'What are you optimistic about?" editor John Brockman asked some of the world's leading scientists on his Web site, www.edge.org [4].

As I've yet to complete my unified theory of the universe, he did not include me in his survey. If he had, I'd have answered: Just about everything.

As I reported in last week's column, Brockman's respondents were forward-looking, describing cutting-edge research that will help combat global warming and other looming problems. My optimism is anchored in the past.

By almost any measure -- greater wealth, better health, diminishing levels of violence -- the world is good and getting better. My only regret is that I am alive today because tomorrow will be even brighter.

Where to start with the good news? How about with the Big Kahuna: During the 20th century, life spans for the average American rose from 44 years to 77 as we tamed age-old scourges such as smallpox, malaria, polio and plague.

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