A number of discoveries contributed

A number of discoveries contributed to the reshaping of general assumptions about physical reality', but Einstein’s work stands out as pivotal because of its wide-ranging impact upon the public’s consciousness. Einstein’s Special Theory of Relativity expands the features of measurements from three to four dimensions—adding duration to the familiar length, width, height —to form a space-time continuum. Within this construct the speed of light remains constant, and all other features vary according to the situation. In a devastating critique of quotidian assumptions, Einstein’s Special Theory of Relativity makes the world of time and space a far more elastic place than people had previously imagined.1Continuing the assault upon Cartesian assumptions, Einstein’s General Theory of Relativity takes on another long-held Newtonian assumption — the effect of gravity. Einstein asserts that light curves as it moves through space, not as a result of gravitational fields but rather because space itself is a curved four-dimensional field. Matter changes the geometry of space from flat to curved in much the way a heavy object reconfigures the shape of a taut sheet on which it is resting. As a result, gravity loses its privileged position as a constant, for depending upon the conditions—traveling in a spaceship, for example—we cannot tell whether gravity or some other nonuniform motion is pulling us down.2