Alternatives to the Multiverse
Nobel laureate, Steven Weinberg, at my alma mater the University of Texas at Austin, in 2017 published an article called “The Trouble with Quantum Mechanics” in which he laments the lack of a clear interpretation of quantum mechanics. This is, as he says, a debate that has been raging for 100 years with no signs of stopping.
The problem is simply that the current mathematical formalism of quantum mechanics and quantum field theory includes no model or indication of how measurements arise from the predictions of the theory. Rather the theory presents us only with probabilities based on a wavefunction state vector. To quote Erwin Schrödinger, describing a radioactive decay experiment,
the emerging particle is described … as a spherical wave … that impinges continuously on a surrounding luminescent screen over its full expanse. The screen however does not show a more or less constant uniform surface glow, but rather lights up at one instant at one spot ….
There are a handful of interpretations of this phenomenon. These can be classed into complete and incomplete interpretations. Complete interpretations are those that say that the quantum wavefunction is a complete description of a quantum system. Incomplete interpretations are sometimes called hidden variable theories. Albert Einstein favored these.
