MIŁOSZ WNUK

**Remembering Professor Michał
Życzkowski**

**A great teacher and scientist who reshaped Cracow University of
Technology**

**And became the unsurpassed Master for his students**

In 1954
Professor Michał Życzkowski graduated from the Cracow University of Technology,
and this date exactly coincided with my graduation at

At
first the subject matter was Strength of Materials to be followed later by the
Theory of Elasticity. Both subjects were taught by Professor Janusz Walczak, an
excellent lecturer. His two-hour lectures were delivered in a large lecture
hall destined for a large audience. The sessions were rather formal and in *ex cathedra *style, leaving little room
for questions or comments from students. However, at the recitation sessions
lead by the young doctor Życzkowski things looked different. Dr.
Życzkowski was an Assistant in Professor Walczak’s Chair of Mechanics of
Materials. During the recitation classes with Dr. Życzkowski the students
had plenty of opportunity to plunge deep into the core of the problems and to
ask all kinds of questions. Dr. Życzkowski was well prepared and ready to
oblige and to explain the problem at hand in great detail. He radiated an
unbounded energy of life combined with an unusual kindness and willingness to
help. In short time it became clear that Dr. Życzkowski is not just a dry
introverted scientist, but rather an extraordinary teacher and a warm human
being. Somebody you would like to have as a friend. His ability to make complex
problems look like a simple matter, and at times almost easy, was uncanny. He
never hesitated to go an extra mile to explain certain mathematical intricate
details necessary to solve a given problem. Only later in life I understood
that such a character trait is a rare trait indeed. It was a rare gift
extremely valuable for the young teacher.

Subjects
taught to us were not easy, and they often required a good deal of
concentration and solid knowledge of the underlying mathematical techniques. It
was my first encounter with the

During
my senior year at the Polytechnics, while majoring in Mechanical Engineering I
attended the weekly seminars arranged by Professor Życzkowski. My notes
gathered during these regular Tuesday meetings turned out to be of greater
value than many prestigious textbooks that I posses. Years later I met with
Professor Życzkowski in the

Since
these words written here are of informal nature, I will take a liberty at
quoting some stories which are more anecdotal than historical. One such story
begins during a certain Tuesday seminar attended not only by graduate students
but also by the faculty from the other departments in the *a priori *that most of what we did was
either wrong or – at best – could not be proved to be correct. Not from the
mathematical point of view, even if the common sense and the intuition
indicated otherwise.

At this particular seminar Professor Barański arrived late and did not have sufficient time to read all the equations that appeared on the blackboard. Thus he did not notice the restrictions on the radius of variable “r” which appeared under the logarithm symbol in the equations for stresses present in the classic Lame problem in the Theory of Elasticity. Suddenly a thought occurred to him; he stood up interrupting the lecture and in a rather indignant voice stated that the equation was “obviously wrong”. It was meaningless – he claimed – “when the variable r was approaching zero, as then the logarithm is not defined.” When he finished, Professor Życzkowski took the floor and responded “you are looking for something that is not there”. Then he went on to explain that the radius “r” used in the formula written on the board could never be less than the finite entity “a”, the inner radius of the cylinder. At “r” equal to “a” the logarithmic function approached zero and it made perfect sense, as expected in real life. Professor Barański stopped his monologue and slightly nodding his head in a gesture of surrender withdrew from the discussion. He sat down and remained silent for the rest of the presentation.

In 1959, when I began my first paid job as an Assistant in the Department of Physics at the Krakow Polytechnics, I also had my very first technical paper published. Of course, it was entirely inspired and co-authored by Professor Życzkowski. On some earlier occasion I came up with the modification of calculations of the moment of inertia. Although I was rather enthusiastic about it, the idea was discarded by Professor Życzkowski, who has shown to Professor Walczak (his boss) and to myself (his student) that the idea could be reduced to just another interpretation of the known process of iteration of a double integral and thus it was not worthy of publication. My second thought, though, was a lucky one and it was approved by the Master. This time the idea had to do with the analogy between post-critical buckling of a beam (a nonlinear problem) and the mathematical pendulum subject to the initial conditions involving large angular amplitude. The formula I proposed was based on Puwein’s approximation of the elliptic integral of the second kind; and this time it worked. Actually it was better than any formula proposed in the literature. The idea was my own, but I owe it entirely to Professor Życzkowski, without whom I would have never noticed the hidden analogy. We published the results as joint paper. Later we did publish jointly a number of papers, but it was the first one, about which I felt most proud.

It was just the beginning of my professional life in science. Within two years, from 1960 to 1962 I completed my doctoral thesis. The work was inspired and supervised from the beginning to the end by Professor Życzkowski. Michał Życzkowski used to teach us, his students and advisees, that all things – meaning calculations – needed to be done at least twice. When the news was announced that the twins were born by Życzkowski’s wife Teresa, someone commented that this fact agreed with the rule “to get it right, do everything twice”. The “rule of two” was from now on referred as “Życzkowski’s rule”. I remember that his boys, Karol and Adam, at a very early age knew from their father how to raise number two to an arbitrary power and how to convert any given number from the decimal to binary base. I also know that Życzkowski’s son Karol received his name after the Polish Pope John Paul II, who happened to be a personal friend with Życzkowskis’ family. Now Karol Życzkowski is a famous physicist in his own right.

Some
elements of my doctoral thesis caught an eye of several prominent scientists at
the *magna cum laude* in the fall of 1962. Soon after this I was promoted
in the Department of Physics to the post of “Adjunct”, which is just one notch
below “Assistant Professor”.

This
was the most memorable time in my professional life, filled with scientific
work and numerous presentations of my original results at the national and
international meetings and conferences. One “very important person” in
Mechanics, Professor Wacław Olszak from

My
textbook on “Introduction to Fracture Mechanics” was printed twice at the

Many
other events would not have taken place. One of which – again – is of anecdotal
nature. In the sixties I was asked to do a presentation summarizing the results
of my doctoral research during a seminar at the Warsaw Institute of Mechanics,
which is a part of the

For the conclusion I choose the quote taken from my superior in the Department of Physics. Professor Michał Halaunbrenner respected and admired Michał Życzkowski. One day Professor Halaunbrenner came up with the following descriptive nickname for Professor Życzkowski – “Michał the Wonderful”. I am convinced that Professor Życzkowski truly deserves this gracious nickname. He was a wonderful man in every sense of the word.

**Acknowledgement**

I feel obliged to thank Professor
Antoni Gajewski, my friend and former Head of the

**Prof. Miłosz Wnuk**