Citation: Mermin, N. David. "Making better sense of quantum mechanics." Reports on Progress in Physics 82.1 (2018): 012002.
Web: https://arxiv.org/abs/1809.01639
Tags: Philosophical, Expository
In this essay, David Mermin advocates a philosophical interpretation of quantum mechanics called "QBism" (pronounced "cubism"). The thesis lies of QBism lies in the following quotation: "It is necessary to acknowledge that science in general, and quantum mechanics in particular, is a tool that each of us uses to organize and make sense of our own private experience". In this sense, everything in quantum mechanics is perfectly clear. Our belief in quantum mechanics is gathered from our lived experience, and it allows us to make very good predictions. What does it mean when we say that the wavefunction has collapsed? We mean that our understanding of the state of the world has updated, and that it has a certain probability of being certain ways. If we can predict everything we want to predict, then that's enough.
In other words, as we go about our lives we are constantly making bets. We bet that a given action will result in us maximizing our overall wellbeing. Science is a tool to help us calculate the odds for our bets better. In this sense, quantum mechanics is not special and requires no explanation.
To give another quotation: "If probabilities are personal expressions of one's willingness to bet, and one of the laws of quantum mechanics determines probabilities from quantum states, then quantum states must also be judgments of the person making the state assignment. Although they describe what one can expect from the world, quantum states are no more objective features of the world than are the probabilities that they encode... The collapse of the state is nothing more than the normal updating of the expectations of that actor on the basis of new experience".
To a large extent, I agree with what is said in this paper. However, I do a few major criticisms. When I do quantum mechanics, I have a strong sense of what I am doing. I am making subjective bets about the world based on lived experiences, and by thinking deeper and performing experiments I am attempting to make myself/others better betters. In this sense I am a QBist, and quantum mechanics does not bother me. However, there is still some discomfort remaining. What are the "objective features of the world", which Mermin refers to? It feels deeply clear to me that even without conscious observers the world exists. What is the nature of this objective world?
Perhaps the QBist answer is that science is not meant to answer these questions. The goal of science is to "make sense of our private experience", not to make sense of the objective nature of the world. It is here that I would disagree. Different people do science for different reasons. Maybe David Mermin only does science to make sense of his own private experience, but many people desire to understand the deeper objective theory of the world.
Going further, I think that when people say that they do not understand the objective world they are saying something very practical. They are saying that they have an intuitive feeling that there is something deeper about the world to learn, and that learning this deeper truth would give them (as private individuals) a sense of clarity.
In this sense, I would say that QBism is incomplete. I think that people, myself included, are correct in their intuitions. I think that there is some way of explaining the objective impersonal world which would give me a sense of clarity and understanding not offered by QBism.