Number 276 (Story #3), June 21, 1996 by Phillip F. Schewe and Ben Stein DIGITAL VERSATILE DISCS (DVDs) will appear in consumer products in early 1997. The same size as conventional compact discs (CDs), DVDs will hold about 14 times more data because of a combination of innovations. For example, both types of disc encode digital data as pits on thin plastic platters, but for DVDs the pits are smaller (.4 microns versus .83 microns for CDs), the tracks of pits are closer together (.7 versus 1.6 microns), and the laser light used to read data has a wavelength of 635-650 nm rather than the 780 nm used for CDs; all of these factors allow data to be crowded in more densely. Furthermore, the DVD consists of two layers, each of which can hold data. With a capacity of 4.7 Gbytes, the DVD will be able to provide a variety of multimedia products, even movies, at least in compressed form. And all of this is without resorting to blue-light lasers (still under development), whose shorter wavelengths would permit even more data to be compressed into a given area. (Scientific American, July 1996.)