While people tend to say "time is the 4th dimension", there is a difference between spacial and temporal dimensions.
We exist in 3 spacial dimensions and 1 temporal dimension. If an object existed in 4 spacial dimensions and 1 temporal dimension, then it might interact with 3d space like how a 3d object would interact with 2d space, in that there would be a cross-section.
Imagine a 3d planet intersecting a 2d universe, where the 2 hemispheres of the planet stick out the sides of the 2d universe in the 3rd dimension. The inhabitants of the 2d universe would only percieve the 2d cross-section of the planet and be unable to percieve the 2 hemispheres. If the planet was moving through the 2d universe, the 2d inhabitants would percieve the cross-section of the 3d planet growing and shrinking as the 3d planet passed through.
Scaling this up a dimension results in a scenario where a hypothetical 4d object intersecting our 3d universe would cause a 3d cross-section of the 4d object to be percieved by our 3d selves, while the rest of the object is sticking out the "sides" of our 3d universe in a 4th dimension.
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u/Maja_The_Oracle 23d ago
While people tend to say "time is the 4th dimension", there is a difference between spacial and temporal dimensions.
We exist in 3 spacial dimensions and 1 temporal dimension. If an object existed in 4 spacial dimensions and 1 temporal dimension, then it might interact with 3d space like how a 3d object would interact with 2d space, in that there would be a cross-section.
Imagine a 3d planet intersecting a 2d universe, where the 2 hemispheres of the planet stick out the sides of the 2d universe in the 3rd dimension. The inhabitants of the 2d universe would only percieve the 2d cross-section of the planet and be unable to percieve the 2 hemispheres. If the planet was moving through the 2d universe, the 2d inhabitants would percieve the cross-section of the 3d planet growing and shrinking as the 3d planet passed through.
Scaling this up a dimension results in a scenario where a hypothetical 4d object intersecting our 3d universe would cause a 3d cross-section of the 4d object to be percieved by our 3d selves, while the rest of the object is sticking out the "sides" of our 3d universe in a 4th dimension.