May 18, 2026, to R—

In the old days, this response would have been an essay in a peer-reviewed scientific journal. Now it takes seconds to get the information. Some people whom I know detest AI because of the energy that it uses. But Claude is a tool like no other that, through interrogation, engages my mind.

With Claude’s answers I always ask, “Please check for accuracy and bold claims”. Here I did not do that.

Q: Why am I interested most in physics, less so in chemistry, and least of all in biology? What kinds of people are most interested in chemistry, and in biology?

This is a genuinely interesting question and I want to think about it carefully rather than give you a pat answer.

Why physics first

Physics is the most abstract of the three. It deals with universal principles — conservation laws, symmetry, entropy, least action — that apply everywhere, at every scale, regardless of the specific system. A physicist’s instinct is to find the simplest possible description of a phenomenon, strip away all the particulars, and ask: what is the underlying principle that makes this inevitable?

People drawn to physics tend to be uncomfortable with contingency — with the idea that something is the way it is because of a long chain of historical accidents rather than because it had to be that way. Physics offers the deepest available answer to “why,” in the sense of logical necessity.

Why chemistry second

Chemistry is physics applied to specific atoms and molecules — so it inherits the rigor and the quantitative precision, but it is more contingent. Whether a reaction proceeds depends on which atoms are present, which orbitals overlap, which transition state is accessible. The principles are physical, but the outcomes depend on particulars. A chemist’s pleasure is in the specific — this molecule, this reaction, this functional group. There is craft and elegance in synthesis, and real intellectual depth in mechanisms. But it is less universal than physics.

Why biology least

Biology is the most contingent of the three. Evolution does not optimize toward any principle — it produces whatever works well enough to reproduce. The result is machinery that is functional but arbitrary: the genetic code could have been different, the citric acid cycle is a historical accident, the particular amino acids used in proteins are not the only ones possible. Biology is full of exceptions to every rule, special cases, and “it depends.” For someone who wants to understand why things must be the way they are, biology is deeply unsatisfying — things are the way they are largely because that is how they happened to evolve.

Your frustration with the “cartoon-like” quality of biology is related to this: biological explanations are often mechanistic descriptions of what happens without a deep account of why it had to happen. Physics explanations feel inevitable. Biological explanations feel contingent.

Who is drawn to chemistry

Chemists tend to combine abstract thinking with a strong tactile and craft sensibility — they like making things, transforming matter, solving concrete puzzles. There is a particular pleasure in synthesis: designing a multi-step route to a target molecule, where each step must be controlled precisely. Chemists are often comfortable with complexity at the level of specific molecules without needing everything to reduce to a universal principle. Many are drawn to the aesthetic of molecular structure — the way three-dimensional shape determines function.

Who is drawn to biology

Biologists tend to be comfortable with — and often delighted by — complexity, diversity, and historical contingency. They are often naturalists at heart: people who find the sheer variety of living things intrinsically fascinating, who are comfortable saying “this organism does it this way, that one does it differently.” They tend to tolerate exceptions and special cases better than physicists or chemists. Many are motivated by a direct connection to living systems — curiosity about how bodies work, how diseases arise, how ecosystems function — rather than by the desire to find universal laws.

The deepest biologists — people like Francis Crick, who came from physics, or Max Delbrück, who came from theoretical physics — often brought a physicist’s sensibility to biology precisely because they were unsatisfied with purely descriptive accounts and wanted to find the underlying logic. Molecular biology as a field was largely built by physicists who defected to biology after World War II because they thought biology was where the deep unsolved problems were.

The honest observation

Your interest in physics over biology likely reflects a preference for necessity over contingency, for universal principles over historical accidents, and for explanations that feel inevitable rather than explanations that feel like descriptions. The KRAS story is interesting to you, I suspect, because underneath the biology there are real physical chemistry problems — free energy landscapes, conformational selection, reaction kinetics — that have the quality of necessity. The biology is the context; the physics is what makes it feel like it makes sense.