Uncertain Principles

This documentary takes an in depth look at the emergence of Heisenberg's uncertainty principle in particle physics and the way it shook up the establishment of the day. A classic film that explains some of the most fundmental principles in modern particle physics.




In 1927 Heisenberg made a startling discovery. Quantum theory implies a limitation on how accurately certain pairs of physical variables could be measured simultaneously. Using some of the matrix mechanics that had been proposed by Max Born, Heisenberg realised that position and momentum (the relationship between mass and velocity) were non-commutable; you could not precisely know them both at the same time.




Hence, there is no way of accurately locating the exact position of a sub-atomic particle unless you are willing to be uncertain about its momentum. But there is no way you can be certain about momentum without being uncertain about position. It is impossible to precisely measure them both at the same time.




There is a large focus on the October 1927 Fifth Solvay International Conference on Electrons and Photons, where the world's most notable physicists met to discuss the newly formulated quantum theory. The leading figures were Albert Einstein and Niels Bohr. Einstein, disenchanted with Heisenberg's "Uncertainty Principle," remarked "God does not play dice." Bohr replied, "Einstein, stop telling God what to do." Seventeen of the twenty-nine attendees were or became Nobel Prize winners, including Marie Curie, who alone among them, had won Nobel Prizes in two separate scientific disciplines.



A. Piccard, E. Henriot, P. Ehrenfest, Ed. Herzen, Th. De Donder, E. Schrödinger, J.E. Verschaffelt, W. Pauli, W. Heisenberg, R.H. Fowler, L. Brillouin; P. Debye, M. Knudsen, W.L. Bragg, H.A. Kramers, P.A.M. Dirac, A.H. Compton, L. de Broglie, M. Born, N. Bohr; I. Langmuir, M. Planck, M. Curie, H.A. Lorentz, A. Einstein, P. Langevin, Ch. E. Guye, C.T.R. Wilson, O.W. Richardson

Fifth conference participants, 1927. Institut International de Physique Solvay in Leopold Park.

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