I think this paragraph from Wikipedia is the most relevant to what follows:
Though holography is often referred to as 3D photography, this is a misconception. A better analogy is sound recording where the sound field is encoded in such a way that it can later be reproduced. In holography, some of the light scattered from an object or a set of objects falls on the recording medium. A second light beam, known as the reference beam, also illuminates the recording medium, so that interference occurs between the two beams. The resulting light field is an apparently random pattern of varying intensity which is the hologram. It can be shown that if the hologram is illuminated by the original reference beam, a light field is diffracted by the reference beam which is identical to the light field which was scattered by the object or objects. Thus, someone looking into the hologram 'sees' the objects even though it may no longer be present. There are a variety of recording materials which can be used, including photographic film.There are two other notable repetitions within this first section: Hal uses the word "lately" (intentionally homophonous to Gately, no doubt) on the very first page, and he asserts "I am in here" on both p. 3 and p. 13. Well, on p. 13, he says, "I'm in here."
I think what is being expressed is a certain fear of the mediation of existence, a feel of being antecedent to (and trapped behind) an after-image or reconstruction of the self. Hal feels that he is "no longer present" at or in the moment he is perceived, which is why "lately" is repeated and why he needs to assert that he is "in here"—he is in the hologram that the deans are seeing and interacting with.
I don't want to get ahead of myself here, but in some notable ways I think this fear is linked to the concerns Wallace expressed in his essay on television and U.S. culture, "E Unibus Pluram" [pdf]. In particular, I wonder if we can't think of irony itself as a sort of holographic image of culture, at least it is used in those manners which Wallace critiques.
This post is meant more as a sort of opening up of one line of thought I believe I'll be returning to over the course of my reading, rather than as a full exploration of this idea. Clearly, we're not very far into the novel, so doing more than remarking on a theme which may recur would be premature.
What about you—first thoughts, anyone?
1I'm pretty certain that should be "post-Fourier transforms," right? I mean, that's more common/more standard.