If one could travel back to AD 1000 and ask people to predict the technologies that would change the world, they might have guessed a few of them: better crops, a machine to replace horses, a means for humans to fly.
But they would almost certainly not understand how science and technology have transformed this millennium.
The age runs so thick with breakthroughs that even with hindsight, picking the top scientific and technological discoveries remains daunting. This period built and rebuilt itself with inventions like the clock and the computer, the car and the moldboard plow. Its scientists discovered evolution and DNA. How does one choose?
Nevertheless, certain events and people stand out, science historians say, because they cleared away the fog and transformed the way societies work and think. Here is our list of five breakthroughs that changed the world.
1455, Germany - First printing press using movable type.
Johannes Gutenberg's invention spawned the first mass media, boosted the importance of literacy, inspired the Reformation of Martin Luther and John Calvin, and made ideas far more accessible.
Within a half century, some 35,000 separate editions of books - perhaps 15 million copies - had been published.
"Without a Gutenberg, a Jefferson would have never read a John Locke," says Richard Berendzen, a science historian at American University in Washington, D.C. "And if Jefferson had never read John Locke and other philosophers, would he have written the great document that he did?"
Today, we take the spread of books and ideas for granted; back then, it was astonishing.
1687, Britain - Publication of Newton's "Principia."
Arguably the single most important scientific breakthrough of the millennium, Isaac Newton's masterwork explained the world as it had never been explained before. Instead of divine fiat, natural laws ran the world. This was the scientific revolution.
Copernicus, who theorized that planets moved around the sun, inaugurated it, Galileo ran the first real scientific experiments (sometimes incorrectly) to prove it. What Newton did was synthesize their ideas into simple laws that were fully testable.
"He was able to put the pieces together so neatly that it proved to people that this new science worked," says Pamela Mack, a professor of history at Clemson University in Clemson, S.C. "Suddenly, science got a whole lot more respect." (However, she ranks Galileo above Newton because he created the scientific experimental method.)
Either way, the scientific revolution changed the way humans looked at the universe and themselves. And authorities, such as the church, that tried to dictate scientific rules lost credibility.
1711, Britain - Invention of the steam engine.
Thomas Newcomen designed the first practical steam engine. The steam engine powered the Industrial Revolution. It drew people from farmlands to factories and plucked their economy from its agrarian roots into a whole new world. For the first time, power didn't depend on a river. It could be taken anywhere. Although Newcomen's engine was far less powerful than James Watt's version 50 years later, it was used successfully to pump water out of mines. And it presaged the arrival of the steam locomotive, the riverboat, and, ultimately, electrical and internal-combustion engines. As a result of the Industrial Revolution, populations grew; so did material wealth. The West became more recognizably modern. Pollution increased.
Mid-19th century, France - Development of the germ theory of disease.
By studying fermentation, Louis Pasteur pointed to microorganisms in the air as the culprit for food spoiling and for some diseases. As a result of his experiments, he saved the French wine and silk industries, invented pasteurization of milk, and originated the use of vaccines to treat diseases. Many historians consider him the father of modern medicine."It was through the work of Pasteur that more people's lives were saved than by any single other person," says Professor Berendzen. His work represented the first steps in preventative medicine, where doctors treat patients to avoid sickness, rather than treating it after it appears. "Up until that time, it was largely a matter of, 'We've got a crisis, let's deal with it.' "
1905-1916, Germany - Theories of relativity and the quantum properties of light.
When Albert Einstein published his theories of relativity and the quantum properties of light, he revolutionized the world's view of itself. General relativity demonstrated that the philosopher's standbys - space and time - were not as fixed as Newton's theories suggested. Space could be curved, and time could differ from point to point. Einstein's special theory of relativity (E=mc2) suggested that a little mass of matter could create tremendous energy - a finding other scientists used to design an atomic bomb.
Einstein's early work on how light moves in little bundles (quanta) anticipated other scientists' work on quantum mechanics. These principles have led to the development of lasers, the transistor, and the semiconductor, crucial building blocks for the modern electronic age. Einstein's theories predicted the presence of black holes and neutron stars, and suggested ways that astronomers could look for them.
Nuclear weapons have had the greatest impact. For 40 years, they kept the superpowers from launching an all-out war. But their spread into more national arsenals gives mankind pause because for the first time man-made weapons could annihilate life on earth. It's a powerful reminder that breakthroughs in science and technology don't always have positive results.
The rise of science parallels the rise of Western civilization. And in ways that historians still don't completely understand, the two have been inextricably linked.
(c) Copyright 1999. The Christian Science Publishing Society