In a development that appears to defy the laws of television industry physics, the medium's expanding universe may have reached its limit much sooner than anyone would have imagined--and it seems to be one that is considerably less than the apocryphal 500 channels it was ultimately projected to deliver. For the first time since Nielsen Media Research began tracking it, the number of channels receivable by the average U.S. household declined last year, and appears to have stalled out at about 100. The development has surprised some Nielsen clients, which have asked the researcher to investigate why the number of channels available to the average TV household would decline even as the percentage of households migrating to digital cable and satellite TV systems--with literally hundreds of channels available--continues to expand. "Nielsen is looking into it," was all Alan Wurtzel, president of research and media development at NBC, would say about it when he made the observation at a recent industry conference. Nielsen executives so far have declined to comment on potential reasons for the decline, which dropped from an average of 102.1 channels in 2002 to 100.4 channels in 2003, according to a Nielsen 2004 report on the television universe. It's unclear whether it is something methodological, such as unusual turnover in the Nielsen sample that might have changed the representation of households based on the number of channels available to them, or whether it is a genuine marketplace phenomenon. If the decline in channels received is a genuine development, it seems to defy the TV industry's claims of ultimately delivering a virtually unlimited channel universe via digital cable and satellite TV, and other new technologies such as video-on-demand. Still others think we've already reached a "channel-less" era of television, brought on by digital video recorders, where viewers essentially record and watch programming from their hard drives detached of the channels that originally televised them. Interestingly, the number of channels that are actually tuned by the average U.S. household has not changed and remains constant at 15, or roughly 15 percent of channels receivable. That percentage has eroded from about 27 percent in 1985, the base year that Nielsen started reporting such data, and a year in which the average number of channels receivable was only 18.8, but the average number of channels tuned was only five. Average Number Of TV Channels Receivable 1985 18.8 1990 33.2 1995 41.1 2000 74.6 2001 89.2 2002 102.1 2003 100.4 Source: Nielsen Media Research.