COMPLEXITY EXPLAINED: 1. What is Complexity?

(Note: This is the first part in the series on Complexity. Please read Part 2 and Part 3)

Humans wonder about the origin of life on the Earth. For most of us it is difficult to imagine how life can arise out of no-life, so we tend to think in terms of a Creator who created not only life, but also everything else. This is not a satisfactory answer for a rationalist. It so happens that a satisfactory answer can indeed be found within the ambit of the scientific method of posing and answering questions. The problem is that since most people have not been brought up in an atmosphere of free enquiry, certain scientific truths become hard to accept. This is particularly true about the irrelevance of the God concept. Another problem is that some scientific ideas are difficult to understand and explain, and may sometimes require a lifetime of training and practice. One solution to this problem is that scientists should do their best to reach out to the public at large, and explain science to them in a simple language. Carl Sagan, Richard Dawkins, and Jayant Narlikar are some notable examples of eminent scientists who have been doing that.

The science of complexity is a relatively new branch of science, in the sense that research work in it has exploded during the last couple of decades complex_network_managementonly. The fascinating thing about it is that it aims at explaining some of the most difficult questions covering just about all branches of science, and much else. Complexity studies have strategic importance also. As Stephen Hawking said, the present century will be the century of complexity. Heinz Pagels was more specific:

“I am convinced that the nations and people who master the new sciences of complexity will become the economic, cultural, and political superpowers of the next century (meaning the present century).”

Through a series of articles on this website, I shall try to explain complexity in a somewhat nontechnical language. In this opening article, I answer the question: What is complexity? As we shall see in due course, the origin of life, and of much else, has a rational and natural (rather than supernatural) answer in terms of the evolution of complexity in Nature. Even consciousness can be regarded as a manifestation of the ever-increasing degree of complexity in the universe.

A complex system usually consists of a large number of simple members, elements or agents, which interact with one another and with the environment, and which have the potential to generate qualitatively NEW collective behaviour, the manifestations of this behaviour being the spontaneous creation of new spatial, temporal, or functional structures. A complex system is an ‘open’ system involving ‘nonlinear interactions’ among its subunits which can exhibit, under certain conditions, a marked degree of coherent or ordered behaviour extending well beyond the scale or range of the individual subunits.

The word ‘open’ has been used above in the thermodynamic sense. It means that the system can exchange energy (e.g. heat) and matter with the surroundings. By contrast, an ‘isolated’ thermodynamic system is one which cannot exchange energy or matter with the surroundings.

And the term ‘nonlinear interactions’ in the above definition of a complex system means that the proportionality factor determining the output Y of the system for a given input X is not a constant; i.e. it is not independent of the input (Y = A(X) X). This nonlinearity has far-reaching consequences for the time-evolution of the system. In particular, its future progression of events may become very sensitive to conditions at any given point of time. ‘Chaotic systems’ are striking examples of this.

Here are some example of complex systems: whirlpools; beehives; ant colonies; investors in a stock market; the set of neurons comprising the brain of a mammal; a biological cell; the economy of a nation; the world economy; a social network; human culture; our ecosphere; and so on. A characteristic feature of complex systems is the emergence of UNEXPECTED properties or behaviour (this will be explained later). The emergence of life out of no-life is one such unexpected property.


Our interest in the sciences of complexity arises from the fact that we want satisfactory answers to questions like the following:

Why is there something rather than nothing?

Why has structure evolved in the universe; e.g. galaxies, stars, planets, bacteria, plants, animals, brains?

How did the first living cell arise?

Why and how did individual cells form alliances into more complex living forms?

Can Darwinian selection alone account for the emergence of such intricate organs as the eye?

What is life?

What is mind?

How does the brain give rise to feelings, thought, purpose, consciousness?

Why are we not able to make long-term predictions about the behaviour of stock markets?

Why are we not able to predict weather on a long-term basis?

Why do civilizations collapse?

Why have certain ancient species remained stable for long periods and then disappeared?

How do social organizations arise?

And so on.

All these questions are about complex systems. Although good progress has been made during the last couple of decades, we still have a long way to go before we can claim to have understood complexity to a decent level. Nevertheless, the study of complex systems helps make connections, and draw parallels, among widely different subjects of enquiry like physics, biology, behavioural sciences, arts, and humanities. There is a common thread running through all types of complex systems: In a living system, a huge number of molecules organize themselves into an entity that moves, that responds to stimuli, and that reproduces. In a brain, a network of billions of neurons self-organizes to give rise to a sense of identity to the living being. Even in inanimate matter, simple particles governed by the simple laws of physics organize themselves unexpectedly into galaxies, stars, complexcrystals, snowflakes, and hurricanes. The marketplace involves a large number of people. Here also the principle of increasing returns, or positive feedback, gives rise to wild and unpredictable fluctuations, in violation of the classical economic theory of equilibrium or negative feedback (which ensures a balance between demand and supply) championed by Adam Smith.

