I can only think of two, the so-called Copenhagen Interpretation in which Schrodinger’s cat is both simultaneously alive and dead in one universe until an event occurs which forces the cat to be either alive or dead (ie-observation), and the so-called Everett interpretation where every time there is a possibility of more than one choice, all choices occur, only this happens by the universe “splitting” up where each choice happens in a contained universe.
Are there other interpretations of which I am not aware of? Which is the most “popular” seeing as, AFAIK, none of them could be tested? Or, in fact, do most quantum physicists simply view QM as a cheat sheet in getting things done, and not as an indication of an underlying truth about reality? Seeing as I don’t know any physicists who could tell me offhand I figured I pop in where I know a few hang out.
Currently popular is the “decoherence” theory, which holds that superimposition of states before a measurement is a real condition, but so fragile that in practice it’s never observed on the classical level. Adherents of this interpretation are currently trying to show that a “measurement” is an objectively definable interaction with the system in question, and not dependant on human conciousness.
Been 10 years since my QM classes but from the top of my head…
I would say that it is both a “cheat sheet” and an “underlying truth”. In short, QM describes and predicts with high (some say exact) accuracy that which we can observe about the microcosmos through direct experiment and observation. The predicts portion of QM theory is especially important because it has lead to new avenues of theory and research that would otherwaise have not been explored (the discovery of the “top” quark is a famous example). These later discoveries suggest that QM theory has a lot more going for it than simply being a mathematical cheat sheet, and is much closer to being an actual description of nature’s inner workings.
As for the 2 views you list, the first (Schrodinger’s cat) is a fundamental aspect of QM. The 2nd is something that I would consider to be a theoretical extension of QM theory. An important difference.
Essentially, QM all starts with Heisenberg (uncertainty principle) and Schrodinger (that long messy equation with the funny greek symbols). Everything else is just butter on the muffin.
I’ll also qualify this by saying that I am not a QMist professionally, merely an engineer, and my Physics education is 10 years out of date
It’s hard to say what view is “most widely accepted”, since most physicists, when asked which they accept, will say “I don’t know”… Which is, of course, the exactly correct answer, scientifically speaking. Either interpretation still gives the exact same results, when it comes to anything that we can observe.
There’s also the Transactional Interpretation and Bohm’s implicate order interpretation. Both of these are explicitly non local interpretations i.e. they involve faster than light propagation effects.
Bell’s inequality and the Aspect experiment mean that FTL is unavoidable to some degree but not so all encompassing as in the above.
Most working scientists embrace the “shut up and calculate” interpretation.
Schrödinger’s cat is not fundamental. It is an aspect of the Copenhagen interpretation. Bohm set out one of the most complete explications of this interpretation in 1952, then almost immediately refuted it, and went on to develop his Implicate Order.
I have real difficulty trying to understand very big things (the Universe, my mortgage,the number of shoes in Mrs Simba’s wardrobe) and very small things (my bonus this year, people’s appreciation when you’ve helped them with something). Falling into the latter category is Quantum Physics.
So trying to broaden my mind during lunch hours, I have recently buffed up a bit on the subject. There was a good link that explained most of the thinking in very accessible language (taken from a special report in the New Scientist), but the link is no longer there. I will e-mail the Word document to whoever wants it (but ask me quickly, I’m on paternity leave after today). It contains: Spooky connections, EPR paradox, Heisenberg, Bohm’s “hidden variables” theory, Schroendinger’s cat, Bose-Einstein, Pauli exclusion principle, strings and singularities etc etc. Here’s a quote from the article to whet your appetite:
