cardboard adolescent

i found this paper i wrote a while back, might be interesting food for thought for some of you or at least get you thinking about theoretical physics :P

Choosing Sides:
The Argument for the Many-Worlds Interpretation as
the Best Alternative to Copenhagen Quantum Mechanics
t-om

As I start to write this paper, my mind can not help but wander. I consider that, in my imagination at least, there exists a Tom who stopped after writing that first sentence and went back to daydreaming about transtemporal identity. I'm willing to accept that as this other Tom gets closer to the deadline the probability that he writes a second sentence will increase; however, if we discretely branch off Toms, eventually there will remain one who never writes the paper. At face level, all this tells me about my self-identity is that I have a low likelihood of acting particularly irresponsibly. If, however, I assume that all these Toms actually exist, as the Many Worlds Interpretation of quantum mechanics suggests, what distinguishes me, the Tom who wrote this particular paper, from the one who wrote a much better paper, or the one who didn't write it at all? Ultimately, the issues of philosophy are the issues of quantum mechanics. As such, the ambiguity of philosophy is reflected in the ambiguity of quantum mechanics. The empirical underdetermination of quantum mechanics almost inevitably leads interpretational arguments into the domain of philosophy, where abstractions like “realism” and “locality” become trading cards to score points for your theory. The playing field has been wide open since the early thirties, and is still the source of heated debate. On the grounds of restoring realism to quantum mechanics, however, one theory has slowly risen and accumulated credibility over the last five decades to provide a “complete” picture of the universe. The Many Worlds Interpretation of quantum mechanics (MWI) preserves intuitive notions while accounting for quantum weirdness more completely than any other non-Copenhagen interpretation.
Our logical first step is to define the Many Worlds Interpretation. This term, however, has come to mean different things over the years. Its history begins with Hugh Everett's 1957 “Relative State Formulation of Quantum Mechanics”, in which Everett attempted to solve the “measurement problem” by reducing measurement to an interaction between two quantum systems which could become entangled. In other words, he postulated that the Schrödinger wave function described the complete state of an isolated system at all times and that “collapse” of the wave function was an illusion of subjective experience. Everett's theory was highly mathematical, and left a lot of glaring ambiguities. As a result, there are a number of modern theories which expand on Everett's ideas. The MWI was first introduced by Bryce DeWitt in his 1970 paper, “Quantum Mechanics and Reality.” According to the MWI, measurement does not cause the wave function to collapse, rather, it causes our universe to split into universes corresponding to all the possible measurement outcomes. Thus, according to this theory, the universe we perceive doesn't constitute the whole of reality; instead, it is part of a larger structure known as the “multiverse,” which consists of an infinite amount of constantly branching universes (Vaidman, 2002). At first this structure seems blatantly counter-intuitive and unnecessarily extravagant, but the former is never a suitable reason for abandoning a theory and the latter is ultimately very subjective and questionable.
What possible reasons could one have to adopt such a theory? The most obvious is, as mentioned before, that it solves the measurement problem of standard quantum mechanics. This problem states that the observation of a quantum system indeterministically changes its state in a way which requires a discrete extension of the quantum formalism. This problem was at the root of Schrödinger's cat paradox, and is rendered meaningless by the MWI. Similarly, the MWI allows us to restore determinism because all systems evolve deterministically according to the wave function, and realism, because all elements of a system are completely described by the wave function. These two standards, determinism and realism, are at the core of our inherited classical intuitions. If the MWI can restore these ideals without necessitating a super- or sub-structure independent from Schrödinger's wave function, it would seem to be the ideal “alternative” interpretation. Whether this can actually be accomplished, however, is the subject of much debate.
Before we balance the MWI on the edge of Ockham's razor, however, there are other advantages it offers us which should be considered. One of these is locality, which is violated by hidden-variables theories like Bohm's. Locality is considered especially important in resolving Quantum Mechanics with Special Relativity, and is a key element to the study of Quantum Field Theory (Berkovitz, 2007). In some aspects though, it would seem as though the MWI is not a completely local theory. After all, it seems to say that a quantum observation here on Earth results in the duplication of a star system light-years away. However, this view of the MWI is quickly becoming replaced with localized splitting based on decoherence. According to this view, splitting occurs when a thermodynamically irreversible process has occurred and interference effects can no longer occur. A Geiger counter measurement is one such thermodynamic process (Zeh, 2005). Thus, when we detect the presence of a particle, splitting occurs locally at the microscopic level, and spreads throughout the universe causally. It is in this way that the MWI can be best understood as preserving locality.
...