New theory probes the fundamental limits of technology

17 February 2014

Portrait of Dr Toby Ord

by Dr Toby Ord
James Martin Fellow, Future of Humanity Institute

Toby Ord's background combines theoretical computer science with analytic philosophy. He is especially interested in how certain key future technologies may seriously affect society for good or ill, on a timescale of around thirty to a hundred years....

I Stock agsandrew Quantum
© Istock/agsandrew

What are the fundamental limits of technology? A new paper from Professor David Deutsch describes an innovative new approach to how to think about physics and the terminal state of technology.

'Constructor Theory' draws on von Neumann's work on universal constructors, a project that formalised cellular automata and our understanding of self-reproductive systems. However, Deutsch's programme is more ambitious: he emphasises the fundamental nature of construction tasks, what he calls "transformations", suggesting that such transformations could express the fundamental questions of physics. Deutsch hypothesises that "it may be that construction tasks are the primitive entities in terms of which the laws of nature are expressed"; constructor theory would effectively be the language in which physics, computability theory, and philosophy are written.

This serves as a unique alternative to the prevailing conception of physics in which the basic components are the initial conditions and a set of equations representing how the state of the world evolves over time. Constructor theory's advantages chiefly come from its ability to directly examine which things are possible or impossible and its high level of abstraction.

In order to explore this idea, Deutsch explores some possible principles of Constructor Theory (CT). In doing so, he suggests how CT could be used to succinctly and clearly express conservation laws, irreversibility principles such as the second law of thermodynamics and quantum decoherence, and a variety of ideas in philosophy: testability of physical laws, universality of computation, counterfactuals, the causal role of information, knowledge, and emergent behaviour.

In addition to all of these is a very direct connection to the fundamental physical limits of technology: which systems are constructible and which are not?

It is too early to say what role CT will end up having in the shape of theoretical physics, computer science, the study of technology, and the philosophy of science. Perhaps there will be roadblocks in the development of the theory. However it is a very intriguing new framework and we will be excited to see how it progresses.