Born position probability
A normalized wavefunction assigns probabilities to position intervals.
Key knowledge
For a normalized one-dimensional position wavefunction ψ(x,t), the Born rule assigns probability density |ψ(x,t)|². The probability of a position measurement in [a,b] is the integral of that density over the interval.
Values and equations
∫_domain |ψ(x,t)|² dx = 1; P(a ≤ x ≤ b; t) = ∫_a^b |ψ(x,t)|² dx
- ψ
- Normalized position wavefunction m⁻¹ᐟ²
- |ψ|²
- Position probability density m⁻¹
- P
- Dimensionless position-interval probability
- x
- Position coordinate m
- a, b
- Interval endpoints with a ≤ b within the allowed domain m
- t
- Time s
Conditions and scope
- The wavefunction describes a single-particle pure state and is square-integrable and normalized over its allowed position domain.
- Density has units of inverse length; its value at a point is not an interval probability.
- Other observables and mixed states require their corresponding measurement rules; no classical pre-existing trajectory is asserted.
Sources · 3
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
- University Physics, volume 3: Wave FunctionsSamuel J. Ling, Jeff Sanny and William Moebs / OpenStax, Rice UniversityTextbook chapter
- 8.04 Quantum Physics I (2016), Lecture 6: normalization and probability currentBarton Zwiebach — Massachusetts Institute of TechnologyCourse notes · PDF
- Quantum Mechanics · wavefunctions and one-dimensional dynamicsDavid Tong · University of CambridgeCourse notes · PDF
Evidence and review
OpenStax 7.1: modulus-squared density, interval integration and normalization; Zwiebach Lecture 6 equations 1.3–1.4 and 3.12, page 6 units.
2026-10-10 · Position probabilities for a normalized one-dimensional pure state only; no ontological interpretation or general measurement calculus is certified.
Foundational review
2026-10-10 · Fresh primary-source inspection of the complete compact record, including every statement, equation, quantity and material condition, followed by independent AI editorial review. This check does not certify all linked lessons or every passage of every cited publication.
Sources from other places
Agreement within this scope
A normalized pure-state wavefunction gives position probability by integrating its squared modulus over the region.
In one dimension this is a density per length, not the probability of an exact point; unnormalized plane waves require separate treatment.
University of Cambridge · DAMTP
- Quantum Mechanics · wavefunctions and one-dimensional dynamics United KingdomEnglish
1.1–1.1.1, pp3–6; Chapter2 opening, p19; 2.1 nonnormalizable plane wave, p21
- Quantum Mechanics · wavefunctions and one-dimensional dynamics
Entry details
Permanent link to this entry ↗- Record identity
- physics-born-position-probability
- Revision
- core.1
- Structured reference record
- Essential core · first collection · University core expansion