Matt Leifer, whose blog I hadn’t previously encountered, has a long and fascinating post on evaluation criteria for quantum interpretations. “Interpretation” here means the stuff of countless “Isn’t Quantum Mechanics weird?” books– Copenhagen, Many-Worlds, Bohmian hidden variable theories, all that stuff. These are the “meta-theories” that are used to explain how you get from all that weird and messy wavefunction stuff up to the reality that we see and observe in our experiments.
The list is explicitly modeled after the well-known DiVincenzo Criteria for quantum computing (see also Quantum Optics lecture 19), though at the moment, Matt’s list is too long and not punchy enough for people to start talking about the “Leifer Criteria” and making road maps and the like (after the cut):
- An interpretation should have a well-defined ontology.
- An interpretation should not conflict with my direct everyday experience.
- An interpretation should explain how classical mechanics emerges from quantum theory.
- An interpretation should not conflict with any empirically established facts.
- An interpretation should provide a clear explanation of how it applies to the “no-go” theorems of Bell and Kochen Specker.
- An interpretation should applicable to multiparticle systems in nonrelativistic quantum theory.
- An interpretation should provide a clear explanation of the principles it stands upon.
- No facticious sample spaces.
- An interpretation should not be ambiguous about whether it is consistent with the scientific method.
- An interpretation should take the great probability debate into account.
- An interpretation should be consistent with relativistic quantum field theory and the standard model.
- An interpretation should suggest experiments that might exhibit departures from quantum theory.
- An interpretation should address the phenomenology of quantum information theory.
The actual post contains a great deal of explanation of what each of those points means, and the interested reader is encouraged to follow the link and read, as they say, the whole thing.
This sort of research on the foundations of quantum theory is fascinating stuff, and one of those odd areas of science that gets both too much and not enough attention. These are Big Questions– every bit as Big as the questions addressed by cosmology and string theory– and more people ought to be working on figuring out what really goes on in the transition from quantum to classical. More sane people, anyway– as it stands, there are probably more kooks than serious researchers in the field.
In some ways, I think this stuff is actually more important and interesting than particle physics and string theory. It’s at least within ten or twelve orders of magnitude of being relevant to my daily life… Then again, string theory might have a better chance of experimental confirmation, as interpretations of quantum theory are almost by definition experimentally indistinguishable.