We humans and our interactions with one another, and with our biosphere, are among the most complex imaginable systems. What is our future going to be like? Although we cannot make definite predictions, even probabilistic statements about the more likely scenarios can have a salutary effect on how we conduct our affairs (e.g. regarding the management of global warming) to achieve high levels of sustainability.

Notions like individuality, intelligence, consciousness etc. are perhaps the ultimate outgrowths of the relentless evolution of complexity in Nature. Progress in understanding complexity will hopefully help us in understanding ourselves better.

I hope I have given you a feel for what complexity is all about. The next question is: Can we quantify complexity? Yes we can, in terms of the ‘DEGREE OF COMPLEXITY’ of a system, provided we are clear about what type of complexity we are taking about. Part 2 of this series of articles will address that question.

I conclude this introduction to complexity with a beautiful quotation:

“The flower invites the butterfly with no-mind,

The butterfly visits the flower with no-mind.

The flower opens, the butterfly comes;

The butterfly comes, the flower opens.

I don’t know others,

Others don’t know me.

By not knowing we follow nature’s course.”

— Ryokan

(Note: This is the first part in the series on Complexity. Please read Part 2 and Part 3)

About the author

Vinod Wadhawan

Dr. Vinod Wadhawan is a scientist, rationalist, author, and blogger. He has written books on ferroic materials, smart structures, complexity science, and symmetry. More information about him is available at his website. Since October 2011 he has been writing at The Vinod Wadhawan Blog, which celebrates the spirit of science and the scientific method.


  • Dr. Wadhawan,

    I thoroughly enjoyed your article. Thank you for helping me in understanding reality as the progression of complexity. I am no physicist and your method of simple description is very helpful for me in understanding the subject. I certainly went from having no idea what complexity meant or what it’s implications were, to being informed on it’s criteria (A new collective interaction in an open and non-linear system). I recall learning that all biological systems are ‘open’, thermodynamically speaking. As for the ‘non-linear’ part, I can see how a system of complex interactions could produce a disproportionate output to different magnitudes of a particular input. It makes sense especially in biological systems where threshold levels and feedback mechanisms are built into the biochemical control of the organisms involved in the system.

    You have stated “Notions like individuality, intelligence, consciousness etc. are perhaps the ultimate outgrowths of the relentless evolution of complexity in Nature”, and in your profile you profess that “consciousness is probably the ultimate manifestation of the evolution of complexity in the cosmos”. This is what fascinates me the most. I can tell that you have only scratched the surface of this perspective of reality, in this article. I look forward to the next articles in the series!

    • I shall discuss ‘Consciousness and Complexity’ in the concluding part of this set of articles. Since I am trying to talk in a non-technical language, I have to introduce many concepts on my way to explaining the origins of life, and the evolution of consciousness. Of course, I am not saying anything original. It is all there in the literature.

  • Dr. Wadhawan,

    Thanks a bunch, for the wonderful introduction to complexity. I am eagerly looking forward to the next article in this series.
    When we talk about complexity, don’t we have to take the nature of human mind into account ? I mean, any thing looks complex until we understand it, and then it becomes simple. OR, the word complexity as used in scientific literature has a different meaning than our intuitive notion of complexity ?

  • Thanks for making people in general / common like us, understand the scientific features, the many of which, do we common people not understand

  • I would like to make two points with regard to your discussion.
    1. It seems to me that existance of God does not explain creation as it only moves the problem one step further. Bacause if god exists, it must be more complex than what he created. Then the question is who created God. By assumption of God we are only shifting the question from who created universe to who created God.
    2. While scientific arguments as given by you may make it possible to understand that God need not exist to explain things, these do not prove that God does not exists.

    • 1. I agree with you completely. A scientist can at best make the statement that PROBABLY THERE IS NO GOD.

      2. As you also said, the God hypothesis is not a a useful hypothesis. Therefore we should not spend too much time or effort chasing this hypothesis.

      3. The question of the relative degree of complexity of the universe and of the ‘God’ who MIGHT have created the universe is more complicated than what appears at first sight. I hope to discuss it in one of the future articles in this series.

