it is the interpretation we use for all practical calculations how to think about it more deeply is a different question and I think because of the split in the Copenhagen interpretation between the thing we study and the Observer himself that it can't survive in a fundamental sense one has to remember that before bore did this work uh there was a sense of mystery about quantum mechanics nobody really knew how to use the results of say calculating the wave function to make predictions about experiments with the copen Haagen interpretation we have a way of using calculations
to make predictions that we could all agree on the philosophical understanding of it is probably not satisfactory [Music] bore thought that OB observers scientists measuring apparatus have to be treated by the old Newtonian methods of classical physics whereas electrons and atoms and so on would be treated by quantum mechanics um and that's I think the way we do think about it from a practical point of view uh because after all measuring apparatus and physicist are big compared to atoms and they are well described by the laws of Newtonian mechanics from a fundamental point of view
we can't accept this kind of dualism that there is on one hand Quantum Mechanics for the electron and classical Mechanics for us it's got to be the same physics for every for everything and presumably that physics is quantum mechanic sometime you decide to measure this one and you find it's in a spin down state you immediately know that the other one is in a spin up state now this is what bothered Einstein because how that object that was going off like this must have had what he called an element of reality the spin must have
been in some state it didn't develop a certain State simply because you measured this but in fact it did it develops that state because you measured this one so you have a sort of an instantaneous action at a distance which was very unsettling ever when I received it I was simultaneously shocked and delighted I was delighted because it was the first new idea on quantum theory that had been published or had been written up in years ever the paper was published and then there was total silence here was this young man who had interjected a
brand new idea into quantum mechanics and he was being totally ignored and I felt that this this young man had not gotten his proper recognition so I resolved to correct the situation I wrote a popular account for physics today which appeared in 1970 and after that Everett could no longer be [Music] ignored I just couldn't swallow it because it implied that I split and I don't feel myself split so he added a footnote to his paper in which he said that is like the anti- capern in the time of Galileo who didn't feel the earth
move the point is that the theory in both cases tells you precisely what that you will not feel it in the case of quantum mechanics you will not feel yourself split in the case of classical mechanics you will not feel the earth [Music] [Music] move my own view is that for the present we're stuck with the many world's interpretation of quantum mechanics uh we don't have anything better uh it may be that we will find some way of becoming comfortable with it I'm not comfortable with it uh or it may be that quantum mechanics will
change in some way I mean that the theory not just the interpretation but the theory itself will turn out to be a little different unfortunately it's very hard to imagine a theory which is close to quantum mechanics we we know that any new Theory would have to be very very similar to Quantum Mechanics because quantum mechanics work so well so the corrections must be small it's very hard to find a theory which is nearly quantum mechanics but not is not exactly quantum mechanics I've tried and I haven't succeeded in doing that they say that it
violates the aam's principle of aam's Razor that that scientists should always keep entities to a minimum and that it is ridiculous to ascribe reality to Worlds of which you cannot be aware well if you take this argument seriously then you are not allowed to ascribe reality to planets in distant galaxies now someday maybe both those planets and the many worlds will become observable at least indirectly I I always like to say that it's always valuable to push any formalism to its extreme logical conclusions this has been shown over and over again uh Maxwell's electromagnetic Theory
Einstein's relativity Theory Quantum field Theory you know in the 19th century there were many physicists who didn't believe in the reality of atoms so it's not wise to to ignore what the formalism is trying to tell you [Music]
