Physics and the

1
Physics and the Real Patterns theory of
ontology

• James Ladyman

2
Thanks to Joss and Richard and the Lorentz Centre

• The document that describes the topic of the
  conference does a great job of identifying a lot
  of important and fascinating issues.
• Thanks to the physicists for informing us about
  the relevant phenomena.
• My ideas owe a lot to my co-authors Steven French
  and Don Ross.
• The material on phlogiston is forthcoming in a
  paper in Synthese

3
Three Ideas

• Structure is retained on theory change even when
  ontology is not.
• Structuralism about a domain involves the idea
  that the entities in the domain are mutually
  dependent on each other for their
  existence/individuation.
• Real Patterns
• In the case of physical structures I contend that
  these three ideas all centrally involve modality.

4
Of what is everything made?

• Western philosophy allegedly started when the
  pre-Socratics asked this question.
• This is a metaphysical question physics is
  supposed to answer.
• It presupposes that the world comes in a
  hierarchy of levels and that there is a
  fundamental level with a few basic kinds of
  entities.
• The most naïve picture is one of physical objects
  ordered by (spatial) size and ultimately composed
  of elementary particles.

5
Levels

• There is not necessarily a single hierarchy
• Ordering by spatiotemporal scale
• Ordering by energy
• Ordering by composition
• Anomalous sciences evolution, game theory,
  economics, thermodynamics,

6
Scepticism about Levels

• Spatiotemporal scale may not be a fundamental
  feature of reality. It is an open question
  whether quantum gravity will take the
  spatiotemporal manifold as primitive rather than
  emergence.
• The same may be true of the energy scale.
• The levels structure based on the composition
  relation is undermined by the fact that the
  notion of composition does not translate well
  into physics
• Of what are quasiparticles composed?
• Are particles composed of quantum fields?
• What composes a black hole?

7
1. Theory Change as a Motivation for
Structuralism

• Antirealism science saves the phenomena
• Realism science describes the furniture of the
  world
• Structural Realism science tells us about the
  structure of the world - more than merely saving
  the phenomena but less than full ontological
  commitment
• Example even the existence of central
  theoretical entities is necessary for more than
  empirical adequacy.

8
The Theory of Phlogiston

• Burning is a process in which a principle of
  combustion is given off by the fuel and enters
  the air.

9
The Theory of Phlogiston

• Burning is a process in which a principle of
  combustion is given off by the fuel and enters
  the air.
• All flammable substances are supposed to contain
  phlogiston and it is what all metals have in
  common.

10
The Theory of Phlogiston

• Burning is a process in which a principle of
  combustion is given off by the fuel and enters
  the air.
• All flammable substances are supposed to contain
  phlogiston and it is what all metals have in
  common.
• There is no such substance and ordinary
  combustion is the addition of oxygen to something
  and not the emission of something by the fuel.

11
The Theory of Phlogiston

• Burning is a process in which a principle of
  combustion is given off by the fuel and enters
  the air.
• All flammable substances are supposed to contain
  phlogiston and it is what all metals have in
  common.
• There is no such substance and ordinary
  combustion is the addition of oxygen to something
  and not the emission of something by the fuel.
• So it seems obvious that phlogiston theory must
  be bad science.

12
The Theory of Phlogiston (heyday 1700-1790)

• Becher (1635-1682) proposed combustible earth (as
  one of three earths composing ordinary
  substances).

13
The Theory of Phlogiston (heyday 1700-1790)

• Becher (1635-1682) proposed combustible earth (as
  one of three earths composing ordinary
  substances).
• Stahl (1660-1734) proposed phlogiston in 1697
  (also year the worlds first heat engine was
  built) parallels between metals heated in air
  (calcination) and ordinary combustion creation
  of dust and light often given off, lots of air
  needed. Phlogiston given off in combustion -
  flames

14
The Theory of Phlogiston (heyday 1700-1790)

• Becher (1635-1682) proposed combustible earth (as
  one of three earths composing ordinary
  substances).
• Stahl (1660-1734) proposed phlogiston in 1697
  (also year the worlds first heat engine was
  built) parallels between metals heated in air
  (calcination) and ordinary combustion creation
  of dust and light often given off, lots of air
  needed. Phlogiston given off in combustion -
  flames
• Wood turns to ash when burnt (phlogiston must
  therefore have mass).
• Iron rusts to calx also giving off phlogiston.
• Charcoal combusts almost completely so charcoal
  is very nearly pure phlogiston.

15
The Theory of Phlogiston (heyday 1700-1790)

• Becher (1635-1682) proposed combustible earth (as
  one of three earths composing ordinary
  substances).
• Stahl (1660-1734) proposed phlogiston in 1697
  (also year the worlds first heat engine was
  built) parallels between metals heated in air
  (calcination) and ordinary combustion creation
  of dust and light often given off, lots of air
  needed. Phlogiston given off in combustion -
  flames
• Wood turns to ash when burnt (phlogiston must
  therefore have mass).
• Iron rusts to calx also giving off phlogiston.
• Charcoal combusts almost completely so charcoal
  is very nearly pure phlogiston.
• Phlogiston was supposed to have a metallic
  quality. Metal calx burnt in charcoal becomes
  ordinary metal - adding phlogiston adds the
  metallic quality to the true form (calx) of the
  metal (practical application to copper mining).

16
The Theory of Phlogiston (heyday 1700-1790)

• Becher (1635-1682) proposed combustible earth (as
  one of three earths composing ordinary
  substances).
• Stahl (1660-1734) proposed phlogiston in 1697
  (also year the worlds first heat engine was
  built) parallels between metals heated in air
  (calcination) and ordinary combustion creation
  of dust and light often given off, lots of air
  needed. Phlogiston given off in combustion -
  flames
• Wood turns to ash when burnt (phlogiston must
  therefore have mass).
• Iron rusts to calx also giving off phlogiston.
• Charcoal combusts almost completely so charcoal
  is very nearly pure phlogiston.
• Phlogiston was supposed to have a metallic
  quality. Metal calx burnt in charcoal becomes
  ordinary metal - adding phlogiston adds the
  metallic quality to the true form (calx) of the
  metal (practical application to copper mining).
• When something burns in a sealed container it
  uses up the oxygen in the air until eventually
  the fire goes out. This was explained in terms of
  the saturation of the air with phlogiston.
• Combustion, respiration and calcification are all
  the same kind of reaction (oxidisation). (Animals
  in a sealed chamber phlogisticate the air
  (Boyle).)

17
The Theory of Phlogiston

• Big Problem
• Since Rey (1630) it was known that the calx of a
  metal could be heavier than its metallic form.
• Some Stahlians posited negative weight for
  metallic phlogiston but most believed that
  impurities caused the weight increase.

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Priestley (1733-1804)

• Plants dephlogisticate the air (cycle between
  plants and animals).
• Air without any phlogiston is air whose potential
  to be burnt is maximal.
• Dephlogisticated air by heating a calx (red
  mercury) (1774)
• Scheele (1742-1786) fire air (1771-2,
  published 1777)
• There is a clear sense in which the
  dephlogisticated air that Priestley describes
  breathing is oxygen.

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Priestley (1733-1804)

• Plants dephlogisticate the air (cycle between
  plants and animals).
• Air without any phlogiston is air whose potential
  to be burnt is maximal.
• Dephlogisticated air by heating a calx (red
  mercury) (Priestley 1774)
• Scheele (1742-1786) fire air (1771-2,
  published 1777)
• There is a clear sense in which the
  dephlogisticated air that Priestley describes
  breathing is oxygen.
• Phlogisticated air is air saturated with
  phlogiston.
• Inflammable air hydrogen (Cavendish 1766) is
  pure phlogiston not charcoal according to
  Cavendish.
• Priestley burned metal oxide in inflammable air
  to make pure metal (and water) - reduction
  inverse of oxidisation.
• But inflammable air is obviously not just
  ordinary air with phlogiston in higher
  concentration, since ordinary air becomes
  saturated with phlogiston during combustion and
  eventually the fire goes out.
• Some of the phlogisticated air dissolves in water
  (carbon dioxide) and some does not (mostly
  nitrogen). Neither supports ordinary combustion
  (like Oxygen) or reduction (like hydrogen).

