Origin Story: A Big History of Everything

by David Christian

What makes humans different from all other brainy species is language, a communication tool that is extraordinarily powerful because it allows us to share our individual world maps and, in so doing, form maps much larger and more detailed than those created by an individual brain.

At the earliest moment for which we have some evidence, a split second after the big bang, the universe consisted of pure, random, undifferentiated, shapeless energy. We can think of energy as the potential for something to happen, the capacity to do things or change things.

Some structures or patterns will last for billions of years, some for a split second, but none are conserved. They are evanescent, like waves on the ocean’s surface. The first law of thermodynamics tells us that the ocean of energy is always there; it’s conserved. The second law of thermodynamics tells us that all the forms that emerge will eventually dissolve back into the ocean of energy. The forms, like the movements of a dance, are not conserved.

The laws of physics filtered out those states of the universe that were not compatible with them, so at any given moment, the universe existed in only one of the many states that were compatible with the universe’s operating rules. These new states, in turn, generated more rules that steered change down new pathways.

It seemed that the dark lines were the result of light from the sun’s core being absorbed by atoms of different elements in the sun’s cooler outer regions. This reduced the energy at those frequencies, leaving dark lines on the emission spectrum. We call these dark lines absorption lines, and different elements generate different patterns of absorption lines.

Fortunately, in the early twentieth century, Henrietta Leavitt, a Harvard Observatory astronomer, found a way to measure the distance to remote stars and nebulae using a particular type of star known as a Cepheid variable, a star whose brightness varies with great regularity (the polestar is a Cepheid). She found a simple correlation between the frequency of the variations and the star’s luminosity, or brightness, so she could calculate a Cepheid’s absolute brightness.

Then, by comparing that with the apparent brightness the star had when seen from Earth, she could calculate how far away it was, because the amount of light from a star diminishes by the square of the distance through which it travels.

Most astronomers were shocked by the idea of an expanding universe and assumed there was an error in Hubble’s calculations. Hubble himself was not at all sure about it, and Einstein was so convinced the universe was stable that he fiddled with the equations of general relativity so they would predict a stable universe, by adding what he called a cosmological constant.

Thermodynamic theory distinguishes between energy flows that are completely random and energy flows that have direction, structure, and coherence so they can do work. Structured flows of energy are known as free energy, and unstructured flows are known as heat energy. The difference is not absolute.

The first law of thermodynamics tells us that the total amount of energy in the universe never changes. It is conserved. Our universe seems to have arrived with a fixed potential for things to happen. So the first law is really telling us about the primordial ocean of possibilities. The second law of thermodynamics tells us that the things that emerge from the ocean of possibilities can be more or less structured, like the ripples in a stream. But we should expect most of them to be less structured and become even less structured over time. That is because most possible arrangements of matter and energy have little or no structure, and if by chance you do find structure, expect it to decay fast.

But unlike energy in general, free energy is not conserved. It’s unstable, like an uncoiling spring. As it does work, it loses both its structure and the ability to do more work. When the water from a waterfall smashes into rocks at the bottom, it turns into the scattered, incoherent energy of heat. Every molecule jiggles around more or less independently. The energy is still there; it’s still conserved (that’s the first law). But the molecules push in so many directions that their energy can no longer drive a turbine. Free energy has turned into heat energy.

The second law of thermodynamics tells us that, in the very long run, all free energy will turn into heat energy.

Heat energy, like a drunken traffic cop, directs energy every which way and creates chaos. Free energy, like a sober traffic cop, directs energy ...

Gravity had kick-started the transformation of matter into stars by fusing protons despite the barrier created by their positive charges. This is a pattern we will see over and over again. It’s a bit like the cup of coffee that helps you get going in the morning. Chemists refer to this initial shot of energy as activation energy; it’s the energy of a lit match that starts a conflagration. One kind of energy changes something so as to release other flows of free energy that are much greater than the activation energy. In the story of star formation, gravity provided the activation energy for fusion and star formation and for all that followed.

Some white dwarfs die more spectacularly in vast supernova explosions if they get sucked into nearby stars. These explosions are so hot that they can create many of the elements in the periodic table. The spectacular death-by-explosions of white dwarfs generates what are known as type 1a supernovas. These all blow up at about the same temperature, so if you see one, you know how bright it is, and that means you can estimate its true distance. Type 1a supernovas allow astronomers to estimate distances hundreds of times farther away than Cepheid variables.

Stars more than about seven times the mass of our sun will also end their lives spectacularly in another type of explosion, known as a core-collapse supernova. When the core has formed a ball of iron larger than our sun, the central furnace will shut down for the last time. Gravity will smash the core together in a fraction of a second and with extreme violence, creating energies and temperatures higher than ever before in the star’s lifetime.

