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The history of our world in 18 minutes | David Christian


First, a video. Yes, it is a scrambled egg. But as you look at it, I hope you’ll begin to feel
just slightly uneasy. Because you may notice
that what’s actually happening is that the egg is unscrambling itself. And you’ll now see the yolk
and the white have separated. And now they’re going to be
poured back into the egg. And we all know in our heart of hearts that this is not the way
the universe works. A scrambled egg is mush —
tasty mush — but it’s mush. An egg is a beautiful, sophisticated thing that can create even more
sophisticated things, such as chickens. And we know in our heart of hearts that the universe does not travel
from mush to complexity. In fact, this gut instinct is reflected in one of the most
fundamental laws of physics, the second law of thermodynamics,
or the law of entropy. What that says basically is that the general
tendency of the universe is to move from order and structure to lack of order, lack of structure — in fact, to mush. And that’s why that video
feels a bit strange. And yet, look around us. What we see around us
is staggering complexity. Eric Beinhocker estimates
that in New York City alone, there are some 10 billion SKUs,
or distinct commodities, being traded. That’s hundreds of times
as many species as there are on Earth. And they’re being traded by a species
of almost seven billion individuals, who are linked by trade,
travel, and the Internet into a global system
of stupendous complexity. So here’s a great puzzle: in a universe ruled
by the second law of thermodynamics, how is it possible to generate the sort
of complexity I’ve described, the sort of complexity
represented by you and me and the convention center? Well, the answer seems to be, the universe can create complexity, but with great difficulty. In pockets, there appear
what my colleague, Fred Spier, calls “Goldilocks conditions” — not too hot, not too cold, just right for the creation of complexity. And slightly more complex things appear. And where you have
slightly more complex things, you can get slightly more complex things. And in this way, complexity
builds stage by stage. Each stage is magical because it creates the impression
of something utterly new appearing almost out of nowhere
in the universe. We refer in big history to these moments
as threshold moments. And at each threshold,
the going gets tougher. The complex things get more fragile, more vulnerable; the Goldilocks conditions
get more stringent, and it’s more difficult
to create complexity. Now, we, as extremely complex creatures, desperately need to know this story of how the universe creates complexity
despite the second law, and why complexity means
vulnerability and fragility. And that’s the story
that we tell in big history. But to do it, you have do something that may, at first sight,
seem completely impossible. You have to survey the whole
history of the universe. So let’s do it. (Laughter) Let’s begin by winding the timeline back 13.7 billion years, to the beginning of time. Around us, there’s nothing. There’s not even time or space. Imagine the darkest,
emptiest thing you can and cube it a gazillion times
and that’s where we are. And then suddenly, bang! A universe appears, an entire universe. And we’ve crossed our first threshold. The universe is tiny;
it’s smaller than an atom. It’s incredibly hot. It contains everything
that’s in today’s universe, so you can imagine, it’s busting. And it’s expanding at incredible speed. And at first, it’s just a blur, but very quickly distinct things
begin to appear in that blur. Within the first second, energy itself shatters
into distinct forces including electromagnetism and gravity. And energy does something
else quite magical: it congeals to form matter — quarks that will create protons and leptons that include electrons. And all of that happens
in the first second. Now we move forward 380,000 years. That’s twice as long as humans
have been on this planet. And now simple atoms appear
of hydrogen and helium. Now I want to pause for a moment, 380,000 years after the origins
of the universe, because we actually know quite a lot
about the universe at this stage. We know above all
that it was extremely simple. It consisted of huge clouds
of hydrogen and helium atoms, and they have no structure. They’re really a sort of cosmic mush. But that’s not completely true. Recent studies by satellites such as the WMAP satellite have shown that, in fact, there are just tiny differences
in that background. What you see here, the blue areas are about a thousandth
of a degree cooler than the red areas. These are tiny differences, but it was enough
for the universe to move on to the next stage of building complexity. And this is how it works. Gravity is more powerful
where there’s more stuff. So where you get slightly denser areas, gravity starts compacting clouds
of hydrogen and helium atoms. So we can imagine the early universe
breaking up into a billion clouds. And each cloud is compacted, gravity gets more powerful
as density increases, the temperature begins to rise
at the center of each cloud, and then, at the center, the temperature crosses
the threshold temperature of 10 million degrees, protons start to fuse, there’s a huge release of energy, and — bam! We have our first stars. From about 200 million years
after the Big Bang, stars begin to appear
all through the universe, billions of them. And the universe is now
significantly more interesting and more complex. Stars will create
the Goldilocks conditions for crossing two new thresholds. When very large stars die, they create temperatures so high that protons begin to fuse
in all sorts of exotic combinations, to form all the elements
of the periodic table. If, like me, you’re wearing a gold ring, it was forged in a supernova explosion. So now the universe
is chemically more complex. And in a chemically more complex universe, it’s possible to make more things. And what starts happening
is that, around young suns, young stars, all these elements combine,
they swirl around, the energy of the star stirs them around, they form particles, they form snowflakes,
they form little dust motes, they form rocks, they form asteroids, and eventually,
they form planets and moons. And that is how our
solar system was formed, four and a half billion years ago. Rocky planets like our Earth
are significantly more complex than stars because they contain
a much greater diversity of materials. So we’ve crossed a fourth
threshold of complexity. Now, the going gets tougher. The next stage introduces entities
that are significantly more fragile, significantly more vulnerable, but they’re also much more creative and much more capable
of generating further complexity. I’m talking, of course,
about living organisms. Living organisms are created by chemistry. We are huge packages of chemicals. So, chemistry is dominated
by the electromagnetic force. That operates over smaller
scales than gravity, which explains why you and I
are smaller than stars or planets. Now, what are the ideal
conditions for chemistry? What are the Goldilocks conditions? Well, first, you need energy, but not too much. In the center of a star,
