Why Do Reflections Appear Upside Down?
Let’s imagine we are looking at a mirror hanging on the wall. We see that the patterns printed on your t-shirt are vice versa, while the text should be from left to right. You raise your right hand, and your reflection raises your left hand. This situation is rather strange because why are we rotated on the horizontal axis rather than upside down?
To answer this question, we can start by simply talking about how light is reflected. The moment the light ray hits the surface of an object, it is reflected back at an angle equal to the angle it makes with the normal of the surface, that is, with the ninety degree axis drawn in the plane perpendicular to the surface. If it comes in the same axis as the surface normal, it is reflected back on itself. All opaque materials reflect light.
This is how we see the colors. A red shoe absorbs all colors except red. If it is a black shoe, it absorbs all colors. Of course, it reflects some, not all, of all colors, otherwise it would appear as nothing but a pitch-black void. The reason why mirrors reflect all light back rather than color is because they have reflective surfaces. A thin layer of silver is glazed behind the glass surface of the mirror, so that the mirror can reflect light back as it came in. Of course, there is no 100% feedback.
Mirrors have a green color due to the material they are made of. You can see this by putting two mirrors face to face. As the light reflects from one mirror to the other, it will shift to green.
Well, how come the light turns upside down on the horizontal axis before it goes to the mirror? As a matter of fact, the light does not reverse on the horizontal axis, and your reflection in the mirror is not reversed either… the light hits the object as it comes out of the source, and then reaches the mirror, and from the mirror to your eyes.
In other words, the mirror is the reflection of your image without any change. Take a piece of paper and write your name on it. When you hold this paper to a light source, you will get the same image as the reflection in the mirror. Because the mirror takes your image as it is and turns it into a two-dimensional state. So you are pressed against the surface of the mirror. So it sounds like inverted in the horizontal plane.
In the figure, the light coming out of the light source hits the object and reaches the mirror in the same way. This gives you a relatively inverted image because we have depth. That’s why someone in front of you sees your image differently than in a two-dimensional mirror. Someone in front of you sees you as if you are in a mirror. In this way, the prints and texts on your t-shirt are readable. You, on the other hand, see yourself in front of the mirror through the reflection on the surface, so the prints and texts on your t-shirt become illegible.
So how come we see the reflection of Narcissus upside down? What is the explanation for this? Narcissus sees his reflection in the water on the ground. From his point of view, you see Narcissus and the reflective surface on a vertical axis, while his reflection is reversed on the horizontal plane as we mentioned. Narcissus is at the top, the reflective surface is at the bottom, so the reflection turns upside down. The same pressing issue is experienced this time, from top to bottom.
In the figure, the light emanating from the light source is reflected on the object, and on the reflective surface on the ground rather than the object. It reaches the first observer and the second observer from the reflective surface. While the first observer watches the situation over the reflective surface, the second observer witnesses what is happening behind the object. As can be seen, the light reflects normally on the surface, there is no reversal etc., but due to the perspective of the first observer, the reflection (bottom right) is upside down.
The second observer (bottom left) looking at the back of the object from the top does not observe any abnormality in the reflection. While the reflection is the same two-dimensional image, we can see different changes in the same image as we look at the three-dimensional reflection.