THE WORLD FUTURE SOCIETY will be holding its annual conference later this month. That has me worried.

One of the subjects of this year's conference is "the golden era of nanotechnology."

At a prior conference, scientists and futurists discussed how advances in nanotechnology, as well as cell and gene manipulation, could allow humans to live a long time -- anywhere from 120 to 180 years, and maybe even to 500.

Do we really want to live that long? Do we really want baby boomers, who are now beginning to retire, to vote government benefits for themselves for several hundred years?

And what of our younger generations, who are notorious slackers? (Mother to son in year 2075: You're 100 years old, when are you going to move out and get a job?) I don't wish to be a Luddite, but I see only a limited upside on this one.

Sure, I'd love to have my parents around forever. I'd love to swing by for Sunday dinner for at least 100 years more.

It would be great if we were able to keep fellows like Jimmy Stewart and Johnny Carson and Dean Martin around a bit longer.

It would be even greater if we were able to keep around great minds, such as Einstein, who could unlock the mysteries of the universe.

But I see no point in the rest of us sticking around that long. I'm 45 and already showing signs of fatigue.

In my experience, life is largely made up of colds, bills, speeding tickets and people who let you down.

These experiences are connected together by a series of mundane tasks -- drudgeries that are occasionally interrupted by a wonderful meal or really good laugh or a romantic evening with a lovely woman.

Then the mundane stuff starts all over again. I don't know how we'd pay for our long lives. Living is expensive. Are we going to work 35 or 40 years, retire, burn through our nest egg, then sling hamburgers at McDonald's for a few hundred years?

Before our scientists dramatically increase our life spans, they need to remember one important fact: What makes life most worth living is this DYING. Would you enjoy a movie if you knew it was going to play for 24 hours? No, what makes the movie enjoyable is its ending. And it better end within two hours or we all start squirming in our seats.

The key to human happiness, you see, is not an abundance of a thing, but the lack of it. Doesn't pie taste better when we know it's the last slice? Doesn't a football game capture our attention more when it is the last of the season -- the one that determines who goes out the winner and who goes out the loser? And isn't a comedian funnier when he exits the stage before we want him to go? Hey, futurists, we don't want to stick around on Earth too long. If you believe in God, as I do, this is just a testing ground anyhow.

This is just practice. It's like two-a-day football drills. We must first prove ourselves during the agony of summer practice to earn our rights to play in the big game.

Do we really want to spend 500 years running wind sprints in summer practice?

Any fool can look up to the stars and conclude there are better places to go. It's not until we check out of Hotel Earth that we're able to enjoy a place with more amenities and better service.

My religion says that place is heaven, which I figure I'll get to sooner or later -- after doing a long tour of that other place. Though I don't think it will be too bad. My friends will be there.

Purcell is a syndicated columnist based in Pittsburgh, Pa. Reach him at TomPurcell@aol.com.