Anathem Wiki

A Photomnemonic Tablet is an object used to record images from a telescope.

Images can be continually recorded on a Photomnemonic Tablet for a short or long period of time, and played back as a time sequence. Erasmas shows Cord a tablet which contains over 2500 years worth of observations of Saunt Tancred's Nebulae, the expanding nebulae of Saunt Tancred's Star which exploded as a supernova explosion and thus similiar to the real world Crab Nebula.

Images can also be edited and combined in order to create a deeper exposure or a time exposure.

A tablet includes a Syntactic Device which is controlled by moving one's fingers along the outside edge.

A Photomnemonic Tablet is described by Erasmas as a disk with a diameter of "two hands held side by side" and a vertical thickness of "three fingers."

Real World Analog[]

The functions of the Photomnemonic Tablet are similar to that of CCDs which are used in the vast majority of modern telescopes and imaging satellites. A CCD records images as a series of frames, each frame of which can be several seconds to several minutes long, or even longer in some circumstances. The digital information in the frames are processed with software suitable for the telescope or satellite being used, and can be combined to create a deeper image or, for bright objects, a time sequence.

A major difference between a CCD and the fictional Photomnemonic Tablet is that a CCD and associated electronics are not combined with the necessary software into a single object, instead the digital information recorded by the CCD is transferred to a separate computers where scientists can analyze the data.