In Chapter 7, we used the momentum-space wave function to analyze wave packet propagation. A Gaussian wave packet has $\phi(p) = (2\pi\sigma_p^2)^{-1/4}\exp(-(p - p_0)^2/4\sigma_p^2)$, peaked at $p_0$ with width $\sigma_p$. The position-space wave packet is the Fourier transform. Now we see this is