A Discourse on Decision Theory

In April 2010 I presented a seminar at SFI where I demonstrated that certain classic problems in economics can be resolved by methods that present an alternative to the dominant formalism of expected utilities in decision theory. Specifically, I noted that simple mathematical models of economic processes,...

Active Discovery of Network Roles for Predicting the Classes of Network Nodes

We consider a network in which we know how the nodes are connected, but we do not know the class labels of the nodes. We wish to identify the best subset of nodes to label, in order to most accurately predict the class labels of the rest of the nodes. In contrast to previous work, we do not assume that...

A Wild Solution for Climate Change

Our planet’s biology and its climate are inexorably coupled. Warmer and less predictable climates will continue to diminish the planet’s biodiversity. But biological systems can be part of a solution. Conservation biology pioneer Thomas Lovejoy will examine the present and possible future impacts of...

The Lexicon as a Dynamical System: The Drive to Keep Words Distinct and the Evolution of Phoneme Inventories

All human languages make use of small systems of signal categories, such as the sounds [p] and [b], in combination to compose meaningful lexical categories, such as the words "pat" and "bat." These perceptually contrastive, yet individually meaningless signal categories are often called phonemes. Over...

Self-Organized Criticality in Hamiltonian Spin Systems: Intriguingly Ordinary or Ordinarily Intriguing?

Self-organized criticality (SOC) refers to the tendency of dissipative systems to drive themselves into a scale-invariant critical state without any parameter tuning. These phenomena are of crucial importance because fractal objects displaying SOC are found everywhere, e.g., in earthquakes, the structure...

President's Welcome Message

The Omes That Matter: Teleome, Nature-ome, and Culture-ome

To understand biology and brain we must have, in addition to comprehensive mechanistic inventories like the genome and connectome, a comprehensive account of all the functions the biology implements – I call it the teleome, the suite of all teleologically-steeped "purposes" evolution instilled into the...

Turing's Cathedral: The Origins of the Digital Universe

The two most powerful technologies of the 20th century -- the nuclear bomb and the computer -- were developed in New Mexico at the same time and by the same group of young people. But while the history of the Manhattan Project has been well told, the origin of the computer is relatively unknown. In his...

Collective Phenomena, Collective Motion, and Collective Action in Ecological Systems

Gateways to Emergent Behavior in Science and Society

Landscapes and Beyond — Glasses, Proteins, and the Cell

Gateways to Emergent Behavior in Science and Society

Patterns of Synchrony: From Animal Gaits to Binocular Rivalry

Gateways to Emergent Behavior in Science and Society

Insects in Free Flight: Movement and Thoughts

Gateways to Emergent Behavior in Science and Society

The Emergence of Multicellularity

Gateways to Emergent Behavior in Science and Society

Modeling Computer Networks from Chips to the Internet

The Internet is, perhaps, the largest and most complex human artifact ever created, encompassing billions of technologies, organizations, and human users worldwide. It operates simultaneously on several interacting time scales -- from slow processes, such as hardware development, to data transport occurring...

The Complex Science of Cyberdefense: Computer Immunology

Threats are ubiquitous in complex systems: biology is rife with viruses, parasites, and bacteria; social networks abound with bullies; and international relations are stymied by rogue nations. In the second of three lectures, Stephanie Forrest proposes that understanding how complex systems generally...

Software Engineering: Evolving Computer Programs

Software -- used today for everything from shopping and banking to streaming movies -- shapes our daily experience. The software industry contributes billions of dollars annually to the U.S. economy and employs millions of Americans. Programmers like to think of software as the carefully crafted product...

An Exactly Solvable Model of Racial Segregation

In the 1960s and 70s Thomas C. Schelling, an economist then at Harvard, developed a simple agent-based simulation in which a mixed population of two races spontaneously breaks down into segregated enclaves, even though no member of the population seeks that outcome. Many variations of Schelling's model...

Cancer Evolution and Prevention

Since the mid 1970s, cancer has been described as a process of Darwinian evolution, with somatic cellular selection and evolution being the fundamental processes leading to malignancy and its many manifestations (neoangiogenesis, evasion of the immune system, metastasis, and resistance to therapies)....

On Moral Progress: Is the Human Conscience Led by the Head or the Heart?

Is the human conscience led by the head or the heart? Is the moral progress we have enjoyed – religious freedom, the abolition of slavery, anti-war movements, civil, women’s, and gay rights – a gift of empathy and emotion, or of reason and logic? Psychologist and author Steven Pinker and philosopher...

Criticality in the Plasma Membrane of Living Cells

The plasma membrane is a two dimensional liquid composed of a diverse soup of lipids and embedded proteins that surrounds all living cells. In addition to separating inside from outside, the plasma membrane contains much of the cell’s machinery for receiving and processing information. Recent experiments...