’ SPOILER, so if you want to read about the final twist ending of a film without having seen said film – by all means, read on, MacDuff!
In SOURCE CODE, Jake Gyllenhaal plays US helicopter pilot Colter Stevens, whose consciousness is inserted into another man’s body (Sean Fentress, a school teacher in Chicago) through a procedure that requires a miracle exception from the laws of nature (involving quantum mechanics and “parabolic calculus” – by the way, there is no such thing as parabolic calculus). Thanks to some technobabble (or as Q-Bert on Futurama would describe it – weapons grade bolognium) Colter’s mind can only enter Sean’s body in the last eight minutes of Sean’s life. As Sean is sitting on a city bound Chicago commuter train, on which a bomb will explode at 7:58 AM, killing everyone aboard, the goal is for Colter to ascertain who planted the bomb. He cannot stop it from exploding, he is told, because that has already happened. He cannot affect the past, but he can bring information obtained in the past back to his present time. Learning the identity of the bomber would enable the authorities to prevent the detonation of a threatened second “dirty atomic” bomb is downtown Chicago.
While the above can be discerned from the movie trailer, what I am going to discuss next involves the actual ending of the film, and if you do not want this ending spoiled, you should stop reading now.
Colter learns that the reason his last memory is being attacked in his helicopter in Afghanistan is that he in fact died in the crash. His mangled body is kept artificially alive, and his brain can be activated, and sent to inhabit the body of Sean Fentress (who happens to be a neurological match). At the end of the film, after multiple failed attempts, Colter manages to identify the bomber. Providing this information to Col. Goodwin (a military officer played by Vera Farmiga) and Prof. Rutlidge (the great Jeffrey Wright), the scientist who designed the Source Code project, the terrorist is caught before he can set off the second bomb, but after, of course, the first bomb on the Chicago train explodes.
It is left somewhat vague as to whether Colter is going to parallel realities, a la the Many World’s interpretation of Quantum Mechanics, or whether he is engaging in a quantum/ neurological simulation. If the former (which seems to be borne out by the ending) then this would tie into notions of time travel being explored in the context of quantum gravity. That is, if one could time travel into the past, you need not fear any Grandfather paradox (what if you killed your ancestor – preventing your birth, but then you would not be able to travel back in time to ice Grandpa). Some physicists argue that time travel is only possible via parallel realities. You do not go back in time in your own reality, but to an alternate Earth’s past. You can thus kill as many grandparents as you have bullets, remaining safe in your own timeline. In any event it is assumed that the bomber is the same person every time Colter enters the Source Code.
While everyone is celebrating the capture of the bomber, the first successful trial of the Source Code project, Colter convinces Goodwin to send him back one last time, to try to save the passengers on the train. At the end of the eight minutes, he convinces Goodwin to terminate his life support, allowing him to die in actuality, as the world and his father believe happened months ago in Afghanistan. Needless to say, he manages to stop the first bomb from exploding on the train, hands the bomber to the authorities, and kisses his love interest just as the eight minute mark is reached. We see Goodwin make good on her promise and end his life support at that moment, at which point she is arrested my the military police for acting against Rutlidge’s instructions.
On the train however, Sean/Colter is still alive after the kiss. The film implies that he goes on to live happily ever after in Sean’s body, with Colter’s mind, while Colter’s deformed body remains at the Nellis laboratory on life support. As the bomb never went off on the Chicago train – there was no reason to activate Coulter and send him into the Source Code, and the project awaits its first true trial by fire. Thus it is indicated that we are witnessing two alternate realities – one where Goodwin is arrested after pulling the plug on Colter following the successful application of the Source Code, and the other where Sean/Colter is still alive, where the Source Code project has not been activated.
Among the many discussions I’ve noted on the web about the ending of this film, I wish to address two particular issues that are being debated by the Hive Mind. In the film’s final reality, where the bomb does not explode on the train – does Colter’s consciousness reside in two places at once? And, what happens to Sean Fentriss’ consciousness in this final reality?
Reasonable people may reach different conclusions concerning these two points. As I am a physics professor – I will tell you the RIGHT answers!
