Physics — both conceptual and applied — is struck by an almost cult‑like taboo: the unknown.
It must never be mentioned. As if simply pronouncing the word could crack the walls of laboratories or make equations tremble. In contemporary physics, the unknown is not a territory to explore, but an intruder to eliminate. It is bypassed, disguised, covered with a mathematical varnish so that it looks like something familiar. It is renamed parameter, field, boson, constant, energy — anything, as long as it stops being what it is: a hole in understanding. This refusal of the unknown has become a tradition. A habit. A way of saving appearances.
Yet the unknown is not an enemy.
It is the only honest thing in this whole story. It is what the universe shows us when it refuses to bend to our models. It is what remains when equations stop working. It is the raw voice of reality, the one we never listen to because it does not speak the language of textbooks. This reading begins precisely there: not in certainty, but in the unknown. Not in models, but in what the universe says when we stop imposing words it never uttered. Not in frameworks, but in behaviors. Not in equations, but in evidences.
This visceral reluctance to evoke the fundamental, the metaphysical, or even the divine appears at the very beginning of the 20th century, with the Solvay figures:
- Niels Bohr, who repeatedly insisted that there is no quantum world — only descriptions of measurement results. For him, quantum mechanics does not describe what exists but only what can be said about experiments. Any attempt to speak of a reality existing before or independently of observation was declared meaningless.
- Werner Heisenberg, who claimed that concepts such as trajectory, position, or path have no reality before measurement. According to him, quantum mechanics describes knowledge — not objects. Properties are not elements of the world — they are created in the act of observation.
- Wolfgang Pauli, who rejected any attempt to describe what exists behind the formalism. He maintained that quantum mechanics is a theory of knowledge — not a theory of nature. Questions about what is “really there” were, for him, metaphysical — and therefore illegitimate in physics.
- Richard Feynman, who insisted that no one understands quantum mechanics and that trying to understand what “really happens” is a mistake. The theory is a tool for calculating probabilities — not for describing being. He repeated that quantum behavior is absurd and must be accepted without seeking an underlying reality.
- John Wheeler, who pushed operationalism to its extreme. A phenomenon is not a phenomenon until it is observed. He defended a participatory universe in which the observer plays a constitutive role in the very existence of events.
- Steven Weinberg, who openly acknowledged that standard quantum mechanics is instrumentalist — and fundamentally empty. The formalism works — but it does not say what exists. He considered this lack of foundation deeply unsatisfying and a sign that the theory is incomplete.
- Carlo Rovelli, who argues that physical systems have no properties in themselves. Properties exist only in interactions. There is no state of a system independent of the observer. Reality dissolves into a network of relational events.
- Sean Carroll, who emphasizes that standard quantum mechanics does not specify what exists, and that this silence is a major conceptual problem. He argues that only Everett’s interpretation provides a coherent ontology, because it treats the wave function as the real physical entity.
- David Deutsch, who maintains that the orthodox interpretation is logically inconsistent precisely because it refuses to describe reality. For him, quantum mechanics makes sense only if one accepts the existence of the multiverse; otherwise, the theory collapses into contradiction.
So many beautiful theories, often presented as the domain of hard‑core physicists — those who claim to know and predict. But above all, those who forget that the unknown, divine or not, remains unknown, and that by avoiding naming it, physicists have forgotten that the role of God was to stand in for the unknown, the mystery of life and of the planet that hosts us, for better or (mostly) for worse. And because one does not believe in it, suddenly should the unknown disappear? One becomes a physicist thanks to a paper diploma and right away feels entitled to ignore the mystery, to mathematicize it, to concretize it, calculate it to the point of forgetting what it is?
To be afraid of expressing the fundamental nature of quantum mechanics is, in a way, to deny the fragility and improbability of Man; to forget that, like Papillon on his island, he is a prisoner of a planet drifting through a terrifying void, and that if he tried to escape it, the absence of air would extinguish him like an ordinary candle running out of wax.
Denying the mysterious origins of humanity is forgetting that science itself was born from wonder — and that wonder, without mystery, no longer has any reason to exist. It is a little like spitting into the hand that feeds you. Mystery is the true master aboard the ship of the universe.
You should never forget that, gentlemen physicists, wherever you may be and wherever you may come from.
Just before this negationist current of the unknown took hold, Einstein could still say that "God does not play dice" to evoke randomness. It wasn’t yet a crime. We could push the philosophical cork even further: How can we imagine that a universe about which we know absolutely nothing could create what we experience and what we are without leaving its mark, its DNA, its fingerprint? Even the simplest potter leaves their touch on the clay. It’s difficult to imagine that objects come from nowhere and to confuse quantum mechanics with a local anomaly, never considering that it might be the signature of the sculptor — God for some, the universe or the unknown for others.
One way or another, there exists an underlying generative principle, whether its detractors approve of it or not.
Yes, whenever we speak of physics, we must never forget — never, under any circumstances — that physics has always been nourished by metaphysical questions. From Leibniz to Laplace to Einstein, its greatest advances have emerged from reflections that reached beyond the merely measurable, while the Earth continues to drift aimlessly through a universe as strange as its Moon and its Sun.
Physics was born of metaphysics, and it will return to it once these fleeting evolutionary interludes of flora, fauna, and humanity have come to an end.
The wise will understand.