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Constructor theory of information
Deutsch Et al. propose a theory of information expressed solely in terms of which transformations of physical systems are possible and which are impossible—i.e. in constructor-theoretic terms. It includes conjectured, exact laws of physics expressing the regularities that allow information to be physically instantiated. Although these laws are directly about information, independently of the details of particular physical instantiations, information is not regarded as an a priori mathematical or logical concept, but as something whose nature and properties are determined by the laws of physics alone. This theory solves a problem at the foundations of existing information theory, namely that information and distinguishability are each defined in terms of the other. It also explains the relationship between classical and quantum information, and reveals the single, constructor-theoretic property underlying the most distinctive phenomena associated with the latter, including the lack of in-principle distinguishability of some states, the impossibility of cloning, the existence of pairs of variables that cannot simultaneously have sharp values, the fact that measurement processes can be both deterministic and unpredictable, the irreducible perturbation caused by measurement, and locally inaccessible information (as in entangled systems).
18 pages, ebook
Published February 8, 2015
266 people want to read
About the author
David Deutsch
32 books1,143 followersDavid Deutsch, FRS is a British physicist at the University of Oxford. He is a non-stipendiary Visiting Professor in the Department of Atomic and Laser Physics at the Centre for Quantum Computation (CQC) in the Clarendon Laboratory of the University of Oxford. He pioneered the field of quantum computation by being the first person to formulate a description for a quantum Turing machine, as well as specifying an algorithm designed to run on a quantum computer. He is also a proponent of the many-worlds interpretation of quantum mechanics.
In his books, he also made philosophical contributions. In epistemology, he stressed the importance of explanation, and proposed 'hard to vary' as a criterion for good explanations. In memetics, he gave an account of how memes work, separating them into 'dynamic' or rational memes and 'static' or anti-rational memes. He also advocates optimism, potentially boundless progress, objective beauty in aesthetics, and reason.
In his books, he also made philosophical contributions. In epistemology, he stressed the importance of explanation, and proposed 'hard to vary' as a criterion for good explanations. In memetics, he gave an account of how memes work, separating them into 'dynamic' or rational memes and 'static' or anti-rational memes. He also advocates optimism, potentially boundless progress, objective beauty in aesthetics, and reason.
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Displaying 1 - 2 of 2 reviews
June 20, 2022
Particular transformations in the physical world are possible, while others are not possible. For example, I can use my agency to cause a cup of water to freeze, but I cannot use my agency to change the freezing point of water.
The rules governing our reality at the most fundamental level, i.e. physics, have traditionally been expressed using initial conditions plus a set of dynamical rules to calculate how the system unfolds from those initial conditions onwards.
Deutsch claims that expressing physics in this way is limiting. It works well for some physical systems, but we cannot use it to describe others, such as information, effectively. Deutch proposes Constructor Theory as an alternative/extension to how we express physics.
Deutsch defines a constructor as a physical object that can perform a task and stay the same after doing it, such as a catalyst. A constructor is capable of doing the task over and over again.
Capturing initial conditions accurately is hard, and any minuscule error in the initial conditions can become amplified as the system unfolds. However, the rules of physics govern all physical systems, and they assert that certain states are impossible regardless of initial conditions. For example, the conservation of mass and energy has never been violated, and we can regard its violation as impossible. This allows us to predict that it will not be violated in the future with arbitrarily high confidence. This makes it relatively easy to predict some properties of a system's future irrespective of initial conditions.
An obvious objection to Deutsch is his use of the terms "possible" and "impossible". Deutsch is a falsificationist, so rest assured that he does not believe that the rules of reality are set in stone. They are precise and rigid (rigid as in they fit together so tightly that you cannot change any part without ruining the whole) assertions about what is out there in reality and how it works but stand defeasible. Nevertheless, we can treat them as provisionally true.
The rules governing our reality at the most fundamental level, i.e. physics, have traditionally been expressed using initial conditions plus a set of dynamical rules to calculate how the system unfolds from those initial conditions onwards.
Deutsch claims that expressing physics in this way is limiting. It works well for some physical systems, but we cannot use it to describe others, such as information, effectively. Deutch proposes Constructor Theory as an alternative/extension to how we express physics.
Deutsch defines a constructor as a physical object that can perform a task and stay the same after doing it, such as a catalyst. A constructor is capable of doing the task over and over again.
In constructor theory, when the laws of physics say that no constructor can perform a given task to arbitrarily high accuracy, that task is impossible. For example, the task of lifting [an object] is impossible without supplying any energy. However, what is possible is the task of lifting [an object] and depleting a battery appropriately charged. The battery cannot be part of the constructor, because it gets depleted during the process. Otherwise, the task is possible – which means that it can be performed in reality to arbitrarily high accuracy and reliability but need not happen.
Capturing initial conditions accurately is hard, and any minuscule error in the initial conditions can become amplified as the system unfolds. However, the rules of physics govern all physical systems, and they assert that certain states are impossible regardless of initial conditions. For example, the conservation of mass and energy has never been violated, and we can regard its violation as impossible. This allows us to predict that it will not be violated in the future with arbitrarily high confidence. This makes it relatively easy to predict some properties of a system's future irrespective of initial conditions.
An obvious objection to Deutsch is his use of the terms "possible" and "impossible". Deutsch is a falsificationist, so rest assured that he does not believe that the rules of reality are set in stone. They are precise and rigid (rigid as in they fit together so tightly that you cannot change any part without ruining the whole) assertions about what is out there in reality and how it works but stand defeasible. Nevertheless, we can treat them as provisionally true.
June 25, 2018
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Displaying 1 - 2 of 2 reviews