Prof. Yakir Aharonov, a world renowned Israeli physicist who has made important discoveries in the field of quantum mechanics, will be among the 10 scientists to receive the National Medal of Science from U.S. President Barack Obama this year. Aharonov has also been considered a leading candidate for the Nobel Prize in Physics for several years now.
Prof. Aharonov, can you tell us a little about the significance of both the Aharonov-Bohm Effect and the "weak values" - two of the discoveries, among others, for which you are being awarded the national medal?
We'll begin with the fact that, in classical theory, the most important terms are the forces that have an effect on particles and make it possible to predict what is going to happen to them in the future. Whereas in classical theory a particle can feel force only if the force is active at the point where it's found, I discovered that this is not true in quantum theory.
One can find situations in which the force is in one place and the particles are remote from it but nevertheless feel its effect. This phenomenon (known as the Aharonov-Bohm effect ) completely alters our understanding of how interaction works in nature.
And the weak values?
The big innovation in quantum theory as opposed to classic theory is that two particles that begin in the same situation will at a later stage behave in a different way from one another. Therefore quantum theory shows that nature is not deterministic - that is to say, the conditions of the past do not determine the activity of systems in the future in an absolute way. Einstein was very dissatisfied with this throughout his entire life and said that it was not possible that God was playing with dice.
My research was aimed at trying to understand why nature behaves this way. I came across the idea that when one looks at two quantum particles from the same situation that nevertheless behave differently in the future, perhaps nature is trying to tell us there was a difference between them - but that this difference is not in the past, but in the future.
I rephrased the equations in such a way that the future was not determined by information flowing from the past to the present, but also by information that flows from the future to the present. It is as if there are two conditions for the present, two functions that together offer a full picture of the present.
I discovered that the way to measure these possibilities is through a new kind of value, which I called "weak values," that view every particle in a very delicate way. When one collects a large number of particles, one gets new information that demonstrates that the future indeed plays a role. I found a completely new type of phenomena in these functions that had not been discovered until then, and I foresaw a great many phenomena.
In the past, you expressed a position of totality according to which "one day physics will advance and achieve the ability to understand, to explain and to anticipate all natural phenomena, including human activities. This encompasses everything related to morality and feelings. In the future, all the various mental forces will be an inseparable part of comprehensive physics." Do these aspirations go hand in hand with the prevalent scientific ethos?
What I intended to say, and what perhaps was not clear from what was quoted, was that we look at our experiences - at the experience of the flow of time, free will or consciousness - these are experiences connected with physical properties of the brain, and I postulate that there is no possibility that they are mental characteristics devoid of physical explanation.
Imagine that I possessed a spiritual characteristic that affected my physiological processes or determined that my hand will move in one way or another, without there being any physical explanation. I therefore include that among the characteristics of our brain ... which is the most complex physical system that exists in nature.
I believe there will be a revolution in physics that will describe these complex systems, and things which we today do not include in the field will be included. But that does not mean that physics will be deterministic.
While science today is moving in the direction of broad cooperation between scientists, you are used to working on your own, among other reasons because of your work as a theoretician. But you also say that you don't read journals and that at scientific conferences you'd only show up for your own presentations. This is the kind of Victorian model of the reclusive scientist.
Since I deal with fundamental problems of physics, I don't need actual experimental points of view. I look at the basic equations of physics that have already been known for centuries and try to find a new way. I don't want to be affected by established opinions so I try to isolate myself. When I think about something new, I share it with my colleagues, but the preliminary discoveries I make entirely independently.
Most theoreticians conduct a different kind of research, which requires investigation of complex systems, and so most of them definitely work in an entirely different way, with a lot of competition. I am far from all of that and in that respect am considered very irregular.
As someone who taught at universities abroad in the past and returned to Israel, how do you relate to the brain drain phenomenon?
The brain drain is certainly a very disturbing phenomenon, which arises from smaller and smaller budgets allotted to the universities in recent years. Some of the most successful young scientists could not come back to Israel because there were no means of employing them. As a result, there was a serious drop in the standard of the universities. Now steps are being taken - insufficient steps, but they are nevertheless headed in the right direction - to allocate funds.
When I was a student, university professors held a tremendous amount of prestige. They were considered the top of Israeli society. People who succeeded in business or as contractors were considered far less important than professors and even than schoolteachers. This began to change and today one can say that the opposite is true. People worship money rather than knowledge. This starts with the fact that the situation for schoolteachers is at a very low ebb.
We have to find a way, with the help of some PR, to explain to the general public that this is a dreadful mistake. The wheel must be turned back and we have to return to being the people of the book, as we once were.
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