НЕОПРЕДЕЛЁННОСТИ ПРИНЦИП

Uncertainty Principle, The

A proposition of quantum mechanics formulated by W. Heisenberg in 1927, according to which it is impossible to specify or determine simultaneously both the position and velocity of a particle as accurately as is wished. The Uncertainty Principle is expressed in terms of the quantitative correlations between the so-called uncertainties of conjugate variables: position and momentum, and also time and energy. The less uncertain a particle's position is, the more uncertain is its momentum, and vice versa. A similar correlation obtains between the measurement of the momentum of time and that of a particle's energy.

The Uncertainty Principle is an objective characteristic of the phenomena of the microcosm associated with their wave-corpuscular nature; uncertainties are inherent in the real state of the microobject and do not limit cognition. Heisenberg and Bohr deduced the Uncertainty Principle from the action of the instrument determining a particle's position upon its momentum (e.g., the action of an aperture in the diaphragm, through which an electron passes, on the electron's momentum) and from the action of the instrument determining the particle's momentum on its position in space. This is also true of the action of time-measuring instruments on the energy of a particle and of energy-measuring instruments on the possibility of an accurate determination of time.

The Uncertainty Principle prompted certain philosophers to draw positivist conclusions up to the point of negating the causality of states of an elementary particle and the objectivity of the microcosm, its independence of cognition (so-called instrumental idealism; see Instrument). Materialist criticism of such idealistic distortions of quantum mechanics was instrumental in ascertaining its actual meaning.