To keep up to date with the subjects on my website I have to read quite a bit. And a lot of highly interesting material on quantum physics is being written and published. But occasionally I come across something that impresses me particularly and seems worth of special attention. Especially when it considerably broadens or clarifies my view on quantum physics and its interpretations. Therefore highly recommended stuff for visitors of my website. So, I’ll discuss two books here. The first one I want to discuss is: “Beyond Weird – Why Everything You Thought About Quantum Physics is .. different” by Philip Ball.

## Beyond Weird

I am grateful to the student who put this book in my hands. Philip Ball is a science journalist who has been writing about this topic in Nature for many years. You don’t need to be able to solve exotic Schrödinger equations to follow his fascinating and utterly clear explanation of the quantum world and the riddles it presents. Also, he clears some misunderstandings up about this subject. Such as the word quantum, which is actually not the fundamental thing in quantum physics but rather an emerging phenomenon. The state wave is not quantized but fundamentally very continuous. He desctibes how quantum physics in its character and history deviates from all previous physical theories. It is a theory that is not built by extrapolation on the older theories. You can’t imagine what happens in the quantum world as you can do with, for example, gravity, electric currents, gas molecules, etc. The mathematical basis of quantum physics, quantum mechanics was not created by starting from fundamental principles but was the result of particularly happy intuitions that worked well but whose creators could not fundamentally explain what they were based on. Examples are: The matrix mechanics of Heisenberg, the Schrödinger equation, the idea of Born that the state function gives you the probability of finding the particle at a certain place when measured. It was all inspired intuitive guesswork that laid the foundation for an incredibly successful theory we still don’t really understand how and why it works. Ball makes presents a good case for the idea that quantum mechanics seems to be about information. It is a pity, in my opinion, that he ultimately appears to adhere to the decoherence hypothesis. That is the point in his book where the critical reader will notice that what was until then comparably good to follow step by step suddenly loses its strict consistency and that from there one has to do with imperfect metaphors. His account remains interesting but isn’t that convincing anymore. Despite that, the book is highly recommended for anyone who wants to understand more about the quantum world and especially about quantum computers.

## The Quantum Handshake

A completely different type of book is “The Quantum Handshake – Entanglement, Nonlocality and Transactions” by John Cramer. His interpretation of quantum physics seems, in my opinion incorrectly, not to be placed on the long list of serious quantum interpretations. Not a big group of supporters. In any case, I had never heard of his interpretation until it was brought forward by someone at a presentation about consilience I attended a short time ago. The subject made me curious because the state wave seems to stretch out backward and forward in time as I see it. Cramers’ hypothesis is that the state wave can also travel back in time, creating a kind of ‘handshake’ between the primary departing state wave and the secondary backwards in time reflected state wave. The reflected state wave traveling back in time arrives at the source thus exactly at the time of departure of the primary wave. This handshake between both waves effects the transfer of energy without the need for the so-called quantum collapse. The measurement problem where the continuous state wave instantaneously changes into an energy-matter transfer would then be explained as the result of a energy transfer by the handshaking state waves. However, in order to finally be able to complete that energy-matter transfer from source to measurement device, Cramer has to assume that the state wave is “somewhat” material-physical. This ephemeral quality of the state wave is considered as a severe weakness in his interpretation. Nevertheless the book provides worthwhile reading for those who want to delve into the various interpretations of quantum physics, also and especially because of Cramer’s discussion of a large number of experiments with amazing implications such as, for example, quantum erasers and delayed choice experiments where retro causality appears to occur. His idea of a state wave that is traveling back in time – which is not forbidden in the formulations of quantum mechanics – remains a fascinating possibility.