Based upon:

Based upon:

Kelly, Kevin. 1989. Simple words about the new science of complexity: A talk with George Cowan. Whole Earth Review 63 (Summer 1989): 94-97.

WAYS OF LOOKING AT THE WORLD

• Humans tend to perceive things either holistically (as irreducible wholes) or reductionistically (as collections of simpler components)

• Both views have their merits• However, we must also consider the

INTERACTIONS between the components

SYSTEMS THEORY

SYSTEMS

• ‘systēma’ (Gr.) – “organised whole”• a set of interacting or interdependent

components forming an integrated whole

• many types and scales of systems, from subatomic particle interactions in matter, through metabolic systems in cells, up to star systems in the universe

SYSTEMS

• Ludwig von Bertalanffy (1901-1972)

• was frustrated by reductionist thinking

• sought a unifying theory that would cover philosophy, psychology, physics, and chemistry

General Systems Theory

• one general organising theory to unite many different areas

• central tenet: all systems, however different, have similar underlying organising principles

• General Systems Theory extends from very simple nonliving systems (e.g., thermostats) to complex living systems (e.g., organisms, societies, institutions & cultures)

SYSTEMS

open systems:• exchange matter and energy with

their surroundings-> most systems are open (living organisms, heat engines, etc.)closed systems: • exchange energy, but not matter, with

their surroundings (e.g., computer programs, planet Earth)

ALL SYSTEMS HAVE…

Structure: components that are directly or indirectly related to each other

Behavior: processes that transform inputs into outputs (material, energy or data);

ALL SYSTEMS HAVE…

Interconnectivity: their parts and processes are connected by structural and /or behavioral relationships

Boundaries: natural or defined limits which determine which parts are inside the system and which parts are outside

A PROBLEM ARISES!

Mid-1980s Desktop PC1977 Apple II Desktop

• ATTEMPTS TO DESCRIBE COMPLEX SYSTEMS IN TERMS OF THEIR

SUBSYSTEMS, SHOWING HOW THE PROPERTIES OF THE SUBSYSTEMS ARISE

FROM THE INTERACTION OF THE SUBSYSTEM “PARTS”

“EMERGENT PHENOMENA”

“EMERGENT PROPERTIES”

e.g.,• Interaction of wind with the surface of

the ocean results in WAVES • interaction of lunar gravity with the

surface of the ocean results in TIDES

• Interaction of water with the surface of the sand results in RIPPLES

• Interaction of win with the surface of the sand results in DUNES and RIPPLES

Computer simulation:

THE FORMATION OF SAND RIPPLES BYWATER WAVES IN A UNIFORM CURRENT The model contains: • topography• grain size distribution• grain volume• compaction• acoustic impedance

Unpublished mathematical model, 2005Dr. Peter Staelens (Brugge, Belgium)www: www.dotocean.eucontact: peter@dotocean.eu

AN EARLY EXAMPLE (1990s) FORETELLING CURRENT SYSTEMS:

Example: Seattle Traffic Flow Map

• http://www.wsdot.wa.gov/traffic/seattle

IMPLICATIONS:

Metastable ecosystem:Freshwater marsh (e.g., Cataraqui Marsh near Kingston, ON)

• Appears very stable and unchanging• Little evidence of growth or renewal

except for seasonal change from summer green to winter brown

• Actually one of the most productive ecosystems on the planet ->

• Rapid cycles of growth, senescence, decomposition -> high energy flowsand quick cycling of materials

Wetlandnutrientcycling

and storage(yellow box)

Wetlandecosystem

components(boxes)

Wetlandecosystemprocesses(arrows)

From Hossleret al. 2011

:

E.g. Audio feedback –

Microphone picks up sound ->Amplifier makes it louder ->Speaker broadcasts it ->

Microphone picks up sound -> Amplifier makes it louder -> Speaker broadcasts it -> Microphone picks up sound -> Amplifier makes it louder -> Speaker broadcasts it ->

SHRIEK!!!SHRIEK!!!SHRIEK!!!SHRIEK!!!

E.g. Positive feedback in a natural system: Greenhouse gases in the atmosphere and climate change

UNCHECKED POSITIVE FEEDBACK LOOPS

MAY TEND TO

DESTROY

THE SYSTEM THATTHEY ARE A PART OF

• The heater kicks on, heating up a room• Heat, the output of the heater, serves as input to the thermostat.• At a certain critical temperature,

the thermostat tells the heater that the room is warm enough.

• The heater, receiving this feedback through an electrical connection, shuts itself off.

• After a while, the thermostat notices that the room has cooled to a specific temperature, and notifies the heater.

• The heater kicks on again.• The information traveling from the heater to the thermostat and back again

is a negative feedback loop.

:

Thermostat Heater

E.g. HEATER AND THERMOSTAT

E.g. Negative feedback in a natural system: Cycles in lynx and hare populations

NEGATIVE FEEDBACK LOOPS

MAY TEND TO

STABILIZE

THE SYSTEM THATTHEY ARE A PART OF

INTERACTIONS BETWEEN NEGATIVE AND POSITIVE

FEEDBACK LOOPS IN A SYSTEMCAN RESULT IN

DYNAMIC EQULIBRIUM