David Peat

Quantum Uncertainty 3able to the point where they had little to say to each other. The Americanphysicist David Bohm related the story of Bohr’s visit to Princetonafter World War II. On that occasion the physicist Eugene Wigner arrangeda reception for Bohr that would also be attended by Einstein.During the reception Einstein and his students stood at one end of theroom and Bohr and his colleagues at the other.How did this split come about? Why, with their shared passion forseeking truth, had the spirit of open communication broken down betweenthe two men? The answer encapsulates much of the history oftwentieth century physics and concerns the essential dislocation betweencertainty and uncertainty. The break between them involves oneof the deepest principles of science and philosophy—the underlyingnature of reality. To understand how this happened is to confront oneof the great transformations in our understanding of the world, a leapfar more revolutionary than anything Copernicus, Galileo, or Newtonproduced. To find out how this came about we must first take a tourthrough twentieth century physics.RelativityEinstein’s name is popularly associated with the idea that “everythingis relative.” This word “relative” has today become loaded with a vastnumber of different associations. Sociologists, for example, speak of“cultural relativism,” suggesting that what we take for “reality” is to alarge extent a social construct and that other societies construct theirrealities in other ways. Thus, they argue, “Western science” can neverbe a totally objective account of the world for it is embedded within allmanner of cultural assumptions. Some suggest that science is just oneof the many equally valid stories a society tells itself to give authority toits structure; religion being another.In this usage of the words “relative” and “relativism” we have comefar from what Einstein originally intended. Einstein’s theory certainlytells us that the world appears different to observers moving at differentspeeds, or who are in different gravitational fields. For example,relative to one observer lengths will contract, clocks will run at differ-