(1) In the final reality – Colter is NOT consciousness in two places at once. He is awake and aware in Sean’s body and at the same time his damaged body is in the Nellis lab – IN A NON-CONSCIOUS STATE. He is not awake and aware in the lab at Nellis, he can not initiate motion or form an independent coherent thought. He is in essence brain dead, kept artificially alive until there is a time and need for him to be activated (if there is a terrorist attack).
Even if he is activated – this would NOT influence or affect Colter in Sean’s body, as it would take place in Sean/Colter’s FUTURE. Remember he was sent back to Chicago at 7:50 AM – the bomb exploded at 7:58. Time progresses forward for both Sean/Colter and Nellis/Colter at the same rate. This was why Goodwin and Rutlidge were upset about how many trials it was taking – for each trial burned up a minimum of eight minutes, and brought the second explosion closer to happening.
What you are doing and thinking now is not affected by what you will be doing and thinking several hours from now. Do you know what you will be thinking about several hours from now (ok – for the guys this is an easy one). Nellis/Colter may not be activated for weeks/months/years later. But even if he is – Sean/Coulter can live his life, unaffected by what is happening in his future. There is no paradox, for Colter in Sean’s body is only awake and conscious at one point in time. Colter is NOT like Schrodinger’s cat, in two different conscious states simultaneously, as they are separated in time.
(2) What happened to Sean’s consciousness? Here there is a potential problem. Basically I believe Sean is dead. When Colter’s mind jumps into his body, it over-writes Sean’s consciousness. Rutlidge probably knows this, and ignores the ethical issues. Sean will be dead when the bomb explodes after all, and Rutlidge believes that cannot be changed. By sending Colter into Sean’s body, he robs Sean of the last eight minutes of his life. As Sean is unaware that a bomb will explode, killing him and everyone on board, he would not do anything extraordinary in those eight minutes. Rutlidge probably believes that it is acceptable to sacrifice the last eight minutes of one man’s life in order to save millions of lives if they can prevent the second bomb blast in downtown Chicago. Every time Coulter enters the Source Code at 7:50 AM, he essentially kills Sean. Sean will die in every reality where Colter does not enter the code, and he will also die in all N – 1 realities where he does – so this is an ethical problem of order 1/N where N goes to infinity.
Alternatively, Sean may be alive in Colter’s damaged body – but there was no suggestion that something like that was happening. Here I’m taking the Quantum Leap analogy too literally. (There is a wonderful tip of the hat to Quantum Leap – listen carefully to Coulter’s Dad).
Sorry this is so long. Never ask a professor a simple question – you always get a lecture in reply!
Ok two things ‘Sean’ wasn’t overwritten…there isn’t a ‘Sean Fentress’ the entire alternate reality is a parallel ‘shadow’ reality that ONLY exists within the ‘source code’ not as a perpetual multi-verse/shroedinger’s cat alternate reality. It’s uniquely created by Colter and the code on each run of the program. However, Colter realizes it’s MORE than just a program, and each time he ‘dies’ and is returned to our timeline he sees that St. Petersburg metal blob art that he sees in the end. Which seems to hint at the whole ‘time’ is just a perspective we have and that the alternate shadow/source code reality WAS in fact ALWAYS real.
IMHO it suggests that Colter created his own parallel reality, and he is now an entirely separate entity than the husk back at the source code homebase.
I’m confused by what is being said in point (1) regarding the consciousnesses of Sean/Colter and Nellis/Colter in the final reality. Are you saying that those consciousnesses are somehow linked, and if Nellis/Colter is activated in the future, Sean/Colter will cease to be? I figured it was simply that the final reality cosisted of two separate Colter consciousnesses: the one in Sean’s body, and the inactive one in the mangled body. If the latter is activated and sent between yet more alternate realities, it will have no affect on the former. Similarly, the original reality now has a truly dead Colter whose consciousness can’t be brought back.
A couple thoughts I had, though, were:
1. What if, before Colter returned to reveal the bomber, he had just stayed alive in an alternate universe for several days? Would the bomb have gone off in the original reality? Did they have some mechanism for pulling him back if he didn’t die?
2. Let’s say he hadn’t been taken off life support in the original reality. When he died of old age in the final reality, would his consciousness have jumped back to the original, years later for both?
