Constructor Theory
A New Perspective Of Deciphering Reality
We developed laws of physics and by adding the inputs in those laws we get outputs or in the language of physics through the motion and velocity of objects their final state can be calculated. That’s how classical physics works. Some scientists believe this approach has limitations as the formulation of theories that describe reality partly and neglect other effects. For decades, physicists have been in dire search of a theory, that can unify the entire physics into one complete theory. Einstein spent years in search of such a theory. The classical model of physics and quantum physics is the basis of all that we know about the world. The two theories are most important in the field of physics, so much that we cannot neglect one and prefer one over the other. General Relativity is a classical theory and doesn’t take into account the uncertainty principle that forms the basis of quantum physics. The real challenge is in combining the two.
Scientists believe the first step to develop such a theory would be to combine general relativity and the uncertainty principle. Some scientists have tried to build something of that sort which they claim to solve the unanswered problems of physics. The theory is called Constructor Theory.
Suppose we say X will be dissolved in Y without even doing so in reality, just by analysing certain properties for instance chemical structure, etc. So we can be aware of the laws of nature by not just reality but by also dormant reality, that is to say, what may be possible. In brief, that’s how the constructor theory works.
Before jumping to the constructor theory let’s understand the meaning of constructor.
What is a Constructor?
A constructor is an entity that can cause the task to occur while retaining the ability to cause it again.
Examples of constructors include a heat engine (a thermodynamic constructor), a catalyst (a chemical constructor) or a computer program controlling an automated factory (an example of a programmable constructor).
Scientists working on the theory
According to David Deutsch, current theories of physics, based on quantum mechanics, do not adequately explain why some transformations between states of being are possible and some are not. If by mistake you spill a glass of water, what the glass and the water droplets do is governed in accordance with the laws of physics. If you’ve a video camera and videotaped the spill and then played the film backward, the film would start running backward. You’ll notice Newton’s Laws, The Laws of Conservation of Energy and Conservation of Momentum would be making sense and obeyed when you played the film backward. And the probability that all the water along with the glass would come together to form a full glass of water again is incredibly small. This is an example of an irreversible process.
Constructor theory provides an explanatory framework built on the transformations themselves, rather than the components.
Concept of superposition and Constructor theory
To get an idea of a constructor we can use the concepts of the quantum world. According to superposition, the particles are not always in just one state and could be in more than one state at the same time, and so when an individual realised what state they were in, they would immediately become in only one state. General relativity describes spacetime curve around a mass. But if superposition is taken into consideration then the meaning of mass entirely undergoes a transition. It states mass could be in more than one place at the same instant. In this manner, it violates general relativity.
In the constructor theory, the objects are tasks. Constructor theory is which tasks are possible and which ones are impossible. It’s somewhat similar to the concept of probability but not entirely. The object that is undergoing change is called a substrate. The properties that describe substrate are called the attributes (shapes, colours, number, etc.). The task is the description of physical transformation on some substrate with input and output attributes.
A constructor doesn’t have any net change at the end of the process, it ends up where it started, and so it remains the same after performing the task.
Counterfactuals
Counterfactual thinking is a concept that involves the human tendency to create possible alternatives to life events that have already occurred; something that is contrary to what actually happened.
A counterfactual is a statement about which transformations are possible and which ones are not possible. The untrue alternative is said to be “counterfactual”. Thinking in counterfactuals requires imagining a hypothetical reality that contradicts the observed facts. Conventional physics has a glitch, that is to say, it doesn’t include counterfactuals. Constructor theory is an attempt to improve physics by bridging this gap, giving a physical model that can express counterfactuals, thus allowing the laws of information and computation to be viewed as laws of physics.
Constructor and laws of physics
A constructor thus makes the transformation possible and can perform it again.
A task is said to be possible if the laws of physics do not impose a limitation. A task is impossible if it is forbidden by the laws of physics else it is possible. For example, the task is considered impossible like transforming the speed of an object greater than that of light. Under physics’ laws only approximate constructors exist. They exhibit non-zero error rates and get worse with consumption or use.
A constructor is a placeholder for the infinite sequence of approximations to the ideal behaviour of a constructor.
Classical physics, gives utmost weightage to the dynamics and bestows it with the tag of being fundamental. According to the proponents of constructor theory, there is hardly any place for counterfactuals in dynamics. The Constructor theory proposes the universe as a set of constructors that can perform the tasks and takes into consideration the counterfactuals too.
When we cite the example of replicators using the language of biology it proceeds in this manner:
The neo-Darwinian synthesis talks about the physical object — the replicator — a particularly remarkable molecule formed by accident (in the case of earth) something that can be copied from generation to generation, by replication, and selected (between a set of variants) under the environment’s action. The natural replicators are good at knowing the art of ‘how to construct and sustain themselves’. Instances of replicators in the Earth’s biosphere are ‘genes’, i.e. portions of certain DNA molecules. Now the building blocks that attach themselves in this manner would automatically be arranged in a sequence that mimics that of the replicator itself. This chain may stack one upon the other or it may lead two chains split apart , and in such a case we have two copies, each of which further creates more copies.
Natural selection relies on gene replication, with occasional errors; the appearance of design is explained as adaptations for gene replication; and the rest of the cell or organism and sometimes other parts of the environment, constitute a medium for the replicators.
Constructor theory of information
David Deutsch and Chiara Marletto are working together on the Constructor theory of information. Information is a unique thing and bringing it into the great fold of fundamental physics is quite a challenge as it has the ability to trascend the physical system and the biggest challenge is, it can’t be perceived.
The Counterfactual property of information — it states how the system would have been observed differently if the system had another information. In the Constructor theory, the recipient could distinguish the information from the other possible ways and could be passed on — termed as the property of copying which we already learnt above. These are the two properties that are regarded as the basis.
Criticism
Like every theory, the Constructor theory isn’t free of criticism. Scientists believe there are certain things that would prove to be a limiting factor.
The first criticism is that the constructor theory is complex, scientists believe the theory is difficult to test. Other criticism includes — A constructor can be constructed to query the known information but is there a constructor for exploring the new information?
We can surely know about information but how information transfers is again the question that would remain unaddressed. Another thing we would have to take into consideration while formulating such a theory would be the principle of stability. Even natural selection was a selection of stable forms and a rejection of unstable ones. The constructor theory has done something of a similar manner giving weightage to the principle of stability, as the constructor by its definition causes the task to occur while retaining the ability to cause it again which is the basis of stability. Anyhow it gives a new perspective in exploring the reality, and it’s quite different from classical and quantum physics.
Apart from providing a theory of information underlying classical and quantum information, these include, generalising the theory of computation to include all physical transformations; unifying formal statements of conservation laws with the stronger operational ones (such as discarding the view regarding perpetual motion machines); allowing exact statements of emergent laws (such as the second law of thermodynamics); and expressing certain attributes such as knowledge in physical terms. Some principles of the theory are suggested and its potential for solving various problems and achieving various unifications is regarded as the ultimate objective……..
