Within the next 40 years, most Americans believe, the United States will get the bulk of its energy from sources other than oil. Computers will converse like people. Cancer will be cured, and artificial limbs will outperform natural ones. Astronauts will land on Mars, and ordinary people will travel in space.

From This Story [×] CLOSE In an unscientific series of interviews, we asked visitors to the Smithsonian if they were optimistic about the next 40 years Video: How Optimistic Are You About the Future?

But that optimistic outlook on scientific achievement—documented in a nationwide opinion poll conducted by the Pew Research Center and Smithsonian—does not extend to the environment. A small majority of those polled said most of the United States would face severe water shortages by 2050. Six in ten said the oceans would be less healthy than they are now, and seven in ten foresaw a major energy crisis. Overall, fewer than half expected the quality of Earth’s environment to improve.

“If the U.S. has a national religion, the closest thing to it is faith in technology,” said Scott Keeter, director of survey research for the Pew Research Center. But “technology is not seen as a panacea for fixing the environment.”

The poll, occasioned by the magazine’s 40th anniversary and designed to assess attitudes about the next 40 years, also documented a drop in expectations. Americans remain generally positive, with 64 percent of those surveyed saying they were somewhat or very optimistic about what the next 40 years holds for them and their families; 61 percent said the same about the nation’s future. But in a Pew poll taken in May 1999, the questions garnered response rates of 81 percent and 70 percent, respectively.

Of course, the 1999 poll was taken at the height of the high-tech boom and on the eve of a new millennium. Since then, terrorists attacked the United States, the nation has engaged in two wars, the cost of living has outpaced wages and a recession has damaged the economy, among other things.

In the new survey, 58 percent of respondents said a world war would occur in the next four decades, 53 percent said terrorists would attack the United States with nuclear weapons, and the same majority said the nation would be less important in the world than it is now.

The Smithsonian/Pew poll was conducted April 21-26—just after the BP oil spill began in the Gulf of Mexico, but well before its magnitude became apparent. The survey included 1,546 adults in the United States reached by residential telephone or cellphone. The margin of error for the total sample is no more than plus or minus 4.5 points.

The documented belief in technological advancement extended from the laboratory (half said an extinct species would be resuscitated through cloning) to outer space (half said evidence of life would be found elsewhere in the universe) to the marketplace (a small majority said gasoline-powered cars would go out of production).

In an exception to the pessimism about the environment, the poll found a ten-point drop in the percentage of respondents who say the earth will get warmer: from 76 percent in 1999 to 66 percent in 2010.

That trend “is very consistent with data we've gathered on the issue of global warming more generally,” Keeter said. “There are many possible explanations, but one thing is quite clear: there is a strong partisan and ideological pattern to the decline in belief in global warming.” The vast majority of the change since 1999, he said, has occurred among Republicans and independents who lean Republican.

Because the U.S. population is expected to increase by more than 100 million by 2050, the poll asked about such growth. More than twice as many respondents (42 percent) said it would be more harmful than beneficial (16 percent). And there was ambivalence about immigration. Roughly a third of respondents said legal immigration had to be decreased to keep the economy strong, but a slightly higher proportion said legal immigration had to be kept at current levels; a quarter said it should be increased.

A clear majority expected race relations to improve (68 percent). Even more expected a Hispanic candidate to be elected president of the United States (69 percent). And 89 percent—the largest majority in the entire poll—said a woman would be elected president.

There was broad agreement that the cultural landscape, however else it changes over the next 40 years, will have less paper. More than six in ten respondents said they believed that paper currency and printed newspapers would disappear and personal letters sent by mail would be exceedingly rare.

And a hopeful outlook on the U.S. economy—56 percent said it would be stronger in 2050 than it is now—came with a caveat: 86 percent said Americans would have to work into their 70s before retiring. Those longer careers, in the respondents’ view, would not be accompanied by longer lives. Those who thought more people would live to be 100 (42 percent) were outnumbered by those who did not (50 percent).