This post was very helpful as I too was left thinking that the freeze at the end of eight minutes would have made a far more rational and understandable ending.
The alternate realities theory helps to explain something I was struggling with which I’ll get to shortly, but it doesn’t sit well with what little we are told about how the source code works. I thought early on that Rutlidge explains that they are using the brains of the commuters on the train to download and recreate the last eight minutes on the train in order to be able to create the source code which can send Colter back. It isn’t clear who’s brain they are using from the train but the implication is it must be Sean’s (plus multiple others perhaps, otherwise they’d be limited to what Sean knows, which doesn’t include anything to do with getting off the train which Colter is able to do). Ignoring for now how they got access to one or more relatively intact brains when everyone on the train seems to have been incinerated, it seemed to me that the underlying premise must be that for Colter to go back, the commuters have to be dead and their brains available to Rutlidge otherwise there is no way to send Colter back. I originally thought you must still have a time paradox here. The only way for Colter to go back and do anything is that the train has to have exploded, so it is impossible for him to save the train. If the commuters don’t die, Rutlidge can’t send him back. To my mind, the 2002 movie “The Time Machine” (although not a great movie) dealt with this far better in that the scientist’s girlfriend dies causing him to finish the time machine in order to go back and save her, but everytime he tries to save her she still dies, but differently, he doesn’t understand until it is pointed out to him that unless his girlfriend dies, he doesn’t finish the machine. I think the alternate realities theory can sort of explain my paradox problem on the basis that you have to accept that the train always explodes in the original reality, but this allows Colter to go back (which again requires you to assume something more is happening here than a simulation using the dead people’s brains) to a parallel reality (as opposed to purely back in time) where he saves the train. However, in that case, his text at the end to Goodwin in the parallel reality that he has created is pretty pointless to my mind other than to tell them that they have something far more powerful than they ever envisaged in their grasp (since in this reality Goodwin has never interacted with Colter) and why would he want to do that? It would be better for him to try and persuade Goodwin to terminate the body of Colter in the altered reality, but even if they didn’t and sent alternate reality damaged Colter back for (another) mission (which in this reality would be his first)and something similar to the movie’s plot happened again, you’d just have another Colter consciousness running around in yet another version of reality. I still think you have a problem with two versions of Colter in the same reality. Injured Colter is clearly rational and has memories when he comes back from source code trips and interacts with Goodwin. Therefore you are going to have the scenario where there is Colter with Colter’s memories in Sean’s body and an injured Colter who has been reawakened in a lab in that same reality also with Colter’s memories. Likewise Colter calling his dad is a bit pointless, he is only calling his alternate dad in the alternate reality who he could in fact actually go and visit (albeit in Sean’s body). There is still a dad in the original reality who never heard from his son. Original reality Rutlidge makes it clear that calls and text messages can’t cross realities when Colter originally tries to call him from the train and on his return to the original reality says Rutlidge will have received a message he called.
I guess the movie succeeded in generating a lot of thought and debate but I still think it was far neater to leave it at the freeze rather than trying to create the “happy ending” out of what I also find a pretty disturbing scenario for Christine and alternate reality Sean and which requires a far greater suspension of disbelief.
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23. Eric Daniels:
Obviously you double-posted because of your app.
There are a few issues with this film which have not been addressed (especially #6, see below.)
1) In the initial reality, Sean Fentiss is experiencing his final eight minutes undisturbed by Coulter’s consciousness. If Coulter just took over his body, Sean would not have eight minutes of memory to download into the simulation.
2) I like AJ’s comment (#4) that this is more than a simulation, that indeed each time he goes back, he is creating a different reality. HOWEVER, these could still merely be different simulations, with since on simulation #n+1 Coulter is adding all the things he has figured out during simulations #1 to #n.
3) As I take it, in the eight simulations, Coulter is inhabiting the “body” of Sean. However, the simulations are based not just on Sean’s last eight minutes, but on the last eight minutes of many of the passengers. Also, when the Scientist talks about the “aura”, is that limited to human consciousness? Could objects and locations also have an aura, which are added to the simulation?
4) How does Coulter figure out the license plate number? Well, if the Bomber’s consciousness
is added to the simulation, that would explain how that gets added to the mix. I know he gets off the train and is not a victim, but he is on the train for part of the last eight minutes, and could have contributed to the general “aura”.
