Seeing in three dimensions.

[Nick]

I came up with an idea: it's impossible to see in three dimensions because the retina cells in front would block the retina cells in the back, which makes us see only in two dimensions.

But what if we discovered a magic elixer (bear with me here) that enabled retina cells to see past the other retina cells (x-ray vision, so to speak). Being able to see past retina cells, they'd be able to focus *through* objects, and would therefore be able to see inside of them.

For instance, take Bob. Say bob had two rows of retina cells, one in front and one in back, and the ones in back could see through the retina cells in front and through other objects. Now let's say that Bob had a square in front of him. He would be able to use the back row to see the first set of points on the square and use the one's in front to see the second set of points (closest to him; this is also assuming the front row of cells could see through stuff too). This could enable him to see two touching lines at the same time, which would in turn enable him to see a two dimensional image.

Whether his brain could understand the images is a completely different matter, please leave it out of any responses.

[4D guy]

A 2D-being would also say that it is impossible to see in 2D. I dont know how the 4D-beings would see their world but i'm pretty shure it is in 3D.

[pat]

The magic elixer would also have to allow photons to penetrate into the object's center, reflect, and make it back out again.

[Nick]

I also just realized that the subject would also need to understand 4d rotations, too.

For example, if Bob could see a series of lines in front of him, he still wouldn't see it from a 3d perspective, he would have to rotate it three-dimensionally in his mind.

[moonlord]

Something closely related is the double-layer DVD. First layer is semitransparent, second is opaque.

[bo198214]

I came up with an idea: it's impossible to see in three dimensions because the retina cells in front would block the retina cells in the back, which makes us see only in two dimensions.

The inability to see fully 3d is not due to restricted retina, but through the inability of the light to pass most objects.

[The_Science_Guy]

Aren't we technically seeing 3D if an object is made of glass (e.g. a glass cube)?

[Nick]

No, not really.. its even harder with glass, because it is extremely difficult, if not impossible, to look at the glass itself and not what is behind the glass.

If you are able to manage looking at the glass, however, you would only see it in multiple 2d sections, no matter how hard you try or how thin it is.

[The_Science_Guy]

No, not really.. its even harder with glass, because it is extremely difficult, if not impossible, to look at the glass itself and not what is behind the glass.

If you are able to manage looking at the glass, however, you would only see it in multiple 2d sections, no matter how hard you try or how thin it is.

Dang. I theorize that a person might be able to see 3D if there are receptors positioned so that they're outlining a pyrmid without a bottom, or something like that.

[moonlord]

No being can see in 3D no matter the number of eyes. Your brain interprets the parallax and co.

[Hugh]

Here is a being that can see all points from within a cube, a dragonfly, with its wrap-around compound eyes.

[Nick]

The inability to see fully 3d is not due to restricted retina, but through the inability of the light to pass most objects.

I have to agree with bo; how can wrap-around eyes give it the ability to see in 3d?

[Hugh]

how can wrap-around eyes give it the ability to see in 3d?

A dragonfly can look up/down, forward/backward and right/left at the same time. Isn't that 3d?

[Nick]

No, 3d is being able to see all points on and in a 3d shape at one time.

[Hugh]

No, 3d is being able to see all points on and in a 3d shape at one time.

Put it in a glass cube then. :wink:

Okay then, could you explain the differences in the number of dimensions that a human can see at one time relative to what a dragonfly can?

[pat]

The dragonfly has a 4-pi steradian field of view. Humans have a field of view that is slightly less than 2-pi steradians.

It's not a difference of dimension; it's a difference of range.

[papernuke]

if the magic elixer actually worked (or if there actually was one) it would only make the other retina cell see past the ones in front, which would just make him see better. a better way to put it is the exlier gave him x-ray sight so he could not only see through tthe retina cells in front of him, but do what you said with the cube, see through or into it

[Nick]

The magic elixer lets retinas see through things. I don't see any problem with that... it can see through the retina cells in front, AND see through the cube.