there’s so much energy that any atoms that combine
will just get busted apart again. But not too little. In intergalactic space, there’s so little energy
that atoms can’t combine. What you want is just the right amount, and planets, it turns out, are just right, because they’re close to stars,
but not too close. You also need a great diversity
of chemical elements, and you need liquids, such as water. Why? Well, in gases, atoms move
past each other so fast that they can’t hitch up. In solids, atoms are stuck together, they can’t move. In liquids, they can cruise and cuddle and link up to form molecules. Now, where do you find
such Goldilocks conditions? Well, planets are great, and our early Earth was almost perfect. It was just the right
distance from its star to contain huge oceans of liquid water. And deep beneath those oceans, at cracks in the Earth’s crust, you’ve got heat seeping up
from inside the Earth, and you’ve got a great
diversity of elements. So at those deep oceanic vents, fantastic chemistry began to happen, and atoms combined in all sorts
of exotic combinations. But of course, life is more
than just exotic chemistry. How do you stabilize those huge molecules that seem to be viable? Well, it’s here that life introduces
an entirely new trick. You don’t stabilize the individual; you stabilize the template, the thing that carries information, and you allow the template to copy itself. And DNA, of course,
is the beautiful molecule that contains that information. You’ll be familiar
with the double helix of DNA. Each rung contains information. So, DNA contains information
about how to make living organisms. And DNA also copies itself. So, it copies itself and scatters the templates
through the ocean. So the information spreads. Notice that information
has become part of our story. The real beauty of DNA though
is in its imperfections. As it copies itself,
once in every billion rungs, there tends to be an error. And what that means
is that DNA is, in effect, learning. It’s accumulating new ways
of making living organisms because some of those errors work. So DNA’s learning and it’s building greater
diversity and greater complexity. And we can see this happening
over the last four billion years. For most of that time of life on Earth, living organisms have been
relatively simple — single cells. But they had great diversity,
and, inside, great complexity. Then from about 600
to 800 million years ago, multi-celled organisms appear. You get fungi, you get fish, you get plants, you get amphibia, you get reptiles, and then, of course,
you get the dinosaurs. And occasionally, there are disasters. Sixty-five million years ago, an asteroid landed on Earth near the Yucatan Peninsula, creating conditions equivalent
to those of a nuclear war, and the dinosaurs were wiped out. Terrible news for the dinosaurs, but great news
for our mammalian ancestors, who flourished in the niches left empty by the dinosaurs. And we human beings are part
of that creative evolutionary pulse that began 65 million years ago with the landing of an asteroid. Humans appeared about 200,000 years ago. And I believe we count
as a threshold in this great story. Let me explain why. We’ve seen that DNA learns in a sense, it accumulates information. But it is so slow. DNA accumulates information
through random errors, some of which just happen to work. But DNA had actually generated
a faster way of learning: it had produced organisms with brains, and those organisms
can learn in real time. They accumulate information, they learn. The sad thing is, when they die, the information dies with them. Now what makes humans different
is human language. We are blessed with a language,
a system of communication, so powerful and so precise that we can share what we’ve learned
with such precision that it can accumulate
in the collective memory. And that means it can outlast the individuals
who learned that information, and it can accumulate
from generation to generation. And that’s why, as a species,
we’re so creative and so powerful, and that’s why we have a history. We seem to be the only species
in four billion years to have this gift. I call this ability collective learning. It’s what makes us different. We can see it at work
in the earliest stages of human history. We evolved as a species
in the savanna lands of Africa, but then you see humans migrating
into new environments, into desert lands, into jungles, into the Ice Age tundra of Siberia — tough, tough environment — into the Americas, into Australasia. Each migration involved learning — learning new ways of exploiting
the environment, new ways of dealing
with their surroundings. Then 10,000 years ago, exploiting a sudden
change in global climate with the end of the last ice age, humans learned to farm. Farming was an energy bonanza. And exploiting that energy,
human populations multiplied. Human societies got larger,
denser, more interconnected. And then from about 500 years ago, humans began to link up globally through shipping, through trains, through telegraph, through the Internet, until now we seem to form
a single global brain of almost seven billion individuals. And that brain is learning at warp speed. And in the last 200 years,
something else has happened. We’ve stumbled on another energy bonanza in fossil fuels. So fossil fuels and collective
learning together explain the staggering complexity
we see around us. So — Here we are, back at the convention center. We’ve been on a journey,
a return journey, of 13.7 billion years. I hope you agree this is a powerful story. And it’s a story in which humans
play an astonishing and creative role. But it also contains warnings. Collective learning is a very,
very powerful force, and it’s not clear
that we humans are in charge of it. I remember very vividly
as a child growing up in England, living through the Cuban Missile Crisis. For a few days, the entire biosphere seemed to be on the verge of destruction. And the same weapons are still here, and they are still armed. If we avoid that trap,
others are waiting for us. We’re burning fossil fuels at such a rate that we seem to be undermining
the Goldilocks conditions that made it possible
for human civilizations to flourish over the last 10,000 years. So what big history can do is show us the nature
of our complexity and fragility and the dangers that face us, but it can also show us
our power with collective learning. And now, finally — this is what I want. I want my grandson, Daniel, and his friends and his generation, throughout the world, to know the story of big history, and to know it so well that they understand
both the challenges that face us and the opportunities that face us. And that’s why a group of us are building a free, online syllabus in big history for high-school students
throughout the world. We believe that big history will be a vital
intellectual tool for them, as Daniel and his generation face the huge challenges and also the huge opportunities ahead of them at this threshold moment in the history of our beautiful planet. I thank you for your attention. (Applause)

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