(If the same holds true for the fellow with motion sickness, the presence of his “aura” in the simulation would explain how Coulter learns about his problem with motion sickness.)
5) HOWEVER, if the combined aura of passengers (and perhaps train and locations) make up the simulation, couldn’t the identity of the Bomber have simply been determined with a “Search” program? Or is Sean/Coulter the metaphoric realization of the “Search” program?
6) Now for the puzzling point I’ve not seen discussed anywhere:
Coulter’s text message to Goodwin ends with something like “Tell Coulter everything is going to be OK.” The alternate-Goodwin received this request. HOWEVER, it is the ORIGINAL-Goodwin who carries out this request. DOES THIS MEAN that the original-Goodwin is actually Goodwin-version n+1, responding to an e-mail that she received from Coulter-version n, where he asks her to “Tell Coulter everything is going to be OK”?
7) If (6) is correct, then every Coulter that gets sent back on a mission, being consistently upbeat guys, manage to turn lemon into lemonade, saves the world and makes it a happier place.
Goodwin is a consistently compassionate comrade, and terminates Coulter-in-the-tank, allowing another alternate world to unfold. So instead of the scientist’s truly creepy idea of sending Coulter back again-and-again for another grim “mission impossible”, Coulter gets to create another happy world for himself at the end of every mission.
8) As for Sean, he had many opportunities to start something with Christina, but didn’t. He might never have made his move. This way, at least Sean’s family get to have some kind of Sean to hold on to. Also, there’s that point about Sean and Coulter being compatible. Perhaps that includes
very similar “wiring” so that in some way Sean manages through Coulter to live the kind of life (only better) that he was meant to live. Haven’t thought too much about this though, nor about the implications of the visions of the Cloud Gate the seem to presage the alternate reality he’s going to inhabit.
I am a person who has experienced events that can only be psychic moments (predictions). These involved me experiencing mental? connections to family members in which premonitions of future events are experienced. I am unable to turn these overwhelming images and analysis of these mental images off. Then these events take place the same day or soon afterward.
I live in the Ann Arbor, Michigan area and experienced what was a psychic event involving a total stranger. I experienced a mental image of a driver of a red convertible Jeep that had been rude to me with his aggressive driving on that day the image ‘arrived’. I could not put this image down of him with the Jeep overturned and him having been thrown from it, with him next to a split rail fence (right shoulder tip touching said fence) well off to the side of the road. I knew that it would be drinking related. Maybe a month later I had an accident that left me with a Tufts break of my fingertip and was having a splint created and placed onto the finger at the U of M Sports Med Clinic in Ann Arbor. In that room, there was that same man with his giant barrel-chested body, same haircut and face and wearing the same style of white tee shirt he had the day he was and impatient and subsequently rude to me while getting off of the expressway. He had his shoulder and arm in a cast permanently in the horizontal position out in front of himself. I asked him what he was here for. He replied that he has dislodged the pins between his right fingers while washing himself. I then asked what his injury to his shoulder was from, and he replied that he had rolled his Jeep and after being ejected out of said Jeep, his body continued moving across the ground. The thing that stopped his bodily movement was the vertical structure of that split rail fence impacting his armpit. His arm/shoulder was almost ripped off of his body.
Now onto the movie…
Something in my head was going on when that movie ended, just like when I am inundated mentally by unexplainable feelings associate with an upcoming psychic ‘reception?’. The intangibles of the movie ending seemed to be directly associated for my state, the type of state I experience when the threads of thoughts enter my head preceding and during a psychic event.
I now keep a log of weird days where I am compelled to sort through/analyze mental images or events that I experience.
that is some fascinating stuff there “Mr. Paoletti”…
the first time i realized that i had psychic moments was when i bought my first Playstation. i remember sitting there playing “wipe-out” when suddenly a thought manifested in my brain: “this game-console can be made even better”. you can’t imagine the chills i had when almost a year later the “Playstation 2” actually came out. later i also predicted the hi-speed internet and the 3rd “Harry Potter” movie among many other things…
Now onto the movie…
when the movie ended, something was going on in my head. i will now keep a log about it.
yours lol, Uncle Jamal