Heisenberg: My Uncertainty Principle Is Not In Conflict With a Unified Field Theory, Linking His Great Work With the Pursuit of Einstein and 20th Century Scientists

He predicts that a Unified Field Theory will be found and "will take a very central place in Physics"

Werner Heisenberg was a German physicist who helped make monumental advances in the field of Quantum Mechanics, a study within physics that analyzes the movements of atoms, photons and other exotic, invisible matter.  He is known as one of the great scientists of the 20th century, primarily due to the development of his Uncertainty Principle, today called simply Heisenberg’s Uncertainty Principle. Simply put, it states that the more precisely the position of some particle is determined, the less precisely its momentum can be known, and vice versa.  This puts a natural limit on the specificity of calculations.  For his work in quantum mechanics, Heisenberg won the 1932 Nobel Prize.

The great movement within physics in the mid to late 20th century onward has been the creation of one equation to define the actions of all matter, a universal physical truth that would underlie the diverse scientific fields. This was often called the Unified Field Theory or the World Equation.  Einstein labored unsuccessfully on this issue until his death and scientists today continue to grapple with it. One issue that scientists struggled with was the surprisingly complex and unpredictable state and movements of electrons within some atoms, among them iron.

In the aftermath of the Second World War, Heisenberg, as many scientists of the era, was drawn into the debate over nuclear weapons, and along with 17 other scientists signed a 1957 manifesto arguing against the arming of West Germany with nuclear weapons. Some controversy surrounded Heisenberg’s activities during the war, as he was leader of the Nazi atomic bomb program.

John Lukacs is a Jewish, Hungarian-born historian and philosopher who carried on extensive correspondence with some of the literary and scientific men of the 20th century.   He wrote to Heisenberg, questioning whether his Uncertainty Principle ruled out the eventual creation of a Unified Theory, or “World Equation,” as he puts it.

Typed letter signed, on his Max-Planck-Institut Fur Physik letterhead, in German with a translation, Munich, October 29 1963, to Lukacs, defining the nature of quantum mechanics and its relation to the Uncertainty Principle.  “Dear Mr. Lukacs, I am still interested in your manuscript concerning “History and Physics”, and I would be very pleased if you could occasionally send me a copy [or: proof/print]. I will gladly answer the other questions in your letter in the order they appear in:

1. In the spring of 1957 a statement was published by 18 physicists who had assembled in Göttingen. I am including the text of this statement in this letter. To the best of my knowledge none of the signers of the statement has changed his opinion.

“2. It is a fact that in the time after the war I met with Ortega y Gasset [liberal Spanish writer and philosopher] on many occasions, the last time at the home of mutual acquaintances in Munich. Unfortunately, I can not determine in which year this last gathering took place.”

Heisenberg goes on to define the fundamental nature of quantum mechanics and its relation to his Uncertainty Principle

“3. I myself have never used the term “Weltgleichung” [world equation]. I spoke of either the 'standardized field theory of sub-particles' [elementary particles], or, using a more technical term, of the non-linear Spinor theory of elementary particles.  It [a Unified Field Theory] is, in my opinion, not at all a matter of something unusual or extravagant, but it is rather a matter of the normal continuation of physics, which has developed in the last few decades. From the physics of the atomic shell, we know, that on the one hand there are very complicated spectra of stationary conditions of an atomic shell (for example that of the iron atom), but that one can, on the other hand, easily represent the entire spectrum mathematically through quantum mechanics or through the Schrödinger Equation or the non-linear wave equation of Klein-Jordan-Wigner and so forth [equations that describe the quantum state of a physical system and allow the analysis of atoms]. All of these mathematical representations are equivalent and already contain the uncertainty principle and all that is connected with it in terms of philosophical consequences. For more than ten years one has known that there exists such a complicated spectrum of elementary particles and that it is, therefore, the task of theoretical physics, to find a mathematical formulation, from which this spectrum will follow in the same way the iron atom follows from the Schröder-Equation. The so-called “Weltgleichung” [world equation] is simply an attempt at this mathematical formulation; whether it will succeed, will be determined in succeeding years through mathematical development and experimental results. In the meantime, neither the mathematical consequences, nor the experimental facts are available.

"When the time comes that this mathematical formulation for the theory of elementary particles is determined, no matter if they can be attributed to the still relatively simple field theoretical form, as I have tried to do it, or whether one needs still more abstract mathematical resources, at that point one will be able to call it a mathematical world formula, because it will take a very central place in Physics. It is simply an empirical fact that in the physics of elementary particles, the various laws of nature (for example the electro magnetic or the chemical or the atomic physical etc) have their common roots. The uncertainty principle is always a part of such mathematical formulations.

"Therefore, I do not see how a conflict could arise between the uncertainty principle and such a mathematical formulation. In particular, I do not see, why, given this, – as you have written-  one could fall back to the train of thought of the 19th century. But perhaps you could explain that to me in a more specific way. W. Heisenberg”

This letter was acquired directly from Lukacs and has never previously been offered for sale.  It is evidently unpublished.