>>10439447Well you have to get into the math of what is a measurement. In this instance we're measuring the momentum of the electron. Just like a wave doesn't exist only at a specific point, it's not going at the same speed everywhere. the part going the fastest is usually called the wavefront.
So whatever "measurement" you did, the entire wave is now moving that speed, by the process of measurement. If it wasn't, your measurement was incorrect. Because, well, if it's moving at different speeds in different areas, they can't both be the speed you measured. This is really the crux of the uncertainty principle.
Now, I said the part moving the fastest was the wavefront. Where's the wavefront? It's everywhere, at least to an extent. No diffraction pattern.
