In 1990, Northwestern University initiated the Master of Management in Manufacturing (MMM) program and Spearman and Hopp were asked to design and teach courses in management science and operations management. By this time they had enough confidence in the factory physics approach to forgo traditional problem-based and anecdote-based approaches to these subjects. Instead, they concentrated on building intuition about basic manufacturing behavior as a means for identifying areas of leverage and comparing alternate control policies. For completeness and historical perspective, they included coverage of conventional topics such as MRP and JIT. They received enthusiastic support from the MMM students for the factory physics approach. Also, because many of the students had substantial industry experience, the students constructively challenged the basic ideas and helped to sharpen the presentation.

In 1993, after a few years of MMM courses and several industry short courses, the two began to write the book, Factory Physics. The book was first published in 1996 and is divided into three parts. Part I, The Lessons of History covers basic maufacturing managment approaches before 1990 including MRP, JIT, and classic inventory control. Part II, factory physics principles describe the basic relations between fundamental manufacturing performance measures and is the heart of the book. Part III, presents how these principles can be implemented in practice.

Factory Physics, the book, has developed a great deal since the days of the terse plant manager tutorials at IBM and will undoubtedly continue to expand and mature. A second edition was published in 2000 and represented the best summary the authors had developed after more than 10 years. The third edition is due out in early 2007 and incorporates substantial advances in knowledge gained through the research and applications conducted since publication of the second edition.