Why does complexity increase?

Entropy: lacking order; a state of disorder

When our Universe first emerged in the Big Bang, it was extremely simple. There was a lot of energy, but not many things. No atoms, no stars, and certainly no human beings. Then, during the 13.8 billion years since the Big Bang, new, more-complex and more-interesting things began to pop up, from stars to planets, from living organisms to humans. And that’s really the main story that is told in Big History.

Looking back, the appearance of new and more-complex things seems magical. This is particularly true because of what physicists call the second law of thermodynamics. This law—one of the most important in all of physics—tells us that most changes in our Universe are likely to create less order and complexity, not more. The force of entropy tends to break things down, to make them simpler.

In other words, according to the laws of physics, the Universe should be getting less and less complex. And yet, over the last 13.8 billion years, it has gotten more complex. Why? Because just the right conditions combined with just the right ingredients at just the right time. Big History traces the story of the Universe by looking for these moments when complexity increased.

The Big History course focuses on eight of these transitions. We call them thresholds because crossing them is a bit like stepping through a door into a place whose existence you had never even imagined until you got there. We could have looked at many more thresholds, but the eight we study in Big History are some of the most important and interesting. At least that’s true if, like you and me, you happen to be a human being, living on planet Earth. Big History helps us understand our place in a vast Universe and a long history.

It is a story about us.

What’s next?

Studying thresholds of increasing complexity raises a big question, one I suspect most of you have already thought about: What is the next threshold?

Of course, we don’t know the answer for certain, because that threshold lies in the future, and we cannot know with certainty what is in the future. But we get lots of hints about likely futures from studying the past. And in this article, I want to describe what I think could be the next threshold. Not everyone will agree with me, and you might have your own ideas about what the ninth threshold will look like. But here’s what I think is most likely:

I think that something new is emerging here on Earth, right now, before our eyes. That new thing is a conscious planet.

The conscious Earth

Conscious: being aware of your surroundings; making deliberate decisions

Planet Earth is becoming conscious. It is becoming conscious in the way that humans are conscious. Most of the things that go on in our body happen without any conscious thought. They are the result of billions of unconscious biological or chemical or psychological processes. But some of the big and important decisions we make are the result of conscious thought. Lift your arm—that’s a conscious decision—but you don’t actually think about all the millions of cells that must be activated to lift your arm, though you did make the big decision to lift your arm—perhaps so you could eat a sandwich—or read this article.

Our home planet, Earth, is becoming conscious in a similar way. Most of the changes on Earth are the result of ancient geological, chemical, and physical processes that have shaped the Earth’s history for billions of years. They’re not the result of conscious planning. The tides will keep coming in and out; mountains will slowly rise and erode away; and the Earth will keep spinning. This is how things have worked since our Earth was created, more than 4.5 billion years ago.

But now, suddenly, things are changing.

Many humans, one Earth

Suddenly, some of the biggest changes that will shape the future of planet Earth are happening because of conscious decisions taken by billions of humans. We have become a new force shaping the evolution of an entire planet. It is as if a vast new super-organism has emerged, one made up of billions of human beings, just as your body consists of trillions of individual cells working together. That’s what I mean when I talk about a “conscious Earth.”

This super-organism is beginning to make conscious decisions that will shape the future of planet Earth. Will we keep pumping greenhouse gases into the atmosphere, even if this might make the climate unbearably hot for future generations? Or should we reverse course and build a better future for our descendants?

Humans are changing many things on Earth. New types of matter have appeared, such as plastics and stainless steel. We have created nuclear weapons, weapons so dangerous that they could destroy much of the surface of the Earth if launched in large numbers. And the burning of fossil fuels on a massive scale is beginning to transform the Earth’s climate in dangerous ways.

The most powerful species

How has one species suddenly got so much power over an entire planet? How have we become the most powerful species to have evolved in the 4 billion years since life first appeared on Earth?

We have these remarkable powers because we are the first species in the planet’s history capable of learning collectively, of sharing and accumulating huge amounts of information about the world. That sharing explains why, over perhaps 200,000 years, human knowledge of the world has grown until today we have so much knowledge we can transform an entire planet.

But there’s a catch. As we humans acquired more knowledge and became more powerful, we didn’t always understand the consequences of our decisions. Our conscious decisions didn’t always turn out the way we had intended. And sometimes we used our knowledge to harm each other. Was inventing atomic bombs really such a good idea?

Will we be able to correct the mistakes of our past and build a better future for our descendants?

Our choices

There are no guarantees. But collective learning gives us two great advantages. First, it means we’re great learners. So we ought to be able to figure out what needs to be done to avoid disaster. Second, to share knowledge you have to collaborate. And today, despite the many conflicts in the world, we’re also learning how to share knowledge and collaborate more and more across the entire planet. The internet even allows us to talk with friends on the other side of the world as if we were talking with our next-door neighbors! That’s remarkable. Finally, we’re an extremely social species, with a very good track record for working together on common goals.

That’s why, here on Earth, we can see the ingredients and Goldilocks Conditions for a new threshold. The ingredients include a planet with such vibrant life forms that one of them has acquired enough power to consciously change how our planet evolves. And the Goldilocks Conditions are that members of that species have the means to work together on planetary scales, to pool their knowledge and manage the planet for the good—or ill—of future generations.

So, the big question is this: Will we humans be able to collaborate sufficiently and use our powers with enough wisdom to build a good future for Earth? Will the emergence of a conscious planet turn out to be good news for us humans and for many of the other species with which we share this planet?

We have no certainty. But personally, I believe Threshold 9 will turn out well for our children and their children.

And one final question: Are there other conscious planets? Or is this the first time this threshold has been crossed? We have no direct evidence for the existence of other conscious planets, but we now know that planets like our Earth are very common. So perhaps some of them have also become conscious, in the same way that our Earth is becoming conscious. But if there are no other conscious planets, then that makes what is happening right now on planet Earth a matter of cosmological significance.

We are living in very interesting times!