The document summarizes Tony Smith's presentation on self-organized criticality. Some key points: - Self-organized criticality describes how dissipative systems with extended degrees of freedom can evolve toward a minimally stable critical state through small, frequent disturbances that follow a power law distribution. - Bak et al's 1987 paper that introduced this concept has been shown to be relevant to many natural phenomena like sandpiles, earthquakes, wildfires, etc. that maintain a critical balance. - Smith's presentation applied self-organized criticality to better understand everyday human behaviors and systems, examining universals, animals, civilization, and modernity in terms of approaching critical thresholds. - Reaching critical states

1. Self-organised Criticality
Tony Smith
Melbourne Emergence Meetup
8 August 2019

2. Placeholder for video slide at
https://vimeo.com/353180022
Self-organised Criticality

3. Supervenience presentation 2 weeks earlier
to Science, Technology and the Future on
Life and Death as Systems Collapse included:
Long histories and quick deaths
Optimisation to threshold of criticality
So a reason to review underlying complex
systems theory that followed the 1987 paper
by Per Bak, Chao Tang and Kurt Wiesenfeld
“Self-organized criticality: an explanation of
1/f noise”.
Long-wavelength perturbations cause a cascade
of energy dissipation on all length scales, which
is the main characteristic of turbulence.
The (currently) “Self-organising, Adaptive”
component of the Supervenience project has
a uniquely chequered history. It follows some
more general principles of Emergence and
Complex Systems, getting into detail of many
and varied processes which underly emergent
complexity, as reflected in its original title:
“Here Now Succession Process Traces Time
Causation?” that didn’t fit well alongside more
succinct component titles so we tried a couple
of others which similarly disappointed:
“Dynamic encodings in condensed matter”
“Maintaining interesting isolates through
cosmological timescales”
Self-organised Criticality
SUPERVENIENCEhow emergent minds and money seize power over matter

4. Too Funny for Words
Abstractions, Category Errors,
Epistemic Cuts
Life on an Active Planet The Two-edged Sword
Multiple Paths to Emergence
Constraints and
Degrees of Freedom
Birds and Others Interweb to Facebook
Better than Out of Control
Information,
Maps and Territories
Urban Hydrology out of Sight
Going Down with
the Egg Basket
Self-organising, Adaptive
Codification and
Communication
Exploiting a
Dissipating Gradient:
creaming, trickle down
Dystopian Utopias and
Science Fiction
Towards Healthy
General Knowledge
The Inside View:
knowing when you're dreaming
Verbal Blindness
Accepting Cosmological
Responsibility

5. We believe that the new concept of self-organized
criticality can be taken much further and might be
the underlying concept for temporal and spatial
scaling in a wide class of dissipative systems with
extended degrees of freedom.
–Bac et al [1987]
This presentation needs to be complemented
by additional information on how natural and
constructed systems evolve towards criticality,
an exploration of benefits and costs of doing
more of whatever seems to be operating well
enough to keep each system holding together.

6. Bak et al’s 1987 paper was perfectly timed to catch the explosion of interest in complex systems that took off
in the mid 1980s, its central concept soon being shown to be relevant to a long list of phenomena, starting
with the classic sandpile which is slowly added to and maintains a critical slope through landslides that
follow a power law distribution with many small and few larger.
The short paper starts by discussing a conceptual “one-dimensional array of damped pendula (...) connected
by torsion springs that are weak compared with the gravitational force” which settles to a “minimally stable”
state rather than to the lowest possible state. It is disturbances to the minimally stable state which follow a
power law as the range of impact is dependent on complexities that only show a pattern statistically.
They then test this with a Von Neumann neighbourhood cellular automata rule (and a 3D analogue) which is
designed to settle from an initially high “energy” random configuration into an equivalent minimally stable
configuration, a rule that also appears analogous to the evolution of cosmological structure dominated by
gravitational interaction of cold dark matter. It is in these CA models that the range in both time and space
of the propagation of disturbances is demonstrated to have a power law distribution.
Bak et al identify various other phenomena as candidates for similar analysis, including: river flow,
luminosity of stars, fractal landscapes such as coast lines and mountains, and turbulence. Subsequently, self-
organised criticality has been applied to understanding electromagnetic domain performance, earthquake
magnitude and aftershock timing, financial indicators, wild fires, epidemics, landslides, and nerve signals
(paraphrasing Wikipedia entry).
“Criticality” here is defined by the proximity of an attractor state rather than a not directly related reference
to phase transitions. This presentation sees an even broader range of phenomena edging ever closer to their
threshold of criticality, both naturally and intentionally. It is particularly concerned with how approaching
such critical thresholds empowers and constrains ecosystems and their inhabitants.

