Speculation with portals
I have ADHD, and I read it all. I feel you are mean to me. 
On the other hand, all that would be the case if 4space really existed, which it does not. The fourth dimension is time, not space.
Other portal speculation, let's see... I'll try to come up with something. Keep discussing this in the meantime.
What I'm saying is for the portal to connect with itself again, you would have to fold the paper again. And again. And again. And again. Again... Again... Again... Until it just becomes impossible to fold anymore, and there's nothing left.
@ volt: Actually, it's from a book called Flatland: A Romance of Many Dimensions by Edwin Abbott Abbott (an appropriately recursive name for such a cat). It was first published in 1885. You can read/download it in its entirety here.
(I took a class called "The Shape of Space" my freshman year in college. We read Flatland and a bunch of other fascinating books, and all of our in-class discussions were exactly like this thread. Good times.)
@ espen: Sorry about the ADHD crack. Really I was trying to make fun of myself for writing such a hellishly long post.
As for "time is the fourth dimension," that's really a matter of semantics. As much as possible, I tried to avoid saying "second dimension" and "fourth dimension" and instead used 2-space, 3-space, 4-space. These terms are shorthand for "a manifold defined by N mutually perpendicular axes." Manifold, by the way, means "a topological surface (2 dimensions) or space (3 dimensions or more) that is locally Euclidean."
The simple way to say this is: We're talking about topology, which is inherently and totally spacial. Time doesn't enter into it. You can imagine a four-dimensional space that is completely static, that never changes over time and in fact is completely untouched by time. Now imagine the same space with 4D people in it that does change over time. To them, time would be the FIFTH dimension. Like I said, it's a matter of relative semantics. Just don't think about time at all for the purposes of this discussion, for simplicity's sake. (Yeah, right. The "simplicity" ship has sailed.)
I can recommend a couple other books if you guys are interested... ? I'm kind of geeking on this, I know.
1-3 - Geometry
4-6 - Time
7-9 - Infinity
10 - All possibilities are contained here.
As for the mentioned tenth dimensional "explanation", it's entirely postulates. The idea that time is the fourth dimension seems readily apparent and unchallenged. I'll even grant the logical extrapolation that you bend n+1 dimension to travel in the n-th dimension. That doesn't explain how the fifth dimension remains to be a various manifestation of time itself.
And the position that the sixth dimension is each quantum choice branch is entirely unsupported. There is no empirical evidence that such branches even exist.
Being a diehard skeptic, I have to reject this theory based on the lack of evidence. And while I understand that my flatlander compatriot would reject the proposition of his movement about a mobius strip because he couldn't observe it, he would be entirely justified in doing so.
Also, as to the attempts to forcibly refocus this thread: a very fascinating discussion is happening here and trying to pointlessly redirect it is pointlessly destructive. If you have some idea related to speculation with portals, lay it out. Otherwise, allow the discourse to proceed unimpeded.
Nice, I'm kind of a geek about this myself. 
@Hober:
http://www.tenthdimension.com/medialinks.php
By the way, should we make a new thread for each speculation topic or keep them all in this one thread?
it would look just like this video at 4:07-4:11
The cake is a PI
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Add me on STEAM: iamafractal
I'm up for coop games & beta testing your maps...
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Yeah, I went back and updated my above post. Read up to see it. And some guy's unsupported speculation does not a citation make.
I started reading Flatland. It's pretty good. Probably finish it up in a couple days. Thanks
Fine. I did some research and found out that there is a theoretical fourth space dimension. An example of a 4-dimensional shape is the Klein Bottle.
I think the confusion here is coming from a disconnect about what exactly we're discussing.
On the one hand, some of us are explicitly discussing topology, which is purely spatial, does not involve time, and is largely abstract/theoretical. That is, it does not address the question of whether 4-space or 5-space or any higher-dimensional manifolds actually exist. It concerns their mathematical properties only.
On the other hand, some people are discussing cosmology, which is the science of trying to understand the actual structure of our universe through experiment and observation. Cosmology can and often does involve multiple dimensions of time.
Hope this clears that up.