Shadows are quite familiar to us, but what are we familiar with? Every object has a shadow, and so does a person? At this moment, I couldn't help but ask what exactly is a shadow? You might say it's an optical phenomenon, but what is the deeper reason? In the encyclopedia, shadows are divided into umbra and penumbra. A solar eclipse is actually a penumbra. I'm not very clear about the relationship between the umbra and the penumbra, but in any case they affect each other.

I've said a lot, and it's time for you to answer my questions. What exactly is a shadow? Mizukawa asked the three of them.

A week ago, when I was bored, I took my mobile phone flashlight and shone it on the pen cap, and there were two shadows. One is a white shadow and the other is a black shadow. I asked the professional, and he said that the white shadow is the reflection, and the black shadow is the shadow of the reflection. I asked him what about the shadow of the pen cap? He said it was a reflection. I asked what the difference was between a reflection and a normal shadow, and he said there was no difference. I didn't believe it, so I searched for the difference between reflection and shadow on a search engine. It turns out that the white shadow is a reflection, which is produced by reflection. And the black shadow is produced by direct rays. In fact, there is no shadow of reflection at all, it is just far-fetched by himself. Dueñas was the first to speak, and he made a point. However, it seems that Walnut's question was not answered.

I would like to add that both refraction and diffraction can produce shadows, and shadows are not the same? If you want to ask what a shadow is, you have to ask a photon. Actually, I think the shadow is the embodiment of the way an object is emitted by light. No, as long as the light does not spread, there is no shadow. And when the number of emission methods increases, so does the number of shadow types. Doesn't that mean that the way the dark light is emitted is the cause of the formation of shadows? Walnut wants to ask what is the nature of the shadow? I think it's a kind of microscopic perspective of the object. Someone will say that the shadow of a person in the mirror is not three-dimensional? And isn't the perspective you're talking about two-dimensional? Of course, this is a problem. I've never said that perspective is two-dimensional, though. It is also said that if you shine on the cover of a book, it will be a black shadow. Can you say that a patch of black is a microscopic perspective of the cover of a book? Yes, the microscopic image of the cover of the book is certainly not a lump of black. However, this does not mean that shadows are wrong as a microscopic perspective. Because if you look at an object from different angles, you can get different images. If you think that there is only one kind of microscopic image, you will have a shallow understanding.

All of the above is my thoughts. Accept it or not, it's all up to you. Margarita said very stiffly, feeling very imposing.

I'm also struggling with what a shadow is. In the case of Dueñas, it is impossible for the white shadow and the black shadow to interfere. But is there an interference between the shadows of the two objects? In the mirror, the shadow is three-dimensional. Or rather, it looks three-dimensional. We assume it's three-dimensional, and we're in three-dimensional space. Note that the dimension of time is not included. Then, there must be interference between the two shadows. And as far as I can see, the two shadows don't seem to interfere. So, it should be two-dimensional. So, what is a shadow? In fact, the shadow is an illusion given to us by light. And the shadow is essentially nothing, without any meaning. Liuzi Fenglai also expressed his opinion.

This one.......