Most supergiants, having blasted away their outer layers in supernovas, will contract so violently that protons and electrons are squashed together to form neutrons. Now the entire massive blob is crushed into a neutron star, an object made of neutrons packed together as closely as the particles in an atomic nucleus. This is a very unusual and extremely dense form of matter, as most atoms consist mainly of empty space. A neutron star just twenty kilometers across would weigh twice as much as our sun, and a teaspoon of neutron-star stuff would weigh a billion tons.

Electrons are the key players. Like human lovers, electrons are unpredictable, fickle, and always open to better offers. They buzz around protons in distinct orbits, each associated with a different energy level. Wherever possible, electrons head for the orbits closest to an atom’s nucleus, which require the least energy. But the number of spaces in each orbit is limited, and if no places are left in the inner orbits, they have to settle for places in an outer orbit. If that orbit has just the right number of electrons, everyone is happy. This is the situation of the so-called noble gases, such as helium or argon, which you find over on the right-hand side of the periodic table. They don’t combine with other atoms because they are more or less content with the status quo.

Sometimes, electrons will feel most comfortable when they are orbiting two nuclei, so the nuclei effectively share their charges in a covalent bond. This is how atoms of hydrogen and oxygen combine to form water molecules. But the molecule they form is lopsided, with two smallish hydrogen atoms glomming on to one side of a larger oxygen atom. That odd shape distributes negative and positive charges unevenly over the molecule’s surface and confuses hydrogen atoms, which often get attracted to the oxygen atoms in neighboring molecules. That attraction explains why water molecules can stick together in droplets, exploiting these weak hydrogen bonds.

In our region, gravity may have been helped by a nearby supernova explosion that shook things up and started the contraction of a huge cloud of gas and dust about 4.567 billion years ago. The supernova left its calling card in distinctive radioactive materials that show up in meteorites within our solar system.

The outer regions of the young solar system, like most of the universe, consisted mainly of the primordial elements, hydrogen and helium. But the inner regions, where the rocky planets—Mercury, Venus, Earth, and Mars—would form, lost so much hydrogen and helium that they had a rare chemical diversity. Oxygen, silicon, aluminum, and iron make up over 80 percent of Earth’s crust, with elements such as calcium, carbon, and phosphorus playing lesser roles. On Earth, hydrogen plays only a medium-size role, and helium is hardly ever sighted.

In 2014, it was found that the Local Supercluster is part of a vast cosmic empire with perhaps a hundred thousand galaxies, and to cross that would take you four hundred million years traveling at the speed of light.

This empire is the Laniakea (Hawaiian for “immeasurable heaven”) Supercluster. At present, this is the largest structured entity we know of in the universe. We assume that Laniakea is built around a scaffolding of dark matter whose gravitational pull holds all these galaxies together as the universe expands.

In atoms with large nuclei, such as uranium, the repulsive power of lots of positively charged protons can destabilize the nucleus until, eventually, it breaks down spontaneously, emitting high-energy electrons or photons or even whole helium nuclei. As chunks of the nucleus are ejected, the element is transformed into different elements with fewer protons. For example, uranium eventually breaks down to lead. In the first decade of the twentieth century, Ernest Rutherford realized that, even if you could not tell when a particular nucleus was about to break apart, radioactive breakdown was a very regular process when averaged over billions of particles.

Every isotope of the same element (isotopes have the same number of protons but different numbers of neutrons) breaks down at different but regular rates, so it is possible to determine precisely how long it will take for half of the atoms in a given isotope to decay.

Something inside each cell seems to drive it, as if it were working its way through a to-do list. The to-do list is simple: (1) stay alive despite entropy and unpredictable surroundings; and (2) make copies of myself that can do the same thing. And so on from cell to cell, and generation to generation. Here, in the seeking out of some outcomes and the avoidance of others, are the origins of desire, caring, purpose, ethics, even love.

Energy causes change, so you can usually see it at work, but information directs change, often from the shadows. As Seth Lloyd puts it: “To do anything requires energy. To specify what is done requires information.”3

All forms of life require mechanisms to interpret local information (such as the presence of different chemicals or local temperatures and acidity levels) so they can respond appropriately (Should I hug it or eat it or run?).

Entropy, of course, keeps a beady eye on all of this. If more complexity means more information, then when you increase complexity and information, you are reducing entropy and its accompanying uncertainty or disorder. And entropy will notice. Entropy is rubbing its hands at the thought of the energy taxes and fees it can levy as complexity and information increase.