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Lavoiser (1743-1794)

• Oxygen (dephlogisticated air) and hydrogen
  (phlogisticated air) found in compound ordinary
  air and make up water.
• Burning, respiration and rusting of iron are all
  oxidisation.
• But he also thought all acids contain oxygen and
  that oxygen was a principle not an element.

21
Realists on Phlogiston

• Among philosophers phlogiston is a prime
  example of a non-referring theoretical term.
• phlogiston refers to nothing (Psillos)
• Phlogiston is a counterexample to the simple
  causal theory since then it would refer to oxygen
  (whatever is involved in combustion) (Bird)

22
Phlogistons Success

• Explains loss of weight of wood, coal and
  ordinary substance when burnt.
• Charcoal leaves hardly any ash because it is
  almost pure phlogiston.
• Air saturated with phlogiston cannot support
  respiration.
• Metal heat (in air) calx metal oxide
  phlogisticated air de-oxygenated air
• Calx charcoal (source of phlogiston) metal (
  fixed air carbon dioxide (Joseph Black
  (1728-1799) 1754))
• So Metal calx phlogiston (explaining what
  metals have in common)
• Charcoal calx (fixed air) phlogiston
• Metal acid salt inflammable air (note
  Lavoisier thought acids had to contain oxygen)
• Metal water calx inflammable air
• (Water inflammable air hydrogen
  dephlogisticated air oxygen)
• Dephlogisticated marine acid (Scheele) chlorine
  (Davy).
• novel prediction heat calx in inflammable air to
  get pure metal
• novel prediction of new acids by Scheele (formic
  acid, lactic acid)
• Animals and plants have opposite effects on the
  air - the former phlogisticate and the latter
  dephlogisticate
• Metals are alike (lost by intermediary science
  between Priestley and electronic chemistry).
• Phlogistication and dephlogistication are inverse
  chemical reactions (reduction and oxygenation)

23

• phlogistication and dephlogistication can be
  regarded as referring to the processes of
  oxidation and reduction, where these are
  understood in the general sense of the formation
  of an ionic bond with an electronegative
  substance, and the regaining of electrons
  respectively.

24

• phlogistication and dephlogistication can be
  regarded as referring to the processes of
  oxidation and reduction, where these are
  understood in the general sense of the formation
  of an ionic bond with an electronegative
  substance, and the regaining of electrons
  respectively.
• If the oxidising agent is oxygen, and the
  oxidised compound is a source of carbon then the
  product is carbon dioxide i.e. fixed air.
  (combustion of fossil fuels)
• If the oxidising agent is an acid, then hydrogen
  is emitted.

25

• phlogistication and dephlogistication can be
  regarded as referring to the processes of
  oxidation and reduction, where these are
  understood in the general sense of the formation
  of an ionic bond with an electronegative
  substance, and the regaining of electrons
  respectively.
• If the oxidising agent is oxygen, and the
  oxidised compound is a source of carbon then the
  product is carbon dioxide i.e. fixed air. If the
  oxidising agent is an acid, then hydrogen is
  emitted.
• We could go further and allow that phlogiston
  rich and phlogiston deficient refer too,
  namely to strongly electro-negative and
  electro-positive molecules respectively.
• One could even argue that phlogiston refers to
  electrons in the outer orbital of an atom.

26
Forgotten Wisdom Whewell, History of the
Inductive Sciences

• But we must not forget how natural it was to
  suppose that some part of a body was destroyed or
  removed by combustionIt would be easy to show,
  from the writings of phlogistic chemists, what
  important and extensive truths their theory
  enabled them to express simply and clearly.
• Combustion, respiration and calcination of metals
  are all the same kind of reaction and there is an
  inverse kind of reaction too.

27
Structural Realism

• John Worrall (1989) introduced structural realism
  (although he attributes its original formulation
  to Poincaré). Using the case of the transition in
  nineteenth century optics from Fresnel's elastic
  solid ether theory to Maxwell's theory of the
  electromagnetic field, Worrall argues that
• There was an important element of continuity in
  the shift from Fresnel to Maxwell and this was
  much more than a simple question of carrying over
  the successful empirical content into the new
  theory. At the same time it was rather less than
  a carrying over of the full theoretical content
  or full theoretical mechanisms (even in
  approximate form) ... There was continuity or
  accumulation in the shift, but the continuity is
  one of form or structure, not of content (1989,
  117).

