Modern Physics

Heisenberg Uncertainty Principle

ΔxΔp2\Delta x \cdot \Delta p \geq \frac{\hbar}{2}

Position and momentum cannot both be precisely known. Fundamental limit of measurement.

Variables

\Delta x
Position uncertainty
m
\Delta p
Momentum uncertainty
kg·m/s
\hbar
Reduced Planck constant
J·s

Derivation

Arises from the wave nature of matter and the commutation relation [x,p] = iℏ.

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Common questions

What is the Heisenberg Uncertainty Principle formula?

Heisenberg Uncertainty Principle is written Δx ·Δp ≥ℏ/2. Position and momentum cannot both be precisely known. Fundamental limit of measurement. It belongs to Modern Physics, under Quantum Mechanics.

What are the units in Δx ·Δp ≥ℏ/2?

In SI units, \Delta x is position uncertainty, measured in m; \Delta p is momentum uncertainty, measured in kg·m/s; \hbar is reduced planck constant, measured in J·s.

How is the Heisenberg Uncertainty Principle formula derived?

Arises from the wave nature of matter and the commutation relation [x,p] = iℏ. The result is Δx ·Δp ≥ℏ/2.