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Quantum world: How is an electron moving in an atom?

Question asked by Mitsuru Yamada on Jan 29, 2015
Latest reply on Mar 15, 2019 by George Bodner

As always, please be relaxed and have some beverage before reading this blog, Sirs.


I am wondering about the way an electron exists and about the way the electron moves in an atom or in a molecule.


It is written in a preface of a book "Quantum Divide" by C. G. Gerry and K. M. Bruno that when we think about an electron in a hydrogen atom, we often image it like a particle orbitting about the proton.  Surely, It is certain that it is really a very comprehensible picture for a hydrogen atom.  But this classical Bohr model was replaced by the succeeding modern quantum mechanical description which states that there is only probability for finding the electron at one place.


The quantum mechanics denies sich a simple picture of "orbitting electron."  The quantum mechanics only gives us a set of rules and a set of equations for calculating some value of an attribute of a system.


The quantum mechanics gives us only the probability.  So we are inclined to suppose that an electron can be here and there simultaneously around the nucleus.  But is it possible for an electron to exist on two places or on many places at once?  "No," says the book, "It is not quite accurate to say that even a quantum particle can be in two places at once.  The things are much more subtle than that."


Much more subtle than that?  Then we cannot but inquire "what is it at all?"  If it were to be the case, then how should we image the way the electron exists?  How should we image the way the electron moves?  The quantum mechanics keeps the secret and only gives us the probability P1 of finding an electron at a position x1.


It reminds us of the paradox of Zeno.  Another book by John Gribbin taught me about that paradox.  The Greek philosopher Zeno of Elea asked: "An archer has fired an arrow to shoot a deer.  The deer has run away.  Thinking every instants, the fired arrow can never be at two places at once.  So the arrow is definitely at one place at a time.  Therefore the arrow cannot reach the deer?"


The same thing can be said about the motion of an electron described by quantum mechanics.  It says only that for an electron there is only the probability P1 at place x1, the probability P2 at place x2,..., and so on.


Then we ask naturally:"How does an electron move from the position x1 to the position x2, from the position x2 to the position x3,... and so on?"  Everyone wishes to see the mental picture of the quantum world which the quantum mechanics might be able to paint.


Or does the quantum mechanics completely defy our any attempt to see such a picture?  Can't the words or the logics of our everyday experience be used for explaining the behavior of any quantum mechanical entity?


How do you think, Sirs?


Thank you for reading