David Bohm
David Bohm | |
|---|---|
| Born | December 20, 1917 Wilkes-Barre, Pennsylvania, United States |
| Died | October 27, 1992 London, England |
| Nationality | American / British |
| Known for | Causal (hidden-variable) interpretation of quantum mechanics, Quantum potential, Implicate order, Aharonov–Bohm effect, Bohm diffusion |
| Scientific career | |
| Fields | Physicist |
David Joseph Bohm (December 20, 1917 – October 27, 1992) was an American-born theoretical physicist whose work stands as the most fully developed alternative to the orthodox Copenhagen interpretation of quantum mechanics. In 1952 he constructed a causal, deterministic account of quantum theory in which particles follow definite trajectories guided by a real physical field — demonstrating that the "hidden variables" the physics establishment had declared impossible were not impossible at all.
Bohm's career is a case study of how unorthodox physics is received. He was driven out of the United States by the anti-communist purges, spent the rest of his life in exile, and saw his interpretation ignored for decades despite making the same experimental predictions as the orthodoxy. His work is nonetheless the direct ancestor of Bell's theorem and of the modern field of quantum foundations.
Early life and education
Bohm was born in Wilkes-Barre, Pennsylvania, in 1917. He studied at Pennsylvania State College and then at the University of California, Berkeley, where he completed his doctorate under J. Robert Oppenheimer and worked on plasma physics — the field in which the effect now called Bohm diffusion bears his name. He went on to a faculty position at Princeton University, where he wrote the well-regarded textbook Quantum Theory (1951), a careful exposition of the orthodox view that he came to doubt in the course of writing it.
HUAC and exile
In the McCarthy era Bohm was summoned before the House Un-American Activities Committee and refused to testify against colleagues. He was arrested in December 1949 on a charge of contempt of Congress. Although he was acquitted, Princeton had already barred him from campus and declined to renew his contract.
Despite being a leading authority on plasma physics, Bohm could find no academic post in the United States or Europe. He emigrated to the University of São Paulo in Brazil, and later worked in Israel before settling in England at Birkbeck College, London, where he remained until his death in 1992. His landmark hidden-variable papers were written and published in the first years of this exile.
The causal interpretation
In two papers of 1952, Bohm set out what he first called a hidden-variable theory and later the causal or ontological interpretation. In it, a particle is a real object with a definite position and trajectory at all times, guided by its wave function acting through a quantum potential. Measurement reveals pre-existing properties rather than creating them; there is no collapse of the wave function, and no need for an observer to bring reality into being.
The theory reproduces all the standard predictions of quantum mechanics. Its significance was therefore not empirical but conceptual: it showed that the indeterminism and observer-dependence of the Copenhagen interpretation are interpretive choices, not consequences of the evidence.
This mattered because John von Neumann's 1932 "impossibility proof" was widely held to have ruled out hidden-variable theories altogether, and had been used for two decades to foreclose the question. Bohm's construction was a working counterexample. The philosopher Grete Hermann had in fact identified the flaw in von Neumann's argument as early as 1935, but her critique was overlooked; the defect was independently rediscovered and made widely known by John Stewart Bell, who wrote that Bohm had shown explicitly what had been declared out of the question. Bell's own celebrated work on non-locality grew directly out of engaging with Bohm's theory.
The price of the theory — and the point on which mainstream physicists most often reject it — is that it is explicitly non-local: the guiding field connects distant particles instantaneously. Proponents reply that Bell's theorem subsequently showed that any theory reproducing quantum predictions must be non-local, so Bohm's model makes explicit a feature the orthodoxy merely conceals.
Implicate and explicate order
In his later work Bohm moved beyond interpretation toward a broader account of nature, set out in Wholeness and the Implicate Order (1980). He proposed that the manifest world of separate objects — the explicate order — unfolds from a deeper, undivided implicate order in which everything is enfolded in everything else. This holistic conception was intended to replace the fragmentation he regarded as endemic to modern science and thought, and it brought him an audience well beyond physics, including his long dialogue with the philosopher Jiddu Krishnamurti.
Other contributions
With Yakir Aharonov, Bohm predicted in 1959 the Aharonov–Bohm effect, in which a charged particle is measurably affected by an electromagnetic potential in a region where the fields themselves vanish — demonstrating that potentials are physically real rather than mere mathematical conveniences. He also made lasting contributions to plasma physics, including Bohm diffusion, and to the theory of metals with the Bohm–Pines treatment of plasmons.
Reception
For decades Bohm's interpretation was largely absent from textbooks and teaching, and it remains a minority position. Critics judge it superfluous, since it makes no distinct predictions, and object to its non-locality and its privileged particle positions. Its defenders — and the critical tradition documented on this wiki — regard the neglect as revealing: a self-consistent, empirically adequate alternative was set aside less on evidence than on the authority of a proof that turned out to be flawed, and against a background in which its author had been made professionally untouchable.
On this wiki
Related material catalogued here includes work on the Aharonov–Bohm effect, such as The Aharonov-Bohm Phase Shift Related to Strain in the Vortex Sponge and Physics' Lingering Indecision in Making Choices Between Schroedinger and Aharanov-Bohm Processing. Bohm's causal tradition connects directly to Louis de Broglie and to Jean Pierre Vigier, who developed a stochastic version of the same programme.