"There will presumably be a constructor generalization of the universal quantum computer, namely the universal quantum constructor, a machine that can be programmed to construct any quantum object that can be constructed, or any quantum object with any achievable properties."
I consider this brief, non-technical paper a "must-read" for anyone interested in the vision of David Deutsch, a leader in the field of quantum computing and the theory of parallel universes.
A few of the key points raised by Deutsch:
The laws of physics allow for a machine — a universal quantum computer — with the property that its possible motions correspond in a suitable sense to all possible motions of all possible physical objects. Therefore the whole of physics and more — the study of all possible physical objects — is just isomorphic to the study of all programs that could run on a universal quantum computer.
Because of universality, the nature of computation and the laws governing it are independent of the underlying hardware. Therefore those laws, and that theory, can’t explain hardware. Explaining hardware, however, is obviously part of science. Hence there must be something to physics beyond the quantum theory of computation. I think we have to conceive of the quantum theory of computation as a special case of a bigger theory: quantum constructor theory, which is the theory of what physical objects can be constructed, using what resources. Here I don’t mean abstract resources, like the number of computational steps or the amount of memory, but physical resources like atoms and energy and entropy and so on.
The full quantum constructor theory will incorporate the particle physicists’ ‘theory of everything,’ including quantum gravity, as well as the quantum theory of computation and thermodynamics. We may hope that it would be able to answer exotic questions like: can we build a black hole and spin it up until it becomes a time machine? Can we collapse a black hole and have it form new universes which we can design, and if so what are the constraints on that?
You can read the full paper here.
