Antony Valentini
(1965-)
Antony Valentini is a British-Italian theoretical physicist known for his work on the foundations of quantum physics. He is a professor of physics and astronomy at Clemson University,
Valentini works on an extension of the causal interpretation of quantum theory based on the work of
Louis de Broglie and
David Bohm.
This interpretation had been proposed in conceptual terms in 1927 by de Broglie, was independently re-discovered by Bohm who brought it to a complete and systematic form in 1952, and was expanded on by Bohm and
Basil Hiley. Emphasizing de Broglie's contribution, Valentini refers to the causal interpretation of quantum mechanics underlying his work as the "
De Broglie–Bohm theory".
The causal interpretation, also known as the pilot wave theory and Bohmian mechanics, is an
interpretation of quantum mechanics that postulates that, in addition to the wave function, a particle
deterministically possesses a definite position and other properties, such as spin, at all times, even when unobserved.
This is in conflict with the Heisenberg-Born-Jordan or
Copenhagen interpretation and Dirac's
projection postulate, which says that measurement
collapses the wave function and projects a particle into a random state.
In the case of
entanglement, two particles are projected into random spin states, either up-down or down-up. Though individually the spins are perfectly random, they are jointly perfectly correlated to conserve the total spin zero of the initial entanglement preparation, which can be considered a
common cause of the perfect correlation.
Bohm suggested in 1952 that the perfect correlation could be caused by "
hidden variables," perhaps traveling with the particles like "instruction sets," but
John Bell showed such variables would show nonlocal behavior and by
David Merminshowed that instruction sets could not reproduce the observed measurements in Bell inequality test experiments.
In 2002 Valentini proposed a theorem of what he called "signal locality".
Bell’s theorem shows that any reasonable deterministic
hidden-variables theory behind quantum mechanics
has to be nonlocal. Specifically, for pairs of
spin-1/2 particles in the singlet state, the outcomes
of spin measurements at one wing must depend
instantaneously on the axis of measurement at the other,
distant wing.
"Signal-locality in hidden-variable theories," Physics Letters A, 297 (2002) 273-278
Valentini's supports a hypothesis that in the remote past the universe relaxed to a state of statistical equilibrium
(at the hidden-variable level) in which nonlocality happens to be masked by quantum noise.
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