What it means
The twenty-third Greek letter. In quantum mechanics ψ is the wave function, which holds the state of a system. It is also a stream function in fluids and the digamma function.
Read aloud in real formulas
iħ ∂ψ/∂t = Ĥψ
Aethel says
i h bar the partial derivative of psi with respect to t equals H hat psi
the Schrödinger equation for ψ
∫ |ψ|² dx = 1
Aethel says
the integral of the absolute value of psi, squared d x equals 1
the probabilities add up to one
Typing it
- LaTeX
- \psi, \Psi
- Unicode
- U+03C8, U+03A8
Formulas that use it
Questions
How do you pronounce psi (ψ)?
It is said “psi”, roughly SIGH (the p is usually silent in English), also PSY.
What does ψ mean in maths?
The twenty-third Greek letter. In quantum mechanics ψ is the wave function, which holds the state of a system. It is also a stream function in fluids and the digamma function.
How do you type ψ?
In LaTeX, write \psi, \Psi. Its Unicode code point is U+03C8, U+03A8.