Temporal gauge for a string
= Temporal gauge for a string
{title2=$X^0=t$}
On a future-directed patch, choose target time as worldsheet time, $X^0=t$. The momentum equation then gives $P^0=1/e$ and $X'^0=0$. Freedom to vary target time at an open-string endpoint sets its shift to zero, simplifying the endpoint momentum-flux condition.