National Geographic : 1999 Oct
celebrate it with firecrackers?" -JOHN A. WHEELER, THEORETICAL PHYSICIST perhaps 11 billion light-years away. U It's easy to forget how rev olutionary modern science really is. U Just a few hundred years ago, in the 16th and 17th centuries, most Europeans thought that the sun revolved around the Earth and that four elements-air, fire, water, and earth-created and defined all life. Scholars mostly parroted what they had learned from classical writers like Aristotle, who believed, among other things, that the Earth was enclosed by celestial spheres where nothing ever changed and everything was always perfect. Then pioneers such as Galileo Galilei and Isaac Newton demonstrated that the natural world can be best understood by experimentation and analysis. U Why didn't the scientific revolution (a phrase that didn't come into popular usage until the mid-20th century) take place much earlier? Ancient Greek mathematicians and astronomers had calculated the circumference of the Earth, charted the stars, and figured the distance to the moon. By A.D. 1100 Chinese scholars had developed a seismograph, a magnetic compass, and the concept of infinite empty space. Why didn't the scientific revolution occur in either of those places? Among the best guesses so far: Only in 16th-century Europe did scientists begin to embrace quantifica tion, the use of mathematics to measure the results of experiments. * One of the most significant effects of the scientific revolution has been population growth. Until modern science brought sewer systems and immunization in the 19th century, about half of all children died before age five. By the end of the 19th century child hood death rates had fallen, and human population began to surge. With advances in medicine, population continues growing - and further challenging our ability to live in harmony with nature. * Will scientific progress continue? Or will science reach some limit like the Pillars of Hercules, the classical and medieval symbol for what lies at the edge of the known? On these gates, accord ing to legend, was written: "Ne plus ultra-No further." The Pillars of Hercules for modern science may become moral and spiritual. Scientists-and society-will have to decide how much to change the genetic structures of plants and animals, and whether to tinker with the very genes that make us human. U In the meantime the achievements and challenges of modern science propel us further into the unknown. 1 The millennium series concludes in December with a look at National Geographic's pioneer ing use of photographic techniques and a sur vey that reveals details of the geography of our personal lives. For more on science and technology millen nium coverage, go to nationalgeographic .com/2000/science.