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More Structural Realism

• Instructive historical examples
• The transition from Fresnels ether theory of
  light to Maxwells electromagnetic field theory.
• The transition from Galilean relativity to
  Lorentz invariance.
• The transition from classical mechanics to
  quantum mechanics.
• The transition from Newtonian gravitation to
  General Relativity.

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Modality

• We have been very focused on the composition of
  wholes by parts and have not addressed the key
  issue of the status of putative causal claims at
  different levels.
• More generally, I consider modality to be a
  central issue for the philosophy of physics.
  (Counterfactual definiteness Locality is
  sufficient to prove Bells theorem (cf. Tomasz
  Bigaj in SHPMP).)

30
Modality

• Realism physics tells us about causation, the
  laws of nature and deep metaphysics
• Antirealism physics gives maximally general
  descriptions of regularities in the phenomena

31
Modality

• Realism physics tells us about causation, the
  laws of nature and deep metaphysics
• Antirealism physics gives maximally general
  descriptions of regularities in the phenomena
• Example the speed limit of light speed - is it
  merely a generalization that is true or does it
  have some kind of necessary status?

32
Modality

• Realism physics tells us about causation, the
  laws of nature and deep metaphysics
• Antirealism physics gives maximally general
  descriptions of regularities in the phenomena
• Example the speed limit of light speed - is it
  merely a generalization that is true or does it
  have some kind of necessary status?
• Example the laws and the constants and the
  fine-tuning argument

33
Is Physics Special and is fundamental physics
special with respect to the rest of physics?

• In science there is only physics all the rest
  is stamp collecting.
• Ernest Rutherford

34
The Incompleteness of the Special Sciences

• In all the special sciences it is acceptable to
  invoke entities and processes from more
  fundamental sciences in explanations.
• For example, the economy may be affected by the
  weather, living systems may be affected by
  radiation, chemical reactions may be affected by
  magnetic fields, and so on.
• There is a fundamental asymmetry between physics
  and the special sciences.

35
The Completeness of Physics

• Fundamental physics aspires to a kind of
  completeness in so far as it is never permitted
  to invoke entities or processes from the special
  sciences in an explanation of the behaviour of
  the the fundamentally physical.
• Physics is analytically complete since it is the
  only science that cannot be left incomplete.

36
Fundamental Physics

• Measurements at all scales and at all locations
  in spacetime are potential falsifications or
  confirmations of fundamental physics.
• This is not true of any other science.
• Fundamental physics may not exist other than as a
  limiting ideal (if there is no fundamental
  level).
• (Many parts of physics are special sciences.)

37
The Primacy of Physics Constraint (PPC)

• Naturalists ought only to accept a form of
  physicalism that is motivated by reflection on
  the history of science and the nature and
  practice of contemporary science. Ladyman and
  Ross argue that this justifies nothing more than
  the PPC (methodological physicalism)
• Special science hypotheses that conflict with
  fundamental physics, or such consensus as there
  is in fundamental physics, should be rejected for
  that reason alone. Fundamental physical
  hypotheses are not symmetrically hostage to the
  conclusions of the special sciences. (2007, 44)
• This leaves it open to the naturalist to believe
  both that the entities posited by the special
  sciences exist, and that the causal relations
  posited by them are genuine.

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2. Structuralism and the Part-Whole relation

• The natural numbers are often said to
  ontologically depend on each other and the
  relations among them - so the parts depend on the
  whole.
• Cf. the identity and individuality of spacetime
  points depends on the metric field and hence
  again the parts depend on the whole.

39

• Structuralism less than ontological commitment
  to the dressing theory is given more than
  relations among the phenomena.

40
Objects and Individuals

• What does it take to be an object?
• What does it take to be an individual?
• Quasi-particles, Bose Einstein Condensates,
  Cooper pairs, entangled photon pairs, quantum
  fields
• Do they exist in the same sense as tables and
  chairs?

