Scientific Americans? Not so much.

While scientific literacy has doubled over the last 20 years, the vast majority of Americans -- the ones mobilizing and voting around issues like abortion, global warming, and stem cell research -- "don't have a clue," says Dr. Jon D. Miller of Northwestern University. A New York Times profile on Miller, who for three decades has surveyed Americans on their attitudes about and knowledge of science, reveals the startling gap in knowledge between what the Times calls the scientific haves and have-nots. For instance:

• Less than a third of Americans can "identify DNA as a key to heredity."

• Approximately one in ten know what radiation is.

• "One adult American in five thinks the Sun revolves around the Earth, an idea science had abandoned by the 17th century."