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A study of 4-dimensional volume preserving covariant changes of the metric leads directly to string theory in 26 dimensions. In any conformally invariant theory of such metric distortions, a new principle of relativity is shown to imply that the maximum number of independent components of the distortion tensor is 26. Within the simplest such theory allowing metric compatible spaces as trivial solutions, we show that this maximum is realized by a solution equivalent to the 26-dimensional bosonic string.

Normally, pure states of coherent light have equal uncertainties for pairs of conjugate variables. In recent years, however, it has become possible to produce and detect light in which fluctuations of one of the quadrature components are suppressed below the corresponding flutuations of a coherent state. Such radiation is said to be in a squeezed state. We explore the possibility that a strong gravitational field can produce a squeezed state of light. Such squeezing does in fact occur, and we derive an expression for the resulting uncertainties in a high frequency or long time limit. These results comprise a new, testable prediction of general relativity.