Parallax

Parallax

In Brief

"Parallax" is a trigonometric tool that astronomers use to measure distances to nearby stars, but it derives from a familiar optical phenomenon whose operative principle can be easily grasped. The idea is that the apparent location of nearby objects seen against ones in the distant background changes when the position of the observer changes. In Lestrygonians Bloom thinks of it as a Greek word that "I never exactly understood," but he recalls what Molly has said about another such word, metempsychosis: "She's right after all. Only big words for ordinary things on account of the sound." Parallax can be applied to many ordinary things. Bloom's and Mollly's thoughts amply demonstrate the idea that one's subject-position influences what one sees, and Joyce's experiments with narration embody parallactic principles in seemingly countless ways.

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The calculation of parallax takes advantage of the dismaying fact that, for the objects studied by astronomers (and, in less obvious ways, for all objects of sight), location can never be more than relative or apparent. The universe has no center, no boundary, no fixed points of reference. Planets and stars and galaxies drift toward or away from one another, and no universal grid assigns them to absolute locations. Ithaca captures the spirit of this vast cosmic rootlessness when it mentions "the parallax or parallactic drift of socalled fixed stars, in reality evermoving wanderers from immeasurably remote eons to infinitely remote futures."

The ingenious human mind, prompted by the ingenious animal brain, has found a way to exploit these ever-shifting spatial relationships so as to determine the distances to nearby objects. Our use of two eyeballs to see things from slightly different angles is no accident, in an evolutionary sense. Unlike prey animals whose eyes are typically oriented in opposite directions to maximize their field of view, the eyes of human beings and many other predators are set in the same plane because, when focused on an object, their angles toward the object enable the brain to calculate depth in the field and accurately gauge the distance.

Normally this happens unconsciously, and we are not aware that our stereoscopically paired eyes are giving us slightly different images. But if one covers first one eye, and then the other, an object near one's face assumes slightly different positions relative to objects in the background. The same principle operates at a slightly larger scale when driving down a road and viewing a tree in the middle distance against a mountain in the background: the image of the tree moves across the mountain in a direction opposite to the movement of the vehicle. Astronomers do the same thing on a cosmic scale. If a nearby star is observed against the field of much more distant stars, and then observed again six months later, its position will appear to have changed, because the earth's revolution around the sun has taken it to a new vantage point comparable to that of a second eye. Just as the predatory brain processes the information gained from two perspectives to fix a distance, astronomers measure the angles generated by their lines of observation to mathematically calculate the distance to the near-field object.

Joyce's novel does not delve into scientific questions of using angles to determine distance, but it does engage with the underlying idea that objects may take on different appearances based on the situation of the observer. The Greek word παράλλαξις (parallaxis) means nothing more complicated or technical than "alteration," and the book offers many instances of the appearances of objects being altered by the condition of the subject.

In Lestrygonians, for example, food looks different to Bloom depending on whether he is in Burton's restaurant or Davy Byrne's pub. Lemon sole seems elegant in a fancy hotel, and "Still it's the same fish perhaps old Micky Hanlon of Moore street ripped the guts out of making money hand over fist finger in fishes' gills can't write his name on a cheque." It is characteristic of Bloom to flop back and forth in this way, seeing things first from one angle and then from another. In Hades he listens to Simon Dedalus fulminating about Buck Mulligan's influence on Stephen and thinks, "Noisy selfwilled man. Full of his son. He is right. Something to hand on." In the third and fourth sentences, when he shifts from his initial position to the perspective of being Rudy's father, Simon's pride and anger take on a different appearance. Molly displays the same quality of mind, for example criticizing her husband for pandering to old Mrs. Riordan and then thinking, "still I like that in him polite to old women like that and waiters and beggars too."

In Cyclops, where the Homeric parallel turns the denizens of Barney Kiernan's pub into one-eyed troglodytes, Bloom's tendency to see things from multiple angles excites the narrator's contempt: "I declare to my antimacassar if you took up a straw from the bloody floor and if you said to Bloom: Look at, Bloom. Do you see that straw? That's a straw. Declare to my aunt he'd talk about it for an hour so he would and talk steady." To the reader, though, Bloom's inclination to look at subjects from different points of view endows him with a kind of sterescopic vision that marks him as a more complex life form.

Parallax also describes the bewildering variety of perspectives on the book's actions taken by its many modes of narrative presentation. From the first page, traditional third-person objective narration veers into the subjective orbits of certain characters, through interior monologue ("Chrysostomos") and free indirect style ("The plump shadowed face and sullen oval jowl recalled a prelate, patron of arts in the middle ages"). At times, notably in Proteus and Penelope, interior monologue can swamp exterior narration, leaving the reader at the mercy of a character's shifting thoughts, clutching at occasional indications of what is "really" going on.

But objective narration too proves to be a shifting, shifty thing. The newspaper headlines of Aeolus, the dramatic speeches and stage directions of Circe, the many parodic styles of Cyclops, Nausicaa, and Oxen of the Sun, the fragmented glimpses of scenes and individuals in Wandering Rocks, the irruption of first-person narration in Cyclops, the catechistic questions and answers of Ithaca: these and other narrative experiments shatter our expectation of a single, trustworthy perspective on the action. Ulysses does not opt, with Mulligan, for the view that we can know "only ideas and sensations" and therefore may dispense with searching for the truth. Its objects of representation and inquiry—e.g., individual lives in crisis, the fates of nations and races, the relations between human beings and animals—ask to be regarded as real entities demanding serious consideration. But those entities look different from different angles, like stars careening through multidimensional space and time

JH 2016
Parallax as demonstrated by closing first one eye and then the other. Source: quillandpad.com.
Parallax as demonstrated by looking out the window of an automobile from two different points on the road. Source: www.eg.bucknell.edu.
Parallax as demonstrated by looking at a star in January and July. Source: hyperphysics.phy-astr.gsu.edu.
The parallax angle (p) used to calculate distance (d). Source: www.atnf.csiro.au.
Degrees of difference in parallax angles seen in relation to different distances. Source: csep10.phys.utk.edu.