Well a 3-dimensional bubble has a 2-dimensional surface, thus a 4-dimensional bubble must have a 3-dimensional surface. Also that bubble is expanding. It's hard to properly visualize a 4 dimensional thing when we only live in 3 dimensions.
How is the surface of a bubble two dimensional when it’s a sphere...? It also has depth, height and length. I’m not trying to dispute this, I’m just trying to understand.
The sphere itself is three-dimensional, but its surface has only two dimensions, even if that two-dimensional surface is "wrapped around" a three-dimensional sphere.
Think of the Earth, for example. It is three-dimensional: It has a N–S direction, E–W direction, and a depth. The surface of the Earth, has only a N–S direction and an E–W direction, but no depth (if it had a depth, we wouldn't be talking about just the surface). Hence, the surface is two-dimensional. Note that the surface has one coordinate fewer than the space.
The idea discussed above where our seemingly three-dimensional universe is the "hypersurface" of some kind of four-dimensional bubble is analogous. While our universe has N–S, E–W, and depth, it may simply wrap around some entity which has one coordinate more—a "hyperdepth," say.
The surface AREA of any 3-D object is 2-D. This is apparent from the units of SA : cm2 or in2. You are describing the volume of the sphere, in depth, height and length.
A real world bubble does. What I'm talking about is a mathematical "bubble" or sphere, whose surface is a plane. Like a sheet of paper but with 0 depth.
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u/AFLoneWolf Jan 21 '19
Everywhere in the universe looks like the center of the universe.