Equations · Physics
Heisenberg uncertainty principle
Position and momentum cannot both be sharply defined at once.
Δx Δp ≥ ħ/2
Aethel says
delta x delta p is greater than or equal to h bar over 2
What it says
The spread in a particle's position times the spread in its momentum is never smaller than half the reduced Planck constant. This is a property of quantum states themselves, not a limit of measuring instruments.
Symbol by symbol
| Symbol | Say it | Means |
|---|---|---|
| Δx | delta x | the uncertainty (standard deviation) in position |
| Δp | delta p | the uncertainty in momentum |
| ħ | h bar | the reduced Planck constant |
More onδDeltaħh-bar (reduced Planck constant)≥Greater than or equal to
Where you meet it
Quantum mechanics courses.
Questions
How do you say Heisenberg uncertainty principle out loud?
Δx Δp ≥ ħ/2 is read: “delta x delta p is greater than or equal to h bar over 2.” That is exactly what Aethel says when it meets the formula in a book.
What does Δx mean in Heisenberg uncertainty principle?
Δx (said “delta x”) is the uncertainty (standard deviation) in position.
What does Δp mean in Heisenberg uncertainty principle?
Δp (said “delta p”) is the uncertainty in momentum.
Can I listen to the equations in my own textbook like this?
Yes. Upload a PDF, EPUB or text file and Aethel reads it aloud with every equation spoken as maths, the way it reads this one, and highlights each sentence as it goes. You can start free.