Eugene Paul Wigner (1902–1995) – born in Budapest, later an American theorist, one of the most important architects of the mathematical quantum mechanics of the 20th century. Nobel Prize in Physics 1963 for the application of symmetry principles to the physics of the atomic nucleus and elementary particles. Co-architect of the Manhattan Project (construction of the Hanford reactor with Leo Szilard), Princeton professor for 33 years, brother-in-law of Paul Dirac. Wigner's contribution to our series: in 1961, in a 14-page essay, he made consciousness an unavoidable component of the foundations of quantum mechanics – and with the thought experiment "Wigner's Friend" he gave the measurement problem a sharpening that is still discussed today.
Who was Eugene Wigner?
Wigner was born in 1902 as Wigner Pál Jenő in Budapest – part of that extraordinary generation of Hungarian-Jewish scientists which also included John von Neumann (a schoolfriend and lifelong friend), Leo Szilard, Edward Teller and Theodore von Kármán. He studied chemical engineering at the Technical University Berlin, took his doctorate in 1925 under Michael Polanyi, and briefly worked on the first applications of group theory to the still young quantum mechanics.
In 1930 he moved to Princeton, from 1937 with American citizenship, from 1938 as Professor of Mathematical Physics at Princeton University – a position he held until his emeritation in 1971. His sister Margit ("Manci") Wigner married the British quantum physicist Paul Dirac in 1937; the two brothers-in-law remained close until Dirac's death in 1984.
Scientific achievements
Wigner's main work is the introduction of group and symmetry principles as a systematic tool of quantum mechanics. Anyone studying physics today encounters his name in almost every textbook index:
- Wigner function – the quasi-classical phase-space representation of quantum-mechanical states (1932).
- Wigner-Eckart theorem – the central structural statement about matrix elements in angular-momentum algebra.
- Wigner-Seitz cell – a basic building block of modern solid-state physics.
- Wigner crystal – the theoretical prediction of an electron crystal from the late 1930s.
- Application of group theory to nuclear spectroscopy – the basis of the 1963 Nobel Prize.
In 1939 Wigner wrote, together with Leo Szilard, the famous Einstein-Szilard letter to President Roosevelt, which led to the establishment of the Manhattan Project. Wigner himself was later substantially involved in the construction of the large plutonium-production reactor in Hanford (Washington). After the war he remained a physicist, but also a deliberate moral voice: a lifelong engagement in the Pugwash movement, in the control of nuclear weapons, in scientific ethics.
"Remarks on the Mind-Body Question" (1961)
In 1961 an essay by Wigner appeared in the volume The Scientist Speculates, edited by I. J. Good, with the title Remarks on the Mind-Body Question. On 14 short pages Wigner argues for an unusual but strictly quantum-mechanically derived thesis: consciousness cannot be operated out of quantum mechanics. It is part of the physical measurement process, and not as an afterthought, but as that step at which the superposition of possible measurement results passes into an actual observation.
The argument builds on an observation by John von Neumann (1932): quantum mechanics knows no physical point at which the wave function would "by itself" collapse. Every possible measuring apparatus can itself be described quantum-mechanically, including the observer – the chain theoretically runs to infinity. Wigner draws from this the conclusion that von Neumann himself had only suggested: somewhere the chain must end, and the only non-physically-describable endpoint is the conscious experience of the observer. Consciousness is therefore, physically speaking, not a belated epiphenomenon but a constitutive component of what we call "reality".
"Wigner's Friend" – the thought experiment
To sharpen this thesis, in the same essay Wigner formulates a thought experiment that has by now entered every textbook of quantum-mechanics foundations as "Wigner's Friend":
Wigner sits outside a laboratory door. Inside the laboratory his friend sits in front of a quantum-mechanical apparatus and measures, for instance, the spin of an electron. From Wigner's perspective – as long as he does not know what his friend has measured – he must describe the entire system "friend + measuring apparatus + electron" as a superposition of all possible measurement outcomes. His friend, however, subjectively experiences an unambiguous specific result.
Who is right? If quantum mechanics holds for all physical systems, Wigner would have to describe his friend consistently as a superposition – that is, in a sense as "in two states of consciousness at the same time". This is plainly absurd if one takes consciousness as a real phenomenon seriously. Wigner's conclusion: there must be a real physical asymmetry between the observer with consciousness and the system without consciousness. Precisely this asymmetry is what standard quantum mechanics does not capture.
