Can shadows have holes? About definitions.

[Thurlor]

Can shadows have holes?

I can't come up with a satisfactory answer to the above question. The answer depends on the subtleties of our definitions of shadow and hole.

In one sense shadows are holes (in the cast light) so the question becomes 'can holes have holes?'.

In another sense 'shadow' refers to the emergent phenomenon of light being blocked So, if an area within the bounds of a shadow was unblocked form the light source it could maybe be considered a 'hole in the shadow'.

In yet another sense a hole has depth and shadows have no depth so they can't have holes.



I'm amazed we can meaningfully communicate at all.

 

[Cognisant]

If there's a hole in the shadow does the shadow have a hole?

Edit: A literal hole in the ground encompassed by a shadow, a hole within the shadow if not exactly a hole in the shadow.

 

[Rook]

areas in shadows still reflect light(even during nighttime, anything that doesn't reflect light is 'darkness' rather than 'shadow'), they simply reflect less... so a shadow, having less photons, has more 'holes' or in more technical language, gaps between photons transmitted to the eye.

seeing as a hole denotes the absence of a thing, a hole in a shadow would be an area with more light, while in truth a shadow that has more holes is one that has less light and therefore less photons. seeing as shadows are a visual distinction brought on by gradients in light though, they won't have holes in truth, much as we don't get temperature holes or atmosphere holes(unless one creates a true vacuum where atmo is concerned).

While there are places on earth where temperature and atmo density is lower(more holier) their outright absence is an anomaly(esp. temp, things just get colder as heat absence increases). Looking at black holes though, one can see that language becomes a bit more complicated as a great concentration of gravity can create a hole of time, light and temperature(i assume, my physics sketchy... are black holes cold, or something else?)

But in terms of art, if you're drawing, say, a tree, and the shadow it casts on surface, thinking in terms of 'a shadow with holes' is definitely beneficial. one can also say that stars and galaxies in the night are 'holes in shadow' in a poetic sense.

 

[dr froyd]

if a shadow cannot have a hole, can it have any properties at all? perhaps we are forced to only talk in terms of the light surrounding the shadow

 

[Thurlor]

@Cognisant
Nice 'thinking outside the box' there.

@Rook
I know this is me being pedantic, but I don't think you are right about the difference between shadows and darkness. The inside of a box is only dark because it is in the 'shadow' of its surface. Also, ambient light is a thing.

@dr froyd
I think shadows have properties. I suppose the darkness that the shadow is made of doesn't have any though.

 

[Rook]

@Thurlor was actually thinking about it last night/this morning and realized that some shadows are indeed in total darkness, so thanks for spotting it -.-

 

[Daddy]

Shadows and light are kind of abstract notions of the oscillating vibrations of atomic particles. Shine a light on something and you increase its atomic vibrations; block the light and it vibrates less, becoming darker. This is why the higher the frequency of light, the more energy it carries, e.g. E=hf, because it moves more, in a sense. Light then is really just the interactions between particles, where every particle is a conglomeration of its own inherit spatial distortions and the distortions imposed on it by other particles.

A shadow then absorbs less of these distortions compared to what's in the light. So a hole in a shadow could just be an area that is darker and absorbs even less distortions. Unless of course you follow the theory that Black Holes have such large gravity that light can not escape; then you could obviously put a Black Hole in a shadow and it would be a hole. But Black Holes that absorb all spatial distortions (or traps all light) and White Holes that reflect all spatial distortions (like a perfect mirror) are kind of special cases and I've never heard good reasoning for why Black Holes can't be pockets of antimatter anyway (I won't get into it) or how a White Hole could reflect all frequencies of light and never absorb them, yet somehow still exist as a thing that can effect other things. They just seem like theoretical ideas that haven't been truly witnessed -> hence my understanding of light.

 

[Ex-User (9086)]

Some cool shadow related words: Albedo, Penumbra, prefix-Umbra (Antumbra), Terminator and Occlusion. One could spend hours talking about surface reflective indexes, unreflective bodies and shadow stuff so I'll just stick to basic OP.

In one sense shadows are holes (in the cast light) so the question becomes 'can holes have holes?'.

A shadow cuts a generally conical hole in the uniform field of light. The cone tapers off to a point if the blocked light source is larger than the covering body or it broadens its base at an angle originating from the smaller light source.

We also say that a light is cast from a source, but a shadow is cast from the occluding body which blocks the light.

How to make holes in holes?
1. By making a hole in the occluding body we get a light cone that cuts a hole in the larger shadow cone. Same if light is shone in a way that doesn't intersect the occluding body but still falls on the umbra.
2. By shining light on the surface covered in shade we make a hole extending towards the occluding body.
3. If the surface under the shadow is uneven, there can be areas covered by shadow and other areas placed lower where light from somewhere else disperses the shadow.

How to cheat holes in a shadow?
1. Close your eyes and imagine light.
2. Imagine that shadow is a cone of light and the area that is in direct light is a shadow.

In another sense 'shadow' refers to the emergent phenomenon of light being blocked So, if an area within the bounds of a shadow was unblocked form the light source it could maybe be considered a 'hole in the shadow'.

What if a light source casting the shadow shines only 60 times per second and goes dark 60 times per second like a lightbulb? Can we make two lightbulbs with one going off 70 times a second and another 60 times a second and get 4 types of holes in shadow? A shadow when both lights are on, shadow with only light A, only light B and no light.

In yet another sense a hole has depth and shadows have no depth so they can't have holes.

Isn't a shadow itself a hole in a light cone? If a shadow on a 2d surface has spots where light shines then these will appear as 2d holes in a larger 2d shadow hole in a light hole and so on.

A few takeaways from thinking about holes in shadow:
Conjecture: Holes, shadows and light sourcess are concepts only understandable by entities able to visualize or perceive in 3 dimensions

Conjecture2: If visual perception and the subject of a sentence are taken to mean the focus of human attention then: A hole is either the focus of perception, or a place entirely omitted by perception OR A hole is the subject of the sentence or a background feature of a long list of items.

Conjecture3: Language relies heavily on the human visual cortex and our ability to see things or remember shapes that we've seen. Can a blind bat describe a shadow, probably yes, but it will be a sonic phenomenon.


What do holes tell us about language: That language is organized in a very similar way to how our brain organizes the sensory input that we perceive. Both language and perception has the focus of attention which is the subject of the sentence or sensory input. They both have a moving context, just as focus of the attention shifts from one sensory input to another so does the new sentence move from one idea or abstraction to another.

Surprise final conjecture: If our primitive brains developed in blind organisms and evolved into organisms with visual perception, then the focus of attention existed before visual input. This means that our brains primary mode of organization is having a mental focus and background on things this is either because our senses evolved this way, or it has to do with how our thinking works which then influenced both our perception and language.

This probably means that thinking precedes language and sensory input. Our senses and speech just organized itself around primitive thought structures that we didn't have words for.