And let me briefly touch on one of my favorite examples to make this point. As you probably know, every particle in the universe has an antiparticle twin. Antiparticles are exactly like their matter counterparts except they have the opposite charge. So the negatively-charged electron has a positively-charged counterpart (the aptly named positron). And as you may also know, when a particle meets its antiparticle, they annihilate and essentially convert their masses into energy, leaving behind only a barrage of photons (with a total energy equal to twice the energy equivalent of the electron mass, accounting for the fact that there are two electron-mass particles disappearing). What does it look like when that happens? Pretty much as you might expect--an electron and a positron wander towards each other, getting closer and closer as time goes on until they converge and vanish.
The physicist Richard Feynman developed a simple pictorial representation of these kinds of interactions called a Feynman diagram. The Feynman diagram below shows an electron and positron converging as time goes on until they annihilate in a flash of gamma rays (and, in that diagram, the blue squiggle gamma rays at some later point in time go through the reverse process and spontaneously convert into a new particle-antiparticle pair, a process known as pair production--but we'll just focus on the electron-positron interaction on the left, i.e. earlier in time).
One way to read this diagram is to say it shows two different particles, an electron (e-) and a positron (e+), getting closer as time moves forward and eventually crashing into each other and annihilating. Certainly that's what things would look like if you were actually watching this process in real life. But there is an alternate interpretation that's equally valid, known as the Feynman-Stueckelberg interpretation.
In this interpretation we can imagine an electron going on its merry way forward through time. At some point it emits a photon with twice its mass equivalent of energy, leaving it with a negative energy equal in magnitude to its regular mass-energy (kind of like how if you were to spend twice the amount you have in your back account, you'd end up with a negative balance equal in magnitude to whatever amount you had in there before). At the same time, the electron does a U-turn in time, now proceeding on its merry way backwards through time, passing itself along the way. To someone observing at any one slice of time, it would look like there were two distinct particles, identical in every way except with opposite charge. Feynman once explained it in terms of an aerial view of roads:
A bombardier watching a single road through the bomb-sight of a low flying plane suddenly sees three roads, the confusion only resolving itself when two of them move together and disappear and he realizes he has only passed over a long reverse switchback of a single road. The reversed section represents the positron in analogy, which is first created along with an electron and then moves about and annihilates another electron.
The "roads" here are the paths traced by the single particle as it goes forward through time, then backwards, then forwards again. Someone watching at a given point in time would apparently see three distinct particles, not realizing it was one that kept doubling back on itself. So a particle-antiparticle annihilation event is, according to Feynman-Stueckelberg, just a single particle that makes a U-turn in time at some point (which, to our untrained eyes, looks like an annihilation event). How do we interpret this? Feynman, never one for philosophy, made a seemingly utilitarian suggestion for wrapping one's mind around this kind of thing: "It may prove useful in physics to consider events in all of time at once and to imagine that we at each instant are only aware of those that lie behind us."
Indeed. But this view of particle-antiparticle annihilation is decidedly fatalistic. When the electron catches sight of its future positron self heading the opposite way in time, it knows that the annihilation/U-turn event lies in its future. In the same way, when (sometime prior to October 1985) Doc Brown taped together Marty's letter about the Libyan terrorists shooting him, he knew that event lay in his future, his bullshit about the future not being written notwithstanding. The future already exists and nothing can be done to change it. Have I mentioned that 12 Monkeys is my favorite time travel movie? Cole's recurring dreams about his own death, witnessed by his nine-year-old self, are exactly the same sort of deal. The future is inescapable precisely because it's not being written, it's out there and only vagaries of human perception keep us from experiencing it (and all time, for that matter) at once. I have another physical model (also from Feynman) demonstrating similar principles that I like even more than Feynman-Stueckelberg but I'll save it, this post is getting long enough.
As I said, I'm a fatalist. My own philosophical thoughts about the universe, my insights stolen from physical theory, lead me to believe in a universe in which tomorrow is no more special than yesterday and my death has already occurred just as surely as my birth has. It's been remarked to me that I take something of a passive approach to life, in that I let things happen to me instead of seeking to shape events. To some extent this is true, in part because I rely on Fate to steer my ship. Believing in Fate is not the same as believing in a god (I'm an agnostic). Rather, it's a sense that the path is there to be discovered, not yours to create. I don't know if that implies a Cosmic Writer, I don't even know if that means free will doesn't exist.
My sense, however, (since I'm sure you asked) is that free will and choice are, like distinctions between the past and future, stubbornly persistent illusions. When I choose a calzone over a taco it's a conscious choice, but based on an innate preference ("I have a taste for a calzone" or "I'm sick of tacos") over which I have no conscious control. Thus it seems to me that ultimately every choice is a Hobson's choice of some form, a bit like a parent allowing a child to "choose" some activity or food or whatever only as long as the child makes the "right" choice. Everyone wins: the parent's (the analogue of Fate) wishes are fulfilled and the child believes he was able to freely make a decision, never knowing the alternative was never a real possibility.
When I was younger, I had a (professional) path in mind. Since I knew the end point, it was easy to determine the path because there was very little leeway in the path that would lead me to the desired endpoint. I liked the concepts and practices of physics, I enjoyed conveying them to others, and I believed I wanted to do research in that area. The obvious conclusion was that I should be a physics professor and the path to that is fairly straight foward: an undergrad physics degree followed by a Ph.D followed by a few postdocs followed by an assistant professor gig and eventually the endgame. The exact path (where? and when?) were mysterious but the contours were clear.
This is where things stood my freshman year of college. But deep down I hoped that in five years I'd be somewhere I would have never imagined at the time (note: five years later, I am in about a dozen ways, including philosophically, mentally, professionally, geographically, and so on--not to imply that all these changes are good things). My inner fatalist seeks to rebel, to know in its heart of hearts that the path is already laid down but that it still holds surprises. I loved physics but remained unhappy in it, in part for reasons revealed in the first installment of these introspective posts. It seems like every week I was thumbing through the course guide waiting for Fate to reach out its hand and show me something new. And it did. When the path turned, I followed it. I explored the places it took me and the ideas it showed me.
And there were a handful of times--terrible, dark, terrifying times--when I lost sight of it. I firmly believe that there isn't a scarier feeling a person can experience than feeling lost, from a child who loses sight of his parents in some public place to a recent college graduate with little idea where or why he is. I think I've only been truly lost--really, truly lost--once in my life, a few years ago, and if I never go back to that place for the rest of eternity it will still be too soon. But I've been quasi-lost a number of times and in those times the path has always eventually reappeared to me.
When I graduated the job market was weak, my credentials could have used a little beefing up, and I wasn't sure I knew what I wanted (I didn't realize it then, but I did have a pretty good idea of the kind of place I wanted to go to and the kind of work I wanted to do). And after a long and laborious job search, I finally go an offer--from the 90th place I applied to--that turned out, fortuitously, to be exactly what I was looking for. The nature of the work, the subject matter (particularly given current events), even the geography turned out to be exactly what I needed and, I realize now, wanted. And this all happened seemingly by accident--there was no planning for this on my part or this wouldn't have been Option 90. The path had reappeared.
That isn't to say that a fatalistic philosophy has worked out perfectly well up to this point. My personal life--conducted by the same principles as my professional life--is nowhere near where I'd like it to be, though much of that can, I believe, be attributed to innate factors beyond control that won't be changing (there's that strand of fatalism again). Time will tell if the path will produce answers to those questions or merely terminate ingloriously. I have no idea what it holds, just suspicions, though I do believe its windings and end have never been in doubt.
And so I'll continue on because the choice to adhere or deviate isn't really mine.
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