The Science Behind The X-Files:

Unrequited

• In this episode, Scully and Mulder face an assassin who can render himself invisible when he is in anyone's direct line of sight. The episode is used more as a vehicle for relevant POW-MIA issues, and thus glosses over the actual science background usually present on the show. Only once during the episode (to my memory) is a scientific explanation proffered. When a woman visiting the Vietnam War Memorial sees the killer disappear, her eye begins to bleed and she is taken to the hospital for treatment. Scully claims that the woman probably has a "floating scotoma." A scotoma is a blind spot in the eye, relegated to either the central or peripheral field of vision, usually caused by a hole ripped in the back of the eyeball by imbalances of the fluid in the eye. However, I can't find anything about a scotoma that "floats" and my biology major college roommate never heard of such a thing either, so I think Scully missed the boat on this one. (On further research, I found a site, listed below, that discusses the difference between temporary "floaters" and permanent scotomas. I still think Scully's full of it....)
  
  POW-MIA issues link: http://www.asde.com/~pownet/
  Vietnam War Memorial site: http://www.vvmf.org/wall.htm
  For a definition of scotoma, go to http://www.spedex.com/resource/documents/veb/scotoma.html.
  For a basic overview of how the eye works according to the Encarta Encyclopedia, check out http://www.eyeinfo.com/wayworks.html.
  For a discussion of the difference between "floaters" and scotomas in multiple sclerosis patients, go to http://dem0nmac.mgh.harvard.edu/neurowebforum/ MultipleSclerosisArticles/1.15.971.09PMMSFloaters.html.

• Mulder mentions that in Vietnam, U.S. soldiers reported the Viet Cong's ability to appear on the fringes of peripheral vision, but then disappear when someone looked in their direction. He suggests that maybe their killer, Nathaniel Teager, learned a trick from his captors in his many years of imprisonment, perhaps some method of superior camouflaging. Camouflage, the technique of breaking up a visual form so that it's harder to discern from its background, is a method of hiding that has been used for hundreds and hundreds of years. Science and technology continually provide better methods of camouflage; apparently, current research is investigating using fractal patterns to create camouflage that works over a wide range of background environments.
  
  Warpig.com article that mentions fractal camouflage: http://www.warpig.com/paintball/technical/camouflage/camo.html
  For an elementary introduction to the optical illusion qualities of camouflage, visit Sandlot Science's page at http://www.sandlotscience.com/Camoflage/Camouflage_frm.htm.
  For a lengthy, but well-written article on the concepts of camouflage from a hunter's perspective, go to http://www.announce.com/vanet/camo.htm.
  To find out more about fractals, and how they're created, visit "The Science and Beauty of Fractals," a first place winner in the ThinkQuest competition at http://library.advanced.org/3288/.

• Well, there's not that much more to speak of concerning the science of this episode...but how could I let this file end with only two articles? We'll finish up with a look at ophthalmology, the medical science of everything related to eyes (and a really tricky word to spell, too).
  
  Ophthalmology definition link: http://www.m-w.com/cgi-bin/netdict?ophthalmology
  For the Mining Co.'s human-mediated clearinghouse on all things ophthalmological, visit http://ophthalmology.miningco.com/.
  To see the resources Yahoo's got filed away on ophthalmology, check out http://www.yahoo.com/Health/Medicine/Ophthalmology/.