fix typo in chapter 11

physics.qmd

@@ -151,5 +151,5 @@ $$
 $$ {#eq-scale}
 If we ignore energies above a certain level, we get a system $\ket{1},\ket{2},\ket{3},\dots,\ket{N}$, where any $\psi$ can be written as $\sum a_m \ket{m}$. That is useful if we do not want to think about infinite dimensional systems.
 
-[^1]: Of cause, technically e.g. $\sin(kx)$ and $2\sin(kx)$ are different solutions. But in @eq-scale below we rescale the solutions anyway, so we do not care. The case $A=0$ is forbidden, since in the time-independent Schroedinger equation we only look for non-zero wave functions.
+[^1]: Of course, technically e.g. $\sin(kx)$ and $2\sin(kx)$ are different solutions. But in @eq-scale below we rescale the solutions anyway, so we do not care. The case $A=0$ is forbidden, since in the time-independent Schroedinger equation we only look for non-zero wave functions.