Category: Matter Waves Matter

As you have probably guessed, the best measurement to exemplify wave-particle duality in matter is the good old double-slit experiment. If a beam of electrons is directed through a pair of narrow slits (where the spacing between the slits is comparable to the de Broglie wavelength of the electrons), peculiar things begin to happen. When… Continue reading Double-Slit Redux

So somewhere along the line, as you go smaller and smaller from planets to potatoes to protons, things that normally behave like classical massive particles start to display wavy characteristics. It is not a sharp transition, and there is no exact size where we can say larger things are just particles and smaller things are… Continue reading A Second Look at Wave-Particle Duality

De Broglie’s relation is general and applies to any particle, large or small. Every moving mass has the potential to display interference and other wave properties. So why didn’t we notice this before 1927? And why don’t we see it all around us now that we know it’s there? Once again, it’s all a question… Continue reading Protons, Potatoes, and Pluto

As we’ve known since the days of Newton, a particle’s momentum is directly proportional to its mass. For a massive particle with large momentum, the size of Planck’s constant makes the de Broglie wavelength very small, even when compared to the wavelengths of light. This made it quite challenging to observe any wavelike behavior of… Continue reading The Davisson-Germer Experiment

We toyed with an intriguing possibility to explain why electrons exist in only certain orbits with certain energies within the atom. If matter particles, electrons in particular, were actually waves in some sense, then perhaps the special orbits in atoms were the ones for which a whole number of wavelengths fit exactly around the circumference… Continue reading De Broglie’s Radical Relation

Quantum physics was born of light and atoms. It was through researching the true nature of each that the great “quantizations” of Planck, Einstein, and Bohr were made. The other unifying theme of these works was that the critical link between light and atoms was tied to the electron. Not only was it a fundamental… Continue reading The Humble Electron

Our goal is to finally make the leap into the “modern” theory of quantum mechanics. The crucial insight, which we hinted is that particles of matter can also display wavelike properties—just like light! Only by appreciating the concept of matter waves can we begin to construct a self-consistent quantum theory that takes the place of… Continue reading Introduction