Evolution of Matter

Have you ever wondered how we, the thinking organisms, came into being?

The most popular theory of our Universe's origin postulates a cosmic cataclysm unmatched in all of history — the Big Bang. According to the proponents of the theory, the massive blast that occurred 10-20 billion years ago allowed  the Universe's known matter and energy — even space and time themselves — to spring from some ancient and unknown type of energy.  In those initial moments only the heavy particles mediating weak nuclear interaction came into being in a background field of radiation or photons (see accompanying graphics). With that, our journey commenced, in some primordial soup!

Diagram outlining the critical stages of evolution of the Universe from the Big Bang to the present. ((c) CERN)

As the Universe rapidly cooled, particles such as proton, neutron and meson emerged around 10^-10 seconds. By the third minute, when the temperature was down to 10⁹K (0 K = -273.15°C), atomic clusters of these particles began to form. The laws of the Universe were solely under the purview of Physics. The Universe had to cool down to 6000K over a period of 300,000 years before the atoms could bond into molecules, ushering the dawn of Chemistry. Finally, Biology took hold when life, based on DNA double helix, emerged on Earth about 3.5 billion years ago. The march of the Universe has been towards matter of increasing complexity, from fundamental particles to thinking organisms — from divided and disordered building blocks, matter became condensed, organized, living and thinking.

What is the driving force behind this evolution? 

Even though we understand perfectly the laws governing the interaction of atoms, we cannot directly extrapolate these laws to explain the beginning of life, or the auto-catalysis of complex molecular networks, or why we have brains that can contemplate the world around us. Due to the overwhelming unlikeliness of random events leading to complex systems like ourselves, it seems as if an organizing agent or “God” must be invoked who puts the building blocks together.

It turns out that the answer to the above query lies in the most basic of all features, the most fundamental concept: self-organization. Under the pressure of information, systems assume greater complexity through self-organization towards more and more complex forms of matter, up to the generation of life and thought.

To this end, a complex system can be thought of as a collection of interacting agents, representing components as diverse as people, cells or molecules. Because of the non-linearity of the interactions, the overall system evolution is to an important degree unpredictable and uncontrollable.  However, because of self-organization, the local interactions eventually produce global coordination and synergy.

The processes of self-organization literally create “order out of disorder.” They are responsible for most of the patterns, structures and orderly arrangements seen in the natural world, e.g., crystallization, thermal convection of fluids, chemical oscillation, and animal swarming. Many phenomena in the realms of mind, society and culture are also due to self-organization. The network effect, where the more users use a product the greater its value becomes, such as the telephone and Facebook, is an example of self-organization through positive feedback.

Complex systems are able to strike a balance between rigidity and turbulence or stay on the “edge of chaos” because of these processes. A number of theorists have proposed that this precarious balance is precisely what is necessary for adaptation, self-organization, and life to occur, and that complex systems tend to spontaneously evolve towards this “edge.”

How does self-organization work?

It is the very first question that comes to anybody’s mind: Does every individual system in nature have to be probed on a case-by-case basis? Indeed, such a “stamp collection” approach has prevailed in sciences, such as in geophysics and biology, and attempts to look for a unifying description have been met with strong skepticism among the practitioners of those sciences, although there have been a handful of exceptions.

Perhaps nature does not need to invent a multitude of mechanisms, one for each system. Indeed the regularities observed in statistical description of complex systems support the view that only a limited number of mechanisms, or principles, contribute to complexity in all its manifestations – from the galactic or universal to the molecular.

For example, rivers, mountain ranges, etc. exhibit scaling behavior, both in spatial and temporal domains, where sediment deposits or landslides interrupt the quiet steady state. The landslides are scale-free, so are the earthquakes. The distribution of energy released during earthquakes is a simple power law, despite the enormous complexity of the underlying system, involving a multitude of geological structures. Forest fires exhibit a similar behavior, as do volcanic activities. Black holes are surrounded by accretion disks, from which the materials collapse into the black hole in intermittent, earthquake-like events, which interrupt the otherwise steady evolution and occur over a wide range of scales.

Biological evolution is also marked by regularities in the form of long periods of little activity punctuated by extinction events of all sizes where many species disappeared, and other species emerged. About 50 million years ago the dinosaurs vanished during such an event, but this is far from the biggest. 200 million years ago we had the Permian mass extinction, and 500 million years ago the Cambrian explosion took place. Paleontologists have coined the term “punctuated equilibrium” to describe the pace of evolution.

Scientific community asserts that punctuated equilibrium dynamics is the essential dynamical process for a system that evolves and becomes complex, with a specific behavior that is strongly contingent on its history. The periods of stasis allow the system to remember its past, the punctuations allow change in response to accumulated forcing factors over long time scales, and the criticality assures that even minor perturbations can have dramatic effects on the specific outcome of a particular system.

These dynamics allow complex systems to have distinct individual histories and forms. For example, the extinction of many species is attributed to seemingly minor accidents. If the tape of the history of life were to be rerun, an entirely different set of species would emerge.

How do complex systems emerge through self-organization?

Complex systems are delicately balanced between order and disorder in a self-organized criticality (SOC). Essentially, the concept of SOC is that due to slow external drive and in presence of dissipation, a system attains a critical operating point through self-organization. Once the criticality is reached, the system remains at the critical point without requiring any fine-tuning of its parameters (as is the case of general criticality). In traffic flow such a criticality would correspond to a uniform flow of cars with all cars moving at maximum possible velocity.

SOC is conceptually illustrated with avalanches in a pile of grains. The grains are dropped onto a pile one by one, and the pile ultimately reaches a stationary “critical” state in which its slope fluctuates about a constant angle of repose that the sand pile cannot exceed no matter how much sand is added. Thus, each new grain is capable of inducing an avalanche on any of the relevant size scales. The mechanism of the local avalanches decreases the local slopes whenever they become too steep.

In the ordered state, every place looks like every other place. In the disordered state, there are no correlations between events that are separated in time or space. It is only in the critical state that very large correlations exist, so the individual degrees of freedom cannot be isolated. The infinite degrees of freedom interacting with one another cannot be reduced to a few. This irreducibility is what makes critical systems complex.

SOC provides a general mechanism for the emergence of complex behavior in nature from spontaneous simple local interactions. It has been proposed that the crust of the earth, river networks, superconductors in a magnetic field, traffic, etc., all operate in SOC.

Complexity is a hierarchical phenomenon, where each level of complexity leads to the next: astrophysics, with its own hierarchy of scales, leads to geophysics, which is the prerequisite for chemistry, biology, and ultimately the social sciences. Although the origin of the hierarchy is not understood, we do have the rudiments of a theory for the emergence of one level out of the previous one. Due to this hierarchy of emergence, it isn’t necessary to understand the mechanism of the Big Bang in order to understand the dynamics of earthquakes.

A common feature of the systems mentioned thus far, and perhaps of all complex systems, is that they are driven by slow pumping of energy from a lower level of the hierarchy. For instance, biological life is driven by the input of energy from the sun. The energy is stored and later dissipated in a scale-free avalanche process like an earthquake.

Even a small increment in energy can trigger a large catastrophe, making these systems strongly contingent on previous history. They operate far from equilibrium, which is necessary since systems in equilibrium tend to become more and more disordered (rather than becoming complex) over time, according to the second law of thermodynamics. That equilibrium states are catastrophically unstable may be seen in the traffic example – a smooth traffic flow is more likely to exhibit breakdown events or avalanches, such as traffic jams, than stopped traffic. Actually, there are some striking statistical regularities indicating that the mass extinctions are part of a self-organized critical process.

Where is the evolution of complex matter heading?

The emergence of thinking organisms is the most recent episode in the evolution saga. To this end, the development of the brain among species is perhaps the strongest evidence that the Universe is evolving towards complex organization and collective operation from small size and individual addressing. The brain is the most complex object known to us and builds up by self-organization. It is also self-wired and self-integrated, as well as self-connected through the sensory pathways.

The emergence of the brain should come as no surprise. In a sub-critical world everything would be simple and uniform – there would be nothing to learn. In a supercritical world, everything would be changing all the time in a chaotic way – it would be impossible to learn. The brain is necessary for us in order to navigate in a complex, critical world.

The only remaining question: what other and what higher forms of complex matter can there be to evolve or be created? Whatever evolves or is created, will likely have novel features unseen thus far. Supramolecular science operating beyond the realm of molecules is trying to unravel the complexification of matter through self-organization.

Together with the corresponding areas in physics and biology, supramolecular chemistry is leading towards a science of complex matter, of informed, self-organized, evolutive matter. The goal is to progressively discover, understand, and implement the rules that govern its evolution from inanimate to animate and beyond, to ultimately acquire the ability to create new forms of complex matter.