"It was not possible to formulate the laws of quantum mechanics in a fully consistent way without reference to consciousness."
— Paraphrase of a core statement by Eugene Wigner in "Remarks on the Mind-Body Question" (1961)
Wigner's later position
In the late 1970s and 1980s Wigner modified his position in part. After intensive discussions with the Polish-American physicist Wojciech Zurek and engagement with the emerging decoherence theory (Zeh, Zurek, Joos), he conceded that some of what he had attributed to consciousness in 1961 could also be explained by objective decoherence – that is, by the unavoidable interaction of macroscopic systems with their environment.
Remarkable, however: Wigner never officially withdrew his original thesis. He was methodologically honest enough to acknowledge an alternative explanatory line as possible, but he did not recant his 1961 position. The "Wigner's Friend" thought experiment has not only been preserved – in 2018/19 the Frauchiger-Renner theorem brought it into a new, mathematically sharpened form, which today is among the most-discussed foundational results in quantum mechanics.
Relation to mediumship and psi research
Wigner was – like Hans-Peter Dürr in our series – not a parapsychologist. He did not conduct sittings with mediums, did not comment publicly on the survival hypothesis, did not adopt a survival position. But he did something related: he introduced consciousness as an independent factor, not reducible to physical apparatus, into quantum mechanics. He thereby created the theoretical frame within which phenomena like non-local states of consciousness, quantum cognition or today's quantum-consciousness models (Penrose-Hameroff, Pribram, Stapp) can be discussed at all.
Wigner belongs in our series as the physicist who in the 20th century secured for consciousness its physically defended place against naturalistic reductionism. That is methodologically a preparatory work for any serious mediumship research, even if he himself did not draw that connection.
What remains
- Maximum professional physical authority. Nobel Prize 1963, co-architect of quantum field theory and of the application of group theory to physics, Princeton professor for 33 years. Wigner's 1961 essay is not the hobby of an outsider but the statement of one of the most important mathematical physicists of the 20th century.
- Consciousness as a quantum question. With Wigner consciousness becomes for the first time systematically a part of the foundations discussion of quantum mechanics. This shift has paved the way for today's quantum-consciousness models and stands in a line with Pauli's unus-mundus thesis and Hans-Peter Dürr's "There is no matter".
- Wigner's Friend as a lasting tool. Sixty years after the original formulation, "Wigner's Friend" is one of the most intensively discussed foundational problems of quantum mechanics – currently extended in the Frauchiger-Renner theorem (2018) from ETH Zurich.
- Intellectual honesty. Wigner later modified his position in part without retracting it. He acknowledged decoherence theory as an alternative explanatory line, without declaring the original consciousness thesis nonsense. That is methodological maturity.
Wigner belongs in the historical line we are tracing on this site: Kepler, Crookes, the Curies, Lodge, Rayleigh, J. J. Thomson, Jung, Pauli, Einstein, Rhine, PEAR, Josephson, Dürr. Among them he is the one who inscribed consciousness directly into the mathematical structure of quantum mechanics – not as speculation, but as a logical consequence of the measurement process.
Sources
- Eugene P. Wigner: Remarks on the Mind-Body Question. In: I. J. Good (ed.), The Scientist Speculates. An Anthology of Partly-Baked Ideas. Heinemann, London 1961, pp. 284–302.
- Eugene P. Wigner: Symmetries and Reflections. Scientific Essays. Indiana University Press, Bloomington 1967 – contains the Mind-Body essay and other philosophical pieces.
- Eugene P. Wigner: The Unreasonable Effectiveness of Mathematics in the Natural Sciences. Communications on Pure and Applied Mathematics, Vol. 13 (1960), pp. 1–14 – Wigner's best-known philosophical essay.
- Andrew Szanton: The Recollections of Eugene P. Wigner. As Told to Andrew Szanton. Plenum, New York 1992 – the official autobiography.
- Daniela Frauchiger & Renato Renner: Quantum theory cannot consistently describe the use of itself. Nature Communications, Vol. 9 (2018), article 3711 – the modern extension of "Wigner's Friend".
- John von Neumann: Mathematische Grundlagen der Quantenmechanik. Springer, Berlin 1932 – the theoretical precursor of Wigner's argument (chapter on the measurement process).