Modern nuclear physics contains a much larger class of subdomains than it did even only ten years ago. The change in the meaning of the name reflects changes in physicists' minds. It is now widely recognized that there exist a unity in the way we perceive all physical systems for which the quantum chromodynamics (QCD) is a fundamental theory. This embraces the QCD vacuum, quarks and gluons, composite particles, like pions and nucleons, and nuclei as aggregates of nucleons.
Typical scales of energy and size range here from 1GeV to 1keV, and from 0.1fm to 10fm, but tools and methods that are used to describe all these systems are very much alike. In particular, in order to cope with difficulties related to the complication of structure of these systems, one has to invoke ideas of the effective field theory (EFT), which separate our approach into several stages of description. Although links between these stages cannot be attacked, at present, with exact methods, at every one of them we can obtain successful understanding of the physical reality. Moreover, methods based on the concept of symmetry breaking are by now standard throughout the domain.
Certainly, the nuclear physics, in this larger sense, is far too broad a domain for a single physicist, and we are forced to specialize in much narrower subfields. However, it is essential that we learn enough of the whole of it, in order to be able to communicate and understand one another. These lectures are prepared with such a goal in mind.
Nuclear physics in three lectures might seem to be an impossible task, and of course it is. There is no point in attempting a balanced or representative overview of neither facts nor approaches. The choices I made below are highly personal; I have tried to discuss things that show similarities of different aspects of the field, and a general philosophy of how we do the business.
Of course, the main question is from where to start such lectures. The background that students carry out from undergraduate and graduate courses differs very much from country to country, and from university to university, and is often meagre. Even worse, students are often told that they can ``understand'' physics without actually learning it. I know, learning is a painful process and intelligent human beings request being liberated from this pain - then they become not physicists but lawyers. In physics, in my opinion, there is no understanding without learning. On the other hand, neither there is learning without teaching, so my first task here is to teach you things that you need to know to follow the course.
The first part of the course (I called it the first four minutes) gives you an overview of elements that are profusely used in the following. It is meant to give you the list of things, and references to main textbooks, rather than real knowledge - each minute here is usually taught one semester at the university. However, there is no understanding of the micro-world without at least two basic abilities: one has to know how to read a Lagrangian and one has to know how to use creation and annihilation operators. This is the mother tongue, which you have to learn as apprentice in nuclear physics.