# uncertainty principle

- the principle of quantum mechanics, formulated by Heisenberg, that the accurate measurement of one of two related, observable quantities, as position and momentum or energy and time, produces uncertainties in the measurement of the other, such that the product of the uncertainties of both quantities is equal to or greater than h/2π, where h equals Planck's constant.

## Origin of uncertainty principle^{}

First recorded in 1930–35

Also called indeterminacy principle, Heisenberg uncertainty principle.

Dictionary.com Unabridged
Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

# uncertainty principle

- the principle that energy and time or position and momentum of a quantum mechanical system, cannot both be accurately measured simultaneously. The product of their uncertainties is always greater than or of the order of h, where h is the Planck constantAlso known as: Heisenberg uncertainty principle, indeterminacy principle

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# uncertainty principle

[ŭn-sûr′tn-tē]

- A principle, especially as formulated in quantum mechanics, that greater accuracy of measurement for one observable entails less accuracy of measurement for another. For example, it is in principle impossible to measure both the momentum and the position of a particle at the same time with perfect accuracy. Any pair of observables whose operators do not commute have this property. As defined in quantum mechanics, it is also called Heisenberg's uncertainty principle. Similar uncertainty principles hold for non-quantum mechanical systems involving waves as well.

The American Heritage® Science Dictionary
Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

# uncertainty principle

The statement in quantum mechanics, formulated by Werner Heisenberg, that it is impossible to measure two properties of a quantum object, such as its position and momentum (or energy and time), simultaneously with infinite precision.

The New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.