I was seven when men landed on the moon. My parents woke me up to see it on TV. The Apollo 11 landing and the following moon missions made such an impression on my generation of young nerds that many of us resolved ourselves to careers in the space program. The only question for me in those days was which profession would get me there more quickly, aerospace engineer or physicist. I remember anguishing with the decision, not really understanding the difference at age 16. In the end I straddled the line majoring in aero/astro engineering at MIT (class of 84) but taking many non-required physics electives and then continuing on to earn a PhD in physics at UIUC. It turns out that my aero class of 1984 had one of the largest enrollments in the history of MIT so I was not the only one who was impacted by Armstrong, Aldrin and Collins. How is being an engineer different from being a physicist? Having started my academic studies in engineering and moving over to physics I have a somewhat unique perspective into both.
The differences between engineers and physicists can be important if you are trying to build a great technical organization employing both. An understanding of how each is trained, how each thinks and works and is motivated can help explain seemingly eccentric behaviors, prevent culture clashes and help your teams to work more effectively. This short blog is written for the engineering manager trying to understand his or her team physicists or the physics manager trying to understand his or her engineering team or the MBA trying to make sense of both. It’s also written for the interested high school or college student struggling to understand the difference between the professions. It contains information I would have liked to have when I was entering college. I should also add that the differences between engineers and physicists become less pronounced at the higher degree levels with PhD’s in engineering and physics looking more similar. This is because they are both shaped by a similar PhD experience. The subtitle of this article could well be PhD’s vs. non-PhDs. As it turns out most of the physicists I know are PhDs and most of the engineers are not so my sampling may just be biased by my personal experience. Everything I write below is a generalization and there are of course numerous exceptions. Nevertheless I think there is truth in the broad categorizations I discuss and taken together they can be a useful guide.
1. Engineers ask “how”. Physicists ask “why”.
Engineers are more often interested in the “how” questions. How does an aircraft work? How does an engine operate? How do you make a radio? Physicists are more interested in the why questions. Why does the aircraft stay in the air? Why are heat, energy and temperature related? Why does light behave like a particle and a wave at the same time? A good example of this is the difference in the way thermodynamics is taught in engineering and physics. Thermodynamics is not usually a favorite class in most engineering programs. It is more often endured or just plain feared. Thermo is taught very practically in a way that intentionally masks the deeper underlying theoretical foundations. This is not a criticism but merely an observation. Engineers need to concern themselves with creating complex systems and processes. Physicists, less concerned with building complex systems, have more time to study simple systems thoroughly and go deeper into the basement of understanding. A good example is perhaps the differing notions of the meaning of entropy in Thermo. The physics equivalent of thermo is statistical mechanics, a topic filled with abstract methods and powerful analysis tools for the study of systems with a large number of particles (e.g. Stirling’s approximation, steepest descent integrals, statistical ensembles, stochastic differential equations, central limit theorem etc. The interested reader should pick up a copy of the classic text by Reif). The engineering treatment of thermo concerns itself with the practical applications of the subject and how it can be used. Physicists study the subject more abstractly seeking out general methods for dealing with very large systems.
Students who desire more depth in the why questions and prefer to study simpler systems in greater depth may be more comfortable in physics programs while those that are more interested in what they can do with or make with the understanding may be more natural engineers. Engineers are trained to build amazing and useful things using their understanding of the laws and relationships of the physical world as a given. Physicists are trained to seek out the answers to the why questions and generalize them into findings that can be applied broadly across many systems.
2. Engineers move from the general to the specific. Physicists move from the specific to the general.
Another way of saying this is that engineers like to build things and physicists like to take things apart. Both are very smart, creative individuals. Engineers express their creativity by constructing new and interesting things from general components of known function. Physicists study a specific complex system and apply creativity to reduce it to universal understandable components. In designing a new aircraft engineers make ample use of the laws of fluid flow and structural mechanics. They are deterministically applied to their systems, sometimes with heuristics or empirical approaches. They take the very general idea of Bernoulli’s principle for the relationship between a pressure and velocity in airflow or the equations of statics and dynamics and apply them to create mind bogglingly complex things like Airbuses and 767’s. Physicists will also study mechanics and fluid flow but they will do so with the goal of understanding something deeper about the laws of nature. Hamiltonian and Lagrangian mechanics for example is taught to physics undergraduates and later finds its place in the study of quantum mechanics through the analog of Poisson brackets. Engineering students will not typically see this approach to the subject unless they advance to the PhD level and then perhaps in the context of finite element methods. Physicists are trained to study problems deeply and identify patterns looking for clues to underlying structure and universal governing equations, trying to abstract general conclusions or find analogous problems they know how to solve. Engineers like to tease physicists who approximate everything with a ‘massless spring’ or a ‘sphere’. There is some truth to this. Physicists systematically reduce new problems to those they understand while retaining the key features that make the system unique.
Keep your physicists happy by allowing them time to explore generalizations and unifying principles. In the context of real work this may look like a study of seemingly disparate disciplines in search of a ‘sensed’ connection or perhaps in a coding example the development of an extensible general framework. Keep your engineers happy by giving them challenging complex systems to build. Allow them to express creativity through building. The most rewarding work people can have is that of creating. Making and animating something complex and new for the first time is deeply satisfying.
3. Engineers are trained to work together. Physicists are more likely to work alone.
Because they often build complex technologies, engineers need to work together and cooperate. The task is too big for any one person. In fact most engineering departments will have group project classes or so-called capstone classes. Teamwork is emphasized and encouraged early. At MIT the aero department was famous for their sophomore year curriculum known as Unified Engineering. In hindsight it’s a pretty ominous “Borg-sounding” title. Unified had 8AM classes Monday through Friday, quizzes every Friday and problem sets due every Monday. It was one of the few MIT classes that started at 8AM, considered inhumane by most college-aged. We were encouraged to work together and we forged friendships, many of which have lasted 30+ years. We knew everyone else in the department. There was a pride in being Aero/Astro, like you were part of something special. I also took many physics classes as an undergrad, many more than were required for my major and the experience could not have been more different. Physics majors worked alone for long periods and consulted periodically with others on a point of clarification or to check their work. “What did you get for problem 3?” was about the peak of collaborative effort. There was little sense of unity or camaraderie in physics. There was also more distance between students and professors who in physics were held in high and lofty regard. While still true in engineering, the professors were more personal and approachable, some were pilots and former military or worked as engineers before teaching and they shared their stories and personal experiences with us. It’s also interesting to look at the heroes of each profession. In engineering the heroes are frequently teams. For example, Lockheed’s famous skunk works group or the Apple Mac development team. Physics heroes are all iconic individuals, Einstein, Bohr, Fermi etc. Engineers are trained to work in teams to create great things, physicists are trained to work alone to develop an understanding of fundamentals. At SRT this has manifested itself in interesting ways. A simple example is in office layout. Physicists like individual offices and personal space. Engineers prefer a lab space and shared offices.
Working effectively in a team is a requirement in almost any worthwhile corporate endeavor. Be aware that your physicists are going to need some training and acclimation time to understand the value of and to work effectively in teams. Allow the opportunity for personal space and quiet areas. Engineers will more naturally adhere to the team environment.
4. Engineers make plans. Physicists embrace uncertainty.
The complexity of engineering projects and the finely tuned coordination of people and resource that is required for success demands attention to planning in the engineering profession at a scale that is unfamiliar and unappreciated by most physicists. The idea of regimented milestones and project management is completely foreign to the physicist schooled in a discovery driven research process. A physicist’s planning process can be summarized by i) work continuously until the problem is solved. ii) Goto step i). This is just fine if you are working independently towards a dissertation and degree but not so when other people are involved. The whole point of the PhD is to do independent creative work and receive the support and approval of your peers through the publication process.
The training process for physicists emphasizes discovery and embraces the unknown for that is where progress is made in deeper understanding. This is a process that has trouble fitting into a normal Gannt chart. It requires frequent course corrections where the current plan is ditched and a new one is formed. Many blind alleys are pursued before a profitable avenue is found.
Engineers prefer and require a plan with well-defined roles and goals. They are trained to execute plans in teams to create great and awesome things that delight and amuse. Physicists are more comfortable with uncertainty and amorphous goals. When your goals are not well defined, for example you are not exactly sure what you want to build or who your customer may be, the physicist’s approach and attitude has a lot of value. Physicists may have trouble understanding the value of a detailed plan and resist project management.
5. Engineers use math as a tool. Physicists enjoy math as an art.
Along with the progression of ideas above asserting the practical bent of engineering I also propose that engineers more often see math as a necessary and useful tool (which of course it is) while physicists are more likely to be captivated by the math. Physicists frequently use words like beautiful or elegant to describe a work of mathematics, a derivation or a particularly concise expression. The derivation of the classical action from Feynman’s path integral formulation, the Hamiltonian treatment of classical mechanics or the ensemble generation of statistical mechanics; all these and more quicken the heart of the physicist perhaps in the same way I like to think that great art, great architecture or great writing does to those that can appreciate it. These peak experiences, their explanation and understanding are what keeps young physicists motivated and moving forward for the promise of more. More often, the students that love the math gravitate to physics, those that tolerate it but know it’s an invaluable tool gravitate toward engineering.
As a team manager you may see your physics team members more easily distracted by mathematical diversions. They may be more concerned with closing up loose ends in the understanding of the problem as opposed to moving on to implementation. For students, if you find yourself enamored and drawn more deeply into the math you may find more satisfaction in a career in physics. If you like the math but you like what you can do with the math even more engineering may be a better fit.
In my company, Stone Ridge Technology, we have physicists and engineers working together and this has led to culture clashes at times. These have manifested themselves in office layout preferences, team composition and roles, engineers’ bristling over physicists’ relentless questioning, the value of analytical work and more. It’s a mistake to lump all technical people together as many do. There are different approaches to problem solving and technical work that have equal merit and this type of diversity is perhaps underappreciated in the workplace. At SRT I encourage a deep understanding of the problems we work on so I embrace the physics approach. We want to understand things ‘down to the metal’. But I also encourage teamwork and knowledge sharing across groups in the way that is common with engineers. Physicists can learn a lot from their engineering friends about how to work together effectively to accomplish great things and find a new dimension on which to enjoy work. Engineers can also learn from physicists and their relentless questioning in search of deeper understanding. Both are needed for success.