# If an electron is thought if more as a wave than a particle, how does it have a mass?

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Thought of*

In: Physics

How old are you? This is not an insult. I am asking because here we study wave-particle duality in high school curriculum.

It basically means that everything behaves BOTH LIKE A WAVE AND A PARTICLE. Not just one of them. So electron has a mass when we treat it as matter, and wavelength when we treat it as a wave. Same goes for light. We have wavelengths corresponding to different colours and we have mass associated with a ‘photon’ which is essentially light as a particle.

What is mass? Mentally, do you associate the property of mass as belonging to something? As you delve deeper into the physics of the small, “real world” intuition starts to break down. What we think of as mass might arise from an interaction of disturbances in one field with another field.

Bottom line: calling it a wave or a particle does not necessarily associate it with a property of mass. Meaning, waves = no mass, particles = mass is not a true intuition.

Without going deep into quantum theories etc, you can think about it like this:

We can define mass as the thing that sets the ratio between the force acting on an object and its acceleration. We can measure that and see that the electron must have a mass.

Another way is that according to General relativity, every massless particle must move at the speed of light. Electrons don’t move at the speed of light – therefore they must have mass.

As a final note – in most contexts I’d say it’s not the the electron is a wave, but that it displays wave like properties. The difference is important exactly because we want to say that the electron has a mass and a charge and a radius and other things that it’s hard(er) to relate to waves. We can do that and still say that an electron location is space is determined by a probability density wave function.

First: Its not correct to say that an electron(or anything else) is thought of more as a wave. Its called duality because it is exactly that, it display properties of both waves and particles simultaneously depending on the circumstance. Double slit experiment is the go to illustration of this behaviour.

https://en.wikipedia.org/wiki/Double-slit_experiment

Second: Energy mass equivalence. In many ways, particularly at the quantum level, mass doesnt exist in any meaningful way that our intuition understands(This is broadly true on any scale). As an example, the mass of a a given atomic nucleus is more than the sum of its constituents. The missing mass is called the mass defect and makes up the binding energy of the nucleus.

https://en.wikipedia.org/wiki/Mass%E2%80%93energy_equivalence

I realize this really isnt ELI5 at all, but to be frank there is no ELI5 answer, which is both accurate and meaningful, to your question.