Introduction

This chapter introduces the problem with the concept of energy and gives an overview of how it will be dealt with. In presenting the problem, physicists appear first, who from the end of the nineteenth century to the present day tell us that we have no answer to the question of what energy is. This is followed by disagreements between physicists, as some define or characterize energy and others criticize these theses. Finally, the authors will be considered who use the substance metaphor. Some of these know that energy is not a substance but talk about it as if it were, because they cannot find anything better. To find a solution to the problem, it would be necessary to determine what it consists of. To do this, it is important to capture its origin and how it developed. The introduction gives an overview of the chapters where this is done, as well as of the final chapter, which answers the question of the book.