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April 30, 2007

The middle is always light

I haven’t been able to make much progress reading The Scientists since the long return flight from Sydney, let alone blog about it. I’ve gotten to the turn of 19th century (late 1700s - early 1800s), and Young’s double-slit light experiment. Assuming the laws of physics apply to human behavior (and why wouldn’t they, since they encompass everything else in the universe?), I find this experiment fascinating. It’s historic note for science is that it provided the proof that light is composed of waves, not particles, but I am intrigued by the way it interacts with itself in the double-slit experiment to create an interference pattern: a sequence of alternating light and shade. The light (from two different sources or directions, the separate slits) results from the peaks of each wave adding together, marching in step, being aligned. The dark spacings are not – as one might guess – where the valleys of each wave converge, but when “the waves from the two slits are out of step with each other (out of phase) so the peak in one wave is cancelled by the trough in the other wave” (2002: 405).

Young explained how to calculate the exact spacing of the resulting light/dark pattern based on the light’s wavelength, calculable by measuring the width of the strips. I haven’t yet wrapped my head around the formula (it seems to be a straightforward proportional equation; the interference link enables play in order to see the results). Nonetheless, two points gripped me: one, that darkness is the result of adding beams of light, and two, this elegant notion: “The middle (of the pattern) is always light” (Thomas Young, in Gribbin, p. 406).

Perhaps I stretch too far to suggest that one person’s “light” (soul, spirit, mind, intellect, intuition) can “cancel out” another’s, but it seems to me this is what occurs in relationships as individuals undulate along a continuum (wavelengths?) of intimacy. Young’s quote includes something about “bright stripes on each side…at such distances”, which I think means at the edges of the patterns. I guess the two-slit experiment is always a matter of light enclosing spaces of darkness rather than darkness at the boundaries limiting light. This is worth further thought. :-) Of course, the experiment is predicated, actually, on a single source of light that is shone through first a single slit in one barrier, and then a double slit in the second, so my analogy may break down at the most crucial point.

Unless one imagines that all life originates from a common source . . . or . . . that peak intimacy/enmity (closeness) occurs when the "middles" of each respective interference pattern overlap. There is less connection (relatedness) when waves at the trough encounter waves at the peak - interactions that cancel each other out = a zero sum?

Posted by Steph at April 30, 2007 8:37 AM


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