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READ: Complexity and Thresholds

Complexity & Thresholds

By David Christian
What does complexity mean, and why is it so important? What role has complexity played in getting us to the world we live in today?
One of the central themes of this course is the idea of increasing complexity. In the 13.8 billion years since our Universe appeared, more and more complex things seem to have appeared—and we’re among the most complex of them all. So it’s natural for complex things to fascinate us. Besides, modern human society is so complex that learning how the Universe creates complexity can also teach us something about today’s world. But we shouldn’t assume there’s anything special about complexity or that complex things are necessarily any better than simple things. Remember that complexity can present challenges.

What does complexity mean?

That’s a tough question and there’s no universally accepted answer. We may feel intuitively that empty space is much simpler than a star, or that a human being is in some sense more complex than an amoeba. But what does that really mean? Here are some ideas that may help you think about complexity during this course.

A continuum from simple to complex

Complexity is a quality, like “hot” or “cold.” Things can be more or less simple and more or less complex. At one end is utmost simplicity, like the cold emptiness of intergalactic space. At the other extreme is the complexity of a modern city.

The qualities of more complex things

Here are three qualities that make some things more complex than others.
  1. Diverse ingredients: More complex things often have more bits and pieces, and those bits and pieces are more varied.
  2. Precise arrangement: In simpler things it doesn’t matter too much how the ingredients are arranged, but in complex things the bits and pieces are arranged quite precisely. Think of the difference between a car and all the bits and pieces of that car after it’s been scrapped and is lying in a junkyard.
  3. Emergent properties: Once the ingredients are arranged correctly, they can do things that they couldn’t do when they weren’t organized. A car can get you around; its component parts cannot. A car’s capacity to be driven is a quality that “emerges” once it’s been assembled correctly, which is why it’s called an “emergent property.”

Complexity is fragile

There’s another important thing to remember about complexity. Complex things need just the right ingredients and they need to be assembled in just the right way. So, complex things are usually more fragile than simple things. And that means that after a time, they fall apart. If they are living creatures, we say they “die.” Death, or breakdown, seems to be the fate of all complex things, though it may take billions of years for a star to break down, and just a day or two for a mayfly to die.

The Second Law of Thermodynamics

Creating complex things is more difficult than creating simple things. The natural tendency of the Universe seems to be for things to get less and less organized. Think of your own house if you just let it be for a month. Tidying your room means arranging everything in just the right way; it takes work. But if you don’t care how it’s arranged you can just let it un-tidy itself naturally. The idea that the Universe tends naturally to get less ordered and less complex is expressed in one of the most fundamental of all the laws of physics: the Second Law of Thermodynamics. That’s one way of explaining why making complex things requires more work, and thus more energy, than making simple things.

Why complexity is rarer than simplicity

The Second Law of Thermodynamics explains why most of the Universe is simple. Intergalactic space is almost completely empty, extremely cold, and randomly organized. Complexity is concentrated in just a few places: inside galaxies and particularly around stars.

Goldilocks Conditions

You find complex things only where the conditions are just right for making them, where there are just the right environments, just the right ingredients, and just the right energy flows. We call these conditions “Goldilocks Conditions.” Remember the children’s story of the three bears? Goldilocks enters their house when they are out. She tastes their porridge and finds that the father bear’s is too hot, the mother bear’s is too cold, but the baby bear’s is just right. Complexity seems to appear only where the conditions are “just right.” So whenever we see complex things appearing, we can ask why the Goldilocks Conditions were “just right.”
Here’s an example. You always need energy. So if there’s no energy flowing, it’s hard to build complexity. Think of a still, calm lake that’s been dammed. Not much is happening. Then imagine opening the gates of the dam and allowing the water to flow downhill. Now you have energy flowing—enough to drive a turbine that can create the electricity to power a computer. Now more complex things can happen.
But of course there mustn’t be too much energy. If there’s too much water pressure then the turbine will be destroyed. So you need just the right amount of energy—not too little, not too much.