41
Individuation

• PII and weak discernibility - structures
  admitting a non-trivial automorphism - complex
  plane, fermions in the singlet state (Michal)
• purely relational individuation
• an asymmetric graph of order 6 pure relations
  can give rise to absolute discernibility

42
Quasi-Particles

• Bipolaron a bound pair of two polarons
• Chargon a quasiparticle produced as a result of
  electron spin-charge separation
• Configuron an elementary configurational
  excitation in an amorphous material which
  involves breaking of a chemical bond
• Electron hole a lack of electron in a valence
  band
• Exciton a bound state of an electron and a hole
• Fracton a collective quantized vibration on a
  substrate with a fractal structure.
• Holon a quasi-particle resulting as a result of
  electron spin-charge separation
• Libron a quasiparticle associated with the
  librational motion of molecules in a molecular
  crystal
• Magnon a coherent excitation of electron spins
  in a material
• Phason vibrational modes in a quasicrystal
  associated with atomic rearrangements
• Phonon vibrational modes in a crystal lattice
  associated with atomic shifts
• Plasmon a coherent excitation of a plasma
• Polaron a moving charged quasiparticle that is
  surrounded by ions in a material
• Polariton a mixture of photon with other
  quasiparticles
• Roton elementary excitation in superfluid
  Helium-4
• Soliton a self-reinforcing solitary excitation
  wave
• Spinon a quasiparticle produced as a result of
  electron spin-charge separation

43
3. Real Patterns

• macroscopic objects as relatively stable and
  enduring patterns that emerge within the
  structure of the quantum state of the world.
• On such a view, the world need not form a
  compositional hierarchy, with or without ultimate
  parts.

44
Special Science Ontology

• In science one is only interested in recovering
  the statistical properties of low-level entities
  when tracking high level ones.
• Coarse-graining and approximation are necessary
  for special science ontologies to emerge. This
  explains why even token identities do not obtain
  between say a cat and its constituent atoms.
• In the special sciences one is usually interested
  in universal forms of behaviour, where
  universal means independent of microphysical or
  lower level constitution. The identification of
  universality and the appropriate descriptive
  categories for tracking it is one of the
  principle tasks of the special sciences.
  
• The scale relativity of ontology (Ladyman and
  Ross)
• The renormalization group view of the world
  (Sokal and Bricmont) the renormalization group
  describes transformations that allow the number
  of degrees of freedom in the Hamiltonian of a
  system to be massively reduced while still
  recovering the critical behaviour of the system.

45
Complexity

• The special sciences are possible because the
  world is to some extent algorithmically
  compressible. At certain levels of description
  it is possible to use much less information to
  predict the behaviour of systems described in an
  approximate and probabilistic way, than would be
  needed to describe their microstates.
• For example, Keplers laws, the ideal gas laws,
  the HardyWeinberg law, In fact all laws in the
  special sciences are like this. The special
  sciences rely upon reduction in the degrees of
  freedom of the system.
• There are real patterns in the world that are
  only visible at the right scales of resolution
  and degrees of approximation. If you dont see
  them you are missing something about reality and
  that is good enough to allow us to say that the
  objects, properties and processes described by
  the special sciences are real.

46
Computational Approaches to Emergence

• between order and randomness
• logical depth, thermodynamic depth, statistical
  complexity, information theoretic entropy,
  algorithmic complexity,
• complex systems involve hierarchical organisation.

47
Real Patterns

• Daniel Dennetts notion of real pattern is a
  computational one.
• The idea is based on the compression of data and
  the reduction of information processing made
  possible by a high level description of a system
  that could in principle be described at a
  fine-grained level but at a much greater
  computational cost.

48

• John Conways Game of Life is based on a simple
  implementation of cellular automata that makes a
  particular range of stable dynamic attractors
  highly salient to people.
• A person using the system naturally book-keeps
  its state sequences by reference to a typology of
  emergent objectsgliders, eaters,
  spaceships, etc.that have only virtual
  persistence. (That is, two successive instances
  of the same glider share only structure, and
  common participation in structures larger than
  themselves.
• A glider is clearly mereologically composed of a
  small number of illuminated cells. However, its
  successive instances are composed of different
  cells, and successive instances a few steps apart
  have no cells in common.)
• Once this descriptive stance is adopted towards
  Life, almost all users spontaneously track the
  dynamics in terms of causal interactions among
  instances of these typesfor example, a glider
  will be caused to disappear through interacting
  with an eater. That is, Life users naturally
  begin logging causal generalizations about the
  types of virtual objects, and thereby seem to
  commit themselves to their objective existence.
• (All the above paragraphs are taken from Ladyman
  and Ross (2007), chapter 4.)

49

• One should be cautious in using the Game of Life
  as a metaphysical model of the universe.
• It is useful for the purposes to which Dennett
  puts it, because it shows how patterns can emerge
  at grains of analysis coarser than the grain at
  which what is analogous to the fundamental
  microphysical level is studied, even when all
  causal processes governing the latter are
  non-complex, known, measurable, and
  deterministic. Life is thus a good antidote to
  romantic interpretations of emergence.
• However, because in Life there is an unambiguous
  fundamental level composed of the aggregation of
  a finite number of little things, and because no
  higher-level object types cross-classify the
  dimensions of any models of the game relative to
  classifications in terms of cells, Life differs
  greatly from the universe with respect to the
  kinds of reductionism sustainable in it. Life
  admits of complete decomposition the universe
  might not.
• (All the above paragraphs are taken from Ladyman
  and Ross (2007), chapter 4.)

50
Definition of Real Patterns (Ladyman and Ross,
2007, chapter 3

• To be is to be a real pattern and a pattern is
  real iff
• it is projectible under at least one physically
  possible perspective and,
• it encodes information about at least one
  structure of events or entities S where that
  encoding is more efficient, in information-theoret
  ic terms, than the bit-map encoding of S, and
  where for at least one of the physically possible
  perspectives under which the pattern is
  projectible, there exists an aspect of S that
  cannot be tracked unless the encoding is
  recovered from the perspective in question.

51

• According to RP, the utility of the intentional
  stance is a special case of the utility of
  scale-relative perspectives in general in
  science, and expresses a fact about the way in
  which reality is organizedthat is to say, a
  metaphysical fact. The fact in question is what
  we (but not Dennett) call the scale relativity of
  ontology.
• Scale relativity of epistemology isnt
  controversial. To borrow an example from Wallace
  (2001), if you want to predict what a hungry
  tiger will do when confronted with a deer, you
  should study whole behavioural patterns of whole
  tigers, not individual tiger cells or molecules.
  It is clearly motivated by any thesis to the
  effect that models of complex systems are
  scientifically useful.
• (All the above paragraphs are taken from Ladyman
  and Ross (2007), chapter 4.)
• trade offs between scope, accuracy and simplicity

52

• Real patterns are preserved on theory change -
  cf. Butterfield on the Krebs cycle.

53

• Dennetts paper is notoriously unclear about
  whether real patterns should be regarded as
  real or as useful fictions.
• realism versus pragmatism - metaphysics versus
  epistemology

54

• Conservative metaphysicians would complain, the
  eater is a redundant causal factor, since the
  program underlying Life, which in its declarative
  representation quantifies only over cells, is
  strictly deterministic. We are reminded that an
  eater or a glider is, at any given time, made
  of cells and nothing else. Then we are invited
  to agree that a thing cannot have causal efficacy
  over and above the summed causal capacities of
  the parts with which it is allegedly identical.
  The result is supposed to be reductionism, and
  instrumentalism about gliders and eaters.
• (The above paragraph is from Ladyman and Ross
  (2007), chapter 4.)

55

• Real patterns are defined modally.
• They are there to be discovered.

56

• David Wallace advocates what he calls a
  functionalist account of ontology based on the
  notion of real patterns in his elucidation of the
  Everettian interpretation of quantum mechanics.
• His ontology is two-tier in that only
  higher-order entities such as cats and tables are
  understood in terms of real patterns, whereas the
  wavefunction or whatever else proves to be
  fundamental in physics is understood in
  categorical rather than functional terms.

57

• On the other hand, James Ladyman and Don Ross
  (2007) advocate a real patterns account of
  ontology across the board.
• All real patterns are real but there is an
  asymmetric relation among them.
• The relation is not composition since emergent
  structure is not reducible to the sum of the
  parts - no building blocks (Healey)

58

• Real patterns theory can be developed in terms of
  the dynamics of phase spaces rather than in
  computational terms. (Jenann Ismael suggested
  this.)
• Reducing the number of degrees of freedom by
  finding objects.
• There are synchronic patterns too of course but
  they could be represented in terms of laws of
  co-existence.