I mean, what does a white object do? Absorbs nothing, reflects all light back.
What does a mirror do? Absorbs nothing, reflects all light back.
Having the same characteristics, how does a mirror reflect an image and a white object, a white texture?
In: Physics
Imagine light as a bunch of tiny invisible bouncy balls. When these bouncy balls hit a white object, they all bounce back together in different directions, making the object look bright. Now, think of a mirror like a special wall that’s really good at bouncing the bouncy balls exactly how they came. So, when the bouncy balls hit the mirror, they bounce back in the same way, showing you a clear reflection of things around it. The mirror is like a super bouncy wall, while the white object is like a party where the bouncy balls scatter everywhere!
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diffusion. White surfaces diffuse the light and send if off in many directions regardless of how the light came in. where as a mirror sends each light ray in roughly its own unique direction based on the angle the mirror was hit at.
The terms you can look up for this exact thing are [diffuse vs specular reflection.](https://www.physics.louisville.edu/cldavis/phys299/notes/lo_speculardiffuse.jpg)
**Mirrors are specular reflection** – they bounce all visible light and their surface is smooth enough that the bumps are smaller than the wavelength of light. That means each light wave “bounces true” and the outgoing angle is the same as the incoming angle.
**White objects are diffuse reflection** – they bounce all visible light, but in random directions. The surface has bumps that are bigger than the wavelength of light. There’s no image because the directions are scattered. So like white paper or a white sweater. They’re bouncing all the visible light but the fiber surface is too rough to produce a specular reflection.
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Let’s say you have a horizontal light particles, all coming in to your mirror at the same angle, say 45° and all spread out 1 micro-meter apart. They will ALL hit the mirror and all bounce off at the same reflected angle (in this case 90° from their original angle) again spread 1 micro-meter apart.
If you took the same particles and sent them at say a white wall, they would NOT all bounce off at the same angle. That’s the difference.
Mirrors maintain angle of reflection, white surfaces don’t. At a small enough level a mirror is more “smooth” and a white surface more “rough”, hence the difference in behavior.
When light hits a surface, two things happen: Reflection and refraction. The ratio of refracted vs reflected light depends on the Index of Refraction of the object it hits, and the angle at which it hits.
Rough surfaces reflect light in random directions, whereas a smooth highly polished surface reflects the light directly.
Mirrors often have a highly polished metal backing. Metal has a complex index of refraction which means it reflects much more light than a dieletric (Or non-metallic) surface. Any light that is refracted (Or not reflected) gets absorbed/converted to heat in a metal, whereas when light refracts in a non-metal, it scatters/bounces around inside the material, losing some energy each time this happens. This is what gives objects their color. A red object absorbs all non-red wavelenghts, so the only wavelengths that survive are red. A white object does not absorb any wavelenghts. (In reality this does not happen, even white objects absorb a small amount of light, but they do it in such a small amount that compared to other objects, they appear white)
So, tl;dr a mirror reflects a large amount of light due to being metal, this reflection is also very sharp since the surface is smooth.
A regular “white” object does not reflect as much light, most of the light enters the object and is scattered around, and re-exits the object in random directions. Some light still gets “reflected” instead of entering the object, but it is much less than a metal mirror. It can be slightly noticable on highly smooth/polished/wet white surfaces though, they can still have a mirror-like reflection, it will just be dimmer.
Black objects (Eg a shiny black car) tend to look more reflective/mirror like, but this isn’t because they reflect more light, it’s just because all non-reflected light is quickly absorbed by the black paint, making the reflected highlights stand out more as they contrast highly with the black underlying surface.
White objects reflect most visible wavelengths of light but there’s no order to the reflection making the reflected light very diffuse. So the reflected light just looks like uniform white light (no picture or image). Mirrors reflect light as well but there is more “order” to the reflections. So the reflected light forms an image as well.
A rough, white surface reflects all wavelengths of light, but it scatters the photons in random directions, so all you see is the whiteness of the object.
A smooth surface reflects light consistently in the same direction, the angle of approach, so you see the image of the surrounding environment.
>Having the same characteristics
False premise.
A mirror has, well, a mirror finish. This means that on a very tiny scale(microscopic), it is still relatively flat and smooth. When something is sufficiently smooth, you will see an even reflection as all light bounces off in the same direction.
On that same scale, a white non-reflective object, is jagged and irregular. This scatters light in all directions.
A good easy to google example of this are modern gravestones. [The exact same material with different finishes in different places.](https://www.whiteman-monumental.co.nz/images/headstone-finishes-7.jpg)
Some polished very smooth, some left very rough.
Edit: It begins to get even more interesting when things are regularly jagged on a microscopic scale. That’s where you get things like reflective tape or coatings on safety clothing, road signs, etc. Sometimes it is small spheres which insure there’s nearly always a ray of light that bounces directly back, other times it is geometric shapes that bounce a light twice so it comes right back out the same way it went in, like in vehicle lights.(imagine the inside of a hollow box all being mirrors)
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