Academy of Sciences of Heroesland

I would call it a three-dimensional sphere after all.

No, a three-dimensional sphere is our Universe. More precisely, I heard somewhere that the Universe is a three-dimensional sphere. :D They say Perelman even calculated its "area" (volume). :eek:

Added 2 minutes ago

on this very sphere we have 2D, but without 3D such a sphere simply cannot exist...

Of course. Therefore, our three-dimensional sphere-Universe is located somewhere in 4D space. ;) Be that as it may, an ordinary sphere is a manifold of dimension 2, not 3. :p

Added 3 minutes ago

Zlobny YashchurNo, of course not. But he believes that the surface of the Earth represents a one-connected closed compact two-dimensional manifold without edges, homeomorphic to a two-dimensional sphere. :D:D:D

Well, spherical. So do you believe it or not?Nope. The Earth has the shape of a body whose surface is a one-connected closed compact two-dimensional manifold without edges, homeomorphic to a two-dimensional sphere. This is 100% KNOWLEDGE! :smile08:

Added 1 minute ago

So this is what I live on! :eek:

And what did you think you lived on? :D