We seem to be entering an era in which some very long-established lines are becoming blurred, not least the lines between countries. More and more, these exist only on the map: people, ideas, products -- good and bad -- flow with little interruption from place to place, producing a world we don't quite yet understand. PNS associate editor Walter Truett Anderson is the author of "The Future of the Self" (Tarcher Putnam, 1997).

A world of "porous boundaries" is one of the most compelling predictions in a recent report by the National Intelligence Council.

"Global 2015 Trends" sees a world with governments are increasingly unable to control traffic across their borders -- not only the comings and goings of people, but also the flows of information, technology, diseases, drugs, weapons, and financial transactions.

Like most really brilliant visions of the future, this is only a good guess that what's already happening will continue to happen. As baseball player Dan Quisenberry once put it, "the future is just like the present, only longer."

The simple -- yet extremely disturbing -- reality of life in an age of globalization is that about the only place you can find really solid national boundaries is on a map or perhaps in the mind of an ardent nationalist or government bureaucrat.

In real life, government control over trans-border traffic has always been limited, and it is becoming weaker. It's not only the Berlin Wall that has crumbled; boundary-maintenance all over the world has been weakening -- either because immigration laws have changed or simply because governments can't or won't enforce the laws they have.

The movement of all kinds of goods -- everything from legal merchandise to outlawed weapons -- is a major piece of the globalizing process. So is the movement of non-human life forms such as the HIV virus.

But the flows that are transforming the world -- and changing the very meaning of nationality -- are the flows of people and symbols. More people are on the move than in all of previous human history, and the flow of symbols through the various electronic communications media is beyond anything predicted a few years ago or even measurable today.

Countries that never aspired to be multiethnic or multicultural are becoming that anyway through escalating immigration, tourism, and business travel.

Rich countries with declining birthrates and aging populations need people -- especially people to work in service and other low-level jobs their own citizens don't want, but countries trying to be economically competitive recruit skilled professionals and technicians.

Countries encouraging tourism find it wise to make coming and going relatively painless -- and the great global travel and tourism industry so far seems to be immune to the slowdowns hitting other sectors of the economy. Free-trade agreements generally call for some relaxation of trans-border regulations, and many countries also take in thousands of people as refugees or seekers of political asylum.

All these add up to an immense volume of legal cross-border flows and inevitably to cultural change in the host countries.

Then there's the other kind of immigration. The greater the wealth gap between rich countries and poor ones, the greater the incentive for people to go where the jobs and opportunities are -- with or without the legal documents.

Illegal immigration causes all kinds of headaches and some of it -- shipments of people long distances in intolerable, even deadly conditions -- is cruel and exploitative. But as long as there is massive economic inequality in the world, there will also be massive illegal migration. It is a kind of do-it-yourself foreign aid.

The global flow of people is nothing compared to the global flow of symbols. Words, data, music -- information and entertainment in all forms -- circulate around the world and across boundaries though all the media.

The Internet is proving extremely hard to control or regulate. It erodes not only national boundaries, but also the boundary between the public and the private: most governments regulate television broadcasts as a public medium, but regard telephone conversations as private. The Internet mixes them up, delivering both private mail and public Web sites.

Yet, despite much official nervousness, most governments promote Internet development with great enthusiasm, simply because they recognize its enormous capacity to generate wealth.

This doesn't mean that nation-states are becoming obsolete, as many armchair pundits speculate, nor does it mean that the whole world is melting into one homogenous mass. National governments are now required by human rights treaty commitments to become almost the opposite of what they were: instead of protecting the purity of their native ethnic groups and traditional cultures, they find themselves thrust into the role of protecting immigrant peoples and their cultures.