  • On The Making of complexity In Nature
    Plain Pointed Science Writing Does’nt Evoke Respect?

    More On
    Plain Pointed Science Writing Does’nt Evoke Respect?
    On Living Systems, Energy Flux And Cosmic Evolution

    A. From Eric J. Chaisson’s
    “Cosmic Evolution: The Rise of Complexity in Nature”

    “living systems evolved in the past within environments rich in energy flux, and thus have inherited the means to acquire the needed energy flow via metabolic processes. The pathways open to biological evolution are constrained, not because few solutions exist but because energy resources are limited; natural selection exploits energy flows, determining which flows are conducive to the system, thereby apparently optimizing them.” (p. 180)

    B. Why gibber, why not write plainly and to the point

    IMO the outstanding common feature of Chaisson’s, and probably of some other books about life and cosmic evolutions, as well as of many reviews and comments about them, is gibberish in various degrees of pseudoscience and pseudosophistication.

    Points that are clear in the mind should be stated plainly and concisely. If they’re clear. Or, are science readers conditioned to trust, respect and prefer gibbering and suspect plainly to the point writing?

    C. On the making of complexity in nature

    Again: All cosmic and life evolutions, of all formats of mass including life, are initiated and proceed AND ACCUMULATE, pile up on top of each other, in answer to one question. This question is the uniform rung of the ladder that serves to develop natural complexity, evolution. The question is: does this one of the next possible alternative expressions, mass modifications, enhance the constrained energy of the mass format, i.e. does it extend the temporal survival of the mass format, does it postpone its constituent energy becoming part of the energy that fuels the ongoing cosmic expansion.

    All evolutionary complexities, of all degrees of complexity, evolve and develop in response to this question and in anticipation, again and again, of this one same question.

    Dov Henis
    (Comments From The 22nd Century)

