Epilog

Abstract

Four weeks before his death,Albert Einstein wrote in a letter of condolence to the family of his life-long friend Michael Besso (Dukas and Hoffman 1979):⁵ „For us believing physicists, the division into past, present and future has merely the meaning of an albeit obstinate illusion.“ There is no doubt that Einstein meant this remark seriously. Evidently, it refers to the four-dimensional (‘static’)spacetime picture of a ‘block universe’ that his theory of relativity uses so effeciently. This picture seems to be at variance with the experience of a present passing through time (the ‘flow’ or ‘passage of time’). In contrast, the relativistic spacetime framework contains only a concept of local events (points in spacetime), which may be regarded as a continuum of dynamically related here-and-nows. Because of hese dynamical relations, characterized by time-symmetric local laws, a local present canbeviewedas ‘moving’ along the world line of an observer. His personal history is a succession of strongly correlated (local clusters of) events, dynamically controlled by proper time, while a global dynamical state would depend on an arbitrary foliation of the spacetime that is characterized by its invariant metric structure.

“Für uns gläubige Physiker hat die Scheidung zwischen Vergangenheit, Gegenwart und Zukunft nur die Bedeutung einer wenn auch hartnäckigen Illusion.”