Deutsch and Marletto's Constructor Theory

Merali, Zeeya. "A Meta-Law to Rule Them All: Physicists Devise a “Theory of Everything.” Scientific American. ay 26, 2014. Accessed Dec 11 2016. <>

Basics of Constructor Theory

In an article from Scientific American, Zeeya Merali describes a new theory from physicists David Deutsch and Chiara Marletto, which they call "constructor theory." Drawing from information theory and its focus on entropy (the second law of thermodynamics), constructor theory unifies classical and quantum mechanics by describing a task-based system governing the transfer of energy (Merali, n. pag).

Today's computer scientists code information according to Claude Shannon's theory from the 1940s, but this theory could not apply to quantum information, so a deeper theory was needed that could encapsulate Shannon's work, and the work in quantum theory that has yet to unfold (Merali n. pag).

This new "theory of everything" takes a simpler, broader view, focusing on how performance of tasks relate to the construction of reality (Merali n. pag)

"According to constructor theory, the most fundamental components of reality are entities—'constructors'—that perform particular tasks, accompanied by a set of laws that define which tasks are actually possible for a constructor to carry out. For instance, a kettle with a power supply can serve as a constructor that can perform the task of heating water" (Merali n. pag). 

Merali quotes physicist and philosopher Dean Rickles who noted, "'In principle, everything possible in our universe could be written down in a big book consisting of nothing but tasks [and in] this big book will also be encoded all of the laws of physics'” (Merali n. pag)

Deutsch and Marletto differentiate classical and quantum information by the ability to make an identical copy of it; classical information can be copied exactly, whereas quantum information cannot (Merali n. pag).  From this starting point, "they then work out which tasks must be possible in such a system to remain in line with Shannon’s theory" (Merali n. pag).

Constructor Theory and Superinformation

"The collaborators then go on to define the concept of a 'superinformation' medium that encodes messages that specify particular physical states—in this case, one in which copying is impossible. They discovered that a special subset of their superinformation media display the properties associated with quantum information processing. 'We found that with this one constraint in place telling you what you cannot do in a superinformation medium—the task of copying—you end up discovering the weird new information-processing power that is a property of quantum systems,' Marletto says" (Merali n.pag).
"Measuring the state of a superinformation medium will inevitably disturb it—a feature commonly associated with quantum systems. But because it is forbidden to make an exact copy of certain sets of states in a superinformation medium this forces some uncertainty into the outcome of the measurement" (Merali n.pag).
Katie Ancheta