My spouse and I are minutes into our early evening walk.
During the first leg of our three mile loop, we have to walk single-file along
the narrow shoulder of a two-lane road. I am leading us, and he is behind me
several paces. We have been walking in near-silence. Intermittent traffic creates
enough noise to keep our conversations minimal.
“Is your hair naturally wavy like that,” he asks suddenly,
“or did you do something to it? Is that what happens to it when you twist it up
into a hair thing?”
“No,” I answer, unsurprised that even though he sees me
every day, he has either forgotten or hasn’t noticed before now that my hair is
wavy. “I washed it last night and let it air-dry, and that’s what it does on
its own.”
“You don’t curl it or do anything? The top half sort of curves
to the left and the bottom half goes to the right.” He takes two slightly longer
strides and is right behind me. I feel his hand at the back of my head now as
we walk, touching and examining the wave, lifting locks and trying to figure
out the mechanics.
“If you Fourier-transformed it, it would have an inch
scale,” he says. “You’d have a big spike at each end representing the waves.”
“What does that mean?”
“You see power in one mode.”
I pause, and then just ask the question. “What does that mean?”
He asks me to imagine being at a lakefront, looking at the
waves on the lake’s surface. A very windy day would create short, choppy waves.
A fetch would create larger waves, spread further apart. Here and there, a
larger swell would appear. He says that if we could look at and measure every
point on the lake and put that data into a Fourier transformation, we’d see
different power points representing the different wavelengths. I would just
have the one wavelength, and one power mode, representing the wave in my hair.
We are now ten minutes into our walk. It has begun to rain
gently. We checked local radar and discussed the weather before leaving the
house. I had expressed feelings that it was going to rain again. He said that we
probably had an hour before it came. We decided to go regardless of what we
each thought. He wants to turn around now, worried that I’ll get irritated at
being rained on. I’m not, but we turn around anyway since I don’t want to catch
a chill.
During the brief walk back to the house, he tries to explain
in plain language what Fourier transformation is, and I try to understand what
he’s telling me. I ask him about it for the tenth time while we’re in the
bedroom together, changing into dry shirts. There’s some frustration in his
answer.
“Are you getting
frustrated? I really am just trying to understand.” I ask.
“No, I’m not,” he says. “I just wish I understood it better
myself so I could explain it clearly to you.”
