clifford_a-_pickover_surfing_through_hyperspacebookfi-org

60 surfing through hyperspace
rassed that the man is so obviously seeking attention. You wish the man
would go away. He does not belong. It's a feeling you frequently have.
You roll up the window. "Sally, I think I can help you understand how
a 3-D retina can visualize a human, inside and out, at the same time.
First consider a blood transfusion for 2-D creatures via a tube that goes
up into the third dimension and back down again into the plane of the
creature. As far as the creature is concerned, you are not breaking the
skin, which might be represented as a line in a drawing. Can you visualize
how 4-D creatures can transfuse us?" (Fig. 3.5).
"Yes, they could transfuse a 3-D creature by using a transfusion tube
that goes upsilon and delta into the fourth dimension without ever
breaking the skin. The same concept applies to stealing objects in safes
without ever breaking the safe wall. Your hand would materialize in the
safe and then dematerialize as you withdrew it. But where does the transfusion
tube really go?" (Fig. 3.6).
"It goes upsilon where the operating room doesn't even exist! Similarly,
a 4-D creature's 3-D retina can see all of your insides without breaking
your skin. This assumes that light rays are reflected into the fourth
dimension—we'll have to research that further. I've memorized Abbott's
nice description of a 2-D creature lifted out of Flatland and looking
down into his 2-D world from a 3-D world":
I felt myself rising through space. It was even as the Sphere had said.
The further we receded from the object we beheld, the larger became
the field of vision. My native city, with the interior of every house and
every creature therein, lay open to my view in miniature. We mounted
higher, and lo, the secrets of the earth, the depths of mines and inmost
caverns of the hills, were bared before me.
Sally nods. "We've talked about how 4-D beings would look to us, but
what would we really look like to them?
"To answer that question, let's talk about the appearance of creatures
living in worlds perpendicular to one another."
"Perpendicular worlds?"
"Yes, again I'll start with a 2-D analogy. Consider two planes on which
thousands of intelligent insects live. Their two worlds intersect in a line.
Along the line of intersection are many moving line segments changing
size, disappearing and reappearing" (Fig. 3.7).