Dear Tom and Ray,
I recently had a single-serving-size epiphany which I thought I’d share with you. I have always wondered why it is that windshield wipers invariably and without fail develop smears and streaks SOLELY in the part of the blade that passes directly through the path of the driver’s vision. I have even gone so far as to take such a defective blade and reinstall it flipped end-for-end, only to have a new smear form smack-dab in the middle of my field of vision.
After years of turning this problem over and over in my head (to the detriment of most other cranial obligations such as family, career, shoe-tying, etc.), I have formed a theory.
The human optical system is, at its heart, a parabolic reflector. Random photons enter the eye and are focused into a coherent image before being sent off for processing in the one-hour photo lab in the brain. My theory is this: When you are driving, you are expending so much effort on your visual systems that the interior of the eye begins to emit some form of energy. This energy bounces around inside of the eyeball until it is focused by the same parabolic reflector used to collect light energy coming in.
The resulting concentrated beam of eyeball energy is then shot out the lens of the eye, where it spot-heats a tiny section of the windshield directly in line with the primary focus of your attention. The heat buildup at this point is transferred to the windshield wiper blade, which promptly warps, resulting in a smear directly across your field of vision.
I am currently fleshing out a series of experiments using various types of sunglasses to see if this eyeball energy can be prevented from making it as far as the windshield. If I make any discoveries, I’ll be sure to let you know.