De Broglie said that all matter is both a wave and a particle. Davisson and Germer proved this in 1927 when they scattered electrons through a single crystal of nickel. Electrons are currently believed to be a fundamental particle and so I can comfortably think of them as having a centralised mass. However I’ve also read that they have managed to diffract Neutrons, Protons and even Helium nuclei and found them all to produce diffraction patterns. Since Neutrons and Protons are made up of quarks and Helium from Protons, Neutrons and Electrons, how is it possible to diffract them? Aren't they just lots of little particles held together by forces? :grumpy: What constitutes a particle? Electrons are held in "orbit" around a nucleus because of electrostatic forces and so count as part of the same particle, but don't electrostatic forces operate across an infinite distance and so arguably every charged particle is connected to every other charged particle. :yuck: Furthermore, would two particles held together by gravity in a vacuum but with no electrostatic bond etc. still diffract as one if they were to simultaneously pass through a slit? Helfen Sie mir bitte!