percentage of reality
26 January 2011)
Today a full day of physical
work; gratifyingly tired. I am reduced to sitting on the floor to write
as I don’t have the heart to shift either of the cats who are inhabiting
the newly arrived chairs. His and hers, crashed out next to the stove.
(I think that M + T, the kind chair donors, will feel that this is the
appropriate hierarchy of users.)
It’s dark and tonight’s scene is illuminated only by the light
from the laptop screen and numerous flames, both naked and encased behind
the mica windows of the aforementioned sizzling stove.
The book lies open at a page showing the title of section 2.3.
Phase of a propagating wave and its wavevector.
I can’t tell if it’s merely the rhythm of the words, or a
combination of that with their subtle rhyme and alliteration, but I cannot
help but roll the phrase around in my mouth for a while, feeling its sound.
It feels good. And visually the veve (vera verity?) embedded in the last
word is somehow both alien, and yet unspeakably perfect.
Yesterday I spent much of the day with the book, revisiting things that
I had glancingly encountered previously. I was making notes, reading around,
and more fully understanding ideas that were being described to me. I
realised I’d previously totally overcomplicated the notion of phase.
What is phase? (– it helps, when dealing with this question, not
to worry about wave particle duality implications, but just to consider
light in terms of its wave properties - in my experience this shifts the
understanding from mind-bendingly impossibly complicated to really pretty
straightforward). It also helps to consider that the time element involved
is fundamental – phase is the proportion of a periodic waveform
that passes some reference point after a time t. Simple. So, on I skipped,
frankly even feeling a little bit smug at how readily it was all going
in this time. But.
Amazing that the simple act of turning a page can move one from lackadaisical
absorption and regurgitation of information, into utter incomprehension.
That thin layer from page 13 to page 14 has a sharp edge, and is followed
by some maths. I stumbled around with a number of the equations, which
I didn’t follow but felt that I should, and which culminated with
the rather uncompromising words:
“Clearly this implies that:
r = 1
and that r is also complex and hence a phase shift is imposed on the reflected
I’m afraid the only thing clear to me at that moment was that clarity
and I had parted company. (Maybe this ‘clearly’, as with other
transparencies, is a relative term, and I simply had some kind of nonlinear
response to the information such that my optical density increased with
the intensity of the mathematics). But I do not wish to infer that the
writings of Reed and Knights (or “the boss” as the former
is currently known among intimate company) are in any way at fault –
only moments earlier I had been applauding the inclusiveness of their
fundamental introductions to various aspects of the subject. No, rather
it was that the brain of the resident artist was not at its best, and
seemed to fall at what is shamefacedly probably quite an easy hurdle.
An urgent injection of low brow was required so I returned to wiki, in
an effort to ease the pressure on my head.
The wiki silicon photonics page is not exactly what I would describe as
low brow, and when I reach the statement that two-photon absorption “
...is related to the Kerr effect, and by analogy with complex refractive
index, can be thought of as the imaginary-part of a complex Kerr nonlinearity.
At the 1.55 micrometre telecommunication wavelength, this imaginary part
is approximately 10% of the real part.”, I decide that my efforts
into comprehension of this realm are probably done for the day. I take
a morsel of comfort from thinking that at least I get a little of what
a wavelength of 1.55 microns implies, but my brain falters at trying to
compute how one can calculate the size of an imaginary nonlinearity, let
alone as a percentage of reality.