[quote] Yes, I know what 2d and 3d are, but why can't living things be 2d?[/quote] Because atoms are not 2 dimensional. Spheres are the most geometrically stable shape, thus everything in the Universe more or less being a sphere. You can get a tad more technical than that by saying that the perturbations in 4 dimensions which lead to natural phenomenon like atoms necessarily have to be multi-dimensional because of how that 4 dimensional area is influenced by these perturbations. Put simply, something with mass necessarily is breaking spacetime symmetry. [quote] Is light 1d, 2d, 3d, or no d ( ͡° ͜ʖ ͡°) (serious question though)[/quote] Depends on how you look at it, but photons are zero dimensional. [quote] Is darkness the same?[/quote] No such thing. Darkness is a lack of light. Just like how coldness is a lack of heat. [quote] Can a 3d object go into the second dimension, as of yet? And 2d to 3d?[/quote] Dimensions are not different realms. A dimension is a measurement. Adding a dimension implies a perpendicular measurement. [quote] What dimension are black holes?[/quote] The singularity is 0 dimensional, by we don't like to talk about that, so we can describe the event horizon as a 3 dimensional sphere about the singularity.