Quantum Interpretation: What Does Quantum Mechanics Mean? (String Theory)

Though quantum mechanics works to explain the results seen in laboratory experiments, there’s still not a single clear description of the physical principle that causes it to work the way it does. Though this is tied to the “collapse of the quantum wavefunction,” the exact physical meaning of the wavefunction, or of its collapse, remains a bit of a mystery. (So if you don’t understand quantum physics, don’t worry . . . physicists are still debating it, even after all these years.)
In topic 7, I explain some of the interpretations of what this may mean — the Copenhagen interpretation, the many worlds interpretation (MWI), consistent histories, and so on — but the fact is that these are just guesses, and physicists really don’t know for sure what’s going on with this strange quantum behavior. Lee Smolin listed this as his second “great problem in theoretical physics.” Though today this is by far the minority opinion among physicists, the great physicists of the quantum revolution — Bohr, Einstein, Heisenberg, Schroedinger, and the rest — also saw it as a key question to resolve.
Today, most physicists tend to just trust in the math and don’t worry about strange things happening behind the scenes. They are perfectly comfortable with quantum mechanics, seeing nothing mysterious in the behavior. (After all, they have equations that describe it!)
In fact, the majority of theoretical physicists don’t seem to believe that it’s possible to determine one interpretation as correct, and don’t even consider it as a question that needs to be answered, even by a theory of everything. Some of those who do want a clear interpretation hope that a theory of everything will provide insights into the physical mechanism explaining quantum phenomena.