On why physics is not about how nature is
It is wrong to think that the task of physics is to find out how Nature is. Physics concerns what we say about Nature.— Niels Bohr
There is a sentence that quietly dissolves a century of misunderstanding about modern physics, and it is not a technical one. It does not mention wavefunctions, observers, or uncertainty. It simply denies that physics ever had the task we keep assigning to it.
Physics, Bohr tells us, is not in the business of discovering how nature is. It is in the business of articulating what can be said about nature under specific conditions.
This sounds, at first hearing, like an evasion. If physics does not tell us how the world is, what exactly has it been doing all this time? But the discomfort here is revealing. We are so accustomed to treating successful theories as mirrors of reality that we mistake the withdrawal of that mirror for intellectual cowardice. Bohr’s claim is not modest. It is surgical.
To take it seriously is to abandon a picture of physics as description and replace it with a picture of physics as articulation.
The trouble with description
The classical image of science is deceptively simple. The world is made of things. Those things have properties. Physics discovers those properties and records them, ideally in mathematical form. Language and mathematics are treated as transparent media: imperfect, perhaps, but aiming at faithful representation.
Modern physics did not overthrow this image by accident. It broke because it could not survive contact with its own success.
At atomic scales, the familiar descriptive vocabulary fails. Particles behave like waves; waves behave like particles; entities refuse to stay entities. Attempts to preserve description lead to contradiction, not insight. Something has gone wrong, but it is not merely empirical.
Bohr’s response was not to invent stranger objects, but to rethink what physics is doing at all. When he says that language can be used only as in poetry when speaking of atoms, he is not indulging metaphor. He is naming a constraint.
Poetry does not describe facts in the way a ledger does. It works by controlled indirection. Meaning arises from relation, context, and use, not from literal correspondence. To say that atomic language is poetic is to say that it is disciplined without being representational, precise without being pictorial.
This is why Bohr insists that physics concerns what we say about nature. Not because nature is unknowable, but because saying is the only mode of access physics has.
Mathematics is not waiting for us
Arthur Eddington makes the same point from a different angle:
The mathematics is not there till we put it there.
This is often misread as a flirtation with subjectivism. It is nothing of the kind. Mathematics is not arbitrary, but neither is it discovered like a fossil embedded in the world. Formal systems are acts of construction, constrained by coherence, applicability, and use.
If mathematics were simply “there,” then its astonishing effectiveness would be unremarkable. The fact that it must be put there—chosen, stabilised, extended—while remaining uncannily effective is precisely the puzzle.
What physics does, then, is not to read equations off reality, but to install formal structures that allow certain regularities to be articulated. The success of those structures is real. Their ontological innocence is not.
Max Born’s remark that theoretical physics is actual philosophy is best read in this light. Physics performs philosophical work whether or not it acknowledges it. It decides what counts as an object, what counts as a law, and what counts as an explanation. It simply does so under the cover of calculation.
Concepts with expiry dates
Werner Heisenberg adds a crucial constraint:
Every word or concept, clear as it may seem to be, has only a limited range of applicability.
This is not a complaint about vagueness. It is a warning against overreach. Concepts fail not because they are unclear, but because they are taken beyond the situations in which they function.
“Particle,” “wave,” “position,” “trajectory”—these did not become meaningless in quantum physics. They became local. Their applicability narrowed. Treated as universal descriptors, they generate paradox. Treated as context-bound tools, they regain precision.
This is a decisive shift. Meaning is no longer guaranteed by reference alone. It is secured by conditions of use. Physics advances not by perfecting descriptions, but by learning where its concepts hold and where they do not.
What survives the collapse
To say that physics is not descriptive is not to say that it is fictional, conventional, or unconstrained. The world pushes back. Experiments fail. Predictions break. Not everything can be said.
But what survives is not a mirror of reality. What survives is a practice of articulation—language, mathematics, and method braided together—that produces stable, repeatable ways of speaking with the world rather than about it from nowhere.
Once this is acknowledged, a deeper problem emerges. If physics does not describe nature, then the objects of physics—the phenomena it studies—cannot be pre-given either. They must arise within the very acts of articulation physics performs.
That discovery forces the next step.
In the next post, we will follow physics as it crosses a more dangerous threshold: the realisation that observation is not passive, and that phenomena are not things waiting to be seen, but events that come into being at the intersection of world and method.
Description collapses. Something else is born.
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