Most modern definitions of life on Earth would include the following five features: 1. Living organisms consist of cells enclosed by semipermeable membranes. 2. They have a metabolism, mechanisms that tap and use flows of free energy from their surroundings so they can rearrange atoms and molecules into the complex and dynamic structures they need to survive. 3. They can adjust to changing environments by homeostasis, using information about their internal and external environments and mechanisms that allow them to react. 4. They can reproduce by using genetic information to make almost exact copies of themselves. 5. But the copies differ in minute ways from the parents, so, over many generations, the features of living organisms slowly change as they evolve and adapt to changing environments.

Living organisms must constantly monitor and adjust to changes in their environments. This constant adjustment is known as preserving homeostasis. To maintain some sort of equilibrium in changing surroundings, cells must continually access, download, and decode information about their internal and external environments, decide on the best response, and then respond. The word homeostasis means “standing still,” which is the opposite of “change.” But it makes sense if you think of standing still in the never-ending molecular hurricane of the cell’s environment.

Though the templates are more or less immortal, the copying process is not perfect. This is good news, because it means the templates can slowly change as a result of tiny copying errors, and that is the key to adaptation and evolution. Tiny genetic changes give life its remarkable resilience because they allow species to adapt to their environments by randomly creating slightly different templates.

Natural selection filters out some genetic possibilities, allowing only those compatible with local rules. So natural selection is a ratchet, like the fundamental laws of physics, because it locks nonrandom patterns in place.

As soon as the young Earth congealed, its diverse slurry of chemicals generated lumps of rock, solids consisting of many different simple molecules jumbled together. Earth’s first minerals also appeared, probably in the form of simple crystals such as graphite or diamonds.14

Luca already contained a lot of neat biochemical gadgets, including many of the recipes for the metabolic and reproductive machinery of modern cells. It probably had a genome based on RNA so it could reproduce much more accurately and precisely than mere chemicals, and that suggests it may have been evolving fast. It was also using the energy flows it tapped to make adenosine triphosphate, the same molecule that transports energy inside modern cells.

Once the enzyme has knocked its target molecule into shape, it breaks away and goes hunting for other molecules that it can bend to its will. Enzymes can also be switched on or off by other molecules that bind to them and slightly alter their shape, and this is how, like billions of transistors in a computer, enzymes govern the fantastically complex reactions that go on inside cells.

With membranes of their own, an independent metabolism, and more precise and stable genetic machinery, the first prokaryotes could leave the volcanic vents in which they had been born and cruise the oceans of the early Earth. They were probably already doing this 3.8 billion years ago.

In the 1970s, James Lovelock and Lynn Margulis showed that the biosphere can be thought of as a system with many feedback mechanisms that allow it to stabilize itself in the absence of major shocks. Lovelock called this vast, self-regulating system Gaia, after the Greek goddess of the Earth.

We now have abundant evidence that Earth’s crust, both oceanic and continental, is broken into distinct plates that jostle for position as they are dragged back and forth by the semimolten magma on which they float. Hot magmas rising from deep within the Earth circulate under the crust, like water boiling in a saucepan. It is these convection currents of semiliquid rock and lava that move the tectonic plates floating above them.

The answer, it turned out, was the amount of greenhouse gases in the early atmosphere. Their levels were high enough to warm the young Earth so that life could evolve. There was hardly any free oxygen in Earth’s first atmosphere, but there were lots of greenhouse gases, particularly water vapor, methane, and carbon dioxide, belched up from the mantle through volcanoes or ferried in by asteroids.

Here’s how the geological thermostat works. Carbon dioxide, one of the most powerful of the greenhouse gases, dissolves in rainfall and reaches the Earth in the form of carbonic acid. It dissolves material in rocks, and the by-products of these reactions, which contain lots of carbon, are swept into the ocean. Here, some of the carbon gets locked up in carbonate rocks. Where tectonic plates dive back into the mantle at subduction zones, some of this carbon (much of it in the form of limestone) can get buried in the mantle for millions, even billions of years. In this way, the tectonic conveyor belt removes carbon from the atmosphere, and that should eventually reduce carbon dioxide levels and generate colder climates. Today we know that much more carbon is buried within the mantle than is present on Earth’s surface or in its atmosphere.

Of course, if too much carbon dioxide was buried in this way, Earth would freeze. That was prevented (most of the time) by the second feature of the geological thermostat. Driven by plate tectonics (a mechanism that is probably not working on icy Mars), carbon dioxide can return to the atmosphere at divergent zones, where material from the mantle, including buried carbon dioxide, rises to the surface through volcanoes.6 There is a balance between the two halves of this mechanism because higher temperatures generate more rainfall, which accelerates erosion, moving more carbon back into the mantle. But if the Earth cools too much, rainfall will dwindle, less carbon dioxide will be buried, carbon dioxide levels will build up as it is pumped up through volcanoes, and that will warm things up again. The geological thermostat has been adjusting to the increasing warmth of our sun over four billion years.

