## Abstract

Constructor theory seeks to express all fundamental scientific theories in terms of a dichotomy between *possible* and *impossible* physical transformations–those that can be caused to happen and those that cannot. This is a departure from the prevailing conception of fundamental physics which is to predict what *will happen* from initial conditions and laws of motion. Several converging motivations for expecting constructor theory to be a fundamental branch of physics are discussed. Some principles of the theory are suggested and its potential for solving various problems and achieving various unifications is explored. These include providing a theory of information underlying classical and quantum information; generalising the theory of computation to include all physical transformations; unifying formal statements of conservation laws with the stronger operational ones (such as the ruling-out of perpetual motion machines); expressing the principles of testability and of the computability of nature (currently deemed methodological and metaphysical respectively) as laws of physics; allowing exact statements of emergent laws (such as the second law of thermodynamics); and expressing certain apparently anthropocentric attributes such as knowledge in physical terms.

## Keywords

Constructor theory Von Neumann machines Physics of computation## Notes

### Acknowledgments

I am grateful to Simon Benjamin for pointing out some subtleties including the non-existence of a universal classical constructor, to him and Mark Probst for illuminating conversations on the themes of this paper, to Alan Forrester and two anonymous referees for numerous useful suggestions, and especially to Chiara Marletto for incisive criticism of earlier versions of the theory and of earlier drafts of this paper.

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