# How can light be both a particle and a wave?

68 views
0

I usually see myself as being pretty solid on my general science knowledge, but this one continues to stump me.

Light is photons, little particles that move through space… but then it’s also a wave, like the visible light portion of the electromagnetic spectrum? How can it be both? How would photons red shift over great distances? Do we just not know what light is, really?

In: 9

It’s less like “little particles” and more like [little packets of wave](https://en.wikipedia.org/wiki/File:Wave_packet_(no_dispersion).gif) that on the whole can exhibit some particle properties. But also retaining their wave properties like being doppler-shifted.

As far as we know, we know what it is. It’s just weird.

The quantum level was always something I found difficult at uni but it does explain alot of real world observations. However the whole entanglement stuff….is so much harder!

The mind blowing part is that when electrons are fired ONE AT A TIME through the double slit experiment, they still produce the classic wave like interference pattern

This should be an impossible result of firing a single particle through one of two slits. There’s is nothing to interfere with. The wave pattern is the result of two waves interfering… Yet one single particle “interferes with itself”.

That is where things get really difficult to comprehend because you have to think of the light as neither wave or particle.. it is just the potential to be either. It is the only logical conclusion

This is proof of the wave particle duality, and that it’s actually not a case of just not knowing what it is. Light behaves as both

It’s pretty much proven magic lol – we know what we see, but nobody knows why. [This](https://youtu.be/ISdBAf-ysI0?t=1413) documentary probably explains things more clearly if you’re interested.

Think of a solid cylinder: if you look at it end-on it looks like a circle, and if you look at it from the side it looks like a rectangle, but a cylinder is neither, it just resembles them under certain circumstances. Similarly, rather than thinking of photons as either waves or particles, think of them as something else entirely which just has some particle-like behavior when you look at it one way, and some wave-like behavior when you look at it a different way.

Red-shifting happens because the universe is expanding—the space through which the photon is traveling is stretching. Imagine you’re walking at your usual pace, only the ground beneath you is continually stretching. As you swing your leg forward to take a next step, the stretching of the ground pulls your rear foot further back, causing you to step a longer distance each time. Now imagine the length of your steps is the wavelength of a photon being red-shifted.

We know a whole lot about light, like each photon is made up of an electric field and a magnetic field oscillating in unison, but at 90^o to each other; that all photons are created as the energy shed by electrons “jumping” to lower-energy orbitals around atomic nuclei; that photons do not obey the Pauli exclusion principle, meaning two or more photons can occupy the same locale and energy level simultaneously; we know they have zero rest mass; and we know their speed, c, is defined by two physical constants: the [vacuum permittivity](https://en.wikipedia.org/wiki/Vacuum_permittivity) and the [vacuum permeability](https://en.wikipedia.org/wiki/Vacuum_permeability) of free space. However, there’s likely a whole lot we have yet to learn about light.

Think of individual particle as just a small part of the field.
Its got an electric and magnetic component.

An increase in electric field drives an increase in magnetic field and thats how it travels.