The Science of Can and Can't - Chaira Marletto

Intro

• Counterfactuals = is something possible or not?
  • Compared to factual statements, such as the fact that steam engines do exist, or that the computer is producing a string of 0s
• Have long been overlooked in science, esp theoretical physics, but have the potential to transform our understanding of the universe, and of understanding itself
  • Progress hindered by focusing only on what does happen— need to take into account all the possibilities, even if they don’t occur
  • This perspective can clarify and unify many theories in areas of physics, knowledge, biology

1: Such Stuff As Dreams are Made Of

Defining laws of physics in much broader terms, including counterfactuals; defining information as knowledge that can be self-perpetuating.

• No-design laws → fundamental laws of physics that have nothing to do with complexity of the systems they govern, like attraction of protons and electrons
  • More complex a system, more likely to be “corrupted” or not maintained (less resilient) by such laws— like how it’s harder to maintain longer texts when copying over by hand
  • Counterfactual → resilience and complex systems like DNA of living systems can exist (vs things like rocks), though they are not guaranteed to
  • Counterfactual → living entities can act on their surroundings
• Objects with counterfactual propriety that of being “copyable” while changing their physical makeup (living creatures, books) = special kind of information
• Knowledge = information with counterfactual property of resilience, self-promotion
  • Can be encoded via natural selection and variation in “the wild,”, or conjecture and criticism in the mind
  • Natural selection can’t perform jumps, but thinking can
• Currently, barrier confining set of possible solutions to problems in the world, esp in physics, due to overlooking counterfactuals
  • Deeper levels of explanation of reality always possible that are more and more primitive (particles → fields → ?)
  • Questions involving initial conditions of universe & fine-tuning dynamic laws require counterfactuals → be able to ask what things would be like with diff circumstances

2: Beyond Laws of Motion

Explanation of physics as it is, relying solely on dynamical and supplementary conditions; why it can’t capture concepts like work, heat, information, or knowledge without counterfactuals

• Quality of a prediction relies on underlying explanation
  • Being testable (a counterfactual propriety) = critical for predictions
  • Physics → more powerful & precise predictions than most fields (ex. that Neptune existed)
• Laws of motion = dynamical laws → property of reversibility; predict final state from initial state along a unique trajectory
  • General relativity and quantum theory both like this
  • Unfortunately, does not work for things like work and heat!
  • Problem 1: When you try to ask why a certain set of initial conditions exists, leads to infinite regress— explained by another set of conditions, and so forth → problems of cosmology
  • Problem 2: Dynamical laws rely on time to order events, but time itself is taken as axiomatic… resolutions require some external explanation
  • Problem 3: Dynamical laws can’t handle specifying whether certain transformations are possible or impossible
• Solution → define underlying explanations of laws of motion in terms of counterfactual principles, then use the laws to make predictions

3: Information

Explains how information in physics can be completely explained with two counterfactuals

• What is different between systems that have and do not have information? Defined by two counterfactuals properties:
  • Must be able to (have possibility of) flip between at least two states (e.g. 0 & 1)
  • Must have possibility of being “copied”— knowledge of state being received at another location
  • Counterfactuals link information into a physics!
  • Also have physical, counterfactual property of interoperability: information can be transferred between any different information media
• Universal computers → can compute all transformations allowed in physics

4: Quantum Information

Explains how quantum information has two more counterfactual properties

• Unpredictably is quantified in probabilities
  • Originally thought to always be subjective and derived from having incomplete information, but in quantum theory → unpredictably exists even when everyone has complete information
• Universal quantum theory → performs all computations allowed by physics relying on quantum mechanisms for processing → superior computation to classical computers
• Additional counterfactual properties of quantum systems:
  • Each bit → both “path” and “superposition of paths” that can be observed, but only one with complete accuracy → not simultaneously copyable
    • All quantum systems have at least two observables that are impossible to simultaneously copy at high accuracy
  • Reversibility: it must be possible for any transformation to be undone → very hard to achieve in real life, because larger systems (even molecules) have more and more intx that all also must be reversible
    • Challenge of quantum computing = creating systems with this propriety
• Once quantum information media achieved, more properties follow:
  • Entanglement → combination of two items contain more info than either alone

5: Knowledge

Explain that any transformation that occurs reliably requires a catalyst, which can repeatedly carry out transformation; all catalysts must contain the abstract catalyst of knowledge (info capable of self-preservation)

• Genome → example of catalyst & abstract catalyst, and thus of knowledge
  • Copyable, capable of self-preservation, causes a transformation and retains this property
• All catalysts must contain abstract catalyst, which is knowledge, which can be defined completely by counterfactuals (vs being subjective, based on a knowing subject)

6: Work and Heat

• Energy = abstract property of physical systems, subject to specific constraints, particularly conservation
• First law of thermodynamics → conservation of energy relies on counterfactuals!
  • In some systems, convert energy freely between forms → interoperability, like information!
• Second law of thermodynamics → makes reversibility of some energy interchanges impossible (heat-like transfers, vs work-like)
  • Distinction of application gets murky at nano-scale → can’t really be a fundamental law without exact definition— hard to come by without counterfactuals
  • Key question: are heat-like reactions just practically very difficult to reverse, or actually impossible to reverse? If just very hard, second law is not fundamental!
  • Potential explanation involving cfs → work-like transfers can occur in either direction by mechanical means only; heat-like by mech means only in one direction → formulates exact second law, BUT doesn’t specify what “mechanical means” are!
  • Concept of interoperability saves the day, as with information… ultimately leads to conclusion that there is an exact definition of a reversible reaction, and these coincide with information systems

7: A Journey There and Back Again

• Counterfactuals can helpful in testing theories against each other to unify quantum theory and general relativity, even when it’s not possible to test laws of motion at present
• Also allow us to address problems in arena of knowledge that are the currently seen as subjective, realm of spirituality (ex. artificial selection, creativity of individuals), because makes knowledge objectively defined