Message #561

From: Melinda Green <>
Subject: Re: [MC4D] How many eyes?
Date: Sun, 14 Sep 2008 16:19:43 -0700

I don’t know about you but I’m able to stand upright in 3 dimensions
with only 2 legs. ;-)
Seriously though I think you are right that N legs are required to build
a stable platform in N dimensions and that this can be shown with a
simple inductive argument. It appears as simple as the fact that a
stable platform in N-1 dimensions will tip over into the new dimension.
That tipping will happen with a single degree of freedom which can be
halted with the addition of a new leg with a displacement in the new

I recently read the book Diaspora
<> by Greg
Egan. in which some of the main characters would move between universes
with different properties and would construct interesting bodies when in
5 dimensional universes. The author was smart enough to realize that
they’d also need brains wired to be able to deal with life in higher
dimensions. It’s not quite as good as his amazing book Permutation City
<>, but at
least it’s still not bad.


Jenelle Levenstein wrote:
> How many legs would a 4D creature need to walk on a 4D planet. On a 3D
> world an object neads at least three legs to stand stably. Would that
> mean that in order for something to stand upright in a 4D world you
> would need at least 4 legs?