Originally Posted by bp2:
“The police box exterior contains the TARDIS interior though. Unless there is a teleport or a door leading to the console room which is outside the police box the interior cannot be 4D. The question is whether a 3D object can contain a 4D object and the answer is no. And the police box having more dimensions and allowing the interior to be 4D is a flawed idea because the interior would have the same x,y,z coordinates as the police box and that is not the case.”
I think I'm just not explaining it very well. All 2d spaces actually extend into 3 dimensions. A piece of paper might be 2 dimensional but the other dimensions around it don't go away.
Imagine you can only perceive 2 dimensions. Then imagine a box of paper. All you would be able to see in your 2 dimensional world would be the top sheet of paper and the edges of the box that bound it. As far as your concerned, nothing larger than the sheet of paper could possibly fit inside the 'box'.
Now imagine that each sheet of paper is actually curved at the edges and as you walk to the edge you just follow the curve round to the underside of another piece of paper in the box. You don't perceive the curve because the curve is a manifestation of the 3rd dimension. To your 2D senses you are just continuing to walk in the same direction but there is a whole extra sheet of paper for you to walk across. Now imagine that every sheet does this for thousands of pages.
Inconcievably to your 2 dimensional senses there is more space within the confines of the box's boundaries than could possibly fit within those boundaries because the 2 dimensional ream of paper has been folded up and, by extending into a 3rd dimension through this folding it is squeezing into the 2 dimensional confines of the box opening.
With the TARDIS we're just adding another dimension to that concept. It's hard to conceptualise because we can't concieve of a 4 dimensional space but it's the same concept as the box of paper. The TARDIS is folding our 3 dimensional space into a four dimensional space which we can't visualise, allowing an infinite amount of 3 dimensional space to occupy what we perceive as the 3 dimensional TARDIS exterior.