    Cosmic Evolution Simplified

    Earlier it was impossible for us to give any satisfactory answer to this question. But modern science, rather we should say that Einstein, has made it an easy task for us. And Stephen Hawking has provided us with the clue necessary for solving this riddle. Actually scientists in their infinite wisdom have already kept the ground well-prepared for us believers so that one day we can give a most plausible and logically consistent answer to this age-old question. Let me first quote from the book “A Brief History of Time” by Stephen Hawking:
    “The idea of inflation could also explain why there is so much matter in the universe. There is something like ten million million million million million million million million million million million million million million (1 with eighty zeroes after it) particles in the region of the universe that we can observe. Where did they all come from? The answer is that, in quantum theory, particles can be created out of energy in the form of particle/antiparticle pairs. But that just raises the question of where the energy came from. The answer is that the total energy of the universe is exactly zero.”
    Here the question stops. So the clue is this: if we can ultimately arrive at zero, then no further question will be raised, and there will be no infinite regression. What I intend to do here is something similar to that. I want to show that our God is a bunch of several zeroes, and that therefore no further question need be raised about His origin. And here comes Einstein with his special theory of relativity for giving us the necessary empirical support for our project.
    God is a Being. Therefore God will have existence as well as essence. So I will have to show that both from the point of view of existence as well as from the point of view of essence God is zero. It is almost a common parlance that God is spaceless, timeless, changeless, immortal, and all-pervading. Here we are getting three zeroes; space is zero, time is zero, change is zero. But how to prove that if there is a God, then that God will be spaceless, timeless, and changeless? From special theory of relativity we come to know that for light both distance and time become unreal. For light even an infinite distance is infinitely contracted to zero. The volume of an infinite universe full of light only will be simply zero due to this property of light. A universe with zero volume is a spaceless universe. Again at the speed of light time totally stops. So a universe full of light only is a spaceless, timeless universe. But these are the properties of light only! How do we come to know that God is also having the same properties of light so that God can also be spaceless, timeless? Scientists have shown that if there is a God, then that God can only be light, and nothing else, and that therefore He will have all the properties of light. Here is the proof.
    Scientists have shown that total energy of the universe is always zero. If total energy is zero, then total mass will also be zero due to energy-mass equivalence. Now if there is a God, then scientists have calculated the total energy and mass of the universe by taking into consideration that there is also a God. In other words, if there is a God, then this total energy-mass calculation by the scientists is God-inclusive, not God-exclusive. This is due to two reasons. First of all, even if there is a God, they do not know that there is a God. Secondly, they do not admit that there is a God. So, if there is a God, then they have not been able to keep that God aside before making this calculation, because they do not know that there is a God. They cannot say that they have kept Him aside and then made this calculation, because by saying that they will admit that there is a God. At most they can say that there is no God. But we are not going to accept that statement as the final verdict on God-issue, because we are disputing that statement. So the matter of the fact is this: if God is really there, then scientists have shown that both the total mass and energy of the universe including God are zero. Therefore mass and energy of God will also be zero. God is without any mass, without any energy. And Einstein has already shown that anything having zero rest-mass will have the speed of light. In other words, it will be light. So, if God is there, then God is also light, and therefore He is spaceless, timeless. So from the point of view of existence God is zero, because he is spaceless, timeless, without any mass, without any energy.
    Now we will have to show that from the point of view of essence also God is zero. If there is only one being in the universe, and if there is no second being other than that being, then that being cannot have any such property as love, hate, cruelty, compassion, benevolence, etc. Let us say that God is cruel. Now to whom can He be cruel if there is no other being other than God Himself? So, if God is cruel, then is He cruel to Himself? Therefore if we say that God is all-loving, merciful, benevolent, etc., then we are also admitting that God is not alone, that there is another being co-eternal with God to whom He can show His love, benevolence, goodness, mercy, compassion, etc. If we say that God is all-loving, then we are also saying that this “all” is co-eternal with God. Thus we are admitting that God has not created the universe at all, and that therefore we need not have to revere Him, for the simple reason that He is not our creator!
    It is usually said that God is good. But Bertrand Russell has shown that God cannot be good for the simple reason that if God is good, then there is a standard of goodness which is independent of God’s will. Therefore, if God is the ultimate Being, then that God cannot be good. But neither can He be evil. God is beyond good and evil. Like Hindu’s Brahma, a real God can only be nirguna, nirupadhik; without any name, without any quality. From the point of view of essence also, a real God is a zero.
    So, why should there be any need for creation here, if God is existentially, as well as essentially, zero?
    But if there is someone who is intelligent and clever enough, then he will not stop arguing here. He will point out to another infinite regression. If God is light, then He will no doubt be spaceless, timeless, etc. Therefore one infinite regression is thus arrested. But what about the second regression? How, and from whom, does light get its own peculiar properties by means of which we have successfully arrested the first regression? So, here is another infinite regression. But we need not have to worry much about this regression, because this problem has already been solved. A whole thing, by virtue of its being the whole thing, will have all the properties of spacelessness, timelessness, changelessness, deathlessness. It need not have to depend on any other external source for getting these properties. Thus no further infinite regression will be there.
    H. S. Pal

  • Doctor:
    It seems to me that you confuse describing something with explaining why it should occur. Why does complexity exist as a factor in our reality structure? You have identified a process, but why does that process exist? How can a scientific theory ever adjudicate what ultimately must be a philosophical question?

  • The Difference Between The Universe And Earthlife Cyclic Evolutions
    April 18, 2015
    A. The Universe And Earthlife Cyclic Evolutions : Whence, whither and how nature drives life/humanity מאין ,לאן ואיך מוביל הטבע את החיים/האנושותGravity is the monotheism of the universe
    (Hebrew and English)
    September 15, 2014
    Whence, whither and how nature drives life/humanity
    מאין ,לאן ואיך מוביל הטבע את החיים/האנושות
    Again, The Universe/ Life Relationship, embarrassingly obvious/simple elucidation…

    B. The Difference Between The Universe And Earthlife Re-Cyclic Evolutions
    April 18, 2015
    Earthlife re-cyclic evolutions are innately evolutionary genome-based memory-continuums, whereas the universe re-cyclic evolutions (approx each 20 billion, 20X10^9,years ) are each fresh, completely devoid of earlier memory via singularity, dual- poles mass-energy systems.
    Dov Henis (comments from 22nd century, one of the many humans with highly exaggerated self-esteem)
    Earth Life Genesis
    Seed Of Human-Chimp Genomes Diversity
    Genetics is modifications of genome’s expressions in response to cultural variations, i.e. to behavioral modifications in response to circumstantial variations. DH
    ומערך הכסף והבנקאות הם התחכמות האדם לדרישת הטבע להצטיד באנרגיה ולהשתמש בה להישרדות… דה
    Beyond historical concepts natural selection is E (energy) temporarily constrained in an m (mass) format. Period.
    Money/banking system is the system-based human circumvention of nature’s drive of the ruthless natural selection melee… DH

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