Eventually, new forms of photosynthesis evolved in a group of organisms known as cyanobacteria. These forms of photosynthesis could extract more energy by using water and carbon dioxide as their primary raw materials. Prying electrons loose from water molecules was tougher than capturing them from hydrogen sulfide or iron. But if you could do it, you got more energy, and of course in water, you had a much more abundant source of energy. Using the energy captured from sunlight, these sophisticated photosynthesizers zapped water molecules and stripped electrons from their hydrogen atoms. Then they added the captured electrons to carbon dioxide molecules to form carbohydrate molecules, which acted as huge energy barns. The oxygen from broken water molecules was released as waste. The general formula for this oxygen-generating form of photosynthesis is H2O + CO2 + energy from sunlight → CH2O (carbohydrates that act as stores of energy) + O2 (molecules of oxygen that are released into the atmosphere).

But at first, any oxygen they released would have been quickly absorbed by iron or hydrogen sulfide or free hydrogen atoms, because oxygen is an electron thief and will combine eagerly with any element that has spare electrons. That is why atoms that have had their electrons stolen are said to have been oxidized. (Atoms with spare electrons are said to be reduced, and the many chemical reactions that involve both processes are known as redox reactions.) Powerful evidence for the evolution of the first cyanobacteria is the disappearance from three billion years ago of sedimentary rocks rich in pyrite (fool’s gold), which, like iron, rusts in the presence of free oxygen. But there was a limit to how much oxygen these mechanisms could absorb, and starting about 2.4 billion years ago, levels of atmospheric oxygen began to rise fast, from less than 0.001 percent of today’s levels to perhaps 1 percent or more.

High up in the atmosphere, oxygen atoms combined to form three-atom molecules of ozone, O3, that began to shield Earth’s surface from dangerous solar ultraviolet radiation and have continued to do so ever since. Protected by the ozone layer, some algae may have started colonizing the land for the first time. Until then, bathed in solar radiation that would have ripped apart any bacteria brave enough to venture onto land, the continents of planet Earth had been more or less sterile.

Rising oxygen levels messed up Earth’s thermostats because as yet there were no mechanisms that could absorb excess oxygen, so the buildup threatened to run out of control. Free oxygen broke down atmospheric methane, one of the most powerful of greenhouse gases, while photosynthesizing cyanobacteria consumed huge amounts of the other crucial greenhouse gas, carbon dioxide. As oxygen levels rose and levels of greenhouse gases fell, early in the Proterozoic eon, Earth froze in the first of several snowball-Earth episodes. Glaciers spread from the poles to the equator, turning the Earth white, and a white Earth reflected more sunlight, cooling it even further in a terrifying positive-feedback loop.

Respiration is the reverse of photosynthesis and is really a way of releasing solar energy that has been captured and stored within cells through photosynthesis. While photosynthesis uses energy from sunlight to turn carbon dioxide and water into energy-storing carbohydrates, leaving oxygen as a waste product, respiration uses the chemical energy of oxygen to pilfer the energy warehoused in carbohydrates, leaving carbon dioxide and water as waste products. The general formula for respiration is CH2O (carbohydrates) + O2 → CO2 + H2O + energy.

The most important evidence for endosymbiosis is the odd fact that some of the organelles inside eukaryotes contain their own DNA, and that DNA is quite different from the genetic material in the nucleus. Margulis realized that organelles such as the mitochondria that manage energy in animals and the chloroplasts that manage photosynthesis in eukaryotic plants look as if they were once independent prokaryotic cells. Exactly how they ended up inside other cells remains unclear, and some have argued that such mergers must be extremely rare. If so, that probably means that even if bacterialike organisms are common in the universe, large organisms like us may be extremely rare, because, on our planet at least, only eukaryotes can build large organisms.

Evolution is not just a matter of competition. Nor is it just a matter of constant divergence as new species appear. We also see collaboration, symbiosis, and even convergence.

It took time for this machinery to evolve, so to build metazoans, planet Earth needed one more Goldilocks condition: stability. Life-friendly conditions are not enough. You also need those conditions to persist for a long time so that life can keep evolving and experimenting. A stable sun helps here, and our sun fit the bill nicely. By stellar standards, it’s a solid citizen, unlikely to do anything too unpredictable. Erratic orbits mean wild climatic gyrations, so stable planetary orbits help. Our Earth ticks this box, too. Our unusually large moon helped stabilize Earth’s orbit and tilt. And, as we have seen, plate tectonics, erosion, and then life itself provided thermostats that stopped temperatures from wobbling too much at the Earth’s surface.