What's the difference between the new economy and the old economy," writes a reader, "if people are still just buying things?" Her question is precisely what's vexing tech-stock and big-picture pundits alike. Behind the breathless hype, is there anything truly world-changing about the digital age?

New Economy boosters certainly think so. The Internet, they claim, is reshaping our world as much as cars and freeways transformed once sleepy horse-and-buggy communities.

Others, such as Northwestern University economist Robert Gordon, are not so sure. IT, he argues, pales in comparison with the great innovations of the early twentieth century, including electricity, internal combustion engines, chemistry, telephone and telegraph communications, and indoor plumbing. Unlike the Internet, each of those inventions decisively changed the way we live our lives.

As late as the 1880s, America's streets were seas of mud and clogged with horse manure. In many cities, pigs were set free to eat kitchen slops, and garbage piled high on the sidewalks. Unrefrigerated food and contaminated water triggered frequent epidemics. In 1882, only 2 percent of New York City's homes had running water. In 1890, 10,000 people died in U.S. railway mishaps, and one in every 300 rail workers was killed on the job. But, Gordon maintains, five great inventions of the early twentieth century radically changed all that.

Electricity provided better lighting and reduced the fire hazard and dangerous emissions from oil lamps. Backbreaking laundry and manufacturing tasks were automated. Electric-powered air conditioning helped preserve food and cooled once unbearably hot workplaces. The internal combustion engine forever changed city design, commerce and where people chose to live. Miracle medicines wiped out diseases that had bedeviled humanity since the beginning of recorded history. Telegraph and telephonic technologies redefined global distance and communication in previously unfathomable ways. And the unprecedented sanitation gains achieved through indoor plumbing spurred the world's enormous pre-World War I mortality rate declines.

Taken together, those great innovations ushered in a golden age of productivity that lasted for more than half a century.

Is the Internet in this league? Many seem to think so, but for a number of reasons, the Internet won't have the far-reaching influence of electricity, engines or even flush toilets.

To begin with, the Internet hasn't even boosted demand for computers much more than what steadily falling microprocessor prices already generated. Despite all the hoopla, computer spending remains about 1.4 percent of total non-farm, non-housing business gross domestic product, and it's stayed at that level for more than a decade. This contrasts with the massive new markets stimulated by mechanical and electrical technology breakthroughs in the past.

Unlike the truly great innovations, moreover, the Internet seems to be displacing, not creating, forms of entertainment, commerce and information. E-mail replaces telephones. Browsing substitutes for TV time. An online purchase is mail order by other means. IT may marginally change certain activities, but it has not yet reinvented them.

These somewhat meager achievements are offset by the often ignored productivity losses the Internet encourages, like on-the-job personal correspondence, shopping or stock trading. As I wrote in an earlier column, "The New Economy's Downside," productivity is declining in the nearly 90 percent of our economy that is not making durable goods. Electrification and chemical technologies unquestionably expanded the scope of what people could produce, and their economic upsides were all but limitless. Thus far, the Internet's net social benefits are far more equivocal.

Then there's the fact that much of the recent IT investment boom appears to have been spurred more by "me-too" corporate defensiveness than by dazzling new market opportunities. In many industries, such as books, airline travel and auto sales, a single, well-publicized firm could trigger widespreat IT spending that many companies later regretted upon more sober reflection. Amazon.com's high-profile online bookselling gambit in the late 1990s spurred a massive countermove by Barnes & Noble, but both companies' Internet-related stock values fell by more than 60 percent amid this year's emphasis on profit.

Given all this, it's telling that even the simplest predictions of the digital age have failed to materialize. At the very least, for example, New Economy advocates confidently claimed that IT would do away with paper. The future of communication was unquestionably digital.

Instead, as the Internet expanded, worldwide paper consumption skyrocketed. Confounding the experts, millions of home and office printers churned out even more school essays, community newsletters, and draft budgets, memos and business plans than ever before.

So what's so new about the Economy? Compared with the truly epochal innovations of the past, not much. And there are plenty of unhappy investors who may be just now realizing that fact.