I've never understood how diffraction is possible, which has led me to mistrust a good deal of quantum physics. I'm mystified as to how light starts spreading out in all directions after passing through an aperture. Supposedly it's because light spreads out like a wave, but then how is it possible to have a laser that spreads out very slowly? And why does the laser start spreading out much faster after passing through an aperture? I've never understood diffraction because I've never gotten an answer to this question. Perhaps someone here can enlighten me.