Yanchilin V.L. Quantum nonlocality

Content

Chapter 1. WHAT CAN WE EXPECT FROM QUANTUM MECHANICS?

When a person starts contemplating deeply on the subject of quantum mechanics, he/she often becomes frustrated and fails to understand ins and outs of this theory. Therefore we are obligated to warn a reader what exactly he (she) will encounter in this book.

1.1. Who was the first physicist to blame quantum mechanics for a sin of nonlocality?

Although I got my education at the Physics department in Novosibirsk State University and we attended lectures on quantum mechanics delivered by a famous Russian physicist Joseph B.Khriplovich, I did not hear a word about "quantum nonlocality". I even cannot remember that our teachers pronounced this word during my education course in university.

I remember how I heard about this concept at first time – it was merely by a chance. Once we returned home after a soccer game and had a discussion on science on a way back to home. My friend George told us bravely:

– I cannot accept completely quantum mechanics because this is a nonlocal theory.

George reallocated to Novosibirsk's University from another site. I don't know who his previous lecturer on quantum mechanics was. And sometimes my friend uttered the phrases difficult to grasp immediately. I tried to grasp the meaning of this phrase and asked:

– George, what do you mean by "nonlocal theory"?

– A nonlocal theory is a theory that admits a possibility of instant action over a big distance. For example, the Newtonian theory of gravitation supposes that gravitational impact is transmitted instantly from one body to another.

– What the stuff are you talking about? The age for nonlocal theories had ended in the eighteen century. I suppose, even at that time nobody believed that instant spreading of action is real. After Faraday introduced the concept of a field into physics, it became clear that any interaction occurs due to a specific field and being spread with a final velocity. I don't buy it! – quantum mechanics was formulated after Relativity, so it cannot be nonlocal theory! Most probably, you are talking about non-relativistic quantum mechanics, which describes motion of bodies with velocities much slower than the speed of light. In this case we can disregard the time delay in interaction. But if you want, you can take into account this delay.

But George insisted: nonlocality is the essential part of quantum mechanics! You cannot remove nonlocality without destroying the edifice of this theory.

These words were absolutely against my current vision of scientific world, so I did not take his words seriously. If quantum mechanics were a nonlocal theory, our professors in university would have told us about this bizarre aspect and we would discuss this at our seminars. But as I wrote already, we had not discussed the concept of nonlocality in quantum mechanics in classes; even more, this word was not uttered at all!

My scientific interests were not directly related to quantum mechanics; however, they overlapped often with this theory. When this happened, I have to go deeper and deeper into mysterious and wonderful world of quantum mechanics. "Wow! – I told myself after the next occasion. – Now I start to understand the meaning of Niels Bohr's famous saying [1]:

Anyone who is not shocked by the quantum theory does not understand it.

In some moments I had a feeling that I have just grasped the deepest paradoxes of quantum realm. It seemed to me that the quantum realm cannot present a more inconceivable and bizarre idea that has settled down in my mind recently. But after a next occasion I again was perplexed and confused: the "previous" paradoxes had dimmed on the background of a "new" keen paradox.

As for the subject of nonlocality, I remember a story told us by a professor from my university: he shared his reminiscence about working together with a great Soviet physicist, Lev Landau. Usually Landau's discussions with colleagues about paradoxes of quantum mechanics were wrapped up with the phrase: "In general, this is clear now, although some tricky questions remain, but only Bohr might have ready answers for those" [2]. These words get stuck in my mind. Even great L.Landau did not know all answers to some questions, and he was bold enough to admit this fact in public. I think that some of these tricky questions were generated by problem of quantum nonlocality.

Gradually, fancy melody of quantum realm became more clear, closer, and habitual for me. Ultimately I had an insight. I comprehended the elegance of "quantum jumps" and the beauty of nonlocality concept.

Now I know enough about nonlocality to write this book. I hope I can explain this quantum phenomenon in clear and simple language in a manner accessible both for experts in quantum mechanics and for laymen.

Even more, I believe that teaching of quantum mechanics should be started from the story about nonlocality. In a similar way, before a teacher explains the Newtonian law of gravity, he/she usually stars talking from an example of orbital motion of Earth. It would be silly to give this message later. In the same way, we should inform our listeners about effect of nonlocality before we start writing the formulae of quantum mechanics. Actually, this phenomenon is rather simple. It is comprehensible not only for colleague students, but even for high school students, as well for anyone who wants to know better the edifice of this Universe.

Nonlocality is simple!

The only barrier on this way is prejudice against this phenomenon. Today most of physicists are somehow convinced (and I was among these ranks too) "that's impossible because this is incredible". Here we should remind the golden rule of physics: only properly arranged experimentation can decide what does exist or not in nature.

Reviews

"Gradually, the fancy melody of quantum realm became more clear, closer, and habitual for me. Ultimately I had an insight. I comprehended the elegance of "quantum jumps" and the beauty of nonlocality concept. Previously mysterious and bizarre things became simple and clear. I even felt a slight nostalgia for the period when I wandered by the surrealistic realm of quantum world and was bumping weird things here and there.

Now it is time to use all this – wave-particle dualism, nonlocal connections, and quantum jumps, – in hi-tech industry. If we want to put technical devices onto a higher level, we should work with quantum theory approach."

"The book introduces the reader to the world of quantum mechanics. Original author's style, deep insight into the fundament of the subject thrill the reader immediately. I recommend this book to those, who want to understand the beauty of Nature without equations."

"Recently, I came across a book of Vasily Yanchilin entitled "Quantum nonlocality". For more than twenty years I have been interested in "Einstein-Podolsky-Rosen" paradox and successful experimental testing of nonlocality of quantum mechanics. I find the book of Yanchilin very interesting from both historical point of view as, for example, a detailed analysis of debates between Niels Bohr and Albert Einstein on quantum nonlocality and Yanchilin╥s own new interesting concept of "discrete motion". The latter concept was ingeniously used to explain many phenomena in the quantum world, which are "bizarre and peculiar both for a young researcher and for a recognized scientist" as has been admitted by Richard Feynman. I highly recommend this interesting book for both students and scientists."