clifford_a-_pickover_surfing_through_hyperspacebookfi-org

36 surfing through hyperspoce
Figure 2.11 Identically shaped sperm from a 4-D being. As the hyperellipsoidal
heads intersect our 3-D world, they would first appear as points, then ellipsoids
that changed in size, and then points again as they left our space. Depending on
their intersection with our world, at times they would resemble spheres. We might
only see their heads or tails.
"Just kidding, but you get the point. A sphere is a 3-D stack of circles
with different radii. A cylinder is a 3-D stack of circles of the same radius.
A hypersphere is a 4-D stack of spheres with different radii. A hypercylinder
is a 4-D stack of spheres of the same radii."
"I can't visualize how to stack objects in a fourth dimension."
"Sally, it's very difficult. Some scientists use computer graphics to help
visualize 3-D cross sections of rotating 4-D objects." You pause. "Do you
recall I told you how easy it would be for a 4-D being to impregnate a
woman without being seen?"
"That was too weird to contemplate."
"Well, contemplate this. What do you think 4-D sperm would look
like?"
Sally takes a deep breath. "Instead of having ellipsoidal heads, 4-D
sperm might have hyperellipsoidal heads. As the heads intersect our 3-D
world, they would first appear as points, then ellipsoids that changed in
size. Just before it disappeared, a small blob would remain for some time
as the tail passed through. A 4-D man could, in principle, inseminate a
3-D woman without her even seeing him" 1 (Fig. 2.11).
Outside it is beginning to snow. A few large flakes intersect the plane
of your window and disappear. You are quiet as you watch the headlights