Thresholds of increasing complexity

In this course, we will focus on moments when more complex things seemed to appear, things with new emergent properties. We call these “threshold moments.” Examples include the appearance of the first stars in a Universe that had no stars, and the appearance of the first cities in societies that had never known cities before.
Each time we cross one of these thresholds we’ll ask about the ingredients and the Goldilocks Conditions. And we’ll also ask what was new. What emergent properties do these new complex things have?
There are many such turning points in Big History, but in this course we will focus mainly on eight threshold moments. Some thresholds took place at a very specific point in time, while others were more gradual and we can only approximate the turning point. If this were an astronomy course or a biology course, our choice of thresholds would undoubtedly be different. In fact, during this course we will see many important “turning points” that we could, perhaps, describe as “thresholds.”

For Further Discussion

Think about the your life in terms of thresholds of increasing complexity. What Goldilocks Conditions allowed your thresholds to emerge? What were the emergent properties? Post your answers in the Questions Area below.

Want to join the conversation?

  • leaf red style avatar for user anita.hunt
    I think one of the most important thresholds of complexity in my life came about in my backyard, when I was eight years old, and changed everything for me. It was sunny and warm, and I was alone daydreaming while looking up in the trees. I suddenly became aware that the leaves were more than light green and dark green, the variations on "yellow" green were endless! I realized that any movement of light changed the values of green; I could see how red and blue acted on the local colour. I became aware of the power of observation - it has served me well ever since.
    (9 votes)
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  • aqualine sapling style avatar for user Isaak
    a goldilocks condition for me is when my school only went to sixth grade and there was no other options but home school. at first I was having a hard time but I wanted to stick with It. later on I learned to like it and now love the advantages on it and I'm in a much higher level of school work then I would be if I where still in school. The emergent properties where when I had a chance to achieve more and I wanted to stick with it. That allowed me to go bigger than I originally would have.
    (5 votes)
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  • aqualine ultimate style avatar for user fhxlzk
    Is there another scientific explanation about complexity not using thermodynamics?
    (3 votes)
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    • piceratops ultimate style avatar for user Eugene
      In Mechanical Engineering or design complexity is often measured by the number of parts or 'part count'. For example a car with fewer parts than another would be considered less complex. Another simple example is a log is less complex than a stool with three legs because it is one 'part' and the three legs and a seat or four parts. An individual part is considered less complex if it has fewer features. Features are things like holes, slots, teeth on a gear etc. So a gear with 10 teeth and one hole in the center is less complex than a gear with 20 teeth and one hole in the center.
      (3 votes)
  • piceratops ultimate style avatar for user arsargent
    I love space. I find space fascinating. But how do we know the exact moments when everything started?
    (3 votes)
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  • piceratops ultimate style avatar for user Sebastian Hobbs
    My location was one such Goldilocks Condition; I was placed in an environment wherein I was able to find resources that expanded my body of knowledge and build/improve skills which I would have had trouble honing elsewhere.
    (2 votes)
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  • aqualine sapling style avatar for user Finn
    Cool beans monkey smoothie
    (2 votes)
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  • starky tree style avatar for user tired
    What are diverse ingredients?
    (1 vote)
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    • aqualine tree style avatar for user David Alexander
      Consider, if you will, a pepperoni pizza. The crust is made from a mixture of flour, yeast, water and salt. The sauce is a combination of tomato (vegetable) products and some spices, generally derived from herbs. The cheese is a dairy product, and the pepperoni is meat with spices. Diverse ingredients, but when combined correctly and served hot, very tasty!
      (1 vote)
  • male robot hal style avatar for user Justin Joyce
    While thinking about the "Goldilocks Conditions" in my life that led to a moment in which changed my life or was an event that was significant enough to define a part of my life; the conditions were not what I was expecting. The way the author describes the conditions as "just right" it made me think that these conditions were going to be good things happening in my life when in fact many of the conditions were not pleasant at all but led to a drastic change that defines a lot of who I am and have had great emergent properties. This is not really answering the question, but to me was the big insight I got out of the question.
    (1 vote)
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  • female robot grace style avatar for user Ava Gaughan
    A threshold of increasing complexity was probably when I never had a teacher in 3rd grade, just substitutes, and I realized that it was not a good school for me. Also it was a good thing because I met one of my favorite people in the world, Kelley Jamison, who I love and miss so much( if you are out there reading this Kelley, I miss you and hope to see you soon) .
    (1 vote)
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  • male robot hal style avatar for user ThrownToTheWinds
    In space,can starlight warp it?
    (1 vote)
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