Constructor Theory

 Consider an automated factory for producing goods to a particular specification. Though its purpose may only be to produce those goods, the laws of physics imply that it must transform something into them and, typically, also use other resources and produce waste products. Very few such transformations happen spontaneously; that is to say, almost all require a constructor, which I shall define as anything that can cause transformations in physical systems without undergoing any net change in its ability to do so. I shall call those physical systems the constructor’s substrates:       
                       
                                constructor
input state of substrate(s)  output state of substrate(s) . (1)

A transformation, regarded as being caused by a constructor, I call a construction.

Prevailing conception:

"everything physical is composed of elementary constituents such as particles, fields and spacetime; there is an initial state of those constituents; and laws of motion determine how the state evolves continuously thereafter."

Construction conception:

" a construction (1) is characterized only by its inputs and outputs, and involves subsystems (the constructor and the substrate), playing different roles, and most constructors are themselves composite objects."

arXiv