“I never teach my pupils. I only attempt to provide the conditions in which they can learn.”
— Albert Einstein (1879–1955) —
A view onto a midnight blue of sky with shining stars is free for everyone. The ancient Egyptian conception of heavens as a woman with the stars painted on her body and supported by a man is unforgettable. Ancient peoples were just as curious as we are today. Their wondering about day and night, stars, and the Sun and the Moon led to the observation that the heavenly bodies appear to move in a regular manner – this was the dawn of science.
For as long as I can remember, stars did not impress me under the clear night sky, but under the dome of planetarium. Early in elementary school, during a visit to the local planetarium, where a sunny day changed into the deepest nightly darkness, I saw the clear starry night sky projected and moving on the planetarium’s dome. Astronomy was fascinating, however accessible only to some exceptionally bright people. My first conscious connection with the night sky was a pure simulation.
Soon after that, I became much more interested in more mundane computer programming. Black computing boxes with flashing red lights created by the company with the closefitting name of Thinking Machines Corporation fascinated me. These machines were mainly used to study the principles concerning natural phenomena. Places filled with mystic atmosphere that is violated only by a silent noise of circulating air. As in peaceful meditation places in temples, that are disturbed only by a quiet sound of spoken mantras and accessible only to several chosen ones, who may discover secret knowledge beyond the realm of direct experience.
Nowadays, we have free access to the pictures of the universe in all its glory through the Internet, taken by billion-dollar telescopes that orbit the Earth. Several years ago, the images of the great impressive ensembles of stars, rotating as brilliant cosmic whirlpools, stunned me. Such objects “awake an intense desire to learn something of the laws which give order to these wonderful systems,” as wrote in 1845 Ireland’s Earl of Rosse[1], who first recognized a spiral structure in the “Whirlpool Nebula” now known as the Whirlpool galaxy Messier 51 (M51).
To study these “wonderful systems”, I created my own galaxy simulator. Now, I want to guide others, who may share the same enthusiasm through an easy, yet comprehensive way to get some insight into these exciting systems of stars and lead them to create their own simulations. I am glad that I have had an opportunity and a chance to explore the natural processes governing the movement of heavenly bodies. The simulations of these beautiful systems are challenging, but accessible to everyone.
1.2 History and state-of-the-art
Before the invention of reading and writing, people were taught through the direct and informal education of their parents, elders, and priests. They learned how to survive against natural forces, animals, and other humans. By using a language, people learned to create and use symbols or words to express their ideas. Still, their thinking was limited to the knowledge given to them by their teachers and a limited amount of pre-selected books.
Ongoing technological development is providing means for new methods of education. Students can freely choose what to study without any limitations. Study materials are available not only for general areas of science, but also for specialized fields due to self-teaching educational-research projects. Unfortunately, the educational texts joining education with state-of-the-art research are very young and there is just a small amount of them. Piet Hut and Junichiro Makino[2] are developing similar ideas of educational-research project focused on the simulations of stellar clusters. The self-teaching educational-research project for the simulations of galaxies did not exist until now. It is produced here for the first time.
This work aims to create the self-teaching educational-research project involving many-body computer simulations with the objective of studying galaxy dynamics.
The main goal of this work is to create the self-teaching educational-research project, which will guide a student through the numerical models and computer simulations of galaxy dynamics. It will show in detail a numerical construction of galaxy models and how these artificial galaxies may be evolved with the computer simulation.
Output at the technical level will be a study material for the education of galaxy dynamics showing the development of many body computer simulations step-by-step. Output at the pedagogical level will be the project in computational astronomy with a self-teaching approach. Output at the level of general interest will be animations suited for classic school education and the popularization of astronomy.
Dissertation itself is composed of two parts. Chapters 1 and 2 handle the theoretical pedagogical framework of the thesis and chapters 3–8 contain technical material with my original contribution to the simulations of galaxy dynamics.
The final idea is to lead students into the understanding of the principles behind the many body simulations for galaxy dynamics – reading the technical part of the thesis, experimenting with galaxies, letting them collide, taking a look at the source code, modifying it and developing new modules for it.
The aim of this thesis is to develop numerical model of galaxy dynamics, which permits future maintenance and modification by non-expert programmers. I do not assume that students reading the technical part of the thesis are mathematical or programming experts[3]. These skills will be developed during the creation of models.
I have used computer modeling and simulations throughout the dissertation. Many-body simulations were evolved for up to hundreds of thousands timesteps at different resolutions that allowed me to study galaxy dynamics accurately with modest computational resources. All galaxies were modeled self-consistently as fully three-dimensional collisionless many-body systems. The galaxies were evolved with an algorithm containing no geometrical or spatial limitations.
1.5 Information sources and literature
My diploma and rigorous theses were the starting-point for this thesis. I had to read a lot of new articles and research papers ranging from galaxy dynamics, physics, and astronomy, through computer simulations and numerical methods, to pedagogical and psychological articles.
I used almost entirely digital sources available through the Internet provided with full-text search; I utilized the search engine Google[4]. The majority of papers and articles cited in this work along with many others and references therein were retrieved from astrophysics pre-print archives (astro-ph)[5] operated by the Cornell University and from the NASA Astrophysics Data System (ADS)[6].