Kate Becker Kate Becker  I used to think that, if I tried hard
enough, I would be able to imagine the fourth dimension of
space.  "How hard can it be?" I thought. After all, imagining
one spatial dimension is pretty easy: Just picture a line and
you're done. Thinking in two dimensions is simple, too. Circles,
squares and anything else you can put on a sheet of paper exist
happily in the two-dimensional world. Three dimensions: No
problem there. That's where we live every day.  Yet when it
comes time to add just one more measly dimension, my mind can't
bend to the challenge.  If it could, I would be able to imagine
how space itself might curve along the invisible axis of the
fourth dimension. I would have an instinctive grasp of what it
would be like to live in a spherical universe, where a journey
in any direction would ultimately bring you back home where you
started, or a hyperbolic universe, contoured like a saddle on
the back of that unimaginable fourth dimension.  As it is, I
have to fall back on analogi