Imaginary interview with Max Planck
by Charactorium · Max Planck (1858 — 1947) · Sciences · 5 min read
It is in the grand salon of the house in Grunewald, one evening in the winter of 1929, that I meet my old friend Max Planck. The grand piano is open, the music stands still set with the scores we have just played — my violin rests beside his. We have known each other for over twenty years, ever since his quanta nourished my work on the photoelectric effect, and this evening I come less as a physicist than as a friend, to understand the man behind the formula. Outside, snow falls on the professors' quarter; inside, tea steams and Max is silent, as if before a confession.
—Max, we have just played Brahms, and you are pensive. Tell me at last: that December 14, 1900, what did you really feel before the Physical Society?
You, who took up my quanta before anyone else, deserve the truth, Albert. That day, I did not feel triumphant. I had struggled for six years against classical thermodynamics with no result, and I finally put forward this hypothesis like a man at the end of his rope. It was an act of despair. I cut energy into small portions because nothing else matched the measurements, but I considered it a provisional mathematical trick, to be erased as soon as possible. Before my colleagues, I spoke in a calm voice, as one announces a technical result. No one, myself first, understood that we had just buried Newtonian physics.
It was an act of despair: I had struggled for six years with no result.
—Explain to me, as to your student: what is this blackbody that occupied you so much, and why did the physics of the time lose its Latin over it?
Imagine a closed cavity, pierced with a tiny opening, that absorbs and re-emits all the light it receives: that is my blackbody. We wanted to predict the colors it radiates according to its temperature. But classical laws predicted an absurdity — infinite energy at high frequencies, which my colleagues called the ultraviolet catastrophe. Before my blackboard covered with equations, I sought a formula that exactly matched the Berlin measurements. I found it, but it required a new constant, my h. All of nature seemed to say that energy is not given in a continuous flow, but in grains. I did not believe it — and yet the numbers themselves did not lie.
Classical laws predicted infinite energy: the ultraviolet catastrophe.
—Put down your bow for a moment. When we play together, you at the piano, I on the violin, what does music bring to your scientific thought?
Music is not a relaxation for me, Albert, it is the other side of rigor. When we tune our instruments as this evening, I rediscover that hidden order that I track in my equations — a harmony that is not demonstrated but experienced. At the piano, I do not have to convince skeptics, I only have to listen. In the evening, after calculations, I also read Kant, for he helps me believe that nature obeys laws independent of us. I am convinced that science seeks an objective reality, which exists whether we look at it or not. Music gives me a presentiment of it; mathematics, the proof.
Music is not a relaxation: it is the other side of rigor.
—This constant h, you long considered it provisional. Today, do you hold it as a truth of nature, or do you still regret it?
I fought it, I confess, as one fights an idea one has oneself reluctantly engendered. For years I tried to reconcile it with classical physics, to dilute it into the continuum — in vain. It was you, in 1905, who opened my eyes by daring what I did not dare: to take quanta seriously even in light itself. h sets a limit to the indivisibility of natural processes; below it, the world is no longer ours. Today I no longer regret it. I hold it as a fundamental quantity, as real as the speed of light. But it took me twenty years to love it.
I fought this constant as one fights an idea one has oneself engendered.
—My friend, forgive me for touching your wound. Since the war took your Karl in 1916, how do you still find the strength to work?
You ask the question no one else would dare, and that is why I can answer it. Karl fell at the front, then my twin daughters died in childbirth, one after the other, two years apart. Each time, I thought I would not get up again. And yet I returned to my desk, because work is the only prayer I have left. Physics does not console, but it imposes order when everything inside me is in ruins. I believe a man must fulfill his task to the end, without asking whether heaven is just. The numbers, for their part, await me without pity or compassion — and that silence saved me.
Work is the only prayer I have left.
—Do you remember when you first received me here? You still doubted your quanta. Where did that distrust of your own work come from?
I remember it perfectly, Albert — you were far bolder than I. My distrust came from my temperament: I am peaceful by nature and I shrink from dubious adventures in science. All my training had taught me continuity, the uninterrupted flow of energy; breaking that seemed almost indecent to me. I felt I had committed a sin against the physics I loved. So for years I tried to plug the breach I had opened. It was you who made me understand that the breach was the door. Without your youth and audacity, I might have buried my quanta like a bad dream.
I felt I had committed a sin against the physics I loved.
—You preside over our Kaiser Wilhelm Society and you see threats rising against our colleagues. What duty does your conscience dictate in these troubled times?
I bear this presidency as a burden, not an honor, Albert. The Kaiser Wilhelm Society coordinates all German research; it must remain a refuge for the free spirit, whatever happens. I believe a scholar has a duty to his country, but an even higher duty to truth and to his peers. If one day the best among us were driven out for what they are and not for what they are worth, it would be German science itself that would be mutilated. I would then strive to intercede, to plead, to hold back what can be held. I am not a man of barricades — but I will not desert my post.
A scholar has a duty to his country, but a higher duty to truth.
—When you teach in the afternoon in Berlin, how do you make young minds understand that energy rises in steps, not in a gentle slope?
I tell them to forget the ramp and imagine a staircase. The energy of a resonator, I consider it as composed of a whole number of equal parts — you cannot take half of one, any more than you can step on a half-step. It is counterintuitive, I admit, for our senses never perceive these grains: they are too tiny, measured by my h, a number of dizzying smallness. At our scale, the staircase seems a smooth slope. But in the intimacy of the atom, the steps reappear. I love to see the students' eyes widen at that moment: they touch with their fingers that reality is stranger than anything common sense whispered to them.
Forget the ramp and imagine a staircase: you cannot step on a half-step.
—You who read Kant in the evening, tell me: do you truly believe, as you write, that nature exists independently of the observer?
I firmly believe it, and this is undoubtedly our oldest debate, Albert. For me, the external world is real, autonomous, prior to any observation; our task is to approach it, never to fabricate it. A law of nature does not become true because we measure it — it was true before us and will remain true after. This conviction I owe as much to Kant as to my years in the laboratory. It protects me from vertigo: if everything depended on the observer, science would be only a game of mirrors. I prefer to think that we climb, step by step, toward a truth that awaits us. We will never fully reach it — but it is there.
A law of nature does not become true because we measure it.
—Before we take up our bows again, Max: what would you say to a young person whom pain or doubt tempts away from science?
I would first tell him about my old professor in Munich, who advised me against physics because everything, he said, had already been discovered. I replied that I was not seeking the glory of great discoveries, but only to deepen what was already known. See where that humility led me despite myself. So I would say to this young person: do not chase revolution, simply do your work with accuracy, day after day. Truth lets itself be found by the patient, not the hasty. And when pain strikes — for it will strike — let him lean into his task as one clings to a handrail. That is how I held on, and how I still hold on.
Do not chase revolution: do your work with accuracy, day after day.
This imaginary interview was generated by artificial intelligence from sources documented in Max Planck's profile. It dramatises what the figure might have said based on what we know about them, but does not constitute attested historical testimony. For primary sources and factual documentation, refer to the full profile.