On 10th November, professor Sergei Bulanov gave an “IST Distinguished Lecture” titled “Extreme Light–Matter Interaction through the Lenses of the Relativistic Flying Mirror Concept ”. The lecture took place at Técnico – Alameda campus (Abreu Faro amphitheatre) and was co-organised by the Group of Lasers and Plasmas, the Institute for Plasmas and Nuclear Fusion and the Plasma Physics, Lasers and Nuclear Fusion scientific area of the IST Department of Physics.

In this interview professor Sergei Bulanov shares his journey, challenges and unanswered questions.

How did you become interested in physics?
Professor Sergei Bulanov: My scientific career, like many others, developed over time, and the initial conditions that determined its trajectory are important. On the first day of class (first-year), my teacher gave an inspirational speech predicting who we would become [in the future]. I remember her saying that some of us would stand out as great scientists. At that moment, I knew that science would be part of my life forever.

When I was finishing high school, in the USSR, there was a special attitude towards science, namely physics. It was a time when everyone was interested in satellites, space flights, transistors, huge accelerators, telescopes and radio telescopes. The general mood was such that almost all high school graduates wanted to be physicists, so they tried to enter the Department of Physics at Moscow State University, Moscow Institute of Physics and Technology, and departments of other universities related to physics. The competition was huge.

My choice was greatly influenced by the popular book by Iosif Shklovsky “The Universe. Life. Mind”, which I read when I was a high school student. After so many years, I hardly remember what it says about “life and mind”, but I was strongly impressed by the “Universe”, the greatness of the cosmos and the richness of the diversity of cosmic objects. I consider Iosif Samuilovich Shklovsky to be “The Astrophysicist” (later I got to know him better, when I was attending an astrophysical seminar at Moscow University), and from his book I understood that the universe is explainable provided that you know and understand physics.

Why and how did you become a scientist?
S.B: All this determined my decision to enter the Moscow Institute of Physics and Technology (all over the world it is known as FIZTEKH – the best university in Russia in teaching physics), which I did. In the second half of the 1960s, Lev Landau’s spirit was alive at the Fiztekh. We were taught by such outstanding physicists and mathematicians as E. M. Lifshitz, V. B. Berestetskii, L. P. Pitaevskii, B. T. Geilikman, S. N. Nikolsky, V. V. Vladimirov, Ya. B. Zeldovich, V. L. Ginzburg.

What are the main barriers in your daily work as a Theoretical Physicist?
S.B: Lack of knowledge and lack of time.

What drew you to this field?
S.B: I felt so fascinated by the power and beauty of theoretical physics that I did everything I could to become a theoretical physicist. After several lectures by V. L. Ginzburg, at the Moscow Institute of Physics and Technology, I phoned V. L. Ginzburg and told him that I wanted to study theoretical physics. In response, I heard: “Come.”

I started studying and then working in the Department of Theoretical Physics of the P. N. Lebedev Physical Institute as a student, PhD student, and scientist. Several Nobel Prize winners have been working in this Department, such as I. E. Tamm, A. D. Sakharov and V. L. Ginzburg.

My teachers were S. I. Syrovatsky and V. L. Ginzburg, to whom I am grateful for introducing me to the world of theoretical astrophysics. My research area was the astrophysics of cosmic rays and the theory of solar flares. The work we developed in Ginzburg’s team resulted in a monograph titled “Astrophysics of Cosmic Rays”, which is still a desktop book for experts in astroparticle physics and in high-energy astrophysics.

Then I have extended my research area to the physics of interaction with plasma of a strong electromagnetic field generated by high-power lasers. Here I am lucky to collaborate with Toshiki Tajima and Gerard Mourou. They are not only great scientists but also good friends. I note that a great luck of a scientist is to make good friends while you are collaborating with them.

At the same time, my interest in astrophysical problems has not weakened. One of the areas of great interest for many specialists in relativistic laser plasma is the modeling of astrophysical processes using lasers in terrestrial laboratories. I also contribute to its development.

How do you deal with the level of uncertainty in Science?
S.B: Since physics is a natural science, it is not a science like e.g. mathematics, the uncertainty in experimental data is part of it. Scientists working in the field of theoretical physics must always be ready to accept new paradigms and work in a changing world.

Could you share a turning point or a defining moment in your work as a scientist?
S.B: All my scientific activity is a continuous chain of turning points. I started as a pure theoretical physicist/astrophysicist, then found myself working on the controlled fusion problems of magnetically confined plasma, plasma pinch discharges and microwave radiation interaction with plasma, combining my job with lecturing as a professor of the Moscow Institute of Physics and Technology. Then, I moved from Moscow to Japan and joined the Kansai Photon Science Institute. Being a theoretician, I worked there for several years as the leader of the experimental group, ensuring a high scientific level and originality of scientific studies conducted by the group. At present, I am the head of the Department at the ELI-Beamlines center in the Czech Republic aiming at developing and performing the experimental program for ultra-high power lasers.

What was your most surprising finding?
S.B: All my findings are equally important because they constitute equal parts of my scientific identity.

What are the big questions that Physics can’t answer yet?
S.B: They are quantum gravity, quantum field theory beyond the Standard Model, the nature of Dark Matter and Dark Energy, etc., etc.

In your opinion, what is the biggest challenge facing Science today?
S.B: Nowadays, the biggest scientific challenge is to understand why Science itself cannot fulfil its potential for human civilization.

In your opinion, which fields will be the “hot topics” in science, in the near future?
S.B: In my current area of study, the “hot topics” will be the probing of a texture of nonlinear quantum vacuum with extremely high-power laser radiation. We are witnessing the emergence of a new field of science.