Einstein's Moon: Bell's Theorem and the Curious Quest for Quantum Reality

The other reviewers have been a little excited and mistated the propositions that this book outlines. 1. Einstein never proposed a "hidden variables" theory, he was against this formulation. It was David Bohm who proposed hidden variables. 2. Einstein's ironic statement was "Does the moon disappear when I'm not looking at it?" This was stated in order to show the absurdity of the Copenhagen Interpretation of Quantum Mechanics, which states that there are no particles in the universe until scientists perform experiments; i.e. the experiments themselves 'create' reality ahead of them, creating an illusion that scientists are exploring a reality that is independent of their mental existance. "Einstein's Moon" is an excellent summary of that small, but important, battle that occured between the realists, lead by Einstein, and the quantum nihilists, lead by Niels Bohr. The surprising state of affairs today, summed up under the ruberic of "Bell's Inequality" has yet more surprises waiting just around the corner. This is an area of physics and philosophy that can and will produce world-changing results in the very near future. So, "Einstein's Moon" is excellent reading for anyone who wants to be prepared for the next revolution in man's understanding of the universe!

If I look at the moon does it disappear? The Quantum Double Slit paradox: Quantum theory teaches that light is ultimately made up of finite and indivisible quanta called photons. Common sense dictates that since a photon is indivisible, a single photon can only pass through one slit at a time. Therefore, the photon must pass through slit A or B and then hit the photographic particle screen. If one blocks slit B and measures the results of the photon passing through slit A, the result should match commonsense and since the photon can only pass through one slit the interference pattern can not form; however, when the results of a very large number of these individual events are collected, the familiar interference pattern appears, as if the photon also passed through slit B. This is where the quantum world departs with logic and common sense. The photon acts like it can be at two places at once. It seems light and electrons can behave both like a particle and wave. Radium 228 demonstrates the concept of the quantum jump. An elementary particle sitting inside the nucleus has too much energy and wants to escape, but no event exists to cause the escape; however, a quantum particle seems to move between two points without occupying the intermediate space in between the two points. This is called the quantum jump. The particle makes a discontinuous leap defying commonsense. At the instant before the leap it occupies a local space and later it is somewhere else. It seems space-time changes shape and the particle emerges in a different topology. Plank and Einstein claim light existed in discrete packages called quanta. Quanta are so small they are not observable in the large scale world. In large scale light is observed as continuous wave. In thinking about a model for atom, Bohr realized energy of an electron as it orbits the nucleus could not gradually lose energy. Gradual energy loss would mean the electron would collapse immediately into the nucleus and all matter voids out itself. Electrons can not gradually spin inwardedly, they can only jump orbit to orbit. An electron-planet changes its orbit only by losing or collecting a whole quantum of energy. Heisenburg struggle with the perfect predictable model of the atom and his work in non-communtive matrices formed the uncertainty principle: Error in velocity X Error in position = planks constant, such that, decreasing the error in position increase the uncertainty in velocity and attempting to pin velocity increase uncertainty in velocity. So, if the information about position and velocity is no longer possible to pin down then a prediction about path is impossible. Heisenburg originally believed a path existed but was unknown. Bohr corrected Heisenburg and stated, "the electron does not have a path" meaning that all information about the path was ambiquous. Bohr further introduced the notion of complementarity suggesting Quantum Universe could not be contained within

Einstein thought quantum uncertainty would eventually be explained by "Hidden Variables" . Little did he realize those "Hidden Variables" would travel faster than the speed of light. I wonder what Einstein would say about the breakdown of his speed of light constant by those variables?

I found the explanations of the standard modern physics subjects to be mediocre except the part about Bell's Theorem. The significance lies not in the treatment of the subject (Bell's Theorem) but in the fact that Peat has tackled the subject at all. This theorem may prove to be the most important discovery in human history. Experimental proof (I've heard tell that it has been proven.) of local indeterminacy is mind-boggling. Why every science writer worth his salt isn't jumping to come up with a better write up is beyond me. This book is a must read--even for real students of quantum mechanics.

What a good book! The metaphors for the layman are usually dead-on, although the heart of the paradox of Bell's Theorem is fuzzy, and better handled in "Shroedinger's Kittens". Otherwise, this book does the best job of navigating clearly through the history of the debate over reality.