This is an excellent video that discusses four theories on the foundations of quantum mechanics and it is some of the best explanations I have seen and it is not a dry video. I have pointed out that there are a number of problems with the Copenhagen Interpretation of QM, see http://www.galtsgulchonline.com/posts/37.... The video presents four alternatives to the Copenhagen Interpretation. They are the De Broglie–Bohm theory (see http://en.wikipedia.org/wiki/De_Broglie%...), the many-worlds theory also known as the Everett interpretation (http://en.wikipedia.org/wiki/Many-worlds...), the spontaneous collapse theory (http://en.wikipedia.org/wiki/Ghirardi%E2...), and the QBism theory (http://en.wikipedia.org/wiki/Quantum_Bay...). These ideas were presented with respect to the famous double slit experiment. The video mentions that Einstein was unhappy with the CI, but so was Schrodenger. Here are my thoughts on them, what are yours?

1) De Broglie–Bohm theory
I think this is better than the Copenhagen Interpretation (CI). However, it does not appear to provide any significantly different predictions and requires an additional equation, which makes it problematic.

2) Many-Worlds theory
The other panelists point out a number of problems with this interpretation, but my problem is that it violates conservation of matter and energy, because it requires an infinite number of universes and each event requires infinitely more universes.

3) Spontaneous collapse theory
I did not think this was very well explained. It does appear to solve the measurement problem however, but other than that I do not think it is promising.

4) QBism
I think this may actually be worse than the CI.


Other Thoughts:
In the double slit experiment when we are shooting one electron at a time, we do not consider that the detector is made up of atoms that also have a wave function and therefor a probability of interacting with the free electron. I am not exactly sure how this would change the interpretation of the double slit experiment with single electrons at a time, but it would suggest that the position of the electron may not be as localized as the experiment suggests. Another problem with the single electron double slit experiment is how do we know we are shooting a single electron at a time? If we know this for sure, then we must be measuring it in some way which would affect the experiment. If we don’t know this then we don’t know that one of the free electrons does not make two dots on the screen or no dots on the screen. Again going back to the limits of our detector. In order for a dot to occur, the free electron has to cause an electron in an atom to change state. If the free electron is truly a wave then it might cause a single dot, because of the atomic nature of our detector. However, you would also expect that a single electron might cause two, three, or more dots if it were a wave or no dots at all.
Personally I think we will eventually find that all matter is really waves. We will find that the probabilistic side of QM is a result of these waves being spread out. Point particles of charge cause all sorts of problems, including infinitely intense electrical fields.
Feynman did some work on the wave nature of matter. Carver Mead has done some work in this area as have many others and I am not talking about string theory, but as yet there is no comprehensive ideas in this area.

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