Heisenberg's uncertainty principle

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Heisenberg's Uncertainty Principle is a non-intuitive foundation of quantum theory. When observing a macroscopic body there is little difficulty in measuring its exact location and momentum. When subatomic particles are investigated, however, the simultaneous knowledge of both of these parameters is impossible. This is not through any limitation in whatever device or method is used to perform the measurement but is inherent in the quantum description of matter and energy.

 \Delta p_x \Delta x \geq \frac{\hbar}{2} [1]

  • Standard deviation of position in a direction times standard deviation of momentum in that direction is greater than (or equal to) slash aitch divided by 2.

It has nothing to do with Observer effect.

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[edit] Other quantum uncertainties

Position and momentum aren't the only quantities that can't both be known with arbitrary precision at the same time. Any two observables whose operators do not commute with one another also have an intrinsic uncertainty if you attempt to measure both of them at once.

For example, it is impossible to know all of the components of a particle's spin at any given time with arbitrary accuracy. It is also impossible to know both the energy of a particle, and the time at which the particle had this energy, with arbitrary accuracy.

[edit] See also

[edit] External links

[edit] Footnotes

  1. http://scienceworld.wolfram.com/physics/UncertaintyPrinciple.html
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