Epilogue

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)¹: “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 very seriously. It obviously refers to the four-dimensional (‘static’ or ‘objective’) representation of all events in a spacetime frame which his theory of relativity uses so efficiently. This picture seems to be at variance with the subjective experience of a present passing through time (the ‘flow of time’), a concept which his theory allows to be incorporated into the objective picture only as the local moment of a present (the hereand-now) ‘moving’ along a world line. The above remark of Einstein’s is frequently misinterpreted as a statement in support for an arrow of time that can only be understood subjectively. It is therefore often quoted by the information-theoretical school of statistical mechanics, or even as support for an extra-physical concept of growing knowledge as used in the ‘idealistic interpretation’ of quantum mechanics. The increase of entropy would then also in an essential way have to be interpreted ‘subjectively’ (with respect to information gaining subjects), since an extra-physical concept of changing knowledge would ultimately determine in which direction of time statistical reasoning may be applied.