Number of words: 261

To experience the unification of seemingly separate entities in a higher dimension we do not need relativity theory. It can also be experienced by going from one to two dimensions, or from two to three. In the example of a circular motion and its projection given opposite the opposite poles of the oscillation in one dimension (along a line) are unified in the circular movement in two dimensions (in one plane). The drawing overleaf represents another example, involving a transition from two to three dimensions. It shows a ‘doughnut’ ring cut horizontally by a plane. In the two dimensions of that plane, the surfaces of the cut appear as two completely separate discs, but in three dimensions they are recognized as being parts of one and the same object. A similar unification of entities which seem separate and irreconcilable is achieved in relativity theory by going from three to four dimensions. The four-dimensional world of relativistic physics is the world where force and matter are unified; where matter can appear as discontinuous particles or as a continuous field. In these cases, however, we can no longer visualize the unity very well. Physicists can ‘experience’ the four-dimensional space-time world through the abstract mathematical formalism of their theories, but their visual imagination-like everybody else’s-is limited to the three dimensional world of the senses. Our language and thought patterns have evolved in this three-dimensional world and therefore we find it extremely hard to deal with the four dimensional reality of relativistic physics. 

Excerpted from Page 151 of ‘The Tao of Physics’ by Fritjof Capra