Fred Alan Wolf (aka ‘Dr. Quantum’) is a best-selling author of philosophically-oriented books on modern physics for the general reader. He recently offered this review of my new book, *Understanding Our Unseen Reality: Solving Quantum Riddles* (Imperial College Press):

“Ruth Kastner is emerging as one of the latest new interpreters of the mysteries of quantum physics and as such provides a unique perspective that she calls the Possibilist Transactional Interpretation or PTI based on the TI theory of John Cramer, expounded earlier by Paul Davies, with both theories based on Richard P. Feynman’s earlier absorber theory. In her latest book she expands on her PTI through using some clever everyday analogies to bring the complexities of quantum physics into the realm of the non-expert. I think that she handles the non-relativistic quantum physics quite well with the PTI, but I find it difficult extending the PTI into quantum field theory although she does make a clear distinction between virtual and real processes using it. For example, there is little discussion of how antiparticles are related to their mirror image particles using the PTI—something that Feynman’s concept of a particle going backward in time with negative energy appearing as an antiparticle going forward in time with positive energy handles quite well. This is certainly a well-worthwhile read for those of you interested in how we are still grappling with understanding quantum physics 115 years after its inception.”-Fred Alan Wolf

I thank Dr. Quantum for his review and for his question concerning antiparticles. PTI has no problem handling antiparticles, but I decided to hold off on that topic and to address it in a future work. For this introductory book, I wanted to focus on the basics. But in a nutshell, for those who are curious, there are four solutions to the Dirac equation and two of those involve negative energies. Those are still antiparticle states (i.e., positrons) in PTI, and they end up conveying positive energy in any transaction. Remember also that at the virtual or offer-wave level, we are dealing only with *possible* energy, and this is not restricted to positive values. It is only actualized energy that must be positive. I welcome discussion concerning this or any other aspect of PTI, via this website.

I should add that I neglected to reference Prof. Wolf’s book* Star Wave* (1984, Macmillan) which was the first book for the general reader to discuss Cramer’s TI. I apologize for this oversight. It should be noted however that his interpretation of the transactional picture (invoking consciousness to explain collapse) differs from PTI in that PTI takes the physical process of absorption, together with a form of spontaneous symmetry breaking, as sufficient to explain the fact that we find deterninate measurement results. This issue is also discussed in Chapter 4 of my earlier book.