7. Tonight’s presentation looks at
everyday behaviour through the
lens of self-organised criticality,
recognising that nothing occurs
in isolation. Understanding the
parts relies on recognising their
environmental dependencies.
We take this Big History tour in
four major stages of increasing
proximity to our present crises:
• Universals
• Animals
• Civilisation
• Modernity
Within each, half a dozen topics
are introduced, typically by a
couple of images as examples of
a much larger set of criticality
to be briefly explored.
Limpets at low tide
Crayfish Bay 2016

8. Universals

9. Gravitational aggregation at cosmic scales produces rotating
disks and cores through conservation of angular momentum

10. On big enough planets orbiting stars, atmospheric physics
and chemistry drives condensation into clouds and storms

11. Impact cratering & internal tectonics feed surface processes

12. Stuart Kauffman [1995] proposed Autocatalytic Sets as a
key step on the journey via an RNA world to Prokaryotes

13. Stromatolites formed by oxygenising cyanobacteria, ancient
fossil from the Pilbara and current from nearby Shark Bay

14. Sunlight reflecting off Titan’s hydrocarbon lakes and off
Wingecarribee Reservoir in NSW Southern Highlands

15. Animals

16. Development of animal zygotes is highly conserved but
development of plants is more accessible to observation

17. Minimum set of requirements to function as mobile animal
evidenced by sea snail art produced filtering food from sand

18. Us us us us and Them them them them
And after all we’re only ordinary men (…)
With with with with, without
And who’ll deny that’s what the fighting’s all about
—Wright and Waters, Pink Floyd
from the album Dark Side of the Moon 1973
Life demands identifying one’s own kind and other kinds
making the challenge to broaden inclusion to at least aves

19. All manner of nests and dens are created by animals to give
the next generation a good start in life, including knowledge

20. Animals thrive on excess (re)production of other life forms
which a few assist with the reproduction of in the process

21. Crested Terns and Silver Gulls happily share patch of sand

22. Civilisation

23. Wurundjeri cultural revival on the Merri highlights methods
of preserving oral knowledge, complementing song lines

24. Awareness of Aboriginal agriculture too recent for pictures
Imported domestication of other species, food processing

25. Human settlements were close to life sustaining resources
until cities grew powerful enough to extract more widely

26. Language and opposable thumbs enabled division of labour
and specialisation to reach new levels before settlements
started to grow and provide support for more of the same

27. Long distance travel exploited seasonal variations, allowed
trade, water flow provided energy, quarries useful minerals

28. Transition from autocracy to representative democracy and
legal process gentrified everyday life, enabling many dreams

29. Modernity

30. Misinformation spread by writing, printing and the internet

31. Capital accumulation went from privilege to expectation
Businesses avoid scrutiny via limited liability, externalities

32. After ownership changes glass bottles are still manufactured
at old site of Australian Glass Manufacturers and its heritage
celebrated. Coal seam exposed at beach shows fracking risk

33. Electricity generation and transmission underpins modernity
enabling refrigeration to add dimensions to food processing

34. Academic scholarship built on the shoulders of giants
Science found patterns in things measured in isolation

35. Expectation of a full life followed sanitation, medication and
indiscriminate industrial killing of other life for convenience

36. Suggestions!
Questions?