Physicists
Explanation
The Joke
A physicist claims they can solve any problem in any field because everything reduces to physics. They are then presented with an actual problem from biology, economics, or social science, and their "physics approach" (assume a spherical cow, ignore friction, etc.) produces a hilariously wrong and useless answer.
The Humor
The comic skewers "physics imperialism" — the tendency of physicists to believe their tools and methods can be applied to any domain. While physics is foundational in one sense, treating a complex biological or social system the same way you'd treat a frictionless plane leads to absurd oversimplifications. The "spherical cow" reference is a classic physics joke about the discipline's love of simplifying assumptions.
Context
The tension between physics and other sciences is a real cultural phenomenon in academia. Physicists who move into biology, economics, or social science sometimes bring a reductionist toolkit that ignores important domain-specific complexity. The comic is a knowing joke from someone (Weinersmith) who has a physics background but clearly appreciates the limitations of the approach.