Dimensional analogy [ ] A net of a tesseract To understand the nature of four-dimensional space, a device called dimensional analogy is commonly employed Introducing Einstein's Relativity Reprint ed
In 1886 described his method of visualizing four-dimensional objects with A position along the w axis can be called spissitude, as coined by

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For example, two-dimensional objects are bounded by one-dimensional boundaries: a square is bounded by four edges.

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The perspective projection of three-dimensional objects into the retina of the eye introduces artifacts such as foreshortening, which the brain interprets as depth in the third dimension
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[ ] Because these surfaces are two-dimensional, they can form much more complex knots than strings in 3D space can
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In this case, the 'retina' of the four-dimensional eye is a three-dimensional array of receptors
They can be used to generate rotations in four dimensions Card Shuffles and Tricks of Lightning Calculators to Roller Coaster Rides into the Fourth Dimension 1st ed
But the geometry of spacetime, being , is profoundly different from that popularised by Hinton ; published in the magazine

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On the left is the cube viewed corner-first.

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Similarly, the other 7 cells of the tesseract are not seen here because they are obscured by the visible cell
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Projections [ ] A useful application of dimensional analogy in visualizing higher dimensions is in
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The analogous viewpoint of a tesseract is the face-first perspective projection, shown on the right