Astrophysics (Index)About

e-folding time

(time to increase by a factor of e)

A quantity's e-folding time is the time it takes to grow by a factor of e (2.171828.., Euler's number), presuming it is growing exponentially. The term is also sometimes used for quantities decreasing exponentially, for the time to decrease by that factor, e.g., in the sense of relaxation time or scale height.

Further reading: