clifford_a-_pickover_surfing_through_hyperspacebookfi-org

4 surfing through hyperspace
"I'd like to apologize for not rescuing you sooner. In less than a
minute, I found you lying beside a tombstone. You weren't harmed."
She nods. "I still don't understand what happened to me."
"That's why we're here. I'm going to teach you about the fourth
dimension and show you things you've never dreamed of."
She rolls her eyes. "You sound like my ex-husband. All talk."
You hold up your hand in a don't-shoot pose. "Don't worry, you'll like
this. Take a seat."
You take a deep breath before starting your lecture. "The fourth
dimension corresponds to a direction different from all the directions in
our world."
"Isn't time the fourth dimension?"
"Time is one example of a fourth dimension, but there are others. Parallel
universes may even exist besides our own in some ghostly manner,
and these might be called other dimensions. But I'm interested in a fourth
spatial dimension—one that exists in a direction different from up and
down, back and front, right and left."
Sally lowers herself evenly into a chair. "That sounds impossible."
"Just listen. Our ordinary space is three-dimensional because all movements
can be described in terms of three perpendicular directions." You
remain standing and gaze down at Sally. "For example, let's consider the
relative position of our hearts. You do have a heart, Sally?"
"Very funny."
From your desk drawer, you remove a tape measure and hand one end
of it to her. "I can say that your heart is about four feet south of mine,
one foot east of mine, and two feet down from mine. In fact, I can specify
any location with three types of motion."
She nods, apparently growing more interested in your talk. Outside
there is a crack of lightning. You look toward the sky and then back at
Sally. The gathering clouds and mists reflected in her eyes make them
seem like gray puffs of smoke.
A fly enters your office, so you close a small vent by the window before
any other insects can take refuge. "Another way of saying this is that
motion in our world has three degrees of freedom." You write three words
in big letters on the blackboard:
DEGREES OF FREEDOM