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Prof. Aryeh Warshel in an interview with the Hidaan site: "I always settled for the first formula in the book, and entered it into the computer." First part of the series

In the pre-computer era, it was necessary to describe the physics of molecular systems over a whole book of formulas, Prof. Warschel chose to ignore them and let the computer do the work and thanks to these developments he won the Nobel Prize in Chemistry

Prof. Aryeh Warshel, winner of the 2013 Nobel Prize in Chemistry. Photo courtesy of him.
Prof. Aryeh Warshel, winner of the 2013 Nobel Prize in Chemistry. Photo courtesy of him.

In the pre-computer era, it was necessary to describe the physics of molecular systems over a whole book of formulas, Prof. Varschel chose to ignore them and let the computer do the work and thanks to these developments he won the Nobel Prize in Chemistry. He misses his time studying at the Technion and the Weizmann Institute and talks about the scientific experiences from that time and in an interview with the Hidan website he says that it took him a long time to digest that he won the Nobel, and that he thought that others (who developed other fields of chemistry) would win and not the field that he was one of the founders of along with the other two winners, Prof. Michael Levitt and Prof. Martin Karpelos.

How did you feel when you found out about winning the Nobel Prize?

"Of course I felt very good after I made sure it wasn't a prank after hearing a Swedish accent. I'm still digesting it. I would be disappointed if others accepted and I didn't.

Much has been said about your research at the Weizmann Institute, but you did your first degree at the Technion. what did you study there

Prof. Warshel: "I studied what was then called science-chemistry. In the third year I had a project with Yehiel Shalitin, professor of biochemistry at the Technion, to measure fast kinetics of enzymes. I thought I would do it with the help of a nuclear magnetic resonance (NMR) device when no one had done it yet and for the purpose of the project we changed the percentage of salts in the solution and it should change electrostatic energies and it didn't change. Only years later I showed that the reaction is due to electrostatic effects within the active site, but the fact that the external salts have no effect on the electrostatics within the active site is due to the fact that the effect is blocked by the water and this does not mean that there is no electrostatic effect within the active site.

More on the subject on the science website


"He wanted to publish the work I did with Shalitin in the Israel Journal of Chemistry. This could have been a good article but I didn't care. Today I am sorry because it was a good article. The truth is also that I didn't know English that well."

"I was interested in enzymes and I also studied physics with the physicists and we were taught by Kalman Altman, a fantastic lecturer and he would always talk about asymptotic wave function and Impact Parameter. I took his course as a supplement and he showed that if you look after the collision has happened there are simple solutions. I promised my friends that I would solve the asymptotic wave function for the enzymes."

"I worked as a summer student in the Department of Soil Engineering at the Technion with Prof. Rafi Mokidi (who was later killed in the Six Day War) and his partner Binyamin Tzur (they were experts in semi-permeable membranes for irrigation). They let me manually calculate the diffusion constant - that is, how fast the water passes through The membrane we were trying to build. We took clay, put something on it that covers the material and measured the flow velocity in a pressure chamber. I had thousands of numbers and after plugging them into a calculator for eight hours, a number came out that was the result. It was the best summer job I had at the Technion, certainly compared to working at Phenicia . At that time I started talking to computer experts. At that time there were already computers that received input via film, in retrospect I realized that a computer could have helped with this task and in a much shorter time."

How did you get to the Weizmann Institute?

"You can say that I got there quite by accident. I decided to come to the Weizmann Institute and work for Shneor Lipson, who was the scientific director, because I read an article about him in the newspaper (I used to read "La Merhav" because I was from Kibbutz HaMoheed, but it is possible that I read this particular article in "Maariv") It said that he was the new director of the institute and that he was from Kibbutz Tel Amal (today Nir David), which is three kilometers from Sde Nahum and that he travels by bicycle. I came to him and he said he doesn't take students, but I convinced him to accept me."

I was in the right place at the right time and not busy with other ideas

Later, Prof. Warshel tells more about the turn of events at the Weizmann Institute: "At that time, Prof. Lipson decided that he was switching to computers. He worked analytically on the field of statistical mechanics - transitions between the different helix shapes of the proteins. He developed formulas for this without a computer and in 1965 he began trying to calculate the structure and behavior of organic molecules on a computer. I continued a project started by Mordechai Bikson, and we decided to try the method on lactams, which are compounds with four, five, six, or seven rings that include a single peptide bond - that is, a small molecule that is acted upon by the same forces as in a protein. During my work, I saw that it was impossible to use a description of molecules that was accepted at that time: as bonds and angles because the computer program became too complicated. If you have a ring every knot depends on the other knots, there will always be a mistake. The cocoon computer was just there and I decided to check if it was possible to calculate the forces just by looking at the Cartesian axis system (X,Y,Z). The decision turned out to be a good one, because instead of thousands of complicated lines of code, you can be satisfied with one line. Everything was made very simple and I could check it with the help of a numerical derivative - I took the atom and moved it a little to the right and a little to the left and I could check if the formulas I checked were correct. This was greatly helped by the cocoon computer which, thanks to Chaim Pekris, produced results with an accuracy of 18 digits."

At a certain point in the research I decided that it would be good to calculate the vibrations of molecules, so that we could see how well our model of the molecules works according to our calculation (the idea was to calculate and observe the vibrations consistently) I showed how the problems of the vibrations of molecules can be reduced to one line instead of a whole book. Lipson didn't believe it, but the computer was the judge and just then the Six Day War broke out. Since I saved time thanks to this development, I managed to finish the master's in six months, and then Mike Levitt appeared. Mike was (and still is) an excellent programmer, and thanks to that, the software we wrote was efficient and elegant considering the limitations of the space available for data storage at the time. We wrote software that is based on the Cartesian coordinate that made it possible to calculate the structure of proteins. All the difficulties that arose from the fact that the proteins contain rings and bonds that depend on each other - disappeared. From here on you could ask any question, start only from the first formula in the book and teach the computer the rest and not try to write complicated formulas that were necessary when there was no computer. This experience shaped my scientific thought."

At the end of 66 I started my master's degree and finished it in 1967. I finished my doctorate in 1969.

How is it that the best things come early in a career?

Prof. Warshel: "Unlike mathematicians who are required for so much wisdom that disappears at the age of 26, I think it was simply a matter of timing, that right then it was possible to ask the computer any question for the first time and get an answer. If it had happened when I was 35 I might not have been involved in it because I would have already been stuck with something else.

What language did you program in?

"Unlike Mike Levitt, I didn't study anything except Fortran and company" in the computer center at the institute, including the late Amir Panoli, they always said that Fortran was a fad. There are PL1 and others. I still program in Fortran and colleagues come and want to write in C plus plus but are impressed that Fortran is a good language and thanks to that it has been preserved."

In the next part: from a side job to a Nobel Prize - the research on quantum physics

Thanks to Dr. Moshe Nachmani for his help in clarifying the technical terms in chemistry.

The science site will report from the Nobel week in Stockholm. Among other things, this will be possible thanks to your participation in the Israeli crowdfunding project Headstart that started this evening (Thursday). To the project page

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