Is economics Turing Complete? I am interested in economics from the perspective of mathematical physics and complexity theory. An important set of systems in complex systems are systems that are Turing Complete and are cases of universal computation. 

This raises the issue of whether a virtual Turing Computer can be constructed in economics. Can accounting be considered a case of a universal computer? I find it interesting that the Ethereum cryptocurrency's support for smart contracts is Turing Complete.
I am not a CS guy so this answe may be flawed in many ways. Take it more as a long comment and please give some feedback.

Economists view Ethereum as a pure Arrow-Debreu market economy. In an AD economy you can write fully contingent contracts specifying commodity trades conditional on any future event at any particular date. Therefore, an AD economy is, by definition Turing complete. In that sense, for economists Ethereum is a cool implementation of an ideal but nothing new.

The problem is that, as Arrow himself recognized (but not Debreu!), this model of the economy is not realistic in any way because there are frictions to contracting, undescribable events, unawareness, asymmetric information, uninsurable risks, etc.

At a more fundamental level, economics has another problem that seems to me to relate to the halting problem. if an economic system was decidable, then the agents in the economic model would have to either know the answer or not know the answer. In the former case, there would often be an eternal loop, since the answer to the problem would be part of the problem itself (this is the essence of the Lucas critique). If you assume they do not know the answer then you are imposing a certain rule on their actions that will not be universal and therefore would not allow for Turing completeness on the whole economy.