Skip to main content
University Quantum Mechanics I

University Quantum Mechanics I · Measurement and the Uncertainty Principle · 4.08

Δ-x Δ-p ≥ ℏ/2 and the price of confinement

Substituting i ℏ into the general bound gives ℏ/2, and because that commutator is a constant the bound never goes empty; only a Gaussian saturates it, the equality condition reducing to a first-order ODE.

Course-map guide · not a complete lesson or simulation

Scope & orientation

What this subsection covers

Substituting i ℏ into the general bound gives ℏ/2, and because that commutator is a constant the bound never goes empty; only a Gaussian saturates it, the equality condition reducing to a first-order ODE.

A strong response uses outcome histograms beside the ensemble mean and states where the model stops being reliable.

Reasoning checklist

Evidence, assumptions and limits

01

Assumptions to state

State the system, observable, approximation, and conditions held fixed before using a model.

02

Evidence to collect

Does the momentum spread inferred from single-slit diffraction scale as 1/a, and does repeating one slit N times narrow the fitted width or only the error on its mean?

Read the complete note

Does the momentum spread inferred from single-slit diffraction scale as 1/a, and does repeating one slit N times narrow the fitted width or only the error on its mean? Useful evidence includes profiles at five slit widths, fitted angular half-widths, inferred Δ-p against ℏ / 2 Δ-x with the slit named as a state preparation rather than a disturbance, and N repeats on one slit showing the error on the mean fall as 1/root-N while the fitted width holds..

03

Limits to state

This GioPhysics course map is an adaptable learning sequence, not academic credit, accreditation, or a universal university syllabus.

Read the complete note

This GioPhysics course map is an adaptable learning sequence, not academic credit, accreditation, or a universal university syllabus. It is a first dedicated quantum-mechanics course, distinct from University Physics V, which covers quantum mechanics alongside atomic, nuclear and particle physics in twenty units: this course is narrower, slower, and teaches the linear algebra it needs rather than assuming it. Hydrogen appears here as an introduction, with the full radial derivation belonging to a second course. A midterm examination is assumed around week 8. Follow your institution's published scope, notation, laboratory programme, and assessment rules. A result should be checked against units, signs, limiting cases, and the conditions under which its model was derived.

Diagram & examples

Work the claim before choosing an equation

Interactive concept map

Follow the model from claim to evidence.

01 · Physical claimΔ-x Δ-p ≥ ℏ/2 and the price of confinement

Substituting i ℏ into the general bound gives ℏ/2, and because that commutator is a constant the bound never goes empty; only a Gaussian saturates it, the equality condition reducing to a first-order ODE.

Read the complete note

Substituting i ℏ into the general bound gives ℏ/2, and because that commutator is a constant the bound never goes empty; only a Gaussian saturates it, the equality condition reducing to a first-order ODE. It forecasts the confinement energy of the bound states ahead, but states a floor, never a value.

02 · RepresentationThe subsection's claim

Model, evidence, and boundary

03 · TestPrediction before measurement

Which response about Δ-x Δ-p ≥ ℏ/2 and the price of confinement is most defensible?

04 · Evidence & boundaryDecide, then qualify

Does the momentum spread inferred from single-slit diffraction scale as 1/a, and does repeating one slit N times narrow the fitted width or only the error on its mean?

Read the complete note

Does the momentum spread inferred from single-slit diffraction scale as 1/a, and does repeating one slit N times narrow the fitted width or only the error on its mean? Useful evidence includes profiles at five slit widths, fitted angular half-widths, inferred Δ-p against ℏ / 2 Δ-x with the slit named as a state preparation rather than a disturbance, and N repeats on one slit showing the error on the mean fall as 1/root-N while the fitted width holds..

Interactive diagram for Δ-x Δ-p ≥ ℏ/2 and the price of confinement: follow the physical claim through its representation, proposed test, evidence, and model boundary.

modelModel, evidence, and boundary turns the stated idea into a representation that can make a prediction.

Example questions

Try the reasoning before revealing the structure.

Diagram check

Which response about Δ-x Δ-p ≥ ℏ/2 and the price of confinement is most defensible?

Quick check

Test the reasoning, not recall

Which response about Δ-x Δ-p ≥ ℏ/2 and the price of confinement is most defensible?

Choose an answer to test the model.