I was having a discussion on some other forums about this. Here is the conversation Person 1: Here is my favorite hit off a quick google search for an equation intensive look at QM: http://www.physics.sfsu.edu/~greensit/book.pdf [Broken] Starting with De Broglie wavelength since it's the most fun part of the topic. Imagine going out to dinner and convincing your friends that they are in fact a wave, and when you're not looking at them they fluctuate like this " " Person 2: Just be careful in your understanding of this, the particle isn't traveling like a wave, the probability of finding the particle in a certain location is what is waving...it's weird. Me: Something about [Person 2's statement] doesn't seem right. Particles also behave as waves. Particle-wave duality doesn't stem from the shape of the probability function which seems to be what you are saying. Person 2: The particle isn't really traveling as a wave, think of it more as a cloud that travels that when you look at it, it collapses to a certain point with regards to the uncertainty principle. The location that it collapses to is dependent upon the wave function for that particle which describes the probability of it being in any location as it moves through space and oftentimes time. The de Broglie wavelength is really the wavelength of the probability function. It behaves like the particle travels as a wave but current physics doesn't see it that way. Me: I understand how the wave function collapses and the probability function. But I take issue with the idea that it isn't really traveling as a wave. Take the double slit experiment for example. Particles in this case behave as a wave, so to say that they are not waves seems puzzling. Person 2: (this is compiled from a couple posts) The double slits affect the wave functions because the area around the slits are potential barriers, this causes the probability function to take on the form of the interference pattern. It isn't that one electron (in this example) is forming the pattern on its own, it is that all the electrons have certain probabilities to end up at certain points and they are more likely to end up at the center of each fringe. With light, the actual electomagnetic waves are interfering. With particles, its the probability waves that interfere and change the wave function due to the potential barriers that make up the slits. Light is different because light is a wave that has particle like properties and things like electrons are particles that have wave like properties. Just because they have similar properties to each other does not mean they are the same thing. Also, it isn't that the electron is interfering with itself, its that the slits alter the wave function. Me: I don't get the distinction between "a wave that has particle like properties and particles that have wave like properties." Defining something that has both wave and particle properties as either a wave or particle seems meaningless and ambiguous in the context of quantum mechanics. Sorry that is a lot, but that is our conversation. I feel like what he is saying may not be correct. TLDR: The argument is basically that he says light is massless and "is" a wave. It can behave as a particle, called the photon, which is also massless. An electron has mass and "is" a particle. It can behave as a wave, but it's really a probability function that describes the possible locations of the particle, because a wave can't have mass. It is not the electron that is waving, it is the probability. I say that distinguishing between an electron as a wave or particle is meaningless. It has properties of both. It is not the illusion of acting as a wave, it is indeed actually acting as wave. Any semantics around this issue is wrong.