<Minor spoilers for Bioshock Infinite follow>
Last March, Irrational Games released the much-anticipated game Bioshock Infinite. Although it is primarily a first person shooter, the game also explores the consequences of many theories in the field of metaphysics, especially those associated with parallel universes.
Let’s start from the top. Metaphysics is a subfield of philosophy that attempts to discern fundamental truths about the world that we live in. As its name implies, it is heavily tied to the scientific field of physics, and mostly concerns itself with trying to assign some kind of logic to the theories that physicists produce.
One of those theories is Quantum Mechanics, assembled during the early part of the 20th century by prominent scientific minds including Planck, Bohr, Heisenberg, and Schrodinger. In brief, these physicists realized that there is an element of probability on the subatomic level, captured by the Schrodinger wave equation and its potential collapse. Imagined on the macroscopic level, this could be compared to a card standing on its edge. It may fall to the left or to the right and there is no way to tell which will prevail ahead of time.
Unfortunately, there are different ways of interpreting probability. Some say it is fundamentally deterministic (the card will always fall to the right because it is determined to do so) whereas others believe it is random (the card will fall differently each time). Then there are those who believe that it falls both ways, but we are only capable of observing one. These philosophers then debate whether the one that we observe is predetermined or random. As you can imagine, the layers continue to build.
In Bioshock Infinite, the interpretation that is grappled with is the one that says that the card falls both ways. This is Hugh Everett’s Many Worlds Interpretation of quantum mechanics, developed in 1957. In subatomic terms, this theory states that the wave function collapses in all possible ways and yet we only observe one. However, each collapse is equally real and exists in some kind of separate, or parallel, reality. This is akin to the fork in a road. Both roads forward are equally real, but we are forced to only go down one. Replace the road with the flow of time, and you will have some idea of how this works.
In Bioshock, one of the protagonists, Elizabeth, has the ability to open tears between these parallel realities, allowing Booker and her to traverse the gap between them. However, these other realities that they step into already have their own versions of Booker and Elizabeth. Although the game never has the two versions actually meet, this is something that is allowed by the theory and offers some interesting thought experiment material.
However, the game does grapple with something called superposition states. In brief, physicists noticed a phenomenon whereby subatomic systems are fundamentally altered by interacting with an instrument that attempts to measure them. When applied to the wave equation, this results in the theory that the wave function fails to collapse until it is interacted with by an outside observer. In other words, until someone looks, both realities exist in an overlapping, or superposition, state.
In Bisohock, after Elizabeth and Booker travel through a tear, some of the non-playable characters end up in a superposition state. Characters that were killed in one reality but not another now find themselves locked in a superposition state of being both alive and dead at the same time. Of course, such a superposition is impossible on the macroscopic level, but that never stopped Schrodinger from developing his famous cat thought experiment.
In 1935, Erwin Schrodinger came up with a thought experiment involving a cat locked in an opaque box. Also in the box are a decaying element, a device to register it, and a vial of poison. If the element decays, the device will break the vial and the cat will drink the poison and die. If the element does not decay, the cat will still live. Schrodinger, in an attempt to mock the superposition principle, argued that the cat would be both alive and dead until the box was opened and someone saw it. He believed that, due to the absurdity of this notion, the superposition principle was a false interpretation of quantum mechanics.
Bioshock Infinite also deals with many other concepts in metaphysics, such as time travel, causation, and determination. If you haven’t played the game yet, I highly recommend it, not just because it is a fun shooting game, but also because it gets you to think about theories such as these. They are important things to think about, since they attempt to figure out exactly how our world functions at its most fundamental level.