How can light be a particle and wave, or have both properties?



How can light be a particle and wave, or have both properties?

In: Physics

Light is a special thing, with both sets of properties. The properties aren’t mutually exclusive, and light is an example to prove that.

Look at this from the opposite direction, coming from the observation and going towards the model, instead of coming from the model side.

You see a certain set of things. Some of them make you think “well, that’s just like a bowling ball behaves, so it should be a particle!”. But then there are also some that make you think “well, that’s just like ripples on water behave, so it must be a wave!”.

Particle and wave are in the end just attempts to cast the properties of light into a more graspable model. And the best we came up so far is a mixture of a particle and a wave.

It’s not just light, everything has properties of both particles and waves.

However, because light doesn’t have any mass, it’s more ‘wavelike’ than most other stuff.

It is because in reality, nothing is a perfect particle or a perfect wave. Classical waves and particles are concepts created by people in order to model systems, they work fairly well on a human scale and so match our intuition. Down at the atomic level there is no reason for these concepts to hold true, sometimes quantum objects behave more like a classical particle, sometimes more like a classical wave. In reality it is neither, they are just following the laws of quantum mechanics, this makes it difficult to comprehend because we don’t have an intuition for how these systems work. Light isn’t a particle, it isn’t a wave either, it is a quantum mechanical phenomenon which in some regimes can be modeled as a classical particle, and sometimes a classical wave but the reality is more complex.

A simpler way to explain would be that **light is what light is**. It behaves the way it does.

The first experiments we did showed us that it could act as a particle. Later we did experiments that showed us it could act as a wave. We thought light was a certain way, but it turned out differently.

Yes, it has the properties of a wave and of a particle. This isn’t a problem or a paradox, it’s just strange. All of the math and evidence points towards this being perfectly reasonable.

A lot of your ideas about the world are based on assumption. But Mother Nature might not find something like that as strange.

The photon is the ***particle*** associated with light (and all other electro-magnetic radiation). The probability of detecting the photon at a particular point in space is defined by a ***wave*** function.

(That’s a very complicated and unintuitive topic reduced to some words that will fit on a T-shirt.)