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10-08-2015, 15:28

Developments in the Sciences: The Emergence of a New Physics

Science was one of the chief pillars underlying the optimistic and rationalistic view of the world that many Westerners shared in the nineteenth century. Supposedly based on hard facts and cold reason, science offered a certainty of belief in the orderliness of nature that was comforting to many people for whom traditional religious beliefs no longer had much meaning. Many optimistically believed that the application of already known scientific laws would give humanity a complete understanding of the physical world and an accurate picture of reality. The new physics dramatically altered that perspective. Throughout much of the nineteenth century, Westerners adhered to the mechanical conception of the universe postulated by the classical physics of Isaac Newton. In this perspective, the universe was a giant machine in which time, space, and matter were objective realities that existed independently of the parties observing them. Matter was thought to be composed of indivisible, solid material bodies called atoms. These views were first seriously questioned at the end of the nineteenth century. Some scientists had discovered that certain elements such as radium and polonium spontaneously gave off rays or radiation that apparently came from within the atom itself. Atoms were therefore not hard material bodies but small worlds containing such subatomic particles as electrons and protons that behaved in a seemingly random and inexplicable fashion. Inquiry into the disintegrative process within atoms became a central theme of the new physics. Building on this work, in 1900, a Berlin physicist, Max Planck (1858–1947), rejected the belief that a heated body radiates energy in a steady stream but maintained instead that it did so discontinuously, in irregular packets of energy that he called “quanta.” The quantum theory raised fundamental questions about the subatomic realm of the atom. By 1900, the old view of atoms as the basic building blocks of the material world was being seriously questioned, and Newtonian physics was in trouble. Albert Einstein (1879–1955), a German-born patent officer working in Switzerland, pushed these new theories of thermodynamics into new terrain. In 1905, Einstein published a paper, “The Electrodynamics of Moving Bodies,” setting forth his theory of relativity. According to relativity theory, space and time are not absolute but relative to the observer, and both are interwoven into what Einstein called a four-dimensional space-time continuum. Neither space nor time has an existence independent of human experience. Moreover, matter and energy reflect the relativity of time and space. Einstein concluded that matter was nothing but another form of energy. His epochal formula E  mc2—each particle of matter is equivalent to its mass times the square of the velocity of light—was the key theory explaining the vast energies contained